Developing World’s Parasites, Disease Hit U.S.

Stephanie Simon and Betsy McKay, Wall Street Journal, August 22, 2009

Parasitic infections and other diseases usually associated with the developing world are cropping up with alarming frequency among U.S. poor, especially in states along the U.S.-Mexico border, the rural South and in Appalachia, according to researchers.

Government and private researchers are just beginning to assess the toll of the infections, which are a significant cause of heart disease, seizures and congenital birth defects among black and Hispanic populations.

One obstacle is that the diseases, long thought to be an overseas problem, are only briefly discussed in most U.S. medical school classes and textbooks, so many physicians don’t recognize them.

Some of the infections are transmitted by bug bites and some by animal feces contaminated with parasite larvae; still others are viral. All spread in conditions of overcrowding, malnutrition, poor sanitation and close contact with animals receiving little veterinary care.

“These are diseases that we know are ten-fold more important than swine flu,” said Peter Hotez, a microbiologist at George Washington University and leading researcher in this field. “They’re on no one’s radar.”

The insect-borne diseases–among them, Chagas and dengue fever–thrive in shanty towns along the Mexican border, where many homes have no window screens and where poor drainage allows standing puddles for bugs to breed. Outbreaks of a bacterial infection transmitted in rat urine have cropped up among the urban poor in Baltimore and Detroit.

Such parasites as toxocara–shed in animal feces–thrive in the soil and sandpits where poor children often play. There are an estimated 10,000 toxocara infections a year in the U.S. Symptoms include wheezing, fever and retinal scarring severe enough to blind.

These diseases share a common thread. “People who live in the suburbs are at very low risk,” Dr. Hotez said. But for the 37 million people in the U.S. who live below the poverty line, he said, “There is real suffering.”

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Chagas disease, another troubling infection, begins with the innocent-sounding “kissing bug,” an insect endemic in parts of Latin America and also found in across the American South, especially Texas.

The bugs are often infected with a tiny protozoan parasite, which they excrete after snacking on human or animal blood. When a bite victim scratches, he may accidentally rub the parasite into his open wound–and an infection takes hold. Chagas spreads more easily in poor rural communities where homes without window screens get infested.

Many of those ill with Chagas are immigrants or travelers who became infected elsewhere; as many as half develop complications such as cardiac inflammation that can cause heart failure.

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Nationally, one in 30,000 potential blood donors tests positive–yet many don’t seek treatment even after they are told they have Chagas, said Susan Stramer, executive scientific officer of the American Red Cross. Many are immigrants who don’t want to draw attention: “They’re afraid of the consequences of finding out they’re infected in the U.S,” she said.

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Public-health experts say the first step in fighting the infections is to learn more about them. “We understand the basic biology,” said Mark Eberhard, who directs the parasitic-diseases division at the Centers for Disease Control and Prevention. “But we don’t understand that much about the burden of these diseases.”

Hoping to raise awareness–and money for research–the CDC is teaming with private foundations to organize a national summit this fall for doctors, nurses, community activists and politicians.

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