Haiti's Cholera Outbreak

February 11, 2011 (Vienna, Austria) — The cholera epidemic that developed in Haiti became a multifocal event as it spread throughout South America, due to factors such as air travel and immigration that act as "vectors" of infectious disease, a new report suggests.

The findings were reported by Jennifer Malaty, from the Georgetown University Medical Center, in Arlington, Virginia, here at the IMED 2011: International Meeting on Emerging Diseases and Surveillance.

"Cholera's sudden emergence in the Americas and the Caribbean after 100 years of silence was a tragic reminder of how mobile pathogens have become," Ms. Malaty told Medscape Medical News. "The [Haitian] population also had the disadvantage of being immunologically naïve," she said.

According to the researchers, local laboratories confirmed that the form of cholera detected in Haiti is commonly found in South Asia and Africa, and that the outbreak originated from contaminated water near a facility that housed Nepalese troops.

Subsequent to the cholera outbreak in Haiti, the migration of humans led to sporadic clusters of cholera cases in new and previously unaffected regions.

By November 16, 2009, the Dominican Republic detected its first case of cholera in a migrant worker who had returned home from Haiti after the outbreak.

Suspected cases of cholera have since been reported in Bolivia, Brazil, Chile, Colombia, Nicaragua, Panama, Peru, and Venezuela. Confirmed imported cases have been reported in Florida. The CDC has reported 13 suspected imported cases, with 5 confirmed as of December 2010.

Based on models of previous cholera spread, the researchers estimate that up to 200,000 cases could arise in the Caribbean in the next 18 months.

"International bonds, the ease of direct flights, and better medical and professional opportunities abroad [compared with in Haiti] have turned the cholera outbreak into a multifocal disease event," the researchers conclude.

According to Ms. Malaty, the study of emerging outbreaks must have both a microscope and a macroscope. Although there is value in case counts and case fatality ratios, diseases are never bound by national borders, she said.

"Biosurveillance is a multidisciplinary field that is influenced by culture, language, history, economics, and sadly, politics," she added. "Monitoring of diseases must be flexible, both in sources of data and in analysis."

Scott F. Dowell, MD, MPH, from the CDC's Division of Global Disease Detection and Emergency Response, and colleagues from the CDC recently authored a Perspective in the New England Journal of Medicine (2011;364:300-301). According to Dr. Dowell and colleagues, when cholera struck in mid-October, it "moved easily from sewage to drinking water sources and spread within 2 months to all departments (provinces) of the country, sickening more than 170,000 people and killing more than 3,600 by December 31, 2010."

"Cholera spreads easily across international borders, and it is likely that occasional importations to other countries in the region will continue," Dr. Dowell told Medscape Medical News. "Fortunately, it is unlikely to cause epidemic disease in places like Florida, where clean water and improved sanitation systems are in place."

He added that "clinicians in the region should remain aware of the possibility of importation, take careful travel histories, recognize the clinical features of cholera and the potential for rapid and dangerous dehydration, and be prepared to treat individual cases and report them to the local public health authorities."

According to the CDC, rehydration is the cornerstone of treatment for cholera. Oral rehydration salts and, when necessary, intravenous fluids and electrolytes, if administered in a timely manner and in adequate volumes, will reduce fatalities to well below 1%. In addition, antibiotics, indicated in severe cases, reduce fluid requirements and duration of illness.