Monday, October 02, 2006

Chagas Disease



Chagas is a disease caused by a protozoan called Trypanosoma cruzi. You haven´t heard of of Chagas? Maybe because it is only a big problem in poor areas of Central and South America. Chagas was deemed one of the "neglected diseases," along with Kala-Azar (visceral leishmaniasis), and sleeping sickness (aka Human African Trypanosomiasis), by the a non-profit called Drugs for Neglected Diseases (DNDI). DNDI was founded by seven organizations in 2003. They work with scientists and pharmaceutical companies to develop better diagnostic tests and treatment for diseases that primarily affect poor people. Poor countries cannot afford newly patented expensive drugs. Who wants to waste time designing drugs for a feeble market?

Anyway, MSF-Espana has done a lot of work on Chagas. There are on-going projects in Bolivia, Ecuador, and Olopa, Guatemala. The four bad-ass women who run the Olopa project will hand over their project to the Guatemalan local health authorities and close up the office in November 2006 (see friends from Olopa, below).

The skinny on Chagas: T. Cruzi is passed via the reduviid bug "kissing big" (see pic above left). These insects live in the cracks of poorly constructed wood houses. At night, the bugs suck blood from sleeping children, thendefecatee on their skin. When the kid scratches his itchy bug bite, the parasite is passed from the bugs fecal matter into the patient´s blood stream through small breaks in skin.

Chagas is particularly difficult to diagnose because it has a long asymptomatic stage. After the initial bug bite/feces inoculation, the parasite passes from the blood stream into muscle and nerve cells. The acute disease is generally a mild flu-like illness that goes undetected by the patient and/or doctor. After the innocuous acute phase, the parasite load in the blood stream falls, and the patient feels well. Several decades pass.

Twenty to thirty years after the initial infection, about 50% of Chagas patients become ill with the chronic phase. The most common manifestations are cardiomyopathy (heart failure) and megacolon (gastrointestinal disease). By the time a patient becomes symptomatic in the chronic phase, Chagas is almost impossible to treat.

In some United States tertiary referral hospitals (e.g. a certain Northern Manhattan medical center), some patients with Chagas are candidates for heart transplants (if they are lucky enough to have Medicaid or other health insurance, of course). I saw exactly one patient with Chagas in my 10 years in at the northern manhattan medical center. Several months after a heart transplant saved this patient´s life, her new heart failed. The medical team suspected that the parasite load increased while the patient was on immunosuppresant drugs, then the parasite swarm infected her new heart! I cannot remember whether this theory was ever proven by heart biopsy.

For more info on Chagas (including pics of Olopa), check out the MSF-Espana website "virtual Chagas tour."

1 comment:

whats_in_a_name? said...

This was a really interesting post. How often do you see chagas now that you are in Guatemala? How do you treat chagas prior to the chronic phase?