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Wednesday, November 20, 2019

2010s Haiti cholera outbreak

From Wikipedia, the free encyclopedia
 
2010s Haiti cholera outbreak
DateOctober 2010 – present
LocationHaiti
CauseSuspected contamination by United Nations peacekeepers.
Casualties
10,075 dead (all countries)
 Haiti 9,568 dead (28 Dec 2017 )  Dominican Republic 503 dead (28 Dec 2017)  Cuba 3 dead (18 Oct 2013)  Mexico 1 dead (18 Oct 2013)
Cases:
809,262 (Haiti),
33,342 (DR),
678 (Cuba),
190 (Mexico)

Cases recorded in:

The 2010 Haitian cholera outbreak was the first modern large-scale outbreak of cholera – a disease once considered beaten back largely due to the invention of modern sanitation. Since its reintroduction to Haiti in October 2010, cholera has spread across the country and has become endemic, causing high levels of both morbidity and mortality. Since its reintroduction to Haiti following the 2010 Haitian earthquake, nearly 800,000 Haitians have been infected by cholera, and more than 9,000 have died, according to the United Nations (UN). Cholera transmission in Haiti today is largely a function of eradication efforts including WASH (water, sanitation, and hygiene), education, and oral vaccination, and climate variability. Early efforts were made to cover up the source of the epidemic, but thanks largely to the investigations of journalist Jonathan M. Katz and epidemiologist Renaud Piarroux, today it is widely believed to be the result of contamination by infected United Nations peacekeepers deployed from Nepal. In terms of total infections, the outbreak has since been surpassed by the war-fueled 2016–17 Yemen cholera outbreak, although the Haiti outbreak is still the most deadly modern outbreak.

Background


In January 2010, a 7.0 magnitude earthquake hit Haiti, killing over 100,000 people and further disrupting healthcare and sanitation infrastructure in the country. In the aftermath of the earthquake, international workers from many countries arrived in Haiti to assist in the response and recovery efforts, including a number of workers from countries where cholera is endemic. Before the outbreak, no cases of cholera had been identified in Haiti for more than a century, and the Caribbean region as a whole had not been affected by the cholera outbreak originating in Peru in 1991. The population's lack of prior exposure and acquired immunity contributed to the severity of the outbreak.

Outbreak

Cholera is caused by the bacterium Vibrio cholerae that when ingested can cause diarrhea and vomiting within several hours to 2–3 days. Without proper treatment including oral rehydration, cholera can be fatal. The suspected source of Vibrio cholerae in Haiti was the Artibonite River, from which most of the affected people had consumed the water. Each year, tens of thousands of Haitians bathe, wash their clothes and dishes, obtain drinking water, and recreate in this river, therefore resulting in high rates of exposure to Vibrio cholerae.

The cholera outbreak began ten months after the January 2010 earthquake, leading some observers to wrongly suspect it was a result of the natural disaster. However, Haitians grew immediately suspicious of a UN peacekeeper base, home to Nepalese peacekeepers, positioned on a tributary of the Artibonite River. Neighboring farmers reported an undeniable stench of human feces coming from the base, to the extent that local Haitians began getting their drinking water upstream from the base. In response, United Nations Stabilization Mission in Haiti (MINUSTAH) officials issued a press statement denying the possibility that the base could have caused the epidemic, citing stringent sanitation standards. The next day, 27 October 2010, Jonathan M. Katz, an Associated Press correspondent, visited the base and found gross inconsistencies between the statement and the base's actual conditions. Katz also happened upon UN military police taking samples of ground water to test for cholera, despite UN assertions that it was not concerned about a possible link between its peacekeepers and the disease. Neighbors told the reporter that waste from the base often spilled into the river. Later that day, a crew from Al Jazeera English, including reporter Sebastian Walker, filmed the soldiers trying to excavate a leaking pipe; the video was posted online the following day and, citing the AP report, drew increased awareness to the base. MINUSTAH spokesmen later contended that the samples taken from the base proved negative for cholera. However, an AP investigation showed that the tests were improperly done at a laboratory in the Dominican Republic, which had no prior experience of testing for cholera.

For three months, UN officials, the CDC, and others argued against investigating the source of the outbreak. Gregory Hartl, a spokesman for the World Health Organization (WHO), said finding the cause of the outbreak was "not important". Hartl said,"Right now, there is no active investigation. I cannot say one way or another [if there will be]. It is not something we are thinking about at the moment. What we are thinking about is the public health response in Haiti." Jordan Tappero, the lead epidemiologist at the CDC, said the main task was to control the outbreak, not to look for the source of the bacteria and that "we may never know the actual origin of this cholera strain." A CDC spokesperson, Kathryn Harben, added that "at some point in the future, when many different analyses of the strain are complete, it may be possible to identify the origin of the strain causing the outbreak in Haiti."

Paul Farmer, co-founder of the medical organization Partners In Health, and a UN official himself who served Bill Clinton's deputy at the Office of the Special Envoy for Haiti, told the AP's Katz on 3 November 2010 that there was no reason to wait. Farmer stated, "The idea that we'd never know is not very likely. There's got to be a way to know the truth without pointing fingers." A cholera expert, John Mekalanos, supported the assertion that it was important to know where and how the disease emerged because the strain is a "novel, virulent strain previously unknown in the Western Hemisphere and health officials need to know how it spreads."

Some US professors have disagreed with the contention that Nepalese soldiers caused the outbreak. Some said it was more likely dormant cholera bacteria had been aroused by various environmental incidents in Haiti. Before studying the case, they said a sequence of events, including changes in climate triggered by the La Niña climate pattern and unsanitary living conditions for those affected by the earthquake, triggered bacteria already present in the water and soil to multiply and infect humans.

However, a study unveiled in December and conducted by French epidemiologist Renaud Piarroux contended that UN troops from Nepal, rather than environmental factors, had started the epidemic as waste from outhouses at their base flowed into and contaminated the Artibonite River. A separate study published in December in the New England Journal of Medicine presented DNA sequence data for the Haitian cholera isolate, finding that it was most closely related to a cholera strain found in Bangladesh in 2002 and 2008. It was more distantly related to existing South American strains of cholera, the authors reported, adding that "the Haitian epidemic is probably the result of the introduction, through human activity, of a V. cholerae strain from a distant geographic source."

Under intense pressure, the UN relented, and said it would appoint a panel to investigate the source of the cholera strain. That panel's report, issued in May 2011, confirmed substantial evidence that the Nepalese troops had brought the disease to Haiti. The U.S. Centers for Disease Control and Prevention (CDC) utilized DNA fingerprinting to tests various samples of cholera from Haitian patients to pinpoint the specific strand of cholera found in Haiti. During an epidemiological outbreak investigation, DNA fingerprinting of bacteria can be extremely helpful in identifying the source of an outbreak. The results of the CDC tests showed that the specific strain of cholera found in samples taken from Haitian patients was Vibrio cholerae serogroup O1, serotype Ogawa, a strain found in South Asia. This specific strain of cholera is endemic in Nepal, therefore supporting the Haitian suspicion that Nepalese peacekeepers were the source of the outbreak. However, in the report's concluding remarks, the authors hedged to say that a "confluence of circumstances" was to blame.

