Deadly Chagas infection poses threat to blood supply
Pastor Dale Morgan
Deadly Chagas infection poses threat to blood supply*
Updated Tue. Jun. 12 2007 9:12 AM ET
CTV.ca News Staff
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.