Chagas disease is a parasitic infection common in South and Central America with a small percentage of cases found in North America that is spread to people by blood-sucking insects called reduviid bugs.
Chagas disease is a parasitic infection common in South and Central America but also found in North America. It is chronic (long-lasting) and can seriously damage the heart and the digestive system many years after infection. Another name for Chagas disease is American trypanosomiasis (tri-pan-o-so-MY--a-sis). Chagas disease is considered a neglected tropical disease, targeted for greater public health action by the World Health Organization and the Centers for Disease Control and Prevention. The migration of infected people can transport the disease to countries around the world.
The parasite must invade the cells of a mammalian host * such as humans in order to complete its life cycle. Once the parasite invades the cells of a human host, it multiplies within those cells. The cells contain the multiplying parasites until they rupture, releasing chemicals that cause inflammation * as well as the new parasites. This process of cells rupturing and inflammation causes much damage to the body tissues and consequent health problems. When a damaged area is able to heal, the remaining scar tissue may also cause health problems. The most commonly affected organs are the heart, esophagus, and colon.
Reduviid bugs tend to live in the cracks and crevices of poorly built houses in rural South and Central America and in Mexico. Chagas disease used to be largely an illness of the rural poor in those areas. But in the 1970s and 1980s, many people moved from the countryside to Latin American cities, bringing the parasite and disease with them. In the cities, 5 to 20 percent of cases are caused from ingesting contaminated food, transfusions of contaminated blood, and organ transplants. More rarely, it can also be transmitted to the fetus of infected pregnant women at a rate of 2 to 10 percent. About 6 million to 7 million people are estimated to be infected worldwide, mostly in Latin America. Chagas disease is estimated to kill up to 12,000 people per year.
Chagas disease has incubation, acute, indeterminate, and chronic phases. Upon infection, the incubation phase passes without symptoms and lasts 7 to 10 days when infected by the insect, and 20 to 40 days when infected by blood transfusion.
Symptoms most often appear in infected children and usually resolve within three to eight weeks. Symptoms include fever, headache, muscle pain, general malaise, lost appetite, rash, and lethargy. When an insect bites the skin it causes a characteristic lesion called a chagoma. When the insect bites the eye it causes swelling around the eye known as the Romana sign, present in 20 to 50 percent of acute cases. In rare cases, there may be heart damage even as early as the acute phase. In people with weakened immune systems * , such as those with AIDS * , the acute stage can recur later, in a very severe form. In the indeterminate phase, the parasite is still present in the body but causes no symptoms. This stage lasts a lifetime in many infected people. There are blood tests that can identify infection in this phase.
Chagas disease occurs only in the Americas, mainly in South and Central America and in Mexico; however, cases have been reported in the United States. It is believed to create a greater economic burden than any other tropical disease except malaria and schistosomiasis. In South and Central America, about 6 to 8 million people are infected with Chagas disease. Many live in thatch, mud, or adobe houses in poor areas. In the United States, many people who emigrated from South and Central America are thought to be infected with Chagas disease, chiefly in the indeterminate or chronic stages. However, it is extremely rare for someone to catch the disease in the United States. Between about 1980 and 2000, fewer than 20 newly acquired U.S. cases were reported, including three from blood transfusions. About 50,000 people die each year from the disease. The World Health Organization (WHO) reports that about 100 million people are at risk of developing Chagas disease. Illness and death are most common in black individuals as opposed to white or mixed race in the acute phase. There is no difference between genders for the acute phase, but males tend to have more severe cases of cardiomyopathy in the chronic phase.
In the acute stage, the parasites can be seen when blood is examined under a microscope. In the later stages, diagnosis is more difficult, and an array of different blood tests are used. In the acute stage, the parasites often can be eliminated by prescription medication taken for several months. In later stages, there is no proven cure. Instead, doctors try to treat the symptoms of the organ damage the parasites cause.
See also Trypanosomiasis
Delaporte, Francois. Chagas, Disease: History of a Continent's Scourge. Translated by Arthur Goldhammer. New York: Fordham University Press, 2012.
Hernandez, Daisy. “Northern Virginia: ‘Ground Zero’ for Kissing Bug Disease.” The Atlantic. July 24, 2014. Also available online at http://www.theatlantic.com/health/archive/2014/07/northern-virginia-groundzero-for-kissing-bug-disease/374383 (accessed November 27, 2015).
World Health Organization. “Chagas Disease (American Trypanosomiasis).” WHO Fact Sheet No. 340. http://www.who.int/mediacentre/factsheets/fs340/en (accessed November 27, 2015).
Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30333. Toll-free: 800-311-3435. Website: http://www.cdc.gov (accessed November 27, 2015).
Pam American Health Organization/WHO. 525 Twenty-third St. NW, Washington, DC 20037. Telephone: 202-974-3000. Website: http://www.paho.org (accessed November 27, 2015).
* parasite (PAIR-uh-site) is an organism such as a protozoan (one-celled animal), worm, or insect that must live on or inside a human or other organism to survive. An animal or plant harboring a parasite is called its host. A parasite lives at the expense of the host and may cause illness.
* blood transfusions (trans-FYOOzhunz) are procedures in which blood or certain parts of blood (such as specific cells) are given to a person who needs them due to illness or blood loss.
* host is an organism that provides another organism (such as a parasite or virus) with a place to live and grow.
* inflammation (in-fla-MAY-shun) is the body's reaction to irritation, infection, or injury that often involves swelling, pain, redness, and warmth.
* immune system (im-YOON SIStem) is the system of the body composed of specialized cells and the substances they produce that help protect the body against disease-causing germs.
* AIDS or acquired immunodeficiency (ih-myoo-no-dih-FIH-shensee) syndrome is an infection that severely weakens the immune system; it is caused by the human immunodeficiency virus (HIV).