Rita Colwell, former director of the National Science Foundation and climate change expert, still contends that climate changes were an important factor in cholera's spread, stating in an interview with UNEARTH News in August 2013 that the outbreak was "triggered by a complicated set of factors. The precipitation and temperatures were above average during 2010 and that, in conjunction with a destroyed water and sanitation infrastructure, can be considered to have contributed to this major disease outbreak."

In August 2016, after Katz obtained a leaked copy of a report by United Nations Special Rapporteur Philip Alston, Secretary General of the United Nations Ban Ki-moon accepted responsibility for the UN's role in the initial outbreak and stated that a "significant new set of U.N. actions" will be required to help solve the problem. In 2017, Katz also revealed the existence of emails that showed that “officials at the highest levels of the U.S. government were aware almost immediately that U.N. forces likely played a role in the outbreak.” Katz reported that these emails showed “multiple federal agencies, from national security officials to scientists on the front lines, shielded the United Nations from accountability to protect the organization and themselves.”

Reactions

At the beginning of the outbreak, widespread panic regarding the virulence of the disease and the UN's denial of the blame caused increased tension between the UN and the Haitian community. On 15 November 2010, a riot broke out in Cap-Haïtien following the death of a young Haitian inside the Cap-Haïtien UN base and rumours that the outbreak was caused by UN soldiers from Nepal. Protesters demanded that the Nepalese brigade of the UN leave the country. At least 5 people were killed in the riots, including 1 UN personnel. Riots then continued for a second day. Following the riots, the UN continued their position that the Nepalese soldiers were not to blame, and rather said that the riots was being staged for "political reasons because of forthcoming elections", as the Haitian government sent its own forces to "protest" the UN peacekeepers. According to one author, rather than confront the inescapable conclusion that the UN was indeed the cause, "the world’s preeminent humanitarian organization continued to dissemble." During a third day of riots, UN personnel were blamed for shooting at least 5 protestors, but denied responsibility. On the fourth day of demonstrations against the UN presence, police fired tear gas into an IDP camp in the capital.

The outbreak of cholera became an issue for Haitian candidates to answer in the 2010 general election. There were fears that the election could be postponed. The head of MINUSTAH, Edmond Mulet said that it should not be delayed as that could lead to a political vacuum with untold potential problems.

In November 2011, the UN received a petition from 5,000 victims for hundreds of millions of dollars in reparations over the outbreak thought to have been caused by UN members of MINUSTAH. In February 2013, the United Nations responded by invoking its immunity from lawsuits under the Convention on the Privileges and Immunities of the United Nations. On 9 October 2013, Bureau des Avocats Internationaux (BAI), the Institute for Justice & Democracy in Haiti (IJDH), and civil rights lawyer Ira Kurzban's law firm Kurzban Kurzban Weinger Tetzeli & Pratt, P.A.(KKWT) filed a lawsuit against the UN in the Southern District of New York. The lawsuit was dismissed, but an appeal was filed in the Second Circuit. In October 2016, the Second Circuit Court of Appeals upheld the United Nations' immunity from claims. On March 11, 2014, a second lawsuit was filed, Laventure v. United Nations, in the Eastern District of New York, on behalf of more than 1,500 victims of the disaster. In an opinion piece in the Wall Street Journal, an attorney for the plaintiffs wrote:
"Imagine if the United Nations killed thousands on the streets of New York. Or London. Or Paris. And sickened nearly a million more. Would the U.N. claim it was not liable? Of course not. The international community wouldn't allow it."
A lead lawyer for the plaintiffs also noted that the lawsuit was different from the one filed by the IDJH, in that it alleged that liability had been accepted by the U.N. the 1990s. The lawyer stated that immunity: “should not be a shield to hide behind because the United Nations (or the U.S. government) doesn’t like the price tag that comes with the U.N.’s indisputable gross negligence in this case."

This case, too, was dismissed by the U.S. District Court, and the Court of Appeals. The appeal is currently before the United States Supreme Court.

In December 2016, the then UN Secretary-General Ban Ki-moon finally apologized on behalf of UN, saying he was "profoundly sorry" for the outbreak. The Secretary-General promised to spend $400 million to aid the victims and to improve the nation's crumbling sanitation and water systems. As of March 2017, the UN has come through with only 2 percent of that amount.

Morbidity and mortality

Domestic

On October 21, 2010, the Haitian Ministry of Public Health and Population (MSPP) confirmed the first case of cholera in Haiti in over a century. The outbreak began in the rural Center department of Haiti, about 100 kilometres (62 mi) north of the capital, Port-au-Prince. By the first 10 weeks of the epidemic, cholera spread to all of Haiti's 10 departments or provinces. It had killed 4,672 people by March 2011 and hospitalized thousands more. The outbreak in Haiti was the most severe in recent history prior to 2010; the World Health Organization reported that from 2010 to 2011, the outbreak in Haiti accounted for 57% of all cases and 45% of all deaths from cholera worldwide.

When the outbreak began in October 2010, more than 6% of Haitians resulted in acquiring the disease. The highest incidence of cholera occurred in 2011 immediately following the introduction of the primary exposure. The rate of incidence slowly declined thereafter, with spikes resulting from rainy seasons and hurricanes. As reported by the Haitian Health Ministry, as of August 2012, the outbreak had caused 586,625 cholera cases and 7,490 deaths. According to the Pan American Health Organization, as of 21 November 2013, there had been 689,448 cholera cases in Haiti, leading to 8,448 deaths. While there had been an apparent lull in cases in 2014, by August 2015 the rainy season brought a spike in the number of cases. At that time more than 700,000 Haitians had become ill with the disease and the death toll had climbed to 9,000. As of March 2017, around 7% of Haiti's population (around 800,665 people) have been affected with cholera, and 9,480 Haitians have died. Latest epidemiological report by WHO in 2018 indicate a total of 812,586 cases of cholera in Haiti since October 2010, resulting in 9,606 deaths.

International

The first case of cholera was reported in the Dominican Republic in mid-November 2010, following the Pan-America Health Organization's prediction. By January 2011, the Dominican Republic had reported 244 cases of cholera. The first man to die of it there died in the province of Altagracia on 23 January 2011. The Dominican Republic was particularly vulnerable to exposure of cholera due to sharing a border with Haiti, and a large Haitian refugee population displaced following the 2010 earthquake. As of the latest epidemiological report by WHO in 2018, there has been a total of 33,188 cases of cholera in the Dominican Republic resulting in 504 deaths.

In late January 2011, more than 20 Venezuelans were reported to have been taken to hospital after contracting cholera after visiting the Dominican Republic. 37 cases were reported in total. Contaminated food was blamed for the spread of the disease. Venezuelan health minister Eugenia Sader gave a news conference which was broadcast on VTV during which she described all 37 people as "doing well". The minister had previously observed that the last time cholera was recorded in Venezuela was twenty years before this, in 1991.

