Since Dan will be working with Chagas patients, we want to give all our non-medical friends and family a quick overview of this disease.
Chagas disease is an infectious, parasitic disease caused by the bite of the reduviid bug (“vinchuca” in Spanish). This “kissing bug” is endemic in Central and South America (including the Texas-Mexico border), affecting approximately 8 million Latinos with another 109 million at risk for infection (20% of the Latin American population). The bug is a nocturnal assassin, biting humans on the face (Romaña’s sign) while asleep. This “kiss” can be quite hideous, especially when the reduviid bug is infected with the parasite, Trypanosoma cruzi, which results in the transmission of Chagas disease to humans.
The disease itself is a relatively new discovery, though paleoparasitology investigations have discovered DNA from the parasite in human mummies dating back to 9,000 years ago. The Brazilian investigator, Dr. Carlos Chagas, first described the disease back in 1909. Unfortunately, the novelty of this tropical illness hasn’t translated into large-scale attention or interventions, such as occurred with Polio. Along with 14 other diseases, Chagas has earned a notorious ranking as one of the World Health Organization’s (WHO) neglected tropical diseases (WHO Neglected Tropical Diseases).
Acutely, Chagas is typically asymptomatic, thereby resulting in limited detection and treatment. When symptoms do occur, they are typically very non-specific, such as fever, malaise, and inflammation of the lymphatic system (hepato-splenomegaly, lymph node enlargement, etc.). However, an unlucky 5-10% of acutely infected individuals succumb to the disease, dying of myocarditis or meningoencephalitis. If detected early, though, 75% of patients can be cured with the drug of choice for Chagas: Benznidazole (Chagas treatment – Apt). However, for the vast majority of patients, early detection doesn’t occur during these 4-8 weeks of the acute infection. Instead, they proceed to the chronic form of the disease, where treatment is controversial because of limited efficacy and high rates of drug side-effects.
Symptoms during the chronic phase of the disease typically don’t occur until after a latent period of 20-30 years and only occur in 30-40% of patients. At that point, a patient usually experiences one of 4 forms of the disease: (1) Gastrointestinal (GI), (2) Cardiac, (3) Both GI and Cardiac, or (4) Indeterminate (no specific organ system involvement). In general, Chagas causes enlargement of every organ system it affects: MEGA-esophagus, MEGA-colon, cardioMEGAly (for you science nerds, this occurs due to a NO-derived nitrogen free radical).
Though important achievements have been made, such as reducing the incidence of Chagas from 700,000/year in 1990 to 41,200/year in 2006 and the number of Chagas-induced deaths from 50,000 to 12,500 during this same time period, there is still much to be done…especially in Bolivia.
If you wish to learn more, please visit:
- CDC – http://www.cdc.gov/parasites/chagas/
- WHO – http://www.who.int/mediacentre/factsheets/fs340/en/index.html
- Probably the best scholarly article for our med school friends: http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2810%2960061-X/fulltext