9 Jul 2011

Chagas Disease

Diagnostic breakthrough
Nymph of Triatoma infestans, the kissing bug or vinchuca,
the primary vector of Chagas, feeding on a human arm.

Chagas disease is one of the most deadly parasitic diseases in the world. It affects more than 10 million people, primarily in the Americas. In South America it kills 50,000 people a year. A reliable and rapid diagnosis has been a key goal in the fight against infection, but until now, it has never been achieved-Momar Ndao and his associates at the Research Institute of the McGill University Health Centre in Montreal have reported their success in developing a method of diagnosis where others have failed. Their results were recently published in the Journal of Clinical Microbiology.

Regions (red) where Chagas is endemic

Endemic in South America and southern Central America, Chagas disease, also known as American trypanosomiasis, is caused by the parasite Trypanosoma cruzi. Usually, the disease is transmitted through the bite of an infected insect or ‘kissing bug’. The symptoms are variable, but as the disease progresses serious chronic symptoms can appear, such as heart disease and malformation of the intestines. Most people affected may remain without symptoms for years, making diagnosis difficult.
Chagas disease is also transmitted from mother to unborn child and can be passed on for as many as four generations without symptoms. "In other words, a person born in North America by a mother who was infected can transmit the disease to offspring without having traveled," says Ndao, Laboratory Director of the National Reference Center for Parasitology (NRCP) of the Research Institute. They can also unknowingly donate infected blood. There is an urgent need for action on this disease as it is under-diagnosed and there is no effective treatment.
This situation raises some serious public health concerns with respect to blood transfusions and organ transplants, because many people may be silent carriers of the disease. "The aim of our study was to find new approaches to improve reliability of diagnosis and screening of blood banks," says Ndao, who is also a researcher at the Centre for Host Parasite Interactions at McGill University.
The researchers have created a reliable screening technique using mass spectrometry technology that identifies common biological markers - or biomarkers - between the interaction of host (humans) and the parasite. They found that in 99% of cases, the parasites left very specific markers. 'It's as if the parasite left his own signature in the infected person,” says Ndao.
"The use of these biomarkers is a revolution in diagnostic confidence and protection of possible contamination of blood banks,” says Ndao “Moreover, these biomarkers have potential therapeutic effects of paving the way for the development of vaccines for Chagas, which could be extended to other parasitic diseases.”

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