In late June 2012, Cuba confirmed three deaths and 53 cases of cholera in Manzanillo; in 2013 there were 51 cases of cholera reported in Havana. Vaccination of half the population was urged by the University of Florida to stem the epidemic.

Vulnerabilities

Infrastructure

Before the outbreak, Haiti suffered from relatively poor public health and sanitation infrastructure. In 2002, Haiti was ranked 147th out of 147 countries for water security. As of 2008, 37% of Haiti's population lacked access to adequate drinking water, and 83% lacked improved sanitation facilities. As such, families often obtain their water from natural sources, such as rivers, that may be contaminated with V. cholerae. Poor sanitation infrastructure allows cholera bacterium to enter these waterways. Persons are subsequently infected via the fecal-oral route when the water is used for drinking and cooking, and poor hygiene often contributes to the spread of cholera through the household or community. There is also a chronic shortage of health care personnel, and hospitals lack adequate resources to treat those infected with cholera- a situation that became readily apparent after the January 2010 earthquake. Insufficient water and sanitation infrastructure, coupled with a massive earthquake in 2010, made Haiti particularly vulnerable to an outbreak of waterborne disease.

Physiological

Malnutrition of the population, another pre-existing condition that was exacerbated by the earthquake, may have also contributed to the severity of the outbreak. Research from previous outbreaks shows that duration of diarrhea can be prolonged by up to 70% in individuals suffering from severe malnutrition. Furthermore, Haitians had no biological immunity to the strain of cholera introduced since they had no previous exposure to it. Therefore, physiological factors including malnutrition and lack of immunity may have allowed cholera to spread rapidly throughout the country.

Information

Lack of information and limited access to some rural areas can also be a barrier to care. Some aid agencies have reported that mortality and morbidity tolls may be higher than the official figures because the government does not track deaths in rural areas where people never reached a hospital or emergency treatment center. Limitations in the data from Haiti stem from a lack of pre-outbreak lack of surveillance infrastructure and laboratories to properly test samples and diagnose cases. Haiti was tasked with developing surveillance systems and laboratories after the 2010 earthquake and cholera outbreak which caused difficulties tracking the progression and scale of the outbreak. Because of the lack of established surveillance, much of the case report data is anecdotal and potentially underestimated. Also, because of lack of laboratory confirmation for the vast majority of cases of cholera, it is possible that other diarrheal diseases were being falsely classified as cholera.

Environmental

Rainy seasons and hurricanes continue to cause a temporary spike in incident cases and deaths. Moreover, as a result of global warming and climate change, Haiti is at an increased risk of cholera transmission. The Intergovernmental Panel on Climate Change (IPCC) advances that global warming between 1.5-2 degrees Celsius will very likely lead to an increase in frequency and intensity of natural disasters and extreme weather events. Resource-poor countries are poised to be affected more so than more developed and economically secure countries.

Environmental factors such as temperature increases, severe weather events, and natural disasters have a two-fold impact on the transmission potential of cholera in Haiti: 1) they present conditions favorable to the persistence and growth of V. cholerae in the environment, and 2) they devastate a country's infrastructure and strain public health and health care resources. An exhaustive study into environmental factors influencing the spread of cholera in Haiti cites above average air temperatures following the earthquake, “anomalously high rainfall” from September to October 2010, and damage to the limited water and sanitation infrastructure as likely converging to create conditions favorable to a cholera outbreak.

Challenges and solutions to eradication

Hundreds of thousands of dollars have been dedicated towards eradicating cholera in Haiti since its introduction in 2010, yet unsanitary conditions and climate-driven forces allow cholera transmission to continue. While the number of new cases of cholera has drastically decreased from 2010, and is currently the lowest it has been since the outbreak began, the incidence remains at 25.5 per 100,000 population as of October 2018. Over time, there has been significant progress in the reduction of caseloads and overall number of deaths. According to one PAHO/WHO report, “the cumulative case-fatality rate (CFR) has remained around 1% since 2011.” These achievements can be contributed to intensified international and local medical efforts and an increased emphasis on preventative measures, including improved sanitation, such as latrines, and changes in Haitian behaviors such as treating water, thoroughly cooking food, and rigorous hand-washing.  Despite these progresses, cholera remains endemic in Haiti, and further resources are needed to fully eradicate it.

After former UN Secretary General Ban Ki Moon accepted UN responsibility for the introduction of cholera in Haiti in December 2016, Moon projected a necessary $400 million in funding over two years in order to fully eradicate cholera in Haiti.  The Government of Haiti has dedicated itself to the complete eradication of cholera from Haiti by 2022 as presented in the Cholera Elimination Plan (PNEC) 2013 – 2022. UN Secretary-General Antonio Guterres, successor to Ban Ki Moon, took up Moon's commitment to assist Haiti in the eradication of cholera when he took office in 31 December 2016, as demonstrated by strategic objective 2 of the 2017- 2018 Haiti Revised Humanitarian Plan. Strategic objective 2 reads, “Save lives from epidemics – Reduce mortality and morbidity due to cholera outbreaks and other waterborne diseases through the reduction of vulnerability, strengthening of epidemiological surveillance and ensuring of rapid and effective response.”  The 2017 – 2018 Haiti Revised Humanitarian Plan identifies 1.9 million people in need of assistance for the protection from cholera, of which, 1.5 million people are targeted through programming totaling US$21.7 million.  Currently, the UN and Government of Haiti are on target to reach the 2016 – 2018 midterm goal to reduce the incidence of cholera to less than 0.1% by the end of 2018. However, any disruption in funding of support services may result in a spike in transmission and the interruption of the downward trend.

Challenges

Protracted crises: Hurricane Matthew 2016

The first challenge to the eradication of cholera in Haiti is the country's vulnerability to disasters, putting it in a state of protracted crises. The climax of cholera incidence in Haiti was in 2011 with 352,000 new cases following the introduction of cholera in Haiti in late 2010. Incidence rates gradually declined until 2016 when there was another spike in the transmission and incidence of cholera following Hurricane Matthew's destruction in Haiti from October 2–5, 2016. There was a rise in cholera incidence from 32,000 new cases in 2015 to 42,000 new cases in 2016. By re-damaging Haiti's fragile water and sanitation infrastructure, Hurricane Matthew allowed cholera to rear its head. These figures demonstrate that the fight against cholera in Haiti, while improving, is on unstable ground. This indicates that while eradication efforts have largely been focused on vaccination and community education to prevent transmission, and oral rehydration to reduce mortality, the underlying vulnerabilities that perpetuate the disaster remain, particularly insufficient and unequal access to improved water and sanitation.

Funding

While the Government of Haiti's Cholera Elimination Plan (PNEC) 2013 – 2022 and the New UN System Approach on Cholera in Haiti (see solutions below for more information) lay out plans for the elimination of cholera in Haiti by 2022, these are entirely dependent on funding. In former Secretary General Moon's December 5, 2016 remarks he says, “Without political will and financial support from the membership of the United Nations, we have only good intentions and words. Words are powerful — but they cannot replace action and material support.”  Due to the infectious nature of cholera, any lapse in funding for programming will likely result in setbacks in elimination. 

