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Tuesday, 10 May 2011

Origin of Darwin's sickness

The very travels that inspired Charles Darwin's theory of evolution and shaped modern biology may have led to one of the illnesses that plagued the British naturalist for decades and ultimately led to his death, modern researchers say.  
Darwin, who lived from 1809 to 1882, travelled the world in his 20s cataloging and observing wildlife and later published "On the Origin of Species." 

Throughout his life, Darwin sought help for multiple health problems, which included vomiting stomach acids after every meal when the symptoms were at their worst. He was diagnosed with dozens of conditions including 
  • schizophrenia, 
  • appendicitis
  • lactose intolerance




Darwin suffered from cyclic vomiting syndrome early in his life. His weight and nutrition remained normal since he rarely vomited food, just stomach acid and other secretions. Darwin contracted Chagas disease, a parasitic illness that can lie dormant for years, during a five-year trip around the globe on the HMS Beagle in his 20s. That illness would describe the heart disease that beset Darwin later in life and eventually caused his death 

Chagas disease (Portuguese: doença de Chagas, Spanish: enfermedad de Chagas-Mazza, mal de Chagas in both languages; also called American trypanosomiasis) is a tropical parasitic disease caused by the flagellate protozoan Trypanosoma cruzi. T. cruzi is commonly transmitted to humans and other mammals by an insect vector, the blood-sucking insects of the subfamily Triatominae (family Reduviidae) most commonly species belonging to the Triatoma, Rhodnius, and Panstrongylus genera. The disease may also be spread through blood transfusion and organ transplantation, ingestion of food contaminated with parasites, and from a mother to her fetus.
The symptoms of Chagas disease vary over the course of an infection. In the early, acute stage, symptoms are mild and usually produce no more than local swelling at the site of infection. The initial acute phase is responsive to antiparasitic treatments, with 60-90% cure rates. After 4–8 weeks, individuals with active infections enter the chronic phase of Chagas disease that is asymptomatic for 60-80% of chronically infected individuals through their lifetime. The antiparasitic treatments also appear to delay or prevent the development of disease symptoms during the chronic phase of the disease, but 20-40% of chronically infected individuals will still eventually develop life-threatening heart and digestive system disorders. The currently available antiparasitic treatments for Chagas disease are benznidazole and nifurtimox, which can cause temporary side effects in many patients including skin disorders, brain toxicity, and digestive system irritation.
 
Chagas disease is contracted primarily in the Americas, particularly in poor, rural areas of Mexico, Central America, and South America; very rarely, the disease has originated in the Southern United States. The insects that spread the disease are known by various local names, including vinchuca in Argentina, Bolivia, Chile and Paraguay, barbeiro (the barber) in Brazil, pito in Colombia, chinche in Central America, chipo in Venezuela, chupança, chinchorro, and "the kissing bug". It is estimated that as many as 8 to 11 million people in Mexico, Central America, and South America have Chagas disease, most of whom do not know they are infected. Large-scale population movements from rural to urban areas of Latin America and to other regions of the world have increased the geographic distribution of Chagas disease, and cases have been noted in many countries, particularly in Europe. Control strategies have mostly focused on eliminating the triatomine insect vector and preventing transmission from other sources.