The Stages and Transmission of Chagas Disease

Chagas Disease is an infection caused by the parasite Trypanosoma Cruzi. It is a member of the same genus as the infectious agent of the African Sleeping sickness, but the clinical manifestations, geographical distribution, life cycle and insect vector are very different. Chagas Disease was named after a Brazilian physician and infectologist Carlos Chagas, who first described the disease in 1909. Chagas Disease was not seen as a major public health problem in humans until the 1960's. It is reported that 16 to 18 people are infected with Chagas Disease worldwide and that 50,000 people will die from this disease each year. Chagas Disease is also known by the name American Trypanosomiasis (tri-PAN-o-so-MY-a-sis).

Chagas Disease is found mostly in the poor and rural areas of Central and South America including Argentina, Belize, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname and Venezuela. It is also sometimes transmitted in the United States.

Chagas Disease manifests in two stages: An Acute Stage that develops soon after infection and a Chronic Stage that can develop over a period of ten years. In the acute phase a local skin nodule may appear at the site of the inoculation. When the inoculation site is the conjunctival mucous membranes, the patient may develop unilateral periorbital edema, conjunctivitis and preauricular lymphadentis. Although the acute phase is usually asymptomatic, the disease can also present fever, anorexia, lymphadenopatthy, mild hepatosplenomegaly and myocarditis. About 10-20% of acute cases resolve over a period of two to three months into a asymptomatic chronic stage. Unfortunately the disease reappears after several years.

The symptomatic chronic stage may not occur for years or even decades after the initial infection. Chronic infections result in various neurological disorders including dementia, damage to the heart muscle and sometimes it causes dilation of the digestive tract and weight loss. Swallowing may be the first symptom of digestive disturbances. This often leads to malnutrition. After several years of an asymptomatic period 27% of those infected develop cardiac damage, 6% develop digestive damage and 3% show peripheral nervous involvement. Chagas Disease can be fatal if it is left untreated. Most fatalities from this disease are a result of Cardiomyopathy.

Transmission can be made in several ways. Eighty percent of human cases are infected by vectorial transmission which is by the feces of the tritominae. Transmission can also be made by transplacental. A mother with an acute or chronic infection passes the trypanosomes to her unborn child. It has been verified that children born to infected mothers sometimes were not infected with the disease. Transfusion of infected blood is another way of transmission. Sometimes donors ignore the fact that they are infected. The blood is then passed on through transfusion and the recipients are infected. A large percentage of infections are transmitted this way. It is also possible for an infected mother to pass the disease to a child by the breast milk. Although this is very rare, it is advisable that infected mothers not breast feed. Accidental contamination in a laboratory can also result in transmission. There are many cases of accidental infections that are caused by the manipulation of kissing bed bugs, infected animals or biological material from sick people or infected animals. There are also cases of infection caused by the management of infected animals, such as skinning wild or semi-domestic animals. Try panosomes have been found in dogs saliva with high parasitism. The final source of transmission is through contaminated food such as poultry and beef. This is accidental and might happen when eating food that has had contact with the feces from infected bed bugs. This way of transmission is very rare.

It is rumored that Charles Darwin suffered from Chagas Disease as a result of a bite from the so-called Great Black Bug of the Pampas (Vinchuca). The Chronic stages of Chagas Disease remains a major health problem in many Latin American Countries, despite efforts to minimize transmission. Great steps continue to be made to control and eliminate Chagas Disease. Officials remain hopeful that total elimination of the transmission of Chagas Disease could be achieved as soon as the year 2010.