As of 2017, funding for cholera is at risk due to increasing food insecurity and shelter needs for Haitian refugees returning from the Dominican Republic. In the 2017 – 2018 Revised Haiti Humanitarian Plan, funding requirements for cholera programming is the third largest at $21.7 million, behind $76.6 million for food security and $103.8 million for shelter/NFI needs.

Solutions

Vaccination campaigns

In 2013, the Government of Haiti launched an oral cholera vaccination (OCV) campaign in two regions: Cerca Caravajal and Petite Anse. These regions were chosen because of particularly high attack rates, sanitation infrastructure, and access to healthcare. This vaccination effort was slightly controversial because the WHO guidelines at the time did not encourage mass vaccination campaigns in areas where outbreaks had already occurred. Prior to the 2010 outbreak in Haiti, vaccination campaigns were thought to detract from more important prevention measures like water treatment and good hygiene. Relative success rates (up to 65% or higher protective effectiveness 5 years after vaccination) in recent vaccination campaigns in Haiti and other countries affected by cholera has led to more widespread use of oral cholera vaccine programs and a change in the WHO guidelines to encourage use of vaccines in addition to other prevention and treatment strategies.

UN approach

At the end of 2016, former UN Secretary General Ban Ki Moon presented the “New UN System Approach on Cholera in Haiti.” This two-track approach marked the UN's acceptance of responsibility for the introduction of cholera in Haiti and demonstrated its commitment to the eradication of the disease in Haiti. Since the 2016 admission of guilt, there has been increased coordination and goodwill between the Government of Haiti and UN, resulting in great strides towards the elimination of cholera. 2017 was a hallmark year in the elimination of cholera from Haiti. The 2017 – 2018 Haiti Revised Humanitarian Plan reports, “As of 31 December 2017, 13,682 suspected cholera cases and 150 deaths had been registered in the country in 2017 compared to 41,955 cases and 451 deaths for the same period in 2016, a decrease of 67% in both cases.” Newly developed rapid response teams are largely to credit for the reduction in disease incidence. 

The ability for the humanitarian sector to act quickly and bounce back following Hurricane Matthew in 2016, as well as to maintain the downward trend during the heavy rain season, demonstrates progress in the eradication of cholera in Haiti.
Track 1
Track 1 of the New UN System Approach on Cholera in Haiti aims to “intensify efforts to respond to and reduce the incidence of cholera in Haiti” through three main projects.  The first is strengthening and supporting the rapid response framework developed by the Haitian Government which deploys to communities where cholera is suspected within 48-hours. There are currently 13 government led rapid response teams, and 60 mobile teams of humanitarian actors that support the rapid response teams. The goal of rapid response teams is to cut the transmission of cholera by first setting up a perimeter called a cordon sanitaire and investigating the source of the outbreak at the household level. This investigation is coupled with education and awareness raising on cholera prevention, administering oral prophylaxis and distribution of WASH kits.  If an outbreak is confirmed, temporary chlorination points are installed on community water sources. People treated for cholera by the rapid response teams are then recruited to Community Engagement & Hygiene Awareness (CEHA) teams. The CEHA teams return to their communities to conduct outreach and sensitization on how to cut transmission and assist the government in monitoring water sources. This rapid response design with the assistance of the CEHA teams is responsible for a major decline in disease incidence in the Ouest department in 2017. As long as funding continues to support rapid response, a continued decline in disease incidence can be suspected.
 
The second project of track 1 is the continued support of oral cholera vaccination campaigns as a preventative measure.  In 2018, the oral cholera vaccine campaign will focus on departments with the highest incidence of disease, particularly Artibonite and Centre departments.

The final aim of track 1 is to “more effectively address… the medium/longer term issues of water, sanitation and health systems.”  The 2010 earthquake and subsequent cholera outbreak/epidemic exposed to the international community how vulnerable the Haitian water, sanitation, and health infrastructure was. Cholera and other water-borne diseases will continue to circulate in Haiti as long as large sections of their population do not have access to improved water and sanitation facilities. As part of the UN's “New Way of Working” which aims to bridge the development and humanitarian gap, the UN will be working with major development actors including the World Bank and the International Development Bank to address infrastructure vulnerabilities that put Haiti at risk of protracted crisis. The “New Way of Working” aims to draw from funding sources on both sides of the spectrum, both development and humanitarian, to work towards the Sustainable Development Goals.  No joint funded projects have been reported in Haiti yet.
Track 2
The second track of the New UN System Approach on Cholera in Haiti proposes to provide material assistance to individuals and families who were most affected by cholera.  The material assistance package is the UN's attempt at reparations after accepting responsibility for the introduction of cholera in Haiti. The UN reports, “nearly 800,000 Haitians have been infected by cholera since 2010 [as of 2016] and more than 9,000 have died.”  First, consultations will be conducted with the community to identify what materials will be of greatest impact.

Cholera

From Wikipedia, the free encyclopedia
 
Cholera
Adult cholera patient.jpg
A person with severe dehydration due to cholera causing sunken eyes and wrinkled hands and skin.
SpecialtyInfectious disease
SymptomsLarge amounts of watery diarrhea, vomiting, muscle cramps
ComplicationsDehydration, electrolyte imbalance
Usual onset2 hours to 5 days after exposure
DurationFew days
CausesVibrio cholerae spread by fecal-oral route
Risk factorsPoor sanitation, not enough clean drinking water, poverty
Diagnostic methodStool test
PreventionImproved sanitation, clean water, cholera vaccines
TreatmentOral rehydration therapy, zinc supplementation, intravenous fluids, antibiotics
Frequency3–5 million people a year
Deaths28,800 (2015)

Cholera is an infection of the small intestine by some strains of the bacterium Vibrio cholerae. Symptoms may range from none, to mild, to severe. The classic symptom is large amounts of watery diarrhea that lasts a few days. Vomiting and muscle cramps may also occur. Diarrhea can be so severe that it leads within hours to severe dehydration and electrolyte imbalance. This may result in sunken eyes, cold skin, decreased skin elasticity, and wrinkling of the hands and feet. Dehydration can cause the skin to turn bluish. Symptoms start two hours to five days after exposure.

Cholera is caused by a number of types of Vibrio cholerae, with some types producing more severe disease than others. It is spread mostly by unsafe water and unsafe food that has been contaminated with human feces containing the bacteria. Undercooked seafood is a common source. Humans are the only animal affected. Risk factors for the disease include poor sanitation, not enough clean drinking water, and poverty. There are concerns that rising sea levels will increase rates of disease. Cholera can be diagnosed by a stool test. A rapid dipstick test is available but is not as accurate.

