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Saturday, August 23, 2014

Africa

Africa

From Wikipedia, the free encyclopedia

Africa
Africa (orthographic projection).svg
Area 30,221,532 km2 (11,668,599 sq mi)2nd
Population 1.1 billion[1] (2013, 2nd)
Pop. density 30.51/km2 (about 80/sq mi)
Demonym African
Countries 54 (and 2 disputed) (list of countries)
Dependencies
Languages List of languages
Time zones UTC-1 to UTC+4
Largest cities List of metropolitan areas in Africa
List of cities in Africa
Nigeria Lagos
Egypt Cairo
Democratic Republic of the CongoRepublic of the Congo Kinshasa-Brazzaville
South Africa Greater Johannesburg
Somalia Mogadishu
Sudan Khartoum-Omdurman
Tanzania Dar es Salaam
Egypt Alexandria
Ivory Coast Abidjan
Morocco Casablanca

Map of Africa

Africa is the world's second-largest and second-most-populous continent. At about 30.2 million km² (11.7 million sq mi) including adjacent islands, it covers six percent of the Earth's total surface area and 20.4 percent of the total land area.[2] With 1.1 billion people as of 2013, it accounts for about 15% of the world's human population.[3] The continent is surrounded by the Mediterranean Sea to the north, both the Suez Canal and the Red Sea along the Sinai Peninsula to the northeast, the Indian Ocean to the southeast, and the Atlantic Ocean to the west. The continent includes Madagascar and various archipelagoes. It has 54 fully recognized sovereign states ("countries"), nine territories and two de facto independent states with limited or no recognition.[4]

Africa's population is the youngest among all the continents; 50% of Africans are 19 years old or younger.[5]

Algeria is Africa's largest country by area, and Nigeria is the largest by population. Africa, particularly central Eastern Africa, is widely accepted as the place of origin of humans and the Hominidae clade (great apes), as evidenced by the discovery of the earliest hominids and their ancestors, as well as later ones that have been dated to around seven million years ago, including Sahelanthropus tchadensis, Australopithecus africanus, A. afarensis, Homo erectus, H. habilis and H. ergaster – with the earliest Homo sapiens (modern human) found in Ethiopia being dated to circa 200,000 years ago.[6] Africa straddles the equator and encompasses numerous climate areas; it is the only continent to stretch from the northern temperate to southern temperate zones.[7]

Etymology

Afri was a Latin name used to refer to the Carthaginians, who dwelt in North Africa in modern-day Tunisia. This name seems to have originally referred to a native Libyan tribe; however, see Terence#Biography for discussion. The name is usually connected with Phoenician afar, "dust", but a 1981 hypothesis[8] has asserted that it stems from the Berber ifri (plural ifran) "cave", in reference to cave dwellers.[9] The same word[9] may be found in the name of the Banu Ifran from Algeria and Tripolitania, a Berber tribe originally from Yafran (also known as Ifrane) in northwestern Libya.[10]
Under Roman rule, Carthage became the capital of Africa Province, which also included the coastal part of modern Libya.[11] The Latin suffix "-ica" can sometimes be used to denote a land (e.g., in Celtica from Celtae, as used by Julius Caesar). The later Muslim kingdom of Ifriqiya, modern-day Tunisia, also preserved a form of the name.

According to the ancient Romans, Africa lay to the west of Egypt, while "Asia" was used to refer to Anatolia and lands to the east. A definite line was drawn between the two continents by the geographer Ptolemy (85–165 AD), indicating Alexandria along the Prime Meridian and making the isthmus of Suez and the Red Sea the boundary between Asia and Africa. As Europeans came to understand the real extent of the continent, the idea of Africa expanded with their knowledge.

Other etymological hypotheses have been postulated for the ancient name "Africa":
  • The 1st-century Jewish historian Flavius Josephus (Ant. 1.15) asserted that it was named for Epher, grandson of Abraham according to Gen. 25:4, whose descendants, he claimed, had invaded Libya.
  • Isidore of Seville in Etymologiae XIV.5.2. suggests the Latin aprica "sunny".
  • Leo Africanus (1488–1554) proposed the Greek aphrike (Αφρική), "without cold". Africanus suggested that the Greek phrike (φρίκη, "cold and horror"), combined with the privative prefix "a-", indicated a land free of cold and horror.[12]
  • Massey, in 1881, states that Africa is derived from the Egyptian af-rui-ka, "to turn toward the opening of the Ka." The Ka is the energetic double of every person and "opening of the Ka" refers to a womb or birthplace. Africa would be, for the Egyptians, "the birthplace."[13]
  • Yet another hypothesis was proposed by Michèle Fruyt,[14] linking the Latin word with africus "south wind", which would be of Umbrian origin and mean originally "rainy wind".
  • Africa's name is derived from an ancient area in modern day Tunisia known as Ifriqiya or sunny place, in Tamazight.[citation needed]

History

Prehistory


Lucy, an Australopithecus afarensis skeleton discovered on November 24, 1974, in the Awash Valley of Ethiopia's Afar Depression

Africa is considered by most paleoanthropologists to be the oldest inhabited territory on Earth, with the human species originating from the continent.[15][16] During the middle of the 20th century, anthropologists discovered many fossils and evidence of human occupation perhaps as early as 7 million years ago. Fossil remains of several species of early apelike humans thought to have evolved into modern man, such as Australopithecus afarensis (radiometrically dated to approximately 3.9–3.0 million years BC),[17] Paranthropus boisei (c. 2.3–1.4 million years BC)[18] and Homo ergaster (c. 1.9 million–600,000 years BC) have been discovered.[2]

After the evolution of homo sapiens sapiens approximately 150,000 to 100,000 years ago in Africa, the continent was mainly populated by groups of hunter-gatherers.[19][20][21] These first modern humans left Africa and populated the rest of the globe during the Out of Africa migration dated to approximately 50,000 years ago, exiting the continent either across Bab-el-Mandeb over the Red Sea,.[22][23] the Strait of Gibraltar in Morocco,[24] or the Isthmus of Suez in Egypt.[25]

Other migrations of these modern humans within the African continent have been dated to that time, with evidence of early human settlement found in Southern Africa, Southeast Africa, North Africa and the Sahara.[26]

The size of the Sahara has historically been extremely variable, with its area rapidly fluctuating and at times disappearing depending on global climactic conditions.[27] At the end of the Ice ages, estimated to have been around 10,500 BC, the Sahara had again become a green fertile valley, and its African populations returned from the interior and coastal highlands in Sub-Saharan Africa, with rock art paintings depicting a fertile Sahara and large populations discovered in Tassili n'Ajjer dating back perhaps 10 millennia.[28] However, the warming and drying climate meant that by 5000 BC, the Sahara region was becoming increasingly dry and hostile. Around 3500 B.C., due to a tilt in the earth's orbit, the Sahara experienced a period of rapid desertification.[29] The population trekked out of the Sahara region towards the Nile Valley below the Second Cataract where they made permanent or semi-permanent settlements. A major climatic recession occurred, lessening the heavy and persistent rains in Central and Eastern Africa. Since this time, dry conditions have prevailed in Eastern Africa and, increasingly during the last 200 years, in Ethiopia.

