January 12, 2010 Haiti was hit with a massive and devastating earthquake. It’s expected that following such a natural disaster, homes, public buildings, and roads would be damaged, and many lives lost in the rubble. One can even imagine that people will be without lights, food, and housing for extended periods of time, but what is forgotten is that in the aftermath of an earthquake, there comes flooding. Flooding of rivers and land, and the flooding of humanitarian aid workers from afar. Tragically, this flooding has led to the introduction of a pathogen into Haiti that has claimed the lives of many and complicated the recovery from the 2010 earthquake, that leveled the country. The pathogen responsible is Vibrio Cholerae, which causes Cholera. Although pandemic, Cholera had not been seen in Haiti in over a century.
Since Haiti had not been touched by this disease in a century, then where did the Cholera come from?
Recently, the United Nations has publicly acknowledged and taken responsibility for the outbreak in Haiti; though it had already been researched and reported that Cholera entered Haiti with the influx of U.N. troops from parts of the world where Cholera is endemic.
The first victims lived near a base housing 454 United Nations peacekeepers freshly arrived from Nepal, where a cholera outbreak was underway, and waste from the base often leaked into the river. Numerous scientists have since argued that the base was the only plausible source of the outbreak…New York Times
The Pathogen that Causes Cholera
Vibrio Cholerae (V. cholerae) is an anaerobic, facultative, curved bacillus, gram negative bacteria, causing acute Diarrhea. V. cholerae grow best in salt water and are naturally found in estuaries and marine waters; in association with chitinous organisms (algae and shellfish). Cholera can be indistinguishable from other diarrheal illnesses.
History of Cholera
Cholera is endemic to the India Subcontinent and spread from Asia to the rest of the world. There have been 6 documented pandemics of Cholera from 1817 – 1923. A 7th pandemic that began in 1961 and persists till today, originated in Indonesia and spread to Asia, Europe, and Latin America. It was first proposed in 1849 that Cholera was a communicable disease and was spread through human stool. In 1854 the bacterium was first observed under the microscope, it was finally isolated in 1884 by Robert Koch.
There are many species and serogroups of V. Cholerae and these are further divided into serogroups, based on the O antigen of the lipopolysaccharide outer casing of the bacteria. Of these, only two serogroups are pathogenic (able to cause illness): Serogroup O1 and O139. The first 6 epidemics are identified as Classical Cholera, while the latest epidemic is identified as biotype El Tor. The El Tor biotype of V. Cholerae was isolated in 1905 in El Tor, Egypt. El Tor is a recent variant that is responsible for the 7th and present pandemic wave of Cholera that started in 1961. The type of V.Cholerae responsible for the current Cholera outbreak in Haiti is of serogroup O1, and biotype El Tor.
Pathogenesis of Cholera
The way Cholera presents itself in endemic regions and how it is transmitted is why U.N. workers who were infected with the bacterium may not have known that they were sick when volunteering to enter the country. Infection caused by V. cholerae is often mild and asymptomatic. The pathogen is shed in the stool of infected individuals. In asymptomatic individuals for a few days, but in symptomatic individuals for up to 2 weeks from onset of symptoms. Additionally, recently shed V. cholerae from humans is more infectious than the organism normally would be when naturally present in the environment.
Transmission. V. Cholerae is acquired from contaminated food and water. Upon ingestion some of the bacteria are killed immediately by the gastric acid present in the stomach, but bacteria that survive go on to colonize the small intestine. There the bacteria attach to the mucosal lining of the intestinal tract and begin to release Cholera toxin – a virulence factor responsible the pathogenesis of the bacterium.
Cholera toxin is a protein exotoxin that consists of two subunits. Subunit A has one component, and subunit B has five. Subunit B is responsible for the attachment to eukaryotic cells, which then allows subunit A to translocate into the cell. Inside of the cell Subunit A functions as an enzyme (catalyzes reactions more rapidly) an activates adenylate cyclase. Activation leads to a rise in intracellular cyclic AMP, resulting in Chloride secretion .
Simply put, cholera toxin causes electrolyte imbalance which disrupts fluid retention, ultimately triggering diarrhea. There is a second virulence factor — toxin-coregulated pilus —responsible for colonization.
Signs & Symptoms
The characteristic symptom of Cholera is persistent watery diarrhea. Within 2 to 3 days of ingestion, diarrhea develops and may be accompanied by vomiting. Massive loss of body fluid due to electrolyte imbalance progress to dehydration and metabolic acidosis; urine output decreases and blood pressure drops. Without intervention, shock, cardiovascular collapse, and death can occur when enough fluid is lost. Acidosis causes muscle cramping and weakness. Sunken eyes, dry mouth, and cold clammy skin, and lethargy are additional signs of infection with Cholera.
Fever is not associate with Cholera, but if present it is indicative of a secondary infection by another pathogen.
In children, hypoglycemia can develop due to depletion of glycogen stores and impairment of glucogenesis. Hypoglycemia, if severe, can result in altered consciousness, seizures, and coma.
Susceptibility to Cholera
Populations, like that of Haiti, that are immunologically naïve to cholera are more susceptible to developing severe Cholera, and to having a high fatality rate. The El Tor O1 strain responsible for the Haitian epidemic is also associated with inducing a more severe illness. These factors help explain the seemingly high rates of fatality associated with Cholera in Haiti.
Malnutrition that resulted after the earthquake coupled with immunological naivety primed the Haiti’s populace for infection. Malnutrition contributes to the severity of Cholera. Retinol (vitamin A) deficiency has been implicated in susceptibility.
Treatment and Prevention of Cholera
Hydration Therapy. The main treatment for Cholera consists primarily of aggressive rehydration with isotonic fluids; either intravenously or orally. It is important to replace the fluid loss due to diarrhea, but just drinking water is not sufficient. Electrolytes and energy also have to be replaced; fluids containing sodium and glucose given orally are best.
Antibiotic Therapy. Antibiotics are secondary to hydration, and are given adjunctively. Antibiotic therapy helps to reduce the duration and volume of diarrhea, but it is mainly indicated for use in cases of moderate to severe dehydration, as antibiotic resistance to Tetracycline, Doxycycline, and Ciprofloxacin has developed in V.cholorae . Antibiotic therapy improves the condition by 50%; lessening the duration of bacterial shedding; which is critical in reducing the spread of Cholera.
Oral Cholera Vaccine (OCV).
There are two vaccines that are indicated for the prevention of Cholera infection; Dukoral and Shanchol are oral, killed, vaccines that are both safe and immunogenic, (induces a humoral/cell-mediated response in the body that confers long-lasting protection) for up to 2 or 3 years. Much like antibiotics, OCVs reduce the amount of the V. cholerae in the stool and reduce the severity of illness, should infection occur. The vaccine does not necessarily protect against infection, and is therefore not suggested for mainstream use.
However, the use of the oral cholera vaccines and antibiotics as prophylaxis are being recommended for the prevention of the international spread of Cholera during personnel deployment from countries that are endemic for Cholera.
Supplements in the Remediation of Malnutrition.
Vitamin A and Zinc have been shown to improve recovery from Cholera infection. Potassium , Magnesium, and Calcium supplements aid in reestablishing the electrolyte imbalance and alleviate muscle cramping.
The spread of Cholera into Haiti by troops from the United Nations Peacekeeping Mission after the 2010 earthquake was not intentional. Cholera is a water-borne disease, and large outbreaks of cholera are related to contamination of water supplies with fecal matter containing shed bacterium of V.cholerae. Without the proper infrastructure for sanitation and water treatment, waste water from U.N. facilities, leached into the Artibonite watershed. Flooding compounded the situation by spreading contaminated water throughout the environment. The first cases were seen in adult men who worked in fields that were downstream from the U.N. base.
The strain of Vibrio Cholerea that was identified as causing this recent outbreak of in Haiti diverged from strains that were currently circulating in Nepal; at the time when almost 500 troops from Nepal were deployed to Haiti.
As Cholera is known to spread from person to person, especially among members of the same household, it is imperative that not only are advanced water and sanitation programs vital, but personal care must be taken to wash your hands thoroughly, and not to share food or drink with sick individuals. Treatment with antibiotics are not necessary, but are helpful in decreasing the severity and duration of illness. Most important is to re-hydrate the individual with fluids containing electrolytes and glucose, followed by aggressive replacement of fluids with copious amounts of water. Where people cannot reach medical facilities, administering broth-like soups such as chicken soup, which contain ions like chloride and sodium, are beneficial. Rice water (due to magnesium) has been used to help ameliorate the symptoms of cholera, ironically enough since the diarrhea caused by Cholera resembles water that has been used to wash rice.
Screening for V. cholerae, administering antibiotic prophylactics, and immunizing with oral cholera vaccine, of personnel before deployment, is recommended for the prevention of incidences like the this one, that has claimed the lives of nearly 9,000 Haitians from happening again.