Prevention methods against cholera include improved sanitation and access to clean water. Cholera vaccines that are given by mouth provide reasonable protection for about six months. They have the added benefit of protecting against another type of diarrhea caused by E. coli. The primary treatment is oral rehydration therapy—the replacement of fluids with slightly sweet and salty solutions. Rice-based solutions are preferred. Zinc supplementation is useful in children. In severe cases, intravenous fluids, such as Ringer's lactate, may be required, and antibiotics may be beneficial. Testing to see which antibiotic the cholera is susceptible to can help guide the choice.

Cholera affects an estimated 3–5 million people worldwide and causes 28,800–130,000 deaths a year. Although it is classified as a pandemic as of 2010, it is rare in the developed world. Children are mostly affected. Cholera occurs as both outbreaks and chronically in certain areas. Areas with an ongoing risk of disease include Africa and Southeast Asia. The risk of death among those affected is usually less than 5% but may be as high as 50%. No access to treatment results in a higher death rate. Descriptions of cholera are found as early as the 5th century BC in Sanskrit. The study of cholera in England by John Snow between 1849 and 1854 led to significant advances in the field of epidemiology. Seven large outbreaks have occurred over the last 200 years with millions of deaths.

Signs and symptoms

Typical cholera diarrhea that looks like "rice water".
 
The primary symptoms of cholera are profuse diarrhea and vomiting of clear fluid. These symptoms usually start suddenly, half a day to five days after ingestion of the bacteria. The diarrhea is frequently described as "rice water" in nature and may have a fishy odor. An untreated person with cholera may produce 10 to 20 litres (3 to 5 US gal) of diarrhea a day. Severe cholera, without treatment, kills about half of affected individuals. If the severe diarrhea is not treated, it can result in life-threatening dehydration and electrolyte imbalances. Estimates of the ratio of asymptomatic to symptomatic infections have ranged from 3 to 100. Cholera has been nicknamed the "blue death" because a person's skin may turn bluish-gray from extreme loss of fluids.

Fever is rare and should raise suspicion for secondary infection. Patients can be lethargic, and might have sunken eyes, dry mouth, cold clammy skin, or wrinkled hands and feet. Kussmaul breathing, a deep and labored breathing pattern, can occur because of acidosis from stool bicarbonate losses and lactic acidosis associated with poor perfusion. Blood pressure drops due to dehydration, peripheral pulse is rapid and thready, and urine output decreases with time. Muscle cramping and weakness, altered consciousness, seizures, or even coma due to electrolyte imbalances are common, especially in children.

Cause

Scanning electron microscope image of Vibrio cholerae
 
Vibrio cholerae, the bacterium that causes cholera.

Transmission

Cholera has been found in two animal populations: shellfish and plankton.

Transmission is usually through the fecal-oral route of contaminated food or water caused by poor sanitation. Most cholera cases in developed countries are a result of transmission by food, while in the developing world it is more often water. Food transmission can occur when people harvest seafood such as oysters in waters infected with sewage, as Vibrio cholerae accumulates in planktonic crustaceans and the oysters eat the zooplankton.

People infected with cholera often have diarrhea, and disease transmission may occur if this highly liquid stool, colloquially referred to as "rice-water", contaminates water used by others. A single diarrheal event can cause a one-million fold increase in numbers of V. cholerae in the environment. The source of the contamination is typically other cholera sufferers when their untreated diarrheal discharge is allowed to get into waterways, groundwater or drinking water supplies. Drinking any contaminated water and eating any foods washed in the water, as well as shellfish living in the affected waterway, can cause a person to contract an infection. Cholera is rarely spread directly from person to person.

V. cholerae also exists outside the human body in natural water sources, either by itself or through interacting with phytoplankton, zooplankton, or biotic and abiotic detritus. Drinking such water can also result in the disease, even without prior contamination through fecal matter. Selective pressures exist however in the aquatic environment that may reduce the virulence of V. cholerae. Specifically, animal models indicate that the transcriptional profile of the pathogen changes as it prepares to enter an aquatic environment. This transcriptional change results in a loss of ability of V. cholerae to be cultured on standard media, a phenotype referred to as 'viable but non-culturable' (VBNC) or more conservatively 'active but non-culturable' (ABNC). One study indicates that the culturability of V. cholerae drops 90% within 24 hours of entering the water, and furthermore that this loss in culturability is associated with a loss in virulence.

Both toxic and non-toxic strains exist. Non-toxic strains can acquire toxicity through a temperate bacteriophage.

Susceptibility

About 100 million bacteria must typically be ingested to cause cholera in a normal healthy adult. This dose, however, is less in those with lowered gastric acidity (for instance those using proton pump inhibitors). Children are also more susceptible, with two- to four-year-olds having the highest rates of infection. Individuals' susceptibility to cholera is also affected by their blood type, with those with type O blood being the most susceptible. Persons with lowered immunity, such as persons with AIDS or malnourished children, are more likely to experience a severe case if they become infected. Any individual, even a healthy adult in middle age, can experience a severe case, and each person's case should be measured by the loss of fluids, preferably in consultation with a professional health care provider.

The cystic fibrosis genetic mutation known as delta-F508 in humans has been said to maintain a selective heterozygous advantage: heterozygous carriers of the mutation (who are thus not affected by cystic fibrosis) are more resistant to V. cholerae infections. In this model, the genetic deficiency in the cystic fibrosis transmembrane conductance regulator channel proteins interferes with bacteria binding to the intestinal epithelium, thus reducing the effects of an infection.

Mechanism

The role of biofilm in the intestinal colonization of Vibrio cholerae.
 
When consumed, most bacteria do not survive the acidic conditions of the human stomach. The few surviving bacteria conserve their energy and stored nutrients during the passage through the stomach by shutting down protein production. When the surviving bacteria exit the stomach and reach the small intestine, they must propel themselves through the thick mucus that lines the small intestine to reach the intestinal walls where they can attach and thrive.

Once the cholera bacteria reach the intestinal wall, they no longer need the flagella to move. The bacteria stop producing the protein flagellin to conserve energy and nutrients by changing the mix of proteins which they express in response to the changed chemical surroundings. On reaching the intestinal wall, V. cholerae start producing the toxic proteins that give the infected person a watery diarrhea. This carries the multiplying new generations of V. cholerae bacteria out into the drinking water of the next host if proper sanitation measures are not in place.