The domestication of cattle in Africa preceded agriculture and seems to have existed alongside hunter-gatherer cultures. It is speculated that by 6000 BC, cattle were already domesticated in North Africa.[30] In the Sahara-Nile complex, people domesticated many animals, including the donkey and a small screw-horned goat which was common from Algeria to Nubia. In the year 4000 BC, the climate of the Sahara started to become drier at an exceedingly fast pace.[31] This climate change caused lakes and rivers to shrink significantly and caused increasing desertification. This, in turn, decreased the amount of land conducive to settlements and helped to cause migrations of farming communities to the more tropical climate of West Africa.[31]

By the first millennium BC, ironworking had been introduced in Northern Africa and quickly spread across the Sahara into the northern parts of sub-Saharan Africa,[32] and by 500 BC, metalworking began to become commonplace in West Africa. Ironworking was fully established by roughly 500 BC in many areas of East and West Africa, although other regions didn't begin ironworking until the early centuries AD. Copper objects from Egypt, North Africa, Nubia and Ethiopia dating from around 500 BC have been excavated in West Africa, suggesting that Trans-Saharan trade networks had been established by this date.[31]

Early civilizations


Colossal statues of Ramesses II at Abu Simbel, Egypt, date from around 1400 BC.

The origins and spread of the Bantu languages c. 1000 BC to c. 500 AD.

At about 3300 BC, the historical record opens in Northern Africa with the rise of literacy in the Pharaonic civilization of Ancient Egypt.[33] One of the world's earliest and longest-lasting civilizations, the Egyptian state continued, with varying levels of influence over other areas, until 343 BC.[34][35] Egyptian influence reached deep into modern-day Libya, north to Crete[36] and Canaan,[citation needed] and south to the kingdoms of Aksum[citation needed] and Nubia.[citation needed]

An independent center of civilization with trading links to Phoenicia was established by Phoenicians from Tyre on the north-west African coast at Carthage.[37][38][39]

European exploration of Africa began with Ancient Greeks and Romans. In 332 BC, Alexander the Great was welcomed as a liberator in Persian-occupied Egypt. He founded Alexandria in Egypt, which would become the prosperous capital of the Ptolemaic dynasty after his death.[40]

Following the conquest of North Africa's Mediterranean coastline by the Roman Empire, the area was integrated economically and culturally into the Roman system. Roman settlement occurred in modern Tunisia and elsewhere along the coast. The first Roman emperor native to North Africa was Septimius Severus, born in Leptis Magna in present-day Libya—his mother was of Italian Roman extract and his father was Punic, a genetic mix of the Phoenicians and Berber.[41]

Christianity spread across these areas at an early date, from Judaea via Egypt and beyond the borders of the Roman world into Nubia;[42] by AD 340 at the latest, it had become the state religion of the Aksumite Empire. Syro-Greek missionaries, who arrived by way of the Red Sea, were responsible for this theological development.[43]

In the early 7th century, the newly formed Arabian Islamic Caliphate expanded into Egypt, and then into North Africa. In a short while, the local Berber elite had been integrated into Muslim Arab tribes. When the Umayyad capital Damascus fell in the 8th century, the Islamic center of the Mediterranean shifted from Syria to Qayrawan in North Africa. Islamic North Africa had become diverse, and a hub for mystics, scholars, jurists and philosophers. During the above-mentioned period, Islam spread to sub-Saharan Africa, mainly through trade routes and migration.[44]

9th to 18th centuries


African horseman of Baguirmi in full padded armour suit

9th-century bronzes from the Igbo town of Igbo-Ukwu, now at the British Museum[45]

Pre-colonial Africa possessed perhaps as many as 10,000 different states and polities[46] characterized by many different sorts of political organization and rule. These included small family groups of hunter-gatherers such as the San people of southern Africa; larger, more structured groups such as the family clan groupings of the Bantu-speaking people of central and southern Africa; heavily structured clan groups in the Horn of Africa; the large Sahelian kingdoms; and autonomous city-states and kingdoms such as those of the Akan; Edo people, Yoruba and Igbo people (also misspelled as Ibo) in West Africa; and the Swahili coastal trading towns of Southeast Africa.

By the 9th century, a string of dynastic states, including the earliest Hausa states, stretched across the sub-saharan savannah from the western regions to central Sudan. The most powerful of these states were Ghana, Gao, and the Kanem-Bornu Empire. Ghana declined in the 11th century, but was succeeded by the Mali Empire which consolidated much of western Sudan in the 13th century. Kanem accepted Islam in the 11th century.

In the forested regions of the West African coast, independent kingdoms grew up with little influence from the Muslim north. The Kingdom of Nri of the Igbo was established around the 9th century and was one of the first. It is also one of the oldest kingdoms in modern day Nigeria and was ruled by the Eze Nri. The Nri kingdom is famous for its elaborate bronzes, found at the town of Igbo-Ukwu. The bronzes have been dated from as far back as the 9th century.[47]

Ashanti yam ceremony, 19th century by Thomas E. Bowdich

The Ife, historically the first of these Yoruba city-states or kingdoms, established government under a priestly oba ('king' or 'ruler' in the Yoruba language), called the Ooni of Ife. Ife was noted as a major religious and cultural center in Africa, and for its unique naturalistic tradition of bronze sculpture. The Ife model of government was adapted at Oyo, where its obas or kings, called the Alaafins of Oyo, once controlled a large number of other Yoruba and non-Yoruba city-states and kingdoms; the Fon Kingdom of Dahomey was one of the non-Yoruba domains under Oyo control.

The Almoravids were a Berber dynasty from the Sahara that spread over a wide area of northwestern Africa and the Iberian peninsula during the 11th century.[48] The Banu Hilal and Banu Ma'qil were a collection of Arab Bedouin tribes from the Arabian Peninsula who migrated westwards via Egypt between the 11th and 13th centuries. Their migration resulted in the fusion of the Arabs and Berbers, where the locals were Arabized,[49] and Arab culture absorbed elements of the local culture, under the unifying framework of Islam.[50]

Ruins of Great Zimbabwe (11th to 15th centuries)

Following the breakup of Mali, a local leader named Sonni Ali (1464–1492) founded the Songhai Empire in the region of middle Niger and the western Sudan and took control of the trans-Saharan trade. Sonni Ali seized Timbuktu in 1468 and Jenne in 1473, building his regime on trade revenues and the cooperation of Muslim merchants. His successor Askia Mohammad I (1493–1528) made Islam the official religion, built mosques, and brought to Gao Muslim scholars, including al-Maghili (d.1504), the founder of an important tradition of Sudanic African Muslim scholarship.[51] By the 11th century, some Hausa states – such as Kano, jigawa, Katsina, and Gobir – had developed into walled towns engaging in trade, servicing caravans, and the manufacture of goods. Until the 15th century, these small states were on the periphery of the major Sudanic empires of the era, paying tribute to Songhai to the west and Kanem-Borno to the east.

Height of slave trade


Arab–Swahili slave traders and their captives along the Ruvuma River (in today's Tanzania and Mozambique) as witnessed by David Livingstone.

Slavery had long been practiced in Africa.[52][53] Between the 7th and 20th centuries, Arab slave trade (also known as slavery in the East) took 18 million slaves from Africa via trans-Saharan and Indian Ocean routes. Between the 15th and the 19th centuries (500 years), the Atlantic slave trade took an estimated 7–12 million slaves to the New World.[54][55][56] More than 1 million Europeans were captured by Barbary pirates and sold as slaves in North Africa between the 16th and 19th centuries.[57]

In West Africa, the decline of the Atlantic slave trade in the 1820s caused dramatic economic shifts in local polities. The gradual decline of slave-trading, prompted by a lack of demand for slaves in the New World, increasing anti-slavery legislation in Europe and America, and the British Royal Navy's increasing presence off the West African coast, obliged African states to adopt new economies. Between 1808 and 1860, the British West Africa Squadron seized approximately 1,600 slave ships and freed 150,000 Africans who were aboard.[58]

A slave being inspected, from Captain Canot; or, Twenty Years of an African Slaver.

