"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."
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.
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."
...Most blood banks in the U.S. began screening for Chagas in the past two years, as concern about the disease mounted. Hundreds of cases have been detected, with especially high rates among Hispanics in Florida and California.
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.
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.
Health-care legislation pending in the House calls for a full report to Congress about the threat from this cluster of diseases, termed "neglected infections of poverty," as their consequences threaten to increase U.S. health-care costs.
Read More By STEPHANIE SIMON and BETSY MCKAY at Wall Street Journal