The cholera toxin (CTX or CT) is an oligomeric complex made up of six protein subunits: a single copy of the A subunit (part A), and five copies of the B subunit (part B), connected by a disulfide bond. The five B subunits form a five-membered ring that binds to GM1 gangliosides on the surface of the intestinal epithelium cells. The A1 portion of the A subunit is an enzyme that ADP-ribosylates G proteins, while the A2 chain fits into the central pore of the B subunit ring. Upon binding, the complex is taken into the cell via receptor-mediated endocytosis. Once inside the cell, the disulfide bond is reduced, and the A1 subunit is freed to bind with a human partner protein called ADP-ribosylation factor 6 (Arf6). Binding exposes its active site, allowing it to permanently ribosylate the Gs alpha subunit of the heterotrimeric G protein. This results in constitutive cAMP production, which in turn leads to the secretion of water, sodium, potassium, and bicarbonate into the lumen of the small intestine and rapid dehydration. The gene encoding the cholera toxin was introduced into V. cholerae by horizontal gene transfer. Virulent strains of V. cholerae carry a variant of a temperate bacteriophage called CTXφ

Microbiologists have studied the genetic mechanisms by which the V. cholerae bacteria turn off the production of some proteins and turn on the production of other proteins as they respond to the series of chemical environments they encounter, passing through the stomach, through the mucous layer of the small intestine, and on to the intestinal wall. Of particular interest have been the genetic mechanisms by which cholera bacteria turn on the protein production of the toxins that interact with host cell mechanisms to pump chloride ions into the small intestine, creating an ionic pressure which prevents sodium ions from entering the cell. The chloride and sodium ions create a salt-water environment in the small intestines, which through osmosis can pull up to six liters of water per day through the intestinal cells, creating the massive amounts of diarrhea. The host can become rapidly dehydrated unless an appropriate mixture of dilute salt water and sugar is taken to replace the blood's water and salts lost in the diarrhea.

By inserting separate, successive sections of V. cholerae DNA into the DNA of other bacteria, such as E. coli that would not naturally produce the protein toxins, researchers have investigated the mechanisms by which V. cholerae responds to the changing chemical environments of the stomach, mucous layers, and intestinal wall. Researchers have discovered a complex cascade of regulatory proteins controls expression of V. cholerae virulence determinants. In responding to the chemical environment at the intestinal wall, the V. cholerae bacteria produce the TcpP/TcpH proteins, which, together with the ToxR/ToxS proteins, activate the expression of the ToxT regulatory protein. ToxT then directly activates expression of virulence genes that produce the toxins, causing diarrhea in the infected person and allowing the bacteria to colonize the intestine. Current research aims at discovering "the signal that makes the cholera bacteria stop swimming and start to colonize (that is, adhere to the cells of) the small intestine."

Genetic structure

Amplified fragment length polymorphism fingerprinting of the pandemic isolates of V. cholerae has revealed variation in the genetic structure. Two clusters have been identified: Cluster I and Cluster II. For the most part, Cluster I consists of strains from the 1960s and 1970s, while Cluster II largely contains strains from the 1980s and 1990s, based on the change in the clone structure. This grouping of strains is best seen in the strains from the African continent.

Antibiotic resistance

In many areas of the world, antibiotic resistance is increasing within cholera bacteria. In Bangladesh, for example, most cases are resistant to tetracycline, trimethoprim-sulfamethoxazole, and erythromycin. Rapid diagnostic assay methods are available for the identification of multi-drug resistant cases. New generation antimicrobials have been discovered which are effective against cholera bacteria in in vitro studies.

Diagnosis

A rapid dipstick test is available to determine the presence of V. cholerae. In those samples that test positive, further testing should be done to determine antibiotic resistance. In epidemic situations, a clinical diagnosis may be made by taking a patient history and doing a brief examination. Treatment is usually started without or before confirmation by laboratory analysis.

Stool and swab samples collected in the acute stage of the disease, before antibiotics have been administered, are the most useful specimens for laboratory diagnosis. If an epidemic of cholera is suspected, the most common causative agent is V. cholerae O1. If V. cholerae serogroup O1 is not isolated, the laboratory should test for V. cholerae O139. However, if neither of these organisms is isolated, it is necessary to send stool specimens to a reference laboratory.

Infection with V. cholerae O139 should be reported and handled in the same manner as that caused by V. cholerae O1. The associated diarrheal illness should be referred to as cholera and must be reported in the United States.

Prevention

Preventive inoculation against cholera in 1966.
 
The World Health Organization (WHO) recommends focusing on prevention, preparedness, and response to combat the spread of cholera. They also stress the importance of an effective surveillance system. Governments can play a role in all of these areas.

Although cholera may be life-threatening, prevention of the disease is normally straightforward if proper sanitation practices are followed. In developed countries, due to nearly universal advanced water treatment and sanitation practices present there, cholera is rare. For example, the last major outbreak of cholera in the United States occurred in 1910–1911. Cholera is mainly a risk in developing countries

Effective sanitation practices, if instituted and adhered to in time, are usually sufficient to stop an epidemic. There are several points along the cholera transmission path at which its spread may be halted:
  • Sterilization: Proper disposal and treatment of all materials that may have come into contact with cholera victims' feces (e.g., clothing, bedding, etc.) are essential. These should be sanitized by washing in hot water, using chlorine bleach if possible. Hands that touch cholera patients or their clothing, bedding, etc., should be thoroughly cleaned and disinfected with chlorinated water or other effective antimicrobial agents.
  • Sewage and fecal sludge management: In cholera-affected areas, sewage and fecal sludge need to be treated and managed carefully in order to stop the spread of this disease via human excreta. Provision of sanitation and hygiene is an important preventative measure. Open defecation, release of untreated sewage, or dumping of fecal sludge from pit latrines or septic tanks into the environment need to be prevented. In many cholera affected zones, there is a low degree of sewage treatment. Therefore, the implementation of dry toilets that do not contribute to water pollution, as they do not flush with water, may be an interesting alternative to flush toilets.
  • Sources: Warnings about possible cholera contamination should be posted around contaminated water sources with directions on how to decontaminate the water (boiling, chlorination etc.) for possible use.
  • Water purification: All water used for drinking, washing, or cooking should be sterilized by either boiling, chlorination, ozone water treatment, ultraviolet light sterilization (e.g., by solar water disinfection), or antimicrobial filtration in any area where cholera may be present. Chlorination and boiling are often the least expensive and most effective means of halting transmission. Cloth filters or sari filtration, though very basic, have significantly reduced the occurrence of cholera when used in poor villages in Bangladesh that rely on untreated surface water. Better antimicrobial filters, like those present in advanced individual water treatment hiking kits, are most effective. Public health education and adherence to appropriate sanitation practices are of primary importance to help prevent and control transmission of cholera and other diseases.
Handwashing with soap or ash after using a toilet and before handling food or eating is also recommended for cholera prevention by WHO Africa.

Surveillance

Surveillance and prompt reporting allow for containing cholera epidemics rapidly. Cholera exists as a seasonal disease in many endemic countries, occurring annually mostly during rainy seasons. Surveillance systems can provide early alerts to outbreaks, therefore leading to coordinated response and assist in preparation of preparedness plans. Efficient surveillance systems can also improve the risk assessment for potential cholera outbreaks. Understanding the seasonality and location of outbreaks provides guidance for improving cholera control activities for the most vulnerable. For prevention to be effective, it is important that cases be reported to national health authorities.

Vaccine

Euvichol-plus oral vaccine for cholera
 
A number of safe and effective oral vaccines for cholera are available. The World Health Organization (WHO) has three prequalified oral cholera vaccines (OCVs): Dukoral, Sanchol, and Euvichol. Dukoral, an orally administered, inactivated whole cell vaccine, has an overall efficacy of about 52% during the first year after being given and 62% in the second year, with minimal side effects. It is available in over 60 countries. However, it is not currently recommended by the Centers for Disease Control and Prevention (CDC) for most people traveling from the United States to endemic countries. The vaccine that the US Food and Drug Administration (FDA) recommends, Vaxchora, is an oral attenuated live vaccine, that is effective as a single dose.