Action was also taken against African leaders who refused to agree to British treaties to outlaw the trade, for example against "the usurping King of Lagos", deposed in 1851. Anti-slavery treaties were signed with over 50 African rulers.[59] The largest powers of West Africa (the Asante Confederacy, the Kingdom of Dahomey, and the Oyo Empire) adopted different ways of adapting to the shift. Asante and Dahomey concentrated on the development of "legitimate commerce" in the form of palm oil, cocoa, timber and gold, forming the bedrock of West Africa's modern export trade. The Oyo Empire, unable to adapt, collapsed into civil wars.[60]

Colonialism and the "Scramble for Africa"


The Mahdist War was a colonial war fought between the Mahdist Sudanese and the British forces

Areas of Africa under the sovereignty or influence of the colonial powers in 1913, along with modern borders.
  Belgium
  Germany
  Spain
  France
  United Kingdom
  Italy
  Portugal
  independent

In the late 19th century, the European imperial powers engaged in a major territorial scramble and occupied most of the continent, creating many colonial territories, and leaving only two fully independent states: Ethiopia (known to Europeans as "Abyssinia"), and Liberia. Egypt and Sudan were never formally incorporated into any European colonial empire; however, after the British occupation of 1882, Egypt was effectively under British administration until 1922.

Berlin Conference

The Berlin Conference held in 1884–85 was an important event in the political future of African ethnic groups. It was convened by King Leopold II of Belgium, and attended by the European powers that laid claim to African territories. It sought to bring an end to the Scramble for Africa by European powers by agreeing on political division and spheres of influence. They set up the political divisions of the continent, by spheres of interest, that exist in Africa today.

Independence struggles

Imperial rule by Europeans would continue until after the conclusion of World War II, when almost all remaining colonial territories gradually obtained formal independence. Independence movements in Africa gained momentum following World War II, which left the major European powers weakened. In 1951, Libya, a former Italian colony, gained independence. In 1956, Tunisia and Morocco won their independence from France.[61] Ghana followed suit the next year (March 1957),[62] becoming the first of the sub-Saharan colonies to be freed. Most of the rest of the continent became independent over the next decade.

Portugal's overseas presence in Sub-Saharan Africa (most notably in Angola, Cape Verde, Mozambique, Guinea-Bissau and São Tomé and Príncipe) lasted from the 16th century to 1975, after the Estado Novo regime was overthrown in a military coup in Lisbon. Rhodesia unilaterally declared independence from the United Kingdom in 1965, under the white minority government of Ian Smith, but was not internationally recognized as an independent state (as Zimbabwe) until 1980, when black nationalists gained power after a bitter guerrilla war. Although South Africa was one of the first African countries to gain independence, the state remained under the control of the country's white minority through a system of racial segregation known as apartheid until 1994.

Post-colonial Africa

Today, Africa contains 54 sovereign countries, most of which have borders that were drawn during the era of European colonialism. Since colonialism, African states have frequently been hampered by instability, corruption, violence, and authoritarianism. The vast majority of African states are republics that operate under some form of the presidential system of rule. However, few of them have been able to sustain democratic governments on a permanent basis, and many have instead cycled through a series of coups, producing military dictatorships.

Mobutu Sese Seko, Zaire's longtime dictator, embezzled over $5 billion from his country.

Great instability was mainly the result of marginalization of ethnic groups, and graft under these leaders. For political gain, many leaders fanned ethnic conflicts, some of which had been exacerbated, or even created, by colonial rule. In many countries, the military was perceived as being the only group that could effectively maintain order, and it ruled many nations in Africa during the 1970s and early 1980s. During the period from the early 1960s to the late 1980s, Africa had more than 70 coups and 13 presidential assassinations. Border and territorial disputes were also common, with the European-imposed borders of many nations being widely contested through armed conflicts.

Cold War conflicts between the United States and the Soviet Union, as well as the policies of the International Monetary Fund,[citation needed] also played a role in instability. When a country became independent for the first time, it was often expected to align with one of the two superpowers. Many countries in Northern Africa received Soviet military aid, while many in Central and Southern Africa were supported by the United States, France or both. The 1970s saw an escalation, as newly independent Angola and Mozambique aligned themselves with the Soviet Union, and the West and South Africa sought to contain Soviet influence by funding insurgency movements. There was a major famine in Ethiopia, when hundreds of thousands of people starved. Some claimed that Marxist/Soviet policies made the situation worse.[63][64][65] The most devastating military conflict in modern independent Africa has been the Second Congo War; this conflict and its aftermath has killed an estimated 5.5 million people.[66] Since 2003 there has been an ongoing conflict in Darfur which has become a humanitarian disaster. Another notable tragic event is the 1994 Rwandan Genocide in which an estimated 800 000 people were murdered. AIDS in post-colonial Africa has also been a prevalent issue.

In the 21st century, however, the number of armed conflicts in Africa has steadily declined. For instance, the civil war in Angola came to an end in 2002 after nearly 30 years. This has coincided with many countries abandoning communist style command economies and opening up for market reforms. The improved stability and economic reforms have led to a great increase in foreign investment into many African nations, mainly from China,[67] which has spurred quick economic growth in many countries, seemingly ending decades of stagnation and decline. Several African economies are among the world's fastest growing as of 2011. A significant part of this growth can also be attributed to the facilitated diffusion of information technologies and specifically the mobile telephone.[68]

Geography


Satellite imagery of Africa. The Sahara Desert in the north can be clearly distinguished.

A composite satellite image of Africa (center) with North America (left) and Eurasia (right), to scale

Africa is the largest of the three great southward projections from the largest landmass of the Earth. Separated from Europe by the Mediterranean Sea, it is joined to Asia at its northeast extremity by the Isthmus of Suez (transected by the Suez Canal), 163 km (101 mi) wide.[69] (Geopolitically, Egypt's Sinai Peninsula east of the Suez Canal is often considered part of Africa, as well.)[70]

From the most northerly point, Ras ben Sakka in Tunisia (37°21' N), to the most southerly point, Cape Agulhas in South Africa (34°51'15" S), is a distance of approximately 8,000 km (5,000 mi);[71] from Cape Verde, 17°33'22" W, the westernmost point, to Ras Hafun in Somalia, 51°27'52" E, the most easterly projection, is a distance of approximately 7,400 km (4,600 mi).[72] The coastline is 26,000 km (16,000 mi) long, and the absence of deep indentations of the shore is illustrated by the fact that Europe, which covers only 10,400,000 km2 (4,000,000 sq mi) – about a third of the surface of Africa – has a coastline of 32,000 km (20,000 mi).[72]

Africa's largest country is Algeria, and its smallest country is the Seychelles, an archipelago off the east coast.[73] The smallest nation on the continental mainland is the Gambia.

Geologically, Africa includes the Arabian Peninsula; the Zagros Mountains of Iran and the Anatolian Plateau of Turkey mark where the African Plate collided with Eurasia. The Afrotropic ecozone and the Saharo-Arabian desert to its north unite the region biogeographically, and the Afro-Asiatic language family unites the north linguistically.

Climate


Biomes of Africa.

The climate of Africa ranges from tropical to subarctic on its highest peaks. Its northern half is primarily desert, or arid, while its central and southern areas contain both savanna plains and very dense jungle (rainforest) regions. In between, there is a convergence, where vegetation patterns such as sahel and steppe dominate. Africa is the hottest continent on earth and 60% of the entire land surface consists of drylands and deserts.[74] The record for the highest-ever recorded temperature, in Libya in 1922 (58 °C (136 °F)), was discredited in 2013.[75][76]

Fauna



Africa boasts perhaps the world's largest combination of density and "range of freedom" of wild animal populations and diversity, with wild populations of large carnivores (such as lions, hyenas, and cheetahs) and herbivores (such as buffalo, elephants, camels, and giraffes) ranging freely on primarily open non-private plains. It is also home to a variety of "jungle" animals including snakes and primates and aquatic life such as crocodiles and amphibians. In addition, Africa has the largest number of megafauna species, as it was least affected by the extinction of the Pleistocene megafauna.

Ecology and biodiversity


Tropical beach in Mauritius, Trou-aux-Biches

Deforestation is affecting Africa at twice the world rate, according to the United Nations Environment Programme (UNEP).[77] According to the University of Pennsylvania African Studies Center, 31% of Africa's pasture lands and 19% of its forests and woodlands are classified as degraded, and Africa is losing over four million hectares of forest every year, which is twice the average deforestation rate compared to the rest of the world.[74] Some sources claim that approximately 90% of the original, virgin forests in West Africa have been destroyed.[78] Over 90% of Madagascar's original forests have been destroyed since the arrival of humans 2000 years ago.[79] About 65% of Africa's agricultural land suffers from soil degradation.[80]

Africa has over 3,000 protected areas, with 198 marine protected areas, 50 biosphere reserves, and 80 wetlands reserves. Significant habitat destruction, increases in human population and poaching are reducing Africa's biological diversity. Human encroachment, civil unrest and the introduction of non-native species threatens biodiversity in Africa. This has been exacerbated by administrative problems, inadequate personnel and funding problems.[74]

Politics

There are clear signs of increased networking among African organizations and states. For example, in the civil war in the Democratic Republic of the Congo (former Zaire), rather than rich, non-African countries intervening, neighboring African countries became involved (see also Second Congo War). Since the conflict began in 1998, the estimated death toll has reached 5 million.

The African Union


Map of the African Union with suspended states highlighted in light green.

The African Union (AU) is a 54 member federation consisting of all of Africa's states except Morocco. The union was formed, with Addis Ababa, Ethiopia, as its headquarters, on 26 June 2001. The union was officially established on 9 July 2002[81] as a successor to the Organisation of African Unity (OAU). In July 2004, the African Union's Pan-African Parliament (PAP) was relocated to Midrand, in South Africa, but the African Commission on Human and Peoples' Rights remained in Addis Ababa. There is a policy in effect to decentralize the African Federation's institutions so that they are shared by all the states.

The African Union, not to be confused with the AU Commission, is formed by the Constitutive Act of the African Union, which aims to transform the African Economic Community, a federated commonwealth, into a state under established international conventions. The African Union has a parliamentary government, known as the African Union Government, consisting of legislative, judicial and executive organs. It is led by the African Union President and Head of State, who is also the President of the Pan-African Parliament. A person becomes AU President by being elected to the PAP, and subsequently gaining majority support in the PAP. The powers and authority of the President of the African Parliament derive from the Constitutive Act and the Protocol of the Pan-African Parliament, as well as the inheritance of presidential authority stipulated by African treaties and by international treaties, including those subordinating the Secretary General of the OAU Secretariat (AU Commission) to the PAP. The government of the AU consists of all-union (federal), regional, state, and municipal authorities, as well as hundreds of institutions, that together manage the day-to-day affairs of the institution.

Political associations such as the African Union offer hope for greater co-operation and peace between the continent's many countries. Extensive human rights abuses still occur in several parts of Africa, often under the oversight of the state. Most of such violations occur for political reasons, often as a side effect of civil war. Countries where major human rights violations have been reported in recent times include the Democratic Republic of the Congo, Sierra Leone, Liberia, Sudan, Zimbabwe, and Côte d'Ivoire. 

Economy


Map of the African Economic Community.
  CEN-SAD
  COMESA
  EAC
  ECCAS
  ECOWAS
  IGAD
  SADC
  UMA

Satellite image of city lights in Africa showing the lack of modern development on the continent (1994-1995).

Although it has abundant natural resources, Africa remains the world's poorest and most underdeveloped continent, the result of a variety of causes that may include corrupt governments that have often committed serious human rights violations, failed central planning, high levels of illiteracy, lack of access to foreign capital, and frequent tribal and military conflict (ranging from guerrilla warfare to genocide).[82] According to the United Nations' Human Development Report in 2003, the bottom 25 ranked nations (151st to 175th) were all African.[83]

Poverty, illiteracy, malnutrition and inadequate water supply and sanitation, as well as poor health, affect a large proportion of the people who reside in the African continent. In August 2008, the World Bank[84] announced revised global poverty estimates based on a new international poverty line of $1.25 per day (versus the previous measure of $1.00). 80.5% of the Sub-Saharan Africa population was living on less than $2.50 (PPP) a day in 2005, compared with 85.7% for India.[85]

The new figures confirm that sub-Saharan Africa has been the least successful region of the world in reducing poverty ($1.25 per day); some 50% of the population living in poverty in 1981 (200 million people), a figure that rose to 58% in 1996 before dropping to 50% in 2005 (380 million people). The average poor person in sub-Saharan Africa is estimated to live on only 70 cents per day, and was poorer in 2003 than he or she was in 1973 [86] indicating increasing poverty in some areas. Some of it is attributed to unsuccessful economic liberalization programs spearheaded by foreign companies and governments, but other studies and reports have cited bad domestic government policies more than external factors.[87][88][89]

From 1995 to 2005, Africa's rate of economic growth increased, averaging 5% in 2005. Some countries experienced still higher growth rates, notably Angola, Sudan and Equatorial Guinea, all three of which had recently begun extracting their petroleum reserves or had expanded their oil extraction capacity. The continent is believed to hold 90% of the world's cobalt, 90% of its platinum, 50% of its gold, 98% of its chromium, 70% of its tantalite,[90] 64% of its manganese and one-third of its uranium.[91] The Democratic Republic of the Congo (DRC) has 70% of the world's coltan, a mineral used in the production of tantalum capacitors for electronic devices such as cell phones. The DRC also has more than 30% of the world's diamond reserves.[92] Guinea is the world's largest exporter of bauxite.[93] As the growth in Africa has been driven mainly by services and not manufacturing or agriculture, it has been growth without jobs and without reduction in poverty levels. In fact, the food security crisis of 2008 which took place on the heels of the global financial crisis has pushed back 100 million people into food insecurity.[94]

In recent years, the People's Republic of China has built increasingly stronger ties with African nations. In 2007, Chinese companies invested a total of US$1 billion in Africa.[67]

A Harvard University study led by professor Calestous Juma showed that Africa could feed itself by making the transition from importer to self-sufficiency. "African agriculture is at the crossroads," says Dr. Juma. Juma also states, "We have come to the end of a century of policies that favored Africa's export of raw materials and importation of food. Africa is starting to focus on agricultural innovation as its new engine for regional trade and prosperity." [95]

During the President of the United States Barack Obama's visit to Africa in July 2013, he announced a US$7 billion plan to further develop infrastructure and work more intensively with African heads of state. A new program named Trade Africa, designed to boost trade within the continent as well as between Africa and the U.S., was also unveiled by Obama.[96]

Demographics


Woman from Benin

Africa's population has rapidly increased over the last 40 years, and consequently, it is relatively young. In some African states, half or more of the population is under 25 years of age.[97] The total number of people in Africa increased from 221 million in 1950 to 1.1 billion in 2013.[98][99]

