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Chagas disease
Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by Trypanosoma cruzi. It is spread mostly by insects in the subfamily Triatominae, known as "kissing bugs". The symptoms change throughout the infection. In the early stage, symptoms are typically either not present or mild and may include fever, swollen lymph nodes, headaches, or swelling at the site of the bite. After four to eight weeks, untreated individuals enter the chronic phase of disease, which in most cases does not result in further symptoms. Up to 45% of people with chronic infections develop heart disease 10–30 years after the initial illness, which can lead to heart failure. Digestive complications, including an enlarged esophagus or an enlarged colon, may also occur in up to 21% of people, and up to 10% of people may experience nerve damage.
T. cruzi is commonly spread to humans and other mammals by the kissing bug's bite wound and the bug's infected feces. The disease may also be spread through blood transfusion, organ transplantation, consuming food or drink contaminated with the parasites, and vertical transmission (from a mother to her baby). Diagnosis of early disease is by finding the parasite in the blood using a microscope or detecting its DNA by polymerase chain reaction. Chronic disease is diagnosed by finding antibodies for T. cruzi in the blood.
Prevention focuses on eliminating kissing bugs and avoiding their bites. This may involve the use of insecticides or bed-nets. Other preventive efforts include screening blood used for transfusions. Early infections are treatable with the medications benznidazole or nifurtimox, which usually cure the disease if given shortly after the person is infected, but become less effective the longer a person has had Chagas disease. When used in chronic disease, medication may delay or prevent the development of end-stage symptoms. Benznidazole and nifurtimox often cause side effects, including skin disorders, digestive system irritation, and neurological symptoms, which can result in treatment being discontinued. New drugs for Chagas disease are under development, and while experimental vaccines have been studied in animal models, a human vaccine has not been developed.
It is estimated that 6.5 million people, mostly in Mexico, Central America and South America, have Chagas disease as of 2019, resulting in approximately 9,490 annual deaths. Most people with the disease are poor, and most do not realize they are infected. Large-scale population migrations have carried Chagas disease to new regions, which include the United States and many European countries. The disease affects more than 150 types of animals. From 2000–2018, 29 confirmed locally-acquired cases of Chagas disease were reported in eight US states, leading to calls to reclassify Chagas as endemic to the US.
The disease was first described in 1909 by Brazilian physician Carlos Chagas, after whom it is named. Chagas disease is classified as a neglected tropical disease.
Chagas disease occurs in two stages: an acute stage, which develops one to two weeks after the insect bite, and a chronic stage, which develops over many years. The acute stage is often symptom-free. When present, the symptoms are typically minor and not specific to any particular disease. Signs and symptoms include fever, malaise, headache, and enlargement of the liver, spleen, and lymph nodes. Sometimes, people develop a swollen nodule at the site of infection, which is called "Romaña's sign" if it is on the eyelid, or a "chagoma" if it is elsewhere on the skin. In rare cases (less than 1–5%), infected individuals develop severe acute disease, which can involve inflammation of the heart muscle, fluid accumulation around the heart, and inflammation of the brain and surrounding tissues, and may be life-threatening. The acute phase typically lasts four to eight weeks and resolves without treatment.
Unless treated with antiparasitic drugs, individuals remain infected with T. cruzi after recovering from the acute phase. Most chronic infections are asymptomatic, which is referred to as indeterminate chronic Chagas disease. However, over decades with the disease, approximately 30–40% of people develop organ dysfunction (determinate chronic Chagas disease), which most often affects the heart or digestive system.
The most common long-term manifestation is heart disease, which occurs in 14–45% of people with chronic Chagas disease. People with Chagas heart disease often experience heart palpitations, and sometimes fainting, due to irregular heart function. By electrocardiogram, people with Chagas heart disease most frequently have arrhythmias. As the disease progresses, the heart's ventricles become enlarged (dilated cardiomyopathy), which reduces its ability to pump blood. In many cases, the first sign of Chagas heart disease is heart failure, thromboembolism, or chest pain associated with abnormalities in the microvasculature.