One injectable vaccine was found to be effective for two to three years. The protective efficacy was 28% lower in children less than five years old. However, as of 2010, it has limited availability. Work is under way to investigate the role of mass vaccination. The WHO recommends immunization of high-risk groups, such as children and people with HIV, in countries where this disease is endemic. If people are immunized broadly, herd immunity results, with a decrease in the amount of contamination in the environment.

Sari filtration

An effective and relatively cheap method to prevent the transmission of cholera is the use of a folded sari (a long cloth garment) to filter drinking water. In Bangladesh this practice was found to decrease rates of cholera by nearly half. It involves folding a sari four to eight times. Between uses the cloth should be rinsed in clean water and dried in the sun to kill any bacteria on it. A nylon cloth appears to work as well but is not as affordable.

Treatment

Cholera patient being treated by oral rehydration therapy in 1992.
 
Continued eating speeds the recovery of normal intestinal function. The WHO recommends this generally for cases of diarrhea no matter what the underlying cause. A CDC training manual specifically for cholera states: "Continue to breastfeed your baby if the baby has watery diarrhea, even when traveling to get treatment. Adults and older children should continue to eat frequently."

Fluids

The most common error in caring for patients with cholera is to underestimate the speed and volume of fluids required. In most cases, cholera can be successfully treated with oral rehydration therapy (ORT), which is highly effective, safe, and simple to administer. Rice-based solutions are preferred to glucose-based ones due to greater efficiency. In severe cases with significant dehydration, intravenous rehydration may be necessary. Ringer's lactate is the preferred solution, often with added potassium. Large volumes and continued replacement until diarrhea has subsided may be needed. Ten percent of a person's body weight in fluid may need to be given in the first two to four hours. This method was first tried on a mass scale during the Bangladesh Liberation War, and was found to have much success. Despite widespread beliefs, fruit juices and commercial fizzy drinks like cola, are not ideal for rehydration of people with serious infections of the intestines, and their excessive sugar content may even harm water uptake.

If commercially produced oral rehydration solutions are too expensive or difficult to obtain, solutions can be made. One such recipe calls for 1 liter of boiled water, 1/2 teaspoon of salt, 6 teaspoons of sugar, and added mashed banana for potassium and to improve taste.

Electrolytes

As there frequently is initially acidosis, the potassium level may be normal, even though large losses have occurred. As the dehydration is corrected, potassium levels may decrease rapidly, and thus need to be replaced. This may be done by consuming foods high in potassium, like bananas or coconut water.

Antibiotics

Antibiotic treatments for one to three days shorten the course of the disease and reduce the severity of the symptoms. Use of antibiotics also reduces fluid requirements. People will recover without them, however, if sufficient hydration is maintained. The WHO only recommends antibiotics in those with severe dehydration.

Doxycycline is typically used first line, although some strains of V. cholerae have shown resistance. Testing for resistance during an outbreak can help determine appropriate future choices. Other antibiotics proven to be effective include cotrimoxazole, erythromycin, tetracycline, chloramphenicol, and furazolidone. Fluoroquinolones, such as ciprofloxacin, also may be used, but resistance has been reported.

Antibiotics improve outcomes in those who are both severely and not severely dehydrated. Azithromycin and tetracycline may work better than doxycycline or ciprofloxacin.

Zinc supplementation

In Bangladesh zinc supplementation reduced the duration and severity of diarrhea in children with cholera when given with antibiotics and rehydration therapy as needed. It reduced the length of disease by eight hours and the amount of diarrhea stool by 10%. Supplementation appears to be also effective in both treating and preventing infectious diarrhea due to other causes among children in the developing world.

Prognosis

If people with cholera are treated quickly and properly, the mortality rate is less than 1%; however, with untreated cholera, the mortality rate rises to 50–60%.

For certain genetic strains of cholera, such as the one present during the 2010 epidemic in Haiti and the 2004 outbreak in India, death can occur within two hours of becoming ill.

Epidemiology

Cholera affects an estimated 3–5 million people worldwide, and causes 58,000–130,000 deaths a year as of 2010. This occurs mainly in the developing world. In the early 1980s, death rates are believed to have been greater than three million a year. It is difficult to calculate exact numbers of cases, as many go unreported due to concerns that an outbreak may have a negative impact on the tourism of a country. Cholera remains both epidemic and endemic in many areas of the world. In October 2016, an outbreak of cholera began in war-ravaged Yemen. WHO called it "the worst cholera outbreak in the world".

Although much is known about the mechanisms behind the spread of cholera, this has not led to a full understanding of what makes cholera outbreaks happen in some places and not others. Lack of treatment of human feces and lack of treatment of drinking water greatly facilitate its spread, but bodies of water can serve as a reservoir, and seafood shipped long distances can spread the disease. Cholera was not known in the Americas for most of the 20th century, but it reappeared towards the end of that century.

History

Map of the 2008–2009 cholera outbreak in sub-Saharan Africa showing the statistics as of 12 February 2009.
 
The word cholera is from Greek: χολέρα kholera from χολή kholē "bile". Cholera likely has its origins in the Indian subcontinent as evidenced by its prevalence in the region for centuries.

The disease appears in the European literature as early as 1642, from the Dutch physician Jakob de Bondt's description it in his De Medicina Indorum. (The "Indorum" of the title refers to the East Indies. He also gave first European descriptions of other diseases.)

Early outbreaks in the Indian subcontinent are believed to have been the result of poor living conditions as well as the presence of pools of still water, both of which provide ideal conditions for cholera to thrive. The disease first spread by trade routes (land and sea) to Russia in 1817, later to the rest of Europe, and from Europe to North America and the rest of the world. Seven cholera pandemics have occurred in the past 200 years, with the seventh pandemic originating in Indonesia in 1961.

The first cholera pandemic occurred in the Bengal region of India, near Calcutta starting in 1817 through 1824. The disease dispersed from India to Southeast Asia, the Middle East, Europe, and Eastern Africa. The movement of British Army and Navy ships and personnel is believed to have contributed to the range of the pandemic, since the ships carried people with the disease to the shores of the Indian Ocean, from Africa to Indonesia, and north to China and Japan. The second pandemic lasted from 1826 to 1837 and particularly affected North America and Europe due to the result of advancements in transportation and global trade, and increased human migration, including soldiers. The third pandemic erupted in 1846, persisted until 1860, extended to North Africa, and reached South America, for the first time specifically affecting Brazil. The fourth pandemic lasted from 1863 to 1875 spread from India to Naples and Spain. The fifth pandemic was from 1881–1896 and started in India and spread to Europe, Asia, and South America. The sixth pandemic started 1899–1923. These epidemics were less fatal due to a greater understanding of the cholera bacteria. Egypt, the Arabian peninsula, Persia, India, and the Philippines were hit hardest during these epidemics, while other areas, like Germany in 1892 and Naples from 1910–1911, also experienced severe outbreaks. The seventh pandemic originated in 1961 in Indonesia and is marked by the emergence of a new strain, nicknamed El Tor, which still persists (as of 2018) in developing countries.

