Health Threats to School Children from Cockroaches
Jerome Goddard, Ph.D.
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Medical Importance. Cockroaches are among the most predominant residential, commercial, institutional, and industrial pests in the world today. Several of the approximately 3,500 species in the world have become adapted to living in human habitations and are thus referred to as "domestic" or "domiciliary" species.1

Since cockroaches spend a lot of time indoors they can remain active throughout the year. Cockroaches adversely affect human health in several ways: they sometimes bite feebly, especially gnawing the fingernails of sleeping children; they contaminate food, imparting an unpleasant odor and taste; and they may transmit disease organisms on their body parts.2 In addition, cockroach excrement and discarded skins (dander) contain a number of allergens to which sensitive people may develop allergies. In fact, exposure to cockroach allergen early in life may actually contribute to the development of asthma in susceptible children.3 This means that a child with the predisposition for asthma could go for years without onset of asthma (under the right conditions). However, under other conditions such as living in, or going to school in, cockroach-infested buildings, the child may develop asthma. Asthma-related health problems can occur anywhere, but are most severe among children in inner-city areas. Cockroach-infested housing is at least partly to blame. In one study of 476 asthmatic inner-city children, one-half of the children's bedrooms had high levels of cockroach allergen in dust.4 That study also found that children who were both allergic to cockroach allergen and exposed to high levels of this allergen had 0.37 hospitalizations a year, as compared with 0.11 for other children.4

Many human disease-causing organisms have been found on the legs, other body parts, or fecal pellets of cockroaches.5 Accordingly, most health officials consider cockroaches to be mechanical transmitters of disease agents and like to see them kept out of schools and school cafeterias. Several researchers have obtained data indicating that the insects may be most commonly implicated in the transmission of Salmonella.6

Biology of the Pest Species Involved. Cockroaches are flattened from the top, fast-running, nocturnal insects that seek warm, moist, secluded areas. They have prominent, multisegmented antennae, small finger-like projections on the abdomen, and two pairs of wings. Many species can fly, but the domestic U.S. species rarely do so; however, the newly imported Asian cockroach in the Florida area both flies frequently and is attracted to lights. Cockroaches belong to the insect order Blattaria (formerly they were in the Orthoptera) and are closely related to crickets and grasshoppers. They develop by gradual metamorphosis in which the nymphs, when hatched, look similar to the adults, albeit smaller. Some cockroach species live outdoors and feed on vegetation and other organic matter. However, species that live in buildings are mostly scavengers, feeding on a wide variety of foods including starches, sweets, grease, meat products, glue, hair, and bookbindings. Cockroaches usually choose to live in protected areas that provide a warm and humid environment. American and Oriental cockroaches gather in large groups in protected areas such as wall voids or around steam pipes. The German cockroach spends most of its time hiding in cracks and crevices in dark, warm, and humid areas close to food and water. Brown banded cockroaches are generally found on ceilings, high on walls, behind picture frames, or in electric appliances (if someone says cockroaches are living inside their telephone or radio, the brown banded species is probably the culprit). These roaches do not require as close an association with moisture as German cockroaches.

Control Options and Health Effects from Non-use of Pesticides. Cockroach control involves sanitation to remove their available food, water, and harborage, exclusion efforts to keep roaches out of buildings, and pesticidal baits/sprays to reduce their numbers. The most successful cockroach strategies involve using baits - either in bait stations or as gels applied in crack and crevices - and some limited (indoors as crack and crevice treatments, and outdoors as perimeter sprays) spraying with residual insecticides such as carbamates, organophosphates, or synthetic pyrethroids.

If traditional pesticides are not available to pest control personnel for the prevention/control of cockroaches in/around schools, then successful elimination of the pests -- and their associated health risks -- will be extremely difficult, if not impossible. Pesticides should be considered as important "public health tools" in the removal of cockroaches. Failure to have such tools available will ultimately lead to children being exposed to cockroaches and the diseases they cause, as well as possible liability on the school's part for not having provided a safe, pest-free environment.

References.
1. Ebeling W: Urban Entomology. Berkeley: University of California, Division of Agricultural Sciences, 1978.

2. Goddard J: Infectious Diseases and Arthropods. Totowa, New Jersey: Humana Press, 2000.

3. Litonjua AA, Carey VJ, Burge HA, Weiss ST, Gold DR: Exposure to cockroach allergen in the home is associated with incident doctor-diagnosed asthma and recurrent wheezing. J Allergy Clin Immunol 2001; 107: