Little-known parasite putting bite on state residents
Updated 5:16 pm, Monday, April 30, 2012
This disease has an exotic name, an unseemly mode of transmission involving parasites and defecating bugs, and severe health consequences for those who are chronically infected.
Enter Chagas, one of the parasitic diseases the Centers for Disease Control and Prevention considers both serious and neglected by the medical establishment.
On a small scale, it's in our midst.
The disease can show up when people donate blood. The American Red Cross now checks for the Chagas disease parasite before letting people give blood.
Or it can cause heart and gastrointestinal problems that may become manifest decades after infection.
"We see mostly chronic cases," Stratidis said.
Chagas disease, named after Dr. Carlos Chagas, the Brazilian doctor who identified it in 1909, is a disease caused by the parasite Trypanosoma cruzi.
Like many bacteriological diseases, it has established a reservoir in the blood stream of animals.
"It's in wood rats, opossums, raccoons," Montgomery said. It also has shown up in dogs that live in outdoor kennels in the South.
An insect, the triatomine bug, carries the parasite from animals to humans, or from humans to humans. There are 11 triatomine species in the U.S. living in the southern two-thirds of the country. Connecticut is just north of their range.
Ttriatomine bugs spread the disease by biting a human or animal carrying the parasite and carry it in their gut. When they next bite a human, they defecate on the human. That fecal matter carries the parasite.
Triatomine bugs are often called kissing bugs, because they bite people near their mouths. They're active at night.
When people -- half-asleep -- feel a bug bite, Montgomery said, they brush it away. In doing so, they spread the fecal matter and the parasites, which can get into wounds, into people's mouths or into their eyes.
Estimates range from 8 million to 11 million cases of Chagas infection in South America, Central America and Mexico. People living in rural poverty, in homes with dirt floors and thatched roofs -- where the bugs can gather -- are at the greatest risk.
It's estimated 20,000 people die of Chagas disease worldwide every year.
As many as 300,000 people in the United States may be infected with the Chagas parasite, immigrants from countries where the disease is common.
In the acute phase of the disease, right after infection, people can run a fever or get a swollen eye. That lasts a few days, then goes away. But the parasites linger on, multiplying and establishing themselves in human tissue.
Montgomery said 20 to 30 percent of the people who have Chagas infection will develop serious symptoms, often decades after the infection began. It can cause heart arrhythmias, strokes and aneurysms. It can also damage the nerves in the colon and esophagus, causing swallowing and digestive problems.
Montgomery said U.S. doctors aren't aware of it. Cardiologists treat arrhythmias, she said, but not the parasitic infection that may be at the root of the problem.
Anti-parasite drugs are available to treat Chagas. However, doctors have to work through the CDC to prescribe them.
With our 11 native species of triatomine bugs, only a handful of cases have been reported in the U.S. where the disease has been transmitted to another human.
Mongomery said the bugs don't get into people's homes as readily -- we have screens on our windows.
Triatomine bugs in the U.S. are less unsavory than their kissing cousins to the south. In the U.S., she said, there a longer break between the time a bug feeds on humans and when they defecate.
By the time they defecate, she said, they've moved off their human hosts.
"They're less likely to spread the infection," Stratidis said.
Montgomery said some countries are starting campaigns to reduce the number of cases by using insecticide inside homes to kill the insects. Doctors may see far fewer cases of the infection in the future.
But a recent study from researchers at the University of Vermont and Loyola University showed 50 percent of the native triatomine bugs collected in Arizona and California carried the Chagas parasite and nearly 40 percent had human blood in their system.
Researchers said that showed the bugs are feeding on humans and carrying the parasite. The disease may be more of a problem in the South than thought, and some worry that because of climate change, Chagas could become more of a problem.
In the meantime, Stratidis said, he favors spreading the word about Chagas.
In Danbury, a city with a large immigrant population from Brazil, Ecuador and Mexico, doctors should know about it.
"Absolutely," he said. "Education is the key."