Stubborn Infection, Spread by Insects, Is Called ‘The New AIDS of the Americas’.

Stubborn Infection, Spread by Insects, Is Called ‘The New AIDS of the Americas’.(NYTimes).By Donald G. McNeil Jr.Chagas disease, caused by parasites transmitted to humans by blood-sucking insects, has been named “the new AIDS of the Americas” in a lengthy editorial published in PLoS Neglected Tropical Diseases.
The authors, several of whom are tropical disease experts from Baylor College of Medicine in Houston, argue that the dangerous spread of Chagas through this hemisphere somewhat resembles the early spread of H.I.V.

Chagas is also known as American trypanosomiasis, because the bugs carry single-celled parasites called trypanosomes. (Their best-known relative, spread by tsetse flies in Africa, causes sleeping sickness.)

Like AIDS, the authors say, Chagas disease has a long incubation time and is hard or impossible to cure. Chagas infects up to eight million people in the hemisphere, mostly in Bolivia, Mexico, Colombia and Central America. But more than 300,000 of the infected live in the United States, many of them immigrants.

The disease can be transmitted from mother to child or by blood transfusion. About a quarter of its victims eventually will develop enlarged hearts or intestines, which can fail or burst, causing sudden death. Treatment involves harsh drugs taken for up to three months and works only if the disease is caught early.

Signs and symptoms

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.

The acute phase lasts for the first few weeks or months of infection. It usually occurs unnoticed because it is symptom-free or exhibits only mild symptoms that are not unique to Chagas disease. These can include fever, fatigue, body aches, headache, rash, loss of appetite, diarrhea, and vomiting. The signs on physical examination can include mild enlargement of the liver or spleen, swollen glands, and local swelling (a chagoma) where the parasite entered the body. The most recognized marker of acute Chagas disease is called Romaña's sign, which includes swelling of the eyelids on the side of the face near the bite wound or where the bug feces were deposited or accidentally rubbed into the eye. Rarely, young children, or adults may die from the acute disease due to severe inflammation/infection of the heart muscle (myocarditis) or brain (meningoencephalitis).The acute phase also can be severe in people with weakened immune systems.
If symptoms develop during the acute phase, they usually resolve spontaneously within three to eight weeks in approximately 90% of individuals. Although the symptoms resolve, even with treatment the infection persists and enters a chronic phase. Of individuals with chronic Chagas disease, 60–80% will never develop symptoms (called indeterminate chronic Chagas disease), while the remaining 20–40% will develop life-threatening heart and/or digestive disorders during their lifetime (called determinate chronic Chagas disease). In 10% of individuals, the disease progresses directly from the acute form to a symptomatic clinical form of chronic Chagas disease.
The symptomatic (determinate) chronic stage affects the nervous system, digestive system and heart. About two-thirds of people with chronic symptoms have cardiac damage, including dilated cardiomyopathy, which causes heart rhythm abnormalities and may result in sudden death. About one-third of patients go on to develop digestive system damage, resulting in dilation of the digestive tract (megacolon and megaesophagus), accompanied by severe weight loss. Swallowing difficulties (secondary achalasia) may be the first symptom of digestive disturbances and may lead to malnutrition. 20% to 50% of individuals with intestinal involvement also exhibit cardiac involvement.Up to 10% of chronically infected individuals develop neuritis that results in altered tendon reflexes and sensory impairment. Isolated cases exhibit central nervous system involvement, including dementia, confusion, chronic encephalopathy and sensitivity and motor deficits.
The clinical manifestations of Chagas disease are due to cell death in the target tissues that occurs during the infective cycle, by sequentially inducing an inflammatory response, cellular lesions, and fibrosis. For example, intracellular amastigotes destroy the intramural neurons of the autonomic nervous system in the intestine and heart, leading to megaintestine and heart aneurysms, respectively. If left untreated, Chagas disease can be fatal, in most cases due to heart muscle damage.Read the full story here.