San Bushman man from Botswana

Speakers of Bantu languages (part of the Niger–Congo family) are the majority in southern, central and southeast Africa. The Bantu-speaking peoples from West Africa progressively expanded over most of Sub-Saharan Africa.[100] But there are also several Nilotic groups in South Sudan and East Africa, the mixed Swahili people on the Swahili Coast, and a few remaining indigenous Khoisan ("San" or "Bushmen") and Pygmy peoples in southern and central Africa, respectively. Bantu-speaking Africans also predominate in Gabon and Equatorial Guinea, and are found in parts of southern Cameroon. In the Kalahari Desert of Southern Africa, the distinct people known as the Bushmen (also "San", closely related to, but distinct from "Hottentots") have long been present. The San are physically distinct from other Africans and are the indigenous people of southern Africa. Pygmies are the pre-Bantu indigenous peoples of central Africa.[101]

The peoples of West Africa primarily speak Niger–Congo languages, belonging mostly, though not exclusively, to its non-Bantu branches, though some Nilo-Saharan and Afro-Asiatic speaking groups are also found. The Niger–Congo-speaking Yoruba, Igbo, Fulani, Akan and Wolof ethnic groups are the largest and most influential. In the central Sahara, Mandinka or Mande groups are most significant. Chadic-speaking groups, including the Hausa, are found in more northerly parts of the region nearest to the Sahara, and Nilo-Saharan communities, such as the Songhai, Kanuri and Zarma, are found in the eastern parts of West Africa bordering Central Africa.

Berber boys from the Atlas Mountains

The peoples of North Africa consist of three main indigenous groups: Berbers in the northwest, Egyptians in the northeast, and Nilo-Saharan-speaking peoples in the east. The Arabs who arrived in the 7th century introduced the Arabic language and Islam to North Africa. The Semitic Phoenicians (who founded Carthage) and Hyksos, the Indo-Iranian Alans, the Indo- European Greeks, Romans, and Vandals settled in North Africa as well. Significant Berber communities remain within Morocco and Algeria in the 21st century, while, to a lesser extent, Berber speakers are also present in some regions of Tunisia and Libya.[102] The Berber-speaking Tuareg and other often-nomadic peoples are the principal inhabitants of the Saharan interior of North Africa. In Mauritania, there is a small but near-extinct Berber community in the north and Niger–Congo-speaking peoples in the south, though in both regions Arabic and Arab culture predominates. In Sudan, although Arabic and Arab culture predominate, it is mostly inhabited by groups that originally spoke Nilo-Saharan, such as the Nubians, Fur, Masalit and Zaghawa, who, over the centuries, have variously intermixed with migrants from the Arabian peninsula. Small communities of Afro-Asiatic-speaking Beja nomads can also be found in Egypt and Sudan.[citation needed]

Beja bedouins from Northeast Africa

In the Horn of Africa, some Ethiopian and Eritrean groups (like the Amhara and Tigrayans, collectively known as Habesha) speak languages from the Semitic branch of the Afro-Asiatic language family, while the Oromo and Somali speak languages from the Cushitic branch of Afro-Asiatic.

White and South Asian children in Durban, South Africa

Prior to the decolonization movements of the post-World War II era, Europeans were represented in every part of Africa.[103] Decolonization during the 1960s and 1970s often resulted in the mass emigration of European-descended settlers out of Africa – especially from Algeria and Morocco (1.6 million pieds-noirs in North Africa),[104] Kenya, Congo,[105] Rhodesia, Mozambique and Angola.[106] By the end of 1977, more than one million Portuguese whose homes were in Africa returned to Portugal.[107] Nevertheless, White Africans remain an important minority in many African states, particularly South Africa, Zimbabwe, Namibia and Réunion.[108] The African country with the largest White African population is South Africa.[109] The Afrikaners, the British diaspora and the Coloureds are the largest European-descended groups in Africa today.

European colonization also brought sizable groups of Asians, particularly people from the Indian subcontinent, to British colonies. Large Indian communities are found in South Africa, and smaller ones are present in Kenya, Tanzania, and some other southern and southeast African countries. The large Indian community in Uganda was expelled by the dictator Idi Amin in 1972, though many have since returned. The islands in the Indian Ocean are also populated primarily by people of Asian origin, often mixed with Africans and Europeans. The Malagasy people of Madagascar are an Austronesian people, but those along the coast are generally mixed with Bantu, Arab, Indian and European origins. Malay and Indian ancestries are also important components in the group of people known in South Africa as Cape Coloureds (people with origins in two or more races and continents). During the 20th century, small but economically important communities of Lebanese and Chinese[67] have also developed in the larger coastal cities of West and East Africa, respectively.[110]

Languages


Map showing the traditional language families represented in Africa:
  Afroasiatic (Semitic-Hamitic)
  Austronesian (Malay-Polynesian)
  Khoisan
Niger-Congo:
  Bantu
  Central and Eastern Sudanese
  Central Bantoid
  Eastern Bantoid
  Guinean
  Mande
  Western Bantoid
Nilo-Saharan:
  Kanuri
  Nilotic
  Songhai

By most estimates, well over a thousand languages (UNESCO has estimated around two thousand) are spoken in Africa.[111] Most are of African origin, though some are of European or Asian origin. Africa is the most multilingual continent in the world, and it is not rare for individuals to fluently speak not only multiple African languages, but one or more European ones as well. There are four major language families indigenous to Africa.
Following the end of colonialism, nearly all African countries adopted official languages that originated outside the continent, although several countries also granted legal recognition to indigenous languages (such as Swahili, Yoruba, Igbo and Hausa). In numerous countries, English and French (see African French) are used for communication in the public sphere such as government, commerce, education and the media. Arabic, Portuguese, Afrikaans and Spanish are examples of languages that trace their origin to outside of Africa, and that are used by millions of Africans today, both in the public and private spheres. Italian is spoken by some in former Italian colonies in Africa. German is spoken in Namibia, as it was a former German protectorate.

Culture


Some[which?] aspects of traditional African cultures have become less practiced in recent years as a result of years of neglect and suppression by colonial and post-colonial regimes. There is now a resurgence in the attempts to rediscover and revalue African traditional cultures, under such movements as the African Renaissance, led by Thabo Mbeki, Afrocentrism, led by a group of scholars, including Molefi Asante, as well as the increasing recognition of traditional spiritualism through decriminalization of Vodou and other forms of spirituality. In recent years, traditional African culture has become synonymous with rural poverty and subsistence farming.[citation needed]

Visual art and architecture

African art and architecture reflect the diversity of African cultures. The oldest existing examples of art from Africa are 82,000-year-old beads made from Nassarius shells that were found in the Aterian levels at Grotte des Pigeons, Taforalt, Morocco.[citation needed] The Great Pyramid of Giza in Egypt was the world's tallest structure for 4,000 years, until the completion of Lincoln Cathedral around the year 1300. The stone ruins of Great Zimbabwe are also noteworthy for their architecture, and the complexity of monolithic churches at Lalibela, Ethiopia, of which the Church of Saint George is representative.[citation needed]

A musician from South Africa

Music and dance



Egypt has long been a cultural focus of the Arab world, while remembrance of the rhythms of sub-Saharan Africa, in particular West Africa, was transmitted through the Atlantic slave trade to modern samba, blues, jazz, reggae, hip hop, and rock. The 1950s through the 1970s saw a conglomeration of these various styles with the popularization of Afrobeat and Highlife music. Modern music of the continent includes the highly complex choral singing of southern Africa and the dance rhythms of the musical genre of soukous, dominated by the music of the Democratic Republic of Congo. Indigenous musical and dance traditions of Africa are maintained by oral traditions, and they are distinct from the music and dance styles of North Africa and Southern Africa. Arab influences are visible in North African music and dance and, in Southern Africa, Western influences are apparent due to colonization.