Since it became widespread in the 19th century, cholera has killed tens of millions of people. In Russia alone, between 1847 and 1851, more than one million people perished of the disease. It killed 150,000 Americans during the second pandemic. Between 1900 and 1920, perhaps eight million people died of cholera in India. Cholera became the first reportable disease in the United States due to the significant effects it had on health. John Snow, in England, was the first to identify the importance of contaminated water as its cause in 1854. Cholera is now no longer considered a pressing health threat in Europe and North America due to filtering and chlorination of water supplies, but still heavily affects populations in developing countries.

In the past, vessels flew a yellow quarantine flag if any crew members or passengers were suffering from cholera. No one aboard a vessel flying a yellow flag would be allowed ashore for an extended period, typically 30 to 40 days. In modern sets of international maritime signal flags, the quarantine flag is yellow and black. 

Historically many different claimed remedies have existed in folklore. Many of the older remedies were based on the miasma theory. Some believed that abdominal chilling made one more susceptible and flannel and cholera belts were routine in army kits. In the 1854–1855 outbreak in Naples homeopathic camphor was used according to Hahnemann. T. J. Ritter's "Mother's Remedies" book lists tomato syrup as a home remedy from northern America. Elecampane was recommended in the United Kingdom according to William Thomas Fernie.

Cholera cases are much less frequent in developed countries where governments have helped to establish water sanitation practices and effective medical treatments. The United States, for example, used to have a severe cholera problem similar to those in some developing countries. There were three large cholera outbreaks in the 1800s, which can be attributed to Vibrio cholerae's spread through interior waterways like the Erie Canal and routes along the Eastern Seaboard. The island of Manhattan in New York City touched the Atlantic Ocean, where cholera collected just off the coast. At this time, New York City did not have as effective a sanitation system as it does today, so cholera was able to spread.

Cholera morbus is a historical term that was used to refer to gastroenteritis rather than specifically cholera.

Research

Robert Koch (third from the right) on a cholera research expedition in Egypt in 1884, one year after he identified V. cholerae.
 
How to avoid the cholera leaflet; Aberystwyth; August 1849.
 
The bacterium was isolated in 1854 by Italian anatomist Filippo Pacini, but its exact nature and his results were not widely known. 

Spanish physician Jaume Ferran i Clua developed a cholera inoculation in 1885, the first to immunize humans against a bacterial disease.

Russian-Jewish bacteriologist Waldemar Haffkine developed the first cholera vaccine in July 1892.

One of the major contributions to fighting cholera was made by the physician and pioneer medical scientist John Snow (1813–1858), who in 1854 found a link between cholera and contaminated drinking water. Dr. Snow proposed a microbial origin for epidemic cholera in 1849. In his major "state of the art" review of 1855, he proposed a substantially complete and correct model for the cause of the disease. In two pioneering epidemiological field studies, he was able to demonstrate human sewage contamination was the most probable disease vector in two major epidemics in London in 1854. His model was not immediately accepted, but it was seen to be the more plausible, as medical microbiology developed over the next 30 years or so.

Cities in developed nations made massive investment in clean water supply and well-separated sewage treatment infrastructures between the mid-1850s and the 1900s. This eliminated the threat of cholera epidemics from the major developed cities in the world. In 1883, Robert Koch identified V. cholerae with a microscope as the bacillus causing the disease.

Robert Allan Phillips, working at the US Naval Medical Research Unit Two in Southeast Asia, evaluated the pathophysiology of the disease using modern laboratory chemistry techniques and developed a protocol for rehydration. His research led the Lasker Foundation to award him its prize in 1967.
 
More recently, in 2002, Alam, et al., studied stool samples from patients at the International Centre for Diarrhoeal Disease in Dhaka, Bangladesh. From the various experiments they conducted, the researchers found a correlation between the passage of V. cholerae through the human digestive system and an increased infectivity state. Furthermore, the researchers found the bacterium creates a hyperinfected state where genes that control biosynthesis of amino acids, iron uptake systems, and formation of periplasmic nitrate reductase complexes were induced just before defecation. These induced characteristics allow the cholera vibrios to survive in the "rice water" stools, an environment of limited oxygen and iron, of patients with a cholera infection.

Society and culture

Health policy

In many developing countries, cholera still reaches its victims through contaminated water sources, and countries without proper sanitation techniques have greater incidence of the disease. Governments can play a role in this. In 2008, for example, the Zimbabwean cholera outbreak was due partly to the government's role, according to a report from the James Baker Institute. The Haitian government's inability to provide safe drinking water after the 2010 earthquake led to an increase in cholera cases as well.

Similarly, South Africa's cholera outbreak was exacerbated by the government's policy of privatizing water programs. The wealthy elite of the country were able to afford safe water while others had to use water from cholera-infected rivers.

According to Rita R. Colwell of the James Baker Institute, if cholera does begin to spread, government preparedness is crucial. A government's ability to contain the disease before it extends to other areas can prevent a high death toll and the development of an epidemic or even pandemic. Effective disease surveillance can ensure that cholera outbreaks are recognized as soon as possible and dealt with appropriately. Oftentimes, this will allow public health programs to determine and control the cause of the cases, whether it is unsanitary water or seafood that have accumulated a lot of Vibrio cholerae specimens. Having an effective surveillance program contributes to a government's ability to prevent cholera from spreading. In the year 2000 in the state of Kerala in India, the Kottayam district was determined to be "Cholera-affected"; this pronouncement led to task forces that concentrated on educating citizens with 13,670 information sessions about human health. These task forces promoted the boiling of water to obtain safe water, and provided chlorine and oral rehydration salts. Ultimately, this helped to control the spread of the disease to other areas and minimize deaths. On the other hand, researchers have shown that most of the citizens infected during the 1991 cholera outbreak in Bangladesh lived in rural areas, and were not recognized by the government's surveillance program. This inhibited physicians' abilities to detect cholera cases early.

According to Colwell, the quality and inclusiveness of a country's health care system affects the control of cholera, as it did in the Zimbabwean cholera outbreak. While sanitation practices are important, when governments respond quickly and have readily available vaccines, the country will have a lower cholera death toll. Affordability of vaccines can be a problem; if the governments do not provide vaccinations, only the wealthy may be able to afford them and there will be a greater toll on the country's poor. The speed with which government leaders respond to cholera outbreaks is important.

Besides contributing to an effective or declining public health care system and water sanitation treatments, government can have indirect effects on cholera control and the effectiveness of a response to cholera. A country's government can impact its ability to prevent disease and control its spread. A speedy government response backed by a fully functioning health care system and financial resources can prevent cholera's spread. This limits cholera's ability to cause death, or at the very least a decline in education, as children are kept out of school to minimize the risk of infection.

Notable cases

Neurophilosophy

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