A disease that often causes no symptoms, but which can suddenly become fatal years after a person was infected, is receiving a big spotlight from the American Heart Association (AHA). On Monday, the organisation published a scientific statement in its journal Circulation, urging heart doctors in the US to start paying attention to Chagas disease, a parasitic infection mainly spread by bloodsucking kissing bugs.
Chagas disease is caused by the single-celled, whip-tailed protozoan Trypanosoma cruzi. Kissing bugs, nicknamed for their habit of sucking blood from the moist skin around our mouths or eyes, don’t infect us with T. cruzi the way mosquitos give us malaria, though. Instead, the parasites are pooped out while the bugs feed on their unsuspecting, sleeping victims. The parasites then get rubbed into the wound or eyes by our own cloddish hands. Kissing bugs, meanwhile, get the parasite from feeding on the blood of hosts, including humans, starting the whole cycle anew. The parasite can, more rarely, spread through food, blood and organ donations, or from mother to child in the womb.
Chagas disease is mostly found in warmer Latin American countries. And unlike other tropical diseases, such as Zika, the incidence of Chagas has dropped in recent years, thanks to efforts to control kissing bug populations, as well as better detection and early treatment of the disease. But it still affects more than 6 million people worldwide, and there is evidence that its range is expanding, including to the US. The AHA report, according to the authors, is an educational warning for doctors who have little experience with the disease.
“This document will help healthcare providers and health systems outside of Latin America recognise, diagnose and treat Chagas disease and prevent further disease transmission,” senior author Pereira Nunes, a cardiologist at the Federal University of Minas Gerais in Belo Horizonte, Brazil, said in a statement.
About 60 to 70 per cent of people infected with Chagas never become sick with it. Some of those who do only have mild flu-like symptoms or a characteristic swelling around the eye. Others, however, can experience a serious acute heart infection, or carry around a chronic infection that lies dormant. After years, or even decades, a third of these dormant cases will develop into a heart (sometimes gut) condition, caused by chronic inflammation in response to the parasite. This condition can damage and warp the shape of the heart and colon, raising the risk of heart failure, sudden cardiac death, and other cardiovascular complications. As a result, Chagas is thought to cause more disability than any other disease spread by bugs and insects in North and South America, including malaria.
In the US, there are several species of kissing bugs across the Southern half of the country capable of spreading Chagas, as well as plenty of warm-blooded mammals that can act as secondary hosts and keep the local T. cruzi population alive. But while we need better research into and detection of stateside cases, most of the estimated 300,000 people with Chagas in the US are immigrants who contracted it in their home countries, according to the report. And it’s these people who need knowledgeable doctors who can diagnose Chagas before it seriously endangers their health.
“Early detection of Chagas disease is critical, allowing prompt initiation of therapy when the evidence for cure is strong,” co-author Caryn Bern, a professor of epidemiology and biostatistics at the University of California in San Francisco, said in a statement.
If caught in the first eight to 12 weeks after infection, Chagas can be treated and often cured with anti-parasitic drugs. [Circulation]