A deadly parasitic infection that may not produce any symptoms for years poses a new threat to Canada's blood supply, according to tropical disease experts.
Chagas is an infection in which parasites slowly feed on the heart and intestines of an affected person for years without their knowledge. Eventually, the parasite causes so much damage to nerve cells and tissue in the heart, it can trigger heart failure or strokes. Chagas can be spread by the transfusion of infected blood but it is primarily spread through large blood-sucking bugs.
"It's a huge bug that is found in the mud walls and cracks and thatch in the developing world," Dr. Jay Keystone, professor of medicine at the University of Toronto, told CTV's Canada AM.
"You don't see it much in most major centres. It's seen mostly among the poor in Central and South America where this bug lives... Then it bites the host, unfortunately, then defecates and the parasite is released in the stool and gets into the eye or into the bite site."
The parasite enters the bloodstream either through the bite site or through the mucus membrane of the eye or mouth. This can happen if people rub the bite and then their face. Some people may get an acute infection with symptoms similar to flu and may notice swelling at the bite site or in the eyes -- but any further symptoms may not develop for decades.
"People who have this infection don't know about it and about 30 or 40 years later they suddenly go into heart failure or they have difficulty swallowing because the bowel is attacked and the bowel muscle doesn't function and they wind up in serious problems," Keystone said.
The Chagas disease is responsible for 50,000 deaths every year in Central and South America and has infected an estimated 20 million people in the region. Keystone said that between 1 in 500 and 1 in a 1,000 people from the area may be unknowingly carrying the infection in their blood.
"It's a major cause of heart disease in young people because most of the individuals who acquire this infection do so in childhood and it's not always screened routinely -- it's certainly not screened routinely in many parts of the developing world," Keystone told Canada AM. " And here in Canada, we don't usually test for it unless someone presents with the symptoms later in life."
Currently Chagas is not a reportable illness in Canada, so the extent of its prevalence in this country is unknown. In addition, many doctors would not recognize the infection.
What is evident, however, is that the parasitic infection is moving northward because of immigration patterns and adventure travel enthusiasts, as well as eco-tourists visiting areas such as Columbia and Brazil.
Currently, donors who have a history of travelling to Mexico, Central or South America are questioned about potential exposure to Chargas.
Keystone said a more proactive approach to analyzing the blood supply is forthcoming. A new test that will detect the parasite in the blood system will soon be implemented in this country, he said.
"We're going to be screening our blood supply through this test. Before this, we could screen the blood supply by asking questions of the individuals donating, 'Where did you come from?' 'Are you from a rural area?' 'Are you at the risk of infection?,'"said Keystone. "Now, we can detect the infection and therefore remove that blood from the blood supply and prevent transfusions."
To date, two cases of blood-transmitted Chagas have been reported in Canada, in 1986 and 2000.
The disease is named after Brazillian doctor Carlos Chagas, who discovered the disease in 1909.