Sports

Fifty-three African countries have football (soccer) teams in the Confederation of African Football, while Cameroon, Nigeria, Senegal, and Ghana have advanced to the knockout stage of recent FIFA World Cups. South Africa hosted the 2010 World Cup tournament, becoming the first African country to do so. According to FIFA ranking, Egypt currently has the best soccer team in Africa. Their team has won the African Cup seven times, and a record-making three times in a row.[112]
Cricket is popular in some African nations. South Africa and Zimbabwe have Test status, while Kenya is the leading non-test team in One-Day International cricket and has attained permanent One-Day International status. The three countries jointly hosted the 2003 Cricket World Cup. Namibia is the other African country to have played in a World Cup. Morocco in northern Africa has also hosted the 2002 Morocco Cup, but the national team has never qualified for a major tournament. Rugby is a popular sport in South Africa and Namibia.

Religion

Africans profess a wide variety of religious beliefs, and statistics on religious affiliation are difficult to come by since they are often a sensitive a topic for governments with mixed religious populations.[113][114] According to the World Book Encyclopedia, Islam is the largest religion in Africa, followed by Christianity. According to Encyclopædia Britannica, 45% of the population are Christians, 40% are Muslims, and 10% follow traditional religions. A small number of Africans are Hindu, Buddhist, Confucianist, Baha'i, or have beliefs from the Judaic tradition. There is also a minority of Africans who are irreligious.

The Great Mosque of Kairouan, founded in 670, is the oldest mosque in North Africa;[115] it is located in Kairouan, Tunisia

Vodun altar in Abomey, Benin

Nigeria's National Church, Abuja

A map showing religious distribution in Africa

Territories and regions

The countries in this table are categorized according to the scheme for geographic subregions used by the United Nations, and data included are per sources in cross-referenced articles. Where they differ, provisos are clearly indicated.

Physical map of Africa

Political map of Africa
Name of region[116] and
territory, with flag
Area
(km²)
Population[117] Year Density
(per km²)
Capital
Northern Africa
 Algeria 2,381,740 34,178,188 2009 14 Algiers
 Canary Islands (Spain)[118] 7,492 2,118,519 2010 226 Las Palmas de Gran Canaria,
Santa Cruz de Tenerife
 Ceuta (Spain)[119] 20 71,505 2001 3,575
 Egypt[120] 1,001,450 82,868,000 2012 83 Cairo
 Libya 1,759,540 6,310,434 2009 4 Tripoli
 Madeira (Portugal)[121] 797 245,000 2001 307 Funchal
 Melilla (Spain)[122] 12 66,411 2001 5,534
 Morocco 446,550 34,859,364 2009 78 Rabat
 Sudan 1,861,484 30,894,000 2008 17 Khartoum
 Tunisia 163,610 10,486,339 2009 64 Tunis
  Western Sahara[123] 266,000 405,210 2009 2 El Aaiún
Horn of Africa or Northeast Africa
 Djibouti 23,000 623,891 2012 22 Djibouti
 Eritrea 121,320 5,647,168 2009 47 Asmara
 Ethiopia 1,127,127 84,320,987 2012 75 Addis Ababa
 Somalia 637,657 9,832,017 2009 15 Mogadishu
Eastern Africa
 Burundi 27,830 8,988,091 2009 323 Bujumbura
 British Indian Ocean Territory - Chagos Archipelago
(United Kingdom)
56.13 3,000 2012 53.4 Diego Garcia
 Comoros 2,170 752,438 2009 347 Moroni
 Kenya 582,650 39,002,772 2009 66 Nairobi
 Madagascar 587,040 20,653,556 2009 35 Antananarivo
 Malawi 118,480 14,268,711 2009 120 Lilongwe
 Mauritius 2,040 1,284,264 2009 630 Port Louis
 Mayotte (France) 374 223,765 2009 490 Mamoudzou
 Mozambique 801,590 21,669,278 2009 27 Maputo
 Réunion (France) 2,512 743,981 2002 296 Saint-Denis
 Rwanda 26,338 10,473,282 2009 398 Kigali
 Seychelles 455 87,476 2009 192 Victoria
 South Sudan 619,745 8,260,490 2008 13 Juba
 Tanzania 945,087 44,929,002 2009 43 Dodoma
 Uganda 236,040 32,369,558 2009 137 Kampala
 Zambia 752,614 11,862,740 2009 16 Lusaka
 Zimbabwe 390,580 11,392,629 2009 29 Harare
Central Africa
 Angola 1,246,700 12,799,293 2009 10 Luanda
 Cameroon 475,440 18,879,301 2009 40 Yaoundé
 Central African Republic 622,984 4,511,488 2009 7 Bangui
 Chad 1,284,000 10,329,208 2009 8 N'Djamena
 Republic of the Congo 342,000 4,012,809 2009 12 Brazzaville
 Democratic Republic of the Congo 2,345,410 69,575,000 2012 30 Kinshasa
 Equatorial Guinea 28,051 633,441 2009 23 Malabo
 Gabon 267,667 1,514,993 2009 6 Libreville
 São Tomé and Príncipe 1,001 212,679 2009 212 São Tomé
Southern Africa
 Botswana 600,370 1,990,876 2009 3 Gaborone
 Lesotho 30,355 2,130,819 2009 70 Maseru
 Namibia 825,418 2,108,665 2009 3 Windhoek
 South Africa 1,219,912 51,770,560 2011 42 Bloemfontein, Cape Town, Pretoria[124]
 Swaziland 17,363 1,123,913 2009 65 Mbabane
Western Africa
 Benin 112,620 8,791,832 2009 78 Porto-Novo
 Burkina Faso 274,200 15,746,232 2009 57 Ouagadougou
 Cape Verde 4,033 429,474 2009 107 Praia
 Côte d'Ivoire 322,460 20,617,068 2009 64 Abidjan,[125] Yamoussoukro
 Gambia 11,300 1,782,893 2009 158 Banjul
 Ghana 239,460 23,832,495 2009 100 Accra
 Guinea 245,857 10,057,975 2009 41 Conakry
 Guinea-Bissau 36,120 1,533,964 2009 43 Bissau
 Liberia 111,370 3,441,790 2009 31 Monrovia
 Mali 1,240,000 12,666,987 2009 10 Bamako
 Mauritania 1,030,700 3,129,486 2009 3 Nouakchott
 Niger 1,267,000 15,306,252 2009 12 Niamey
 Nigeria 923,768 166,629,000 2012 180 Abuja
 Saint Helena, Ascension and Tristan da Cunha (United Kingdom) 420 7,728 2012 13 Jamestown
 Senegal 196,190 13,711,597 2009 70 Dakar
 Sierra Leone 71,740 6,440,053 2009 90 Freetown
 Togo 56,785 6,019,877 2009 106 Lomé
  Africa Total 30,368,609 1,001,320,281 2009 33

Vaccination

Vaccination

From Wikipedia, the free encyclopedia
 
Vaccination
Intervention
Vaccination-polio-india.jpg
Child receiving an oral polio vaccine
ICD-9-CM 99.3-99.5

