Cholera was a far-away kind of affliction, almost an abstraction, when I first studied microbiology in 1984. The legendary, infectious scourge still affected people in places like Bangladesh or Indonesia, but was a treatable condition that, surely, would be eradicated within a decade or so through progress, if you could call it that, like basic plumbing and sanitation.

The tiny comma-shaped bacteria, Vibrio cholerae, tend to thrive in brackish water, the kind that’s just a bit salty from a mix of ocean and fresh sources. These sometimes stagnant watery places crop up in river deltas, like the Ganges, and coastal estuaries such as those along the U.S. Gulf Coast. We learned that you might, very rarely, pick up a case of cholera by eating contaminated shellfish like crabs or oysters.

The most common symptom of cholera is diarrhea, so rapid and voluminous that a person can die, quickly if without remedy, by straightforward dehydration. The diagnosis of cholera can be tricky, as many people are afflicted with severe gastrointestinal diseases worldwide, but most don’t have this particular, potent toxic germ. Cholera spreads by contamination of infected human feces in the water supply. The disease can afflict people who drink tainted water, who touch it and then put unclean fingers into their mouths, as children do, and who eat food prepared by those with affected hands.

illustration by Robert Seymour (1831), image from the National Library of Medicine, image A021786

Choleraphoby, illustration by Robert Seymour (1831), lithograph from the National Library of Medicine, Image #A021786

Dr. John Snow, an anesthesiologist and founder of public health, recognized the means of cholera’s spread more than 150 years ago in London, where he became famous for mandating the closure of the Broad Street Pump. Snow died at the age of 45, of what was said to be apoplexy, old jargon for a stroke.

In 2009, there were 221,226 cholera cases reported and 4,946 cholera deaths in 45 countries, according to the CDC. Based on information put together by the World Health Organization, the case-fatality rate is 2.24%. A trend in recent years is that the overwhelming majority of cases, roughly 99 percent, are reported in Africa.

According to the 17th edition of Harrison’s Principles of Internal Medicine, there have been seven global cholera pandemics since 1817. The current rage, attributed primarily to the El Tor biotype, started in Indonesia around 1961. That strain spread, eventually, as far as coastal Peru in the early 1990s. There have been no cholera epidemics in North America since the middle of the 19th Century.

What’s happening in Haiti now is the real deal, says the CDC. Thousands are infected, mainly in towns along the Artibonite River, which squiggles on the map and in real terrain through the western section of Hispaniola, north of Haiti’s capital, Port-Au-Prince. Among other concerns are the vast numbers of people living without toilets in tent cities and slums outside of the capital, especially since an earthquake devastated the region last January.

The CDC offers some very practical tips for people who live or travel in areas where cholera is endemic. Most people who are exposed to cholera and survive become immune, although infectious strains vary and immunity may not be long-lasting. In the U.S. there is no available vaccine for cholera, according to the CDC. Treatment consists primarily of giving electrolyte solutions, for rehydration, and antibiotics in some cases.

Now, the mortality rate from cholera in Haiti is running just under 10 percent, according to today’s news. Hopefully, doctors from MSF and other agencies working in the region will get this epidemic under control. But already it’s clear that hundreds of lives have been lost to an illness that it seems should have been eradicated long ago.

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