NEWS & INSIGHTSPublic Health

Chagas: A Tropical Disease Born in the Home

Above: The disease is spread through vector species known as triatomine bugs. (Image: Jim Gathany)

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Migration routes from Latin America and estimation of the total number of infected individuals in non-endemic countries. (Image: Nature)

A little known tropical disease, Chagas was recently compared to the HIV/AIDS epidemic in its first two decades. Like AIDS, its long incubation time, the lack of good treatments, and a widespread ignorance of its existence have allowed it to spread with little resistance, primarily throughout Latin America. With prevention being the most effective approach at the moment, one solution lies in the disease’s inherent link to housing materials and conditions.

The disease is spread through vector species known as triatomine bugs. The insects ingest the parasite when taking a blood meal from infected animals or humans. The parasite is then spread through their feces, either by contact with the bite wound or by subsequent contact with the eye, nose, and mouth mucosa. Chagas can also be spread by blood transfusion, ingesting contaminated foods, and from mother to fetus.

The symptoms of the acute phase are minor and often overlooked: only 50% of infected people may show a marked swelling or rash in one eye, and some flu-like symptoms such as prolonged fever and malaise may appear within about 2 months of infection. After this initial phase, a chronic phase begins that can last years, again frequently unnoticed. This phase involves irreversible damage to the heart, intestines, and nervous system, often culminating in debilitating health complications and death. There are currently only two existing medications to treat Chagas, which lose effectiveness after the acute phase and are often in short supply, with instances of parasite resistance also being reported. An estimated 7 to 8 million people are chronically infected worldwide.

The chronic phase can last years, frequently unnoticed, and involves irreversible damage to the heart, intestines, and nervous system, often culminating in debilitating health complications and death. Above: Gross pathology of chronic Chagas cardiomyopathy (Image: eMedMD)
The chronic phase of Chagas can last years, frequently unnoticed, and involves irreversible damage to the heart, intestines, and nervous system, often culminating in debilitating health complications and death. (Image: eMedMD)

While triatomine bugs feed at night, during the daytime they require dark cracks and crevices to dwell in, specifically the gaps resulting from mud, straw, and certain brick and wood constructions. The WHO recommends eliminating these conditions as an effective way of minimizing and even eliminating triatomine populations. The improvements entailed are relatively simple and inexpensive, and can be entirely implemented at a community level. Mud construction should be plastered to fill in all cracks or gaps, and a layer of cement should be added. All flooring should also be smoothed, compacted, and covered with cement. Straw roofs should be replaced with tiles or corrugated metal. Community-based programs involving local labor and construction materials have been shown to successfully eliminate triatomine infestations in numerous Latin American countries, but greater action and awareness is needed.

As with any housing development, the use of local labor and materials engages the local economy and makes for independent, cooperative communities. However, making sure that programs are community-based is of particular importance with Chagas disease. As the insects can migrate short spaces, it is important that all structures in the community, including public spaces and animal dwellings, be improved and regularly checked for necessary maintenance. Such solutions are an important option or supplement to insecticide spraying, which is temporary, expensive, and risky, as insects can develop resistance. Moreover, these simple housing improvements have health benefits that extend beyond Chagas.

Facing an expanding disease without a reliable cure, a better understanding of the scope of prevention is necessary. Housing improvement is not only inherently linked to the Chagas problem: it is a long-term, cost-efficient, community-based solution with added health and socioeconomic benefits to individuals.

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