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Chagas disease
Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by Trypanosoma cruzi. It is spread mostly by insects in the subfamily Triatominae, known as "kissing bugs". The symptoms change throughout the infection. In the early stage, symptoms are typically either not present or mild and may include fever, swollen lymph nodes, headaches, or swelling at the site of the bite. After four to eight weeks, untreated individuals enter the chronic phase of disease, which in most cases does not result in further symptoms. Up to 45% of people with chronic infections develop heart disease 10–30 years after the initial illness, which can lead to heart failure. Digestive complications, including an enlarged esophagus or an enlarged colon, may also occur in up to 21% of people, and up to 10% of people may experience nerve damage.
T. cruzi is commonly spread to humans and other mammals by the kissing bug's bite wound and the bug's infected feces. The disease may also be spread through blood transfusion, organ transplantation, consuming food or drink contaminated with the parasites, and vertical transmission (from a mother to her baby). Diagnosis of early disease is by finding the parasite in the blood using a microscope or detecting its DNA by polymerase chain reaction. Chronic disease is diagnosed by finding antibodies for T. cruzi in the blood.
Prevention focuses on eliminating kissing bugs and avoiding their bites. This may involve the use of insecticides or bed-nets. Other preventive efforts include screening blood used for transfusions. Early infections are treatable with the medications benznidazole or nifurtimox, which usually cure the disease if given shortly after the person is infected, but become less effective the longer a person has had Chagas disease. When used in chronic disease, medication may delay or prevent the development of end-stage symptoms. Benznidazole and nifurtimox often cause side effects, including skin disorders, digestive system irritation, and neurological symptoms, which can result in treatment being discontinued. New drugs for Chagas disease are under development, and while experimental vaccines have been studied in animal models, a human vaccine has not been developed.
It is estimated that 6.5 million people, mostly in Mexico, Central America and South America, have Chagas disease as of 2019, resulting in approximately 9,490 annual deaths. Most people with the disease are poor, and most do not realize they are infected. Large-scale population migrations have carried Chagas disease to new regions, which include the United States and many European countries. The disease affects more than 150 types of animals. From 2000–2018, 29 confirmed locally-acquired cases of Chagas disease were reported in eight US states, leading to calls to reclassify Chagas as endemic to the US.
The disease was first described in 1909 by Brazilian physician Carlos Chagas, after whom it is named. Chagas disease is classified as a neglected tropical disease.
Chagas disease occurs in two stages: an acute stage, which develops one to two weeks after the insect bite, and a chronic stage, which develops over many years. The acute stage is often symptom-free. When present, the symptoms are typically minor and not specific to any particular disease. Signs and symptoms include fever, malaise, headache, and enlargement of the liver, spleen, and lymph nodes. Sometimes, people develop a swollen nodule at the site of infection, which is called "Romaña's sign" if it is on the eyelid, or a "chagoma" if it is elsewhere on the skin. In rare cases (less than 1–5%), infected individuals develop severe acute disease, which can involve inflammation of the heart muscle, fluid accumulation around the heart, and inflammation of the brain and surrounding tissues, and may be life-threatening. The acute phase typically lasts four to eight weeks and resolves without treatment.
Unless treated with antiparasitic drugs, individuals remain infected with T. cruzi after recovering from the acute phase. Most chronic infections are asymptomatic, which is referred to as indeterminate chronic Chagas disease. However, over decades with the disease, approximately 30–40% of people develop organ dysfunction (determinate chronic Chagas disease), which most often affects the heart or digestive system.
The most common long-term manifestation is heart disease, which occurs in 14–45% of people with chronic Chagas disease. People with Chagas heart disease often experience heart palpitations, and sometimes fainting, due to irregular heart function. By electrocardiogram, people with Chagas heart disease most frequently have arrhythmias. As the disease progresses, the heart's ventricles become enlarged (dilated cardiomyopathy), which reduces its ability to pump blood. In many cases, the first sign of Chagas heart disease is heart failure, thromboembolism, or chest pain associated with abnormalities in the microvasculature.