Friday, March 20, 2009

Fewer Forests, More Chagas

"Guatemala became the first country in Central America to be declared free of Chagas’ disease transmission by the WHO (World Health Organisation)," said Monroy, the founder of the laboratory of entomology and parasitology at the University of San Carlos School of Science and Pharmacy in Guatemala.

The Swiss-educated scientist said that a decade ago, hundreds of cases of Chagas’ disease were reported annually in her country. But this year, after several years of work with local communities, "we have controlled the problem, using a holistic approach," she said.

There is no cure or vaccine for the often deadly Chagas' disease, and in most cases only treatment of symptoms is possible.

The disease is caused by the bite of the reduviid bug, which lives in crevices and gaps in poor rural housing - like thatch, mud or adobe huts - in a number of Latin American countries.

The bug transmits a protozoan parasite named Trypanosoma cruzi through its faeces, which human victims unwittingly rub into the bite wound left by the bug, or into their eyes, mouth or nose. The parasites thus enter the victim's bloodstream and gradually invade organs of the body, often causing severe damage to the heart, digestive tract or nervous system.

The disease has three stages: acute infection, in which symptoms occur soon after infection; an asymptomatic phase, which can last months or years; and chronic infection.

In the first stage, which only a small minority of patients suffer, symptoms include swelling of the eye on one side of the face, exhaustion, fever, enlarged liver or spleen, swollen lymph glands, a rash, loss of appetite, diarrhea and vomiting.

Symptoms in the chronic stage can appear years or even decades after infection. Health problems include serious, irreversible damage to the heart or intestinal tract.

Monroy said that most reduviid bugs live in the forests, and that "when we cut down the forests, the bugs have to go somewhere, and we provide them with ideal conditions. What temperature does the bug like?...23 degrees Celsius, the same temperature I prefer, so they come to our homes where it is warm, slightly damp, and dark," she said.

"We provide the conditions that make Chagas’ disease a public health problem," said the scientific researcher.

Monroy works with health authorities in Guatemala to combat the spread of the disease, with the direct participation of affected communities. Local communities are taught about the disease and its characteristics, and with that information, they adapt their homes to keep the reduviid bug out and to live in harmony with the environment, she said.

Only an "integrated approach that leaves aside spraying as the sole method for fighting the disease" is effective, said the scientist.

PAHO reports that the socioeconomic impact of Chagas’ disease in Latin America is extremely high, ranking it behind respiratory infections, diarrhea and HIV/AIDS.

"In Guatemala we have curbed the disease; we no longer have a significant number of cases, thanks to the integral approach. If this strategy is applied in the rest of the countries, the battle will be won," said Monroy. (END/2008)

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