The nasty, lowly cockroach has been found to be the leading cause of severe childhood asthma in the country's poorest city neighborhoods, where asthma is worst.
Asthma is on the rise in cities and suburbs alike, but it is especially bad in the inner cities, with rates often double those found elsewhere.A major study attempted to learn the reason for this burden. It found that cockroaches are the most common trigger of inner-city asthma, and children who live in roach-infested homes have the most severe cases.
This could have a big impact on the way city parents are educated to lessen the severity of asthma in children who are already sick and to reduce the risk for those who are still healthy. Already, the researchers say, several public health departments have begun new cockroach-control programs as a way of combating asthma.
In their study, conducted in seven cities, the researchers looked at many things that may cause asthma, such as cats, smoking, microscopic bugs called dust mites and the use of gas ranges for heat.
"The only thing that really stood out was that the children who had a lot of cockroach exposure in their bedrooms seemed to be a lot sicker," said Dr. David L. Rosenstreich of Albert Einstein College of Medicine in New York City, lead author of the study.
These children wheezed more, made more trips to the hospital, missed more school and were up more often at night. "Everything we looked at was increased in these children," he said.
Overall, Rosenstreich estimates that cockroaches cause about one-quarter of all asthma in inner cities.
Parts of the study, called the National Cooperative Inner-City Asthma Study, were reported by The Associated Press last June after they were reported at medical meetings. Details of the work are being published in Friday's issue of the New England Journal of Medicine.
Cockroaches give off proteins, mainly in their saliva and droppings, that trigger strong allergic reactions. In roach-infested apartments, these so-called antigens are densest in the kitchen, but they get tracked into other rooms and become ground into rugs and furn-iture.
"In a place that is infested, there is cockroach antigen all over the house," said Dr. Peyton Eggleston of Johns Hopkins University, another of the researchers. "You find appreciable levels in the bedrooms and the beds, even though they are about 10 times lower than in the kitchen."
The study was conducted on 476 asthmatic children who were drawn from a larger sample of 1,528 youngsters living in New York City, St. Louis, Baltimore, Chicago, Detroit, Cleveland and Washington, D.C.
They found that half of the children had high levels of cockroach antigens in their bedrooms. Overall, 37 percent of the children were allergic to cockroaches, 35 percent to dust mites and 23 percent to cats.
Children who were both allergic to cockroaches and exposed to high roach levels in their bedrooms were three times as likely as other asthmatic children to need hospitalization for their condition, and they made twice as many unscheduled doctor visits.
However, no similar patterns were found for children who were allergic to cat dander or dust mites and lived in homes where levels of these things were high.
"It has been appreciated that cockroach is highly allergenic and ubiquitous. It had not been appreciated that there is a clear causal relationship between cockroach allergy, high levels of exposure to cockroach and asthma severity," said Dr. Daniel Rotrosen of the National Institute of Allergy and Infectious Diseases, which financed the $17 million study.
The next phase of the study will be measuring what happens to children's asthma after exterminators clear their homes of cockroaches and built-up bug crud is thoroughly cleaned up.
Other studies have found that low-income apartments often contain 10,000 or more roaches.
Experts say that getting rid of the roaches is difficult but not impossible, even when neighbors have infested homes, and a modest effort is better than doing nothing.
Simple steps include putting out roach traps and keeping food under cover. *****
Additional Information
Cockroach primer
Researchers say cockroaches are the leding cause of severe childhood asthma in poor neighborhoods.
Egg cases
Four common pest species*
Oriental, German (contains 30-40 eggs), American, Brownbanded
* There are approximately 5,000 species of cockroaches worldwide.
What to look for
- At night you will likely see roaches if you turn the lights on unexpectedly or examine the suspected area with a flashlight.
- Empty or intact egg cases, cast skins, dead cockroaches or cochroach parts, and fecal pellets.
Possible entry points
- through crevices in walls connected with an infested area.
- through spaces around pipes and electrical conduits.
- inside objects from an infested area (i.e., appliances, furniture and luggage).
Getting rid of them
- place traps/baits - behind fridge and stove, under sinks, near water heater, behind dishwasher in backes of cabinets
- seal the roach entry points
- seal food containers
- don't allow dirty dishes to pile up
Over the counter insecticides come in liquid, aerosol, fogger and dust form.
Source: University of Nebraska Pesticide Education Resources