Chagas disease is an infectious illness spread by bloodsucking cone-nosed bugs, also known as "kissing bugs." They bite sleeping people, often on the face, injecting saliva containing an anesthetic and anticoagulant. Some bugs carry the protozoan parasite, trypanosoma cruzi, which they excrete when they bite. This organism is the cause of the disease named after Carlos Chagas, a Brazilian physician who characterized it in 1909. The bug is found only in the Americas and is most common in poor, rural areas of Latin America.
According to the U.S. Centers for Disease Control and Prevention (CDC) an estimated 8 to 11 million people in Latin America are infected with the parasite. In addition to infection via the bug bite, the disease can be passed from a pregnant woman to her baby, in blood transfusions and by organ transplants. The CDC estimates that more than 300,000 persons with Chagas disease live in the United States and that most of them were infected in their native countries. Kissing bugs are also pests in the U.S., especially in the deserts of the southwest, but they rarely transmit the disease.
Chagas disease has an acute and a chronic phase. If untreated, infection is lifelong. Acute Chagas symptoms can occur soon after the bug bite and may last up to a few weeks or months. During this phase, parasites may be found in patients' blood. Newly infected individuals may run a fever or see swelling at the site of the bite. Other symptoms include fatigue, body aches, headache, rashes, loss of appetite, diarrhea and vomiting. A characteristic marker of Chagas, called Romaña sign, is swelling of the eyelid on the side of the face near the bug bite or where bug feces were deposited or accidentally rubbed into the eye. Symptoms can last weeks or months. In rare cases, the infection can lead to inflammation of the heart muscle, the brain, and tissues covering the brain.
Once initial symptoms fade, most people may not be aware that they are still infected. Eventually, however, 20 to 30 percent of all infected individuals will develop enlarged hearts or intestines, which can burst, leading to sudden death.
Chagas is diagnosed via a microscopic examination of blood to look for the parasite, but this test is positive only when symptoms are present. Treatment is with anti-parasitic drugs and is recommended for everyone diagnosed who is under the age of 50 and has either symptomatic or chronic infection as well as for all children up to the age of 18 believed to have acute or chronic infection. The decision to treat adults age 50 or older depends on a medical assessment of the benefits versus the risks. The drugs used to treat Chagas disease are not FDA approved and must be obtained from the CDC by physicians. Side effects can be severe.
Chagas was likened to AIDS by infectious disease researchers because it is impossible to cure. In Latin America this disease is a very serious problem, taking an estimated 20,000 lives each year.
Andrew Weil, M.D.
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