Vaccination is the administration of antigenic material (a vaccine) to stimulate an individual's immune system to develop adaptive immunity to a pathogen. Vaccines can prevent or ameliorate morbidity from infection. The effectiveness of vaccination has been widely studied and verified; for example, the influenza vaccine,[1] the HPV vaccine,[2] and the chicken pox vaccine.[3] Vaccination is the most effective method of preventing infectious diseases;[4] widespread immunity due to vaccination is largely responsible for the worldwide eradication of smallpox and the restriction of diseases such as polio, measles, and tetanus from much of the world. The World Health Organization (WHO) reports licensed vaccines are currently available to prevent, or contribute to the prevention and control of, 25 vaccine-preventable infections.[5]

The active agent of a vaccine may be intact but inactivated (non-infective) or attenuated (with reduced infectivity) forms of the causative pathogens, or purified components of the pathogen that have been found to be highly immunogenic (e.g., outer coat proteins of a virus). Toxoids are produced for immunization against toxin-based diseases, such as the modification of tetanospasmin toxin of tetanus to remove its toxic effect but retain its immunogenic effect.[6]

Smallpox was most likely the first disease people tried to prevent by inoculating themselves[7][8] and was the first disease for which a vaccine was produced. The smallpox vaccine was designed in 1796 by the British physician Edward Jenner, although at least six people had used the same principles years earlier.[9] Louis Pasteur furthered the concept through his work in microbiology. The immunization was called vaccination because it was derived from a virus affecting cows (Latin: vacca—cow).[7][9] Smallpox was a contagious and deadly disease, causing the deaths of 20–60% of infected adults and over 80% of infected children.[10] When smallpox was finally eradicated in 1979, it had already killed an estimated 300–500 million people[11][12][13] in the 20th century.

In common speech, 'vaccination' and 'immunization' have a similar meaning. This distinguishes it from inoculation, which uses unweakened live pathogens, although in common usage either can refer to an immunization. Vaccination efforts have been met with some controversy on scientific, ethical, political, medical safety, and religious grounds. In rare cases, vaccinations can injure people and, in the United States, they may receive compensation for those injuries under the National Vaccine Injury Compensation Program. Early success and compulsion brought widespread acceptance, and mass vaccination campaigns have greatly reduced the incidence of many diseases in numerous geographic regions.

Mechanism of function

Generically, the process of artificial induction of immunity, in an effort to protect against infectious disease, works by 'priming' the immune system with an 'immunogen'. Stimulating immune responses with an infectious agent is known as immunization. Vaccination includes various ways of administering immunogens.
Polio vaccination started in Sweden in 1957.

Some vaccines are administered after the patient already has contracted a disease. Vaccinia given after exposure to smallpox, within the first three days, is reported to attenuate the disease considerably, and vaccination up to a week after exposure probably offers some protection from disease or may modify the severity of disease.[14] The first rabies immunization was given by Louis Pasteur to a child after he was bitten by a rabid dog. Subsequent to this, it has been found that, in people with uncompromised immune systems, four doses of rabies vaccine over 14 days, wound care, and treatment of the bite with rabies immune globulin, commenced as soon as possible after exposure, is effective in preventing the development of rabies in humans.[15] Other examples include experimental AIDS, cancer and Alzheimer's disease vaccines. Such immunizations aim to trigger an immune response more rapidly and with less harm than natural infection.

Most vaccines are given by hypodermic injection as they are not absorbed reliably through the intestines. Live attenuated polio, some typhoid and some cholera vaccines are given orally to produce immunity in the bowel.

Adjuvants and preservatives

Vaccines typically contain one or more adjuvants, used to boost the immune response. Tetanus toxoid, for instance, is usually adsorbed onto alum. This presents the antigen in such a way as to produce a greater action than the simple aqueous tetanus toxoid. People who get an excessive reaction to adsorbed tetanus toxoid may be given the simple vaccine when time for a booster occurs.

In the preparation for the 1990 Gulf campaign, Pertussis vaccine (not acellular) was used as an adjuvant for Anthrax vaccine. This produces a more rapid immune response than giving only the Anthrax, which is of some benefit if exposure might be imminent.

Vaccines may also contain preservatives to prevent contamination with bacteria or fungi. Until recent years, the preservative thimerosal was used in many vaccines that did not contain live virus. As of 2005, the only childhood vaccine in the U.S. that contains thimerosal in greater than trace amounts is the influenza vaccine,[1] which is currently recommended only for children with certain risk factors.[16] Single-dose Influenza vaccines supplied in the UK do not list Thiomersal (its UK name) in the ingredients. Preservatives may be used at various stages of production of vaccines, and the most sophisticated methods of measurement might detect traces of them in the finished product, as they may in the environment and population as a whole.[17]

Vaccination versus inoculation

Many times these words are used interchangeably, as if they were synonyms. In fact, they are different things. As doctor Byron Plant explains: "Vaccination is the more commonly used term, which actually consists of a 'safe' injection of a sample taken from a cow suffering from cowpox... Inoculation, a practice probably as old as the disease itself, is the injection of the variola virus taken from a pustule or scab of a smallpox sufferer into the superficial layers of the skin, commonly on the upper arm of the subject. Often inoculation was done 'arm to arm' or less effectively 'scab to arm'..."[18]

Vaccination began in the 18th century with the work of Edward Jenner.[19][20][21]

Types

Vaccines work by presenting a foreign antigen to the immune system to evoke an immune response, but there are several ways to do this. Four main types are currently in clinical use:
  1. An inactivated vaccine consists of virus or bacteria that are grown in culture and then killed using a method such as heat or formaldehyde. Although the virus or bacteria particles are destroyed and cannot replicate, the virus capsid proteins or bacterial wall are intact enough to be recognized and remembered by the immune system and evoke a response. When manufactured correctly, the vaccine is not infectious, but improper inactivation can result in intact and infectious particles. Since the properly produced vaccine does not reproduce, booster shots are required periodically to reinforce the immune response.
  2. In an attenuated vaccine, live virus or bacteria with very low virulence are administered. They will replicate, but locally or very slowly. Since they do reproduce and continue to present antigen to the immune system beyond the initial vaccination, boosters may be required less often. These vaccines may be produced by passaging, for example, adapting a virus into different host cell cultures, such as in animals, or at suboptimal temperatures, allowing selection of less virulent strains, or by mutagenesis or targeted deletions in genes required for virulence. There is a small risk of reversion to virulence, which is smaller in vaccines with deletions. Attenuated vaccines also cannot be used by immunocompromised individuals. Reversions of virulence were described for a few attenuated viruses of chickens (infectious bursal disease virus, avian infectious bronchitis virus, avian infectious laryngotracheitis virus [2], avian metapneumovirus [3])[22]
  3. Virus-like particle vaccines consist of viral protein(s) derived from the structural proteins of a virus. These proteins can self-assemble into particles that resemble the virus from which they were derived but lack viral nucleic acid, meaning that they are not infectious. Because of their highly repetitive, multivalent structure, virus-like particles are typically more immunogenic than subunit vaccines (described below). The human papillomavirus and Hepatitis B virus vaccines are two virus-like particle-based vaccines currently in clinical use.
  4. A subunit vaccine presents an antigen to the immune system without introducing viral particles, whole or otherwise. One method of production involves isolation of a specific protein from a virus or bacterium (such as a bacterial toxin) and administering this by itself. A weakness of this technique is that isolated proteins may have a different three-dimensional structure than the protein in its normal context, and will induce antibodies that may not recognize the infectious organism. In addition, subunit vaccines often elicit weaker antibody responses than the other classes of vaccines.
A number of other vaccine strategies are under experimental investigation. These include DNA vaccination and recombinant viral vectors.

History

Jenner's handwritten draft of the first vaccination.

