American Trypanosomiasis (Chagas)

Chagas’s Disease, caused by Trypanosoma cruzi, continues to expand beyond Latin and South America and can lead to life-threatening heart disease and gastrointestinal problems.

Chagas disease can remain hidden for years. Although up to 10 million people might be currently infected with Trypanosoma cruzi, infected individuals typically remain asymptomatic for over a decade. Estimates of the global annual burden of Chagas’s disease is $627·46 million in health-care costs and 806 170 DALYs.  Most infected people live in poor communities without access to safe drinking water and adequate sanitation.

Disease Burden: 

Chaga’s Disease is endemic in many countries in Latin and South America and has been steadily spreading to other parts of the world including North America, Europe and Australia. Estimates suggest that over 8 million people are infected, but since many cases go undetected, the actual number of infections may be higher.  A study estimated the global annual burden to be $627·46 million in health-care costs and 806,170 DALYs. However, since Chaga’s can result in chronic heart disease after years of being asymptomatic, much of the costs of Chagas’s Disease occur years into the future. Therefore, currently infected individuals are expected to cost $7·19 billion per year and $188·80 billion throughout their lifetimes.

For more on the burden of Chagas’ Disease, please see Global economic burden of Chagas disease: a computational simulation model. (http://www.thelancet.com/journals/laninf/article/PIIS1473-3099(13)70002-1/fulltext)

Transmission Dynamics: 

Transmission mainly occurs via the triatomine bug (also known as the “kissing bug”), which can acquire the T.cruzi parasite by sucking the blood of an infected individual. The bugs tend to remain dormant during the day, hiding in the cracks of buildings and emerging at night to feed. The bugs bite exposed areas of a person’s skin and then defecates on the bitten area, depositing the parasite. The bitten person often facilitates the parasite entering the bloodstream by rubbing the area and smearing the bug faeces into the bite or other areas with ready access to the bloodstream such as the eyes or the mouth. Less frequently, transmission can occur through blood transfusion, congenital transmission (from infected mother to child) and organ donation.  Transmission can also occur though ingesting food contaminated with infected triatomine bug feces and laboratory accidents. 

Interventions: 

Currently the main Chaga’s Disease control methods are triatomine bug control, protecting food from contamination, and screening blood and organs for T. cruzi.  Vector control methods include insecticide spraying, bednets, and fixing the cracks in buildings.  Vaccines and medications are under development.  (http://informahealthcare.com/doi/abs/10.1586/erv.12.85)

Modelling publications