Chagas Disease

Chagas Disease, also known as American trypanosomiasis, is a potentially life-threatening parasitic disease mainly confined to the Americas and notably to Latin America. Increasing population mobility in past decades has led to a spreading of the disease to other continents. Worldwide, about 6 million to 7 million people are estimated to be infected with the parasite that causes the Chagas disease.  Prevention strategies include vector control and blood screening (to prevent infection through transfusion and organ transplantation).  Despite these control methods,  a large reservoir of the parasite in wild animals makes eradication impossible. 

Cause

The disease is caused by a protozoan parasite, Trypanosoma cruzi (T.cruzi).

The parasites are usually transmitted via the faeces of infected triatomine bugs (or “kissing bugs”) because of their tendency to suck blood on exposed area of skin such as faces. T.cruzi can also be transmitted by:

  • mother-to-baby (congenital)
  • contaminated blood products (transfusions)
  • organ transplanted from an infected donor
  • laboratory accident, or
  • contaminated food or drink.

Consequences

The disease occurs in two stages: an acute and a chronic phase. The acute phase lasts up to few weeks or months after infection. During this phase, infection may be asymptomatic and mild with   symptoms such as fever, headache, enlarged lymph glands, pallor, muscle pain, difficulty in breathing, swelling and abdominal or chest pain or vomiting.  One characteristic marker for Chagas disease is a skin lesion or purplish swelling of the eyelid on the side of the face near the bite wound, but this appears only in about 50% of infected people.  These symptoms usually resolve spontaneously. The infection persists and proceeds to the chronic phase

During the acute phase a large number of parasites circulate in the blood, whereas during the chronic phase the parasite is hidden in the heart and digestive muscle.  Cell deaths in these target tissues lead to inflammation and cellular lesions causing cardiac disorders in about 30% of the patients and digestive, neurological or mixed alterations in about 10% of the patients.  The infection can lead to sudden death due to progressive damage to the heart muscle and its system nervous.

Global burden

About 8 million people are infected with Trypanosoma cruzi worldwide, mainly in Latin American countries where the Chagas disease caused incapacity in infected people and more than 10 000 deaths per year.

Chagas disease is emerging in Europe and United States. In 2012, estimate of 238,091 T. cruzi infection were reported in United States.

Treatment

Chagas disease can be effectively treated with benznidazole and nifurtimox when administered soon after infection, but efficacy of both treatments diminishes rapidly with time after the infection.  Both medicines are not suitable for pregnant women or people with kidney or liver failure.  Nifurtimox is also not indicated for people with neurological or psychiatric disorders.

Treatment

The parasite’s inherent capacity to evade the human immune system makes the development of vaccines difficult. New hopes focus on DNA vaccines. The current and most effective methods for prevention of the disease are vector control by insecticide spraying, bednets or house improvements to exclude the vector and blood screening.  There is no vaccine against Chagas disease at present, but more recently the potential of DNA vaccines for immunotherapy of acute and chronic Chagas disease is being tested by several research groups. 

References:

World Health Organisation (WHO). Chagas disease (American trypanosomiasis); (www.who.int/news-room/fact-sheets/detail/chagas-disease-(american-trypanosomiasis), accessed on 18 September 2018

Center for Diseases Control and Prevention (CDC). Parasites - American Trypanosomiasis (also known as Chagas Disease); (www.cdc.gov/parasites/chagas/gen_info/detailed.html), accessed on 18 September 2018

Beaumier CM and al. 2016. Status of vaccine research and development of vaccines for Chagas disease. Vaccine 34: 2996-3000.

Manne-Goehler J, Umeh CA, Montgomery SP and Wirtz VJ (2016). Estimating the Burden of Chagas Disease in the United States. PLoS Negl Trop Dis 10(11): 1-7