With a death toll of more than 2,000 persons (as of this writing) and rising every day, the cholera epidemic in Haiti is major and tragic news. Of course, the impact of this disease is especially devastating in a country that awoke so abrubtly to the earthquake of last January, and where much of the Port au Prince population still lives amid the rubble of that event. Ironically, as sudden and unexpected as the earthquake was, the appearance of cholera on the island this past summer was even less anticipated by many public health agencies.
Last spring, while browsing the internet for health news from Haiti, I read on the CDC (Centers for Disease Control) website that “an outbreak of cholera is very unlikely at this time.” This optimistic reasoning reflected, in part, the observation that epidemic cholera had not been reported from Haiti before. The CDC went on to note that for an outbreak of cholera to occur, certain conditions must be met: “…there must be significant breeches (sic) in the water, sanitation, and hygiene infrastructure used by groups of people, permitting large-scale exposure to food or water contaminated with Vibrio cholera organisms; and… cholera must be present in the population.” Epidemiologists commonly represent the necessary conditions for occurrence of an epidemic with a conceptual “disease triangle”, a shape whose three legs represent essential factors for disease development: susceptible host population, virulent pathogen population, and a conducive environment. The disease triangle looks like the figure below, and theoretically the absence of any one leg would render disease occurrence impossible:
Certainly the population of Haiti was susceptible to this disease; most people around the world are, and while prior exposure to the disease may impart some limited immunity in a population, that isn’t the case for Haiti. CDC correctly identified components of the ‘conducive environment’ leg of the triangle: a breakdown of the water, sanitation, and hygiene infrastructure. However, even pre-earthquake, these systems have long been non-functional over much of Haiti, especially in rural areas. And the final leg of the triangle, presence of a virulent pathogen (i.e., the bacterium Vibrio cholerae), is a true wild card. It’s hard to predict where this organism will show up: certainly it is present in high numbers in the feces of diseased individuals, and anywhere that contaminated fecal material is found including food preparation areas, water supplies, etc. But the bacterium is also an inhabitant of a variety of natural habitats, especially brackish waters where it associates with certain algae and zooplankton as well as with cyanobacteria (‘blue-green algae’). Occasionally persons in the United States have contracted cholera after eating raw contaminated shellfish from the Gulf of Mexico. It is considered possible that a Chinese freighter introduced the pathogen to waters near Lima, Peru, triggering the 1991 cholera epidemic that killed more than 3,500 people. The organism can sometimes be found in freshwater habitats as well. Bottom line, it is difficult to predict where and when the pathogen might show up, and it’s dangerous to assume that it never will.
Some diseases have relatively characteristic symptoms, e.g., the swollen lymph glands (‘buboes’) of bubonic plague, or the cyclic fever which is a hallmark of malaria. The primary cholera symptom is less unique: an acute and copious (though painless) watery diarrhea, often accompanied by vomiting. Many people who ingest the pathogen don’t become noticeably ill, and many others don’t experience serious illness. However, for the approximately 20% who develop advanced symptoms of cholera, dehydration and death can occur rapidly.
For most of us in the U.S., of course, even the mildest cholera-like symptoms would be cause to seek immediate medical attention, which can be as basic as rapid and sustained rehydration with (clean) water and replenishment of electrolytes. In much of Haiti, however, the main initial symptom of cholera, watery diarrhea, is unfortunately a routine fact of life, and can be caused by a variety of agents besides Vibrio cholerae. These pathogens share the characteristic of being spread via fecal contamination of food and water. They include norovirus (Norwalk-like viruses), rotavirus, enterotoxigenic Escherichia coli, Giardia, and cryptosporidia. Clinically, they are pretty much indistinguishable from each other. Many Haitians endure chronic infections with one or more of these pathogens, so that diarrhea is a very common illness. It is a leading cause of death (as high as 16% of deaths) among children. However, as for cholera, the prevention of all these sources of illness is potentially straightforward: clean drinking and cooking water, clean food preparation facilities, and adequate human waste disposal systems. Hence the title of this article, because both the underlying problems, and their eventual solution, transcend even the tragedy of the current cholera epidemic. The health of a country depends on their solution.
Development of a sustainable, microbiologically-based human waste composting system for rural Haiti. A number of rural Haitian towns, such as on the island of La Gonâve (population 160,000), have become de facto large urban areas, due to immigration of earthquake refugees from Port-au-Prince. Water supplies in many villages consist of springs, from which containers of water must be carried by hand, often for long distances. Most sanitation facilities in rural Haiti, primarily pit toilets, were implemented without adequate consideration of waste treatment. Sometimes, the shortage of even pit toilets forces people to simply defecate on the ground. It isn’t surprising that human waste, often containing microbial pathogens, frequently ends up in local water supplies.
(photos: L.M. Dandurand, J. Boughton)
As an alternative to traditional pit toilets, composting toilets have been introduced to a number of villages throughout Haiti. Potentially, composting toilets offer a way to separate human waste from water sources, and, if properly implemented, can even provide badly needed fertilizer for small-scale agricultural use. Paloma Institute is providing support to a citizens’ group, Liberte, in the village of Bwanwa, La Gonâve, for education and training in sanitation and water quality issues related to human waste, as well as construction and implementation of composting toilet systems. This project, still in its early stages, is funded by the generous contributions of our donors, and we hope to be able to fund a significant expansion in the near future.
Although composting toilets are being implemented in much of the developing world, impediments to their sucessful and sustainable use include low composting efficiency in some environments, problems with odor and filth flies, and uncertainty about potential pathogen survival in composted waste. At Paloma Institute, we are actively pursuing additional funding, from both private donors and major granting agencies, to address these problems in a comprehensive program involving fundamental research, education, and collaboration with local citizens’ groups for effective and sustainable implementation. Our overall goal is to address the above problems using a novel and holistic approach that focuses on identification and augmentation of efficient (fast, odor-minimizing) microbial consortia, determining and verifying the process parameters necessary for pathogen elimination to safe levels, and microbial source tracking to verify the fate of waste-associated microorganisms. These will be implemented in an inexpensive modular system using locally-available biodegradable materials.
For more information about our Haiti sanitation project, or about our related projects in environmental protection, agriculture, public health, and the arts, please contact us at email@example.com or visit our website: http://www.paloma-institute.org
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