Chagas Disease: Diagnosing, Treating, Preventing and Control
- Publish Date: 2014/11/19 - (Rev. 2019/03/05)
- Author: Thomas C. Weiss
- Contact : Disabled World
Outline: Information regarding Chagas disease also known as American trypanosomiasis caused by the parasite Trypanosoma cruzi or kissing bug.
Chagas disease is named after the Brazilian physician Carlos Chagas, who discovered the disease in the year 1909. The disease is caused by the parasite, 'Trypanosoma cruzi,' which is transmitted to both animals and people by insect vectors and is found on in the Americas, mainly in rural areas of Latin America where poverty is widespread. Chagas disease is also referred to as, 'American trypanosomiasis.'
In the United States of America, Chagas disease is considered to be one of the, 'neglected parasitic infections (NPI),' a group of five parasitic diseases that have been targeted by the Centers for Disease Control and Prevention (CDC) for public health action. Chagas disease has an acute and a chronic phase. If left untreated, infection is lifelong.
Acute Chagas disease occurs immediately after infection and may last up to a few weeks or months. Parasites may be found in the person's circulating blood. Infection may be mild or asymptomatic. There may be fever or swelling around the site where the parasite entered into the person's skin or mucous membrane. On rare occasion, acute infection may result in severe inflammation of the person's heart muscle, or their brain and lining around their brain.
Following the acute phase, the majority of infected people enter into a prolonged asymptomatic form of the disease called, 'chronic indeterminate,' during which few or no parasites are found in the person's blood. During this time, most people are not aware of their infection. Many people remain asymptomatic for life and never develop Chagas-related symptoms. However, an estimated 20-30% of those infected will develop debilitating and at times life-threatening medical issues over the course of their lifetimes. Complications of chronic Chagas disease may include the following:
- A dilated heart that does not pump blood well
- Heart rhythm abnormalities that can cause sudden death
- A dilated esophagus or colon, leading to difficulties with eating or passing stool
In people who have suppressed immune systems - for example due to AIDS or chemotherapy, Chagas disease may reactivate with parasites found in a person's circulating blood. The occurrence can potentially cause severe disease.
Risk Factors and Epidemiology
Chagas disease is caused by the parasite, 'Trypanosoma cruzi.' Infection is most commonly acquired through contact with the feces of an infected triatomine bug or, 'kissing bug,' a blood-sucking insect that feeds on people and animals. Infection may also occur from:
- Mother to baby
- Laboratory accident
- Contaminated blood products
- Contaminated food or beverage
- An organ transplanted from a donor who is infected
Chagas disease is endemic throughout much of South America, Central America and Mexico where an estimated 8 million people are infected. The triatomine bug thrives under poor housing conditions such as mud walls or thatched roofs, so in endemic countries, people living in rural areas are at greatest risk for acquiring infection. Public health efforts aimed at preventing transmission have decreased the number of newly infected people and completely stopped vector-borne transmission in some areas. Infection acquired from organ transplantation, blood products, or congenital transmission continues to present a threat.
By applying publishes seroprevalence figures to immigrant populations, the CDC estimates that more than 300,000 people with Trypanosoma cruzi infection live in the United States of America. The majority of people with Chagas disease in the United States acquired the infection in endemic countries. While there are triatomine bugs in the United States, only rare vector-borne instances of Chagas disease have been documented.
Diagnosing Chagas Disease
A diagnosis of Chagas disease may be made by observation of the parasite in a blood smear by microscopic examination. A thick and thin blood smear are made and stained for visualization of the parasites. A blood smear; however, works well only in the acute phase of infection when parasites may be seen circulating in a person's blood.
Diagnosis of chronic Chagas disease is made after consideration of the person's clinical findings, as well as by the likelihood of being infected, such as having lived in an endemic country. Diagnosis is usually made by testing with at least two different serologic tests.
Treatment for Chagas disease is recommended for everyone diagnosed with an acute infection, congenital infection, as well as for those with suppressed immune systems and children with chronic infection. Adults with chronic infection might also benefit from treatment.
For cardiac or gastrointestinal problems resulting from Chagas disease, symptomatic treatment may be helpful. People should consult with their primary health care provider. Some people might be referred to a specialist, such as a cardiologist, infectious disease specialist, or a gastroenterologist. In the United States, medication for Chagas is available only through the CDC. A health care provider can communicate with CDC staff about whether and how a person should be treated.
Prevention and Control
In endemic areas of South America, Central America and Mexico improved housing and spraying insecticide inside housing to eliminate triatomine bugs has significantly decreased the spread of Chagas disease. Screening of blood donations for Chagas disease is another important public health tool in helping to prevent transfusion-acquired disease. Early detection and treatment of new instances, to include mother-to-baby instances, also helps to reduce the disease. In the United States and other regions where Chagas disease is now found, yet is not endemic, control strategies are concentrated on preventing transmission from organ transplantation, mother-to-baby, and blood transfusion.
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