It is believed likely that some form of inoculation was developed in India or China before the 16th century.[7] Scholar Ole Lund comments: "The earliest documented examples of vaccination are from India and China in the 17th century, where vaccination with powdered scabs from people infected with smallpox was used to protect against the disease. Smallpox used to be a common disease throughout the world and 20% to 30% of infected persons died from the disease. Smallpox was responsible for 8% to 20% of all deaths in several European countries in the 18th century. The tradition of inoculation may have originated in India in 1000 BCE."[23] The mention of inoculation in the Sact'eya Grantham, an Ayurvedic text, was noted by the French scholar Henri Marie Husson in the journal Dictionaire des sciences médicales.[24] Inoculation was reportedly widely practised in China in the reign of the Longqing Emperor (r. 1567–1572) during the Ming Dynasty (1368–1644).[25] The Anatolian Ottoman Turks knew about methods of inoculation. This kind of inoculation and other forms of variolation were introduced into England by Lady Montagu, a famous English letter-writer and wife of the English ambassador at Istanbul between 1716 and 1718, who almost died from smallpox as a young adult and was physically scarred from it. Inoculation was adopted both in England and in America nearly half a century before Jenner's famous smallpox vaccine of 1796[26] but the death rate of about 2% from this method meant that it was mainly used during dangerous outbreaks of the disease and remained controversial.[27]

It was noticed during the eighteenth century that people who had suffered from the less virulent cowpox were immune to smallpox and the first recorded use of this idea was by a farmer Benjamin Jesty at Yetminster who had suffered the disease and transmitted it to his own family in 1774, his sons subsequently not getting the mild version of smallpox when later inoculated in 1789. But it was Edward Jenner, a doctor in Berkeley, who established the procedure by introducing material from a cowpox vesicle on Sarah Nelmes, a milkmaid, into the arm of a boy named James Phipps. Two months later he inoculated the boy with smallpox and the disease did not develop. In 1798, Jenner published “An Inquiry into the Causes and Effects of the Variolae Vacciniae” which coined the term vaccination and created widespread interest. He distinguished 'true' and 'spurious' cowpox (which did not give the desired effect) and developed an "arm-to-arm" method of propagating the vaccine from the vaccinated individual's postule. Early attempts at confirmation were confounded by contamination with smallpox, but despite controversy within the medical profession and religious opposition to the use of animal material, by 1801 his report was translated into six languages and over 100,000 people were vaccinated .[28]

Since then vaccination campaigns have spread throughout the globe, sometimes prescribed by law or regulations (See Vaccination Acts). Vaccines are now used against a wide variety of diseases besides smallpox. Louis Pasteur further developed the technique during the 19th century, extending its use to killed agents protecting against anthrax and rabies. The method Pasteur used entailed treating the agents for those diseases so they lost the ability to infect, whereas inoculation was the hopeful selection of a less virulent form of the disease, and Jenner's vaccination entailed the substitution of a different and less dangerous disease for the one protected against. Pasteur adopted the name vaccine as a generic term in honor of Jenner's discovery.
A doctor performing a typhoid vaccination in Texas, 1943.

Maurice Hilleman was the most prolific vaccine inventor, and developed successful vaccines for measles, mumps, hepatitis A, hepatitis B, chickenpox, meningitis, pneumonia and Haemophilus influenzae.[29]

In modern times, the first vaccine-preventable disease targeted for eradication was smallpox. The World Health Organization (WHO) coordinated this global eradication effort. The last naturally occurring case of smallpox occurred in Somalia in 1977. In 1988, the governing body of WHO targeted polio for eradication by 2000. Although the target was missed, eradication is very close. The next disease to be targeted for eradication would most likely be measles, which has declined since the introduction of measles vaccination in 1963.[citation needed]

In 2000, the Global Alliance for Vaccines and Immunization was established to strengthen routine vaccinations and introduce new and under-used vaccines in countries with a per capita GDP of under US$1000. GAVI is now entering its second phase of funding, which extends through 2014.

Society and culture

Poster for vaccination against smallpox.

To eliminate the risk of outbreaks of some diseases, at various times several governments and other institutions have instituted policies requiring vaccination for all people. For example, an 1853 law required universal vaccination against smallpox in England and Wales, with fines levied on people who did not comply. Common contemporary U.S. vaccination policies require that children receive common vaccinations before entering public school.

Beginning with early vaccination in the nineteenth century, these policies were resisted by a variety of groups, collectively called antivaccinationists, who object on scientific, ethical, political, medical safety, religious, and other grounds. Common objections are that vaccinations do not work, that compulsory vaccination represents excessive government intervention in personal matters, or that the proposed vaccinations are not sufficiently safe.[30] Many modern vaccination policies allow exemptions for people who have compromised immune systems, allergies to the components used in vaccinations or strongly held objections.[31]

In countries with limited financial resources, limited coverage causes much morbidity and mortality.[32] More affluent countries are able to subsidize vaccinations for at-risk groups, resulting in more comprehensive and effective cover. In Australia, for example, the Government subsidizes vaccinations for seniors and indigenous Australians.[33]

Public Health Law Research,[34] an independent organization, reported in 2009 that there is insufficient evidence to assess the effectiveness of requiring vaccinations as a condition for specified jobs as a means of reducing incidence of specific diseases among particularly vulnerable populations;[35] that there is sufficient evidence supporting the effectiveness of requiring vaccinations as a condition for attending child care facilities and schools.;[36] and that there is strong evidence supporting the effectiveness of standing orders, which allow healthcare workers without prescription authority to administer vaccine as a public health intervention aimed at increasing vaccination rates.[37]

Vaccination-autism controversy

A noteworthy allegation of vaccine-induced injury is the MMR vaccine controversy. A fraudulent 1998 paper by Andrew Wakefield, originally published in The Lancet, presented supposed evidence that the MMR Vaccine (an immunization against measles, mumps and rubella that is typically first administered to children shortly after their first birthday) was linked to the onset of autism spectrum disorders.[38] The article was widely criticized for lack of scientific rigour and then partially retracted in 2004 by Wakefield's co-authors,[39] and was fully retracted by The Lancet in 2010.[40] Wakefield was struck off the UK's medical registry for the fraud.[41]

Side effects and injury

The Centers for Disease Control and Prevention (CDC) has compiled a list of vaccines and their possible side effects.[42] Allegations of vaccine injuries in recent decades have appeared in litigation in the U.S. Some families have won substantial awards from sympathetic juries, even though most public health officials have said that the claims of injuries were unfounded.[43] In response, several vaccine makers stopped production, which the US government believed could be a threat to public health, so laws were passed to shield makers from liabilities stemming from vaccine injury claims.[43]

Routes of administration

Air France Vaccinations Centre in the 7th arrondissement of Paris

A vaccine administration may be oral, by injection (intramuscular, intradermal, subcutaneous), by puncture, transdermal or intranasal.[44] Several recent clinical trials have aimed to deliver the vaccines via mucosal surfaces to be up-taken by common mucosal immunity system, thus avoiding the need for injections.[45]

The Universe - Life and Death of a Star

The Universe - Life and Death of a Star

Original link:  http://farfuturehorizons.blogspot.com/2014/08/the-universe-life-and-death-of-star.html





 
Today on Far Future Horizons we present another exciting episode from season one of the acclaimed documentary series – The Universe, and revisit the whole topic of stellar evolution and our cosmic legacy.

Ignited by the power of the atom, burning with light, heat and wrath, stars are anything but peaceful. They collide, devour each other, and explode in enormous supernovas–the biggest explosions in the Universe.





The Universe is available on DVD from Amazon.com and the History Channel’s online store.
The Universe: Life and Death of a Star


Streaming algorithm

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Streaming_algorithm ...