What is cholera?

Cholera is the clinical disease caused by a bacterium known as Vibrio cholerae. Cholera outbreaks have occurred over the centuries, and seven pandemics have been described since the bacterium was first identified. The current pandemic (started in 1992) is caused by the O1 El Tor biotype. We do not yet know if the Haiti outbreak features the current pandemic strain yet; those laboratory details are still being investigated by teams of field investigators in Haiti.

What illness is caused by V. cholerae?

Cholera is remarkable for its ability to cause profuse watery diarrhea without much in the way of fever or chills. While many bacterial infections kill by dissemination into the bloodstream to sepsis, cholera kills by acting locally in the small intestine to cause dehydration in a matter of hours. Severe and fatal infections may occur even in those without underlying illnesses, though elderly patients and children are at greater risk of death from infection. Not all cholera infections are severe, however. Many recover from cholera without even having symptoms.

The incubation period of cholera is anywhere between two hours to five days. The bacteria can remain present in the feces of infected patients for 7-14 days after infection and are shed back into the environment, potentially infecting other people.

How extensive is the current outbreak?

Only a specific part of northern Haiti appears to be afflicted so far. Though some cases have been described in the capital (Port-au-Prince), these cases were acquired elsewhere. Keeping in mind the weakness of the infection surveillance system in Haiti, the outbreak appears to be confined to the northern area of Haiti that was not afflicted by the January outbreak. However, as the water supply in Port-au-Prince may not be safe (see below), it would not take much for a new outbreak to erupt there.

How is cholera acquired, and how does it spread? How is it prevented?

In many underdeveloped countries -- Haiti being a case in point --, the water supply is directly or indirectly contaminated with sewage at the best of times. Cholera is contracted by ingesting the bacterium that contaminates the water supply.

Alternatively, washing fruit and vegetables with the same contaminated water, followed by failure to adequately cook the same may allow for infection to occur. Keep in mind that in underdeveloped countries, many do not have electricity or cooking fuel to allow for proper cooking or boiling – seemingly measures to prevent infection. In some cases, household spread may occur if a patient with cholera does not wash their hands properly and then contaminates food.

Or, the bathroom facilities (often rudimentary in underdeveloped countries) may be contaminated and allow for others to acquire the infection if they touch contaminated surfaces and fail to wash their hands properly. All of the above considerations explain why the shantytown "tent cities" of Port-au-Prince are concerning as sites of further outbreaks.

How is cholera treated?

If caught early, cholera can easily be treated with oral rehydration solution -- a simple mixture of water, sugar and salt to replace lost fluids. This nearly always results in cure. In especially severe cases, giving fluids through IV may be required. Antibiotics, though of secondary importance, may shorten the duration of the illness, and may decrease the contagiousness of cases.

Is there a connection with the January 2010 earthquake, and the current cholera outbreak?

Though cholera was one of the dreaded consequences of the Haiti earthquake, this outbreak is unrelated and is not a consequence. We know this because the outbreak area is distinct geographically from where the earthq damage was greatest. However, the earthquake has displaced a large number of people who now live in squalid, unhygienic conditions, increasing the risk for the spread of the outbreak if it reaches Port-au-Prince.

Why is Haiti experiencing an outbreak now, after so many years without an outbreak?

This remains an unknown, as the last case of cholera in Haiti occurred in 1961. Cholera may go into a dormant state in rivers, only to cause disease at a later date. Alternatively, a person (with or without symptoms) who acquired the infection elsewhere might have used a latrine in the outbreak area, indirectly allowing for contamination of the water supply.

Could it spread to Canada, or be encountered by Canadians?

In the worst case scenario, a Canadian tourist could contract cholera if the outbreak were to spread to the neighbouring Dominican Republic. However, further spread within Canada would be almost impossible, as we have a safe drinking water supply that is not contaminated by sewage.

Is there a vaccine to prevent infection?

The currently available generation of vaccines are not highly effective, and take too long to offer protection in the setting of an outbreak.

Is the Dominican Republic affected?

Haiti and the DR share the same island, named Hispaniola, but so far, it appears that cholera hasn't spread outside of Haiti. The Dominican Republic has sealed its border with Haiti, banning most Haitians from entering the country. Health authorities in the DR have also ordered doctors to be on alert for patients with acute vomiting or diarrhea.

If you have a question about cholera, send them along to health@ctv.ca, or leave a comment at the end of this post, and we'll do our best to answer them.