Chagas disease is an inflammatory, infectious disease caused by the parasite Trypanosoma cruzi, which is found in the feces of the triatomine (reduviid) bug. It is a tropical parasitic disease caused by the protist Trypanosoma cruzi. It is spread mostly by insects known as Triatominae, or “kissing bugs”. Chagas disease is common in South America, Central America and Mexico, the primary home of the triatomine bug. Rare cases of Chagas disease have been found in the southern United States, as well.
Also called American trypanosomiasis, Chagas disease can infect anyone. Left untreated, Chagas disease later can cause serious heart and digestive problems.
Treatment of Chagas disease focuses on killing the parasite in acute infection and managing signs and symptoms in later stages. You can take steps to prevent the infection, too.
Experts estimate that up to eight million people living in Mexico, Central America, and South America — the areas where the infection occurs most often — currently have Chagas disease. In the U.S Chagas disease is not considered to be endemic. This means it’s not regularly found among people living in any certain area. For this reason, in the U.S. “control strategies” to reduce the spread of the disease are the main focus. These can include: preventing transmission from blood transfusions or organ transplants, educating the public on symptoms to look out for, and reducing mother-to-baby transmission of the disease.
The human disease occurs in two stages: an acute stage, which occurs shortly after an initial infection, and a chronic stage that develops over many years.
Chagas disease can cause a sudden, brief illness (acute), or it may be a long-lasting (chronic) condition. Symptoms range from mild to severe, although many people don’t experience symptoms until the chronic stage.
The acute phase of Chagas disease, which lasts for weeks or months, is often symptom-free. When signs and symptoms do occur, they are usually mild and may include:
*Swelling at the infection site
*Loss of appetite
*Nausea, diarrhea or vomiting
*Enlargement of your liver or spleen
Signs and symptoms that develop during the acute phase usually go away on their own. If left untreated, the infection persists and, in some cases, advances to the chronic phase.
Signs and symptoms of the chronic phase of Chagas disease may occur 10 to 20 years after initial infection, or they may never occur. In severe cases, however, Chagas disease signs and symptoms may include:
*Congestive heart failure
*Sudden cardiac arrest
*Difficulty swallowing due to enlarged esophagus
*Abdominal pain or constipation due to enlarged colon
In the early stage, symptoms are typically either not present or mild, and may include fever, swollen lymph nodes, headaches, or local swelling at the site of the bite. After 8–12 weeks, individuals enter the chronic phase of disease and in 60–70% it never produces further symptoms. The other 30–40% of people develop further symptoms 10–30 years after the initial infection, including enlargement of the ventricles of the heart in 20–30%, leading to heart failure. An enlarged esophagus or an enlarged colon may also occur in 10% of people.
The cause of Chagas disease is the parasite Trypanosoma cruzi, which is transmitted from an insect known as the triatomine bug. These insects can become infected by T. cruzi when they ingest blood from an animal already infected with the parasite.
Triatomine bugs live primarily in mud, thatch or adobe huts in Mexico, South America and Central America. They hide in crevices in the walls or roof during the day, then come out at night — often feeding on sleeping humans.
Infected bugs defecate after feeding, leaving behind T. cruzi parasites on the skin. The parasites can then enter your body through your eyes, mouth, a cut or scratch, or the wound from the bug’s bite.
Scratching or rubbing the bite site helps the parasites enter your body. Once in your body, the parasites multiply and spread.
You may also become infected by:
*Eating uncooked food contaminated with feces from T. cruzi-infected bugs
*Being born to a woman infected with T. cruzi
*Having a blood transfusion containing infected blood
*Getting an organ transplant containing viable T. cruzi
*Working in a laboratory where there’s an accidental exposure to the parasite
*Spending time in a forest that contains infected wild animals, such as raccoons and opossums
*From consuming contaminated food or water. It’s possible for bugs carrying the parasite to make their way into food or water. Or they may leave behind feces that is carrying the parasite.
The following factors may increase your risk of getting Chagas disease:
*Living in impoverished rural areas of Central America, South America and Mexico
*Living in a residence that contains triatomine bugs
*Receiving a blood transfusion or organ transplant from a person who carries the infection
*It’s rare for travelers to the at-risk areas in South America, Central America and Mexico to contract Chagas disease because travelers tend to stay in well-constructed buildings, such as hotels. Triatomine bugs are usually found in structures built with mud or adobe or thatch.
The presence of T. cruzi is diagnostic of Chagas disease. It can be detected by microscopic examination of fresh anticoagulated blood, or its buffy coat, for motile parasites; or by preparation of thin and thick blood smears stained with Giemsa, for direct visualization of parasites. Microscopically, T. cruzi can be confused with Trypanosoma rangeli, which is not known to be pathogenic in humans. Isolation of T. cruzi can occur by inoculation into mice, by culture in specialized media (for example, NNN, LIT); and by xenodiagnosis, where uninfected Reduviidae bugs are fed on the patient’s blood, and their gut contents examined for parasites.
Various immunoassays for T. cruzi are available and can be used to distinguish among strains (zymodemes of T.cruzi with divergent pathogenicities). These tests include: detecting complement fixation, indirect hemagglutination, indirect fluorescence assays, radioimmunoassays, and ELISA. Alternatively, diagnosis and strain identification can be made using polymerase chain reaction (PCR).
There are two approaches to treating Chagas disease: antiparasitic treatment, to kill the parasite; and symptomatic treatment, to manage the symptoms and signs of the infection. Management uniquely involves addressing selective incremental failure of the parasympathetic nervous system. Autonomic disease imparted by Chagas may eventually result in megaesophagus, megacolon and accelerated dilated cardiomyopathy. The mechanisms that explain why Chagas targets the parasympathetic autonomic nervous system and spares the sympathetic autonomic nervous system remain poorly understood.
Antiparasitic treatment is most effective early in the course of infection, but is not limited to cases in the acute phase. Drugs of choice include azole or nitro derivatives, such as benznidazole or nifurtimox. Both agents are limited in their capacity to completely eliminate T. cruzi from the body (parasitologic cure), especially in chronically infected patients, and resistance to these drugs has been reported.
Studies suggest antiparasitic treatment leads to parasitological cure in more than 90% of infants but only about 60–85% of adults treated in the first year of acute phase Chagas disease. Children aged six to 12 years with chronic disease have a cure rate of about 60% with benznidazole. While the rate of cure declines the longer an adult has been infected with Chagas, treatment with benznidazole has been shown to slow the onset of heart disease in adults with chronic Chagas infections.
Treatment of chronic infection in women prior to or during pregnancy does not appear to reduce the probability the disease will be passed on to the infant. Likewise, it is unclear whether prophylactic treatment of chronic infection is beneficial in persons who will undergo immunosuppression (for example, organ transplant recipients) or in persons who are already immunosuppressed (for example, those with HIV infection).
In the chronic stage, treatment involves managing the clinical manifestations of the disease. For example, pacemakers and medications for irregular heartbeats, such as the anti-arrhythmia drug amiodarone, may be life saving for some patients with chronic cardiac disease, while surgery may be required for megaintestine. The disease cannot be cured in this phase, however. Chronic heart disease caused by Chagas disease is now a common reason for heart transplantation surgery. Until recently, however, Chagas disease was considered a contraindication for the procedure, since the heart damage could recur as the parasite was expected to seize the opportunity provided by the immunosuppression that follows surgery.
There is currently no vaccine against Chagas disease. Prevention is generally focused on decreasing the numbers of the insect that spreads it (Triatoma) and decreasing their contact with humans. This is done by using sprays and paints containing insecticides (synthetic pyrethroids), and improving housing and sanitary conditions in rural areas. For urban dwellers, spending vacations and camping out in the wilderness or sleeping at hostels or mud houses in endemic areas can be dangerous; a mosquito net is recommended. Some measures of vector control include:
A yeast trap can be used for monitoring infestations of certain species of triatomine bugs (Triatoma sordida, Triatoma brasiliensis, Triatoma pseudomaculata, and Panstrongylus megistus).
Promising results were gained with the treatment of vector habitats with the fungus Beauveria bassiana.
Targeting the symbionts of Triatominae through paratransgenesis can be done.
A number of potential vaccines are currently being tested. Vaccination with Trypanosoma rangeli has produced positive results in animal models. More recently, the potential of DNA vaccines for immunotherapy of acute and chronic Chagas disease is being tested by several research groups.
Blood transfusion was formerly the second-most common mode of transmission for Chagas disease, but the development and implementation of blood bank screening tests has dramatically reduced this risk in the 21st century. Blood donations in all endemic Latin American countries undergo Chagas screening, and testing is expanding in countries, such as France, Spain and the United States, that have significant or growing populations of immigrants from endemic areas. In Spain, donors are evaluated with a questionnaire to identify individuals at risk of Chagas exposure for screening tests.
The US FDA has approved two Chagas tests, including one approved in April 2010, and has published guidelines that recommend testing of all donated blood and tissue products. While these tests are not required in US, an estimated 75–90% of the blood supply is currently tested for Chagas, including all units collected by the American Red Cross, which accounts for 40% of the U.S. blood supply. The Chagas Biovigilance Network reports current incidents of Chagas-positive blood products in the United States, as reported by labs using the screening test approved by the FDA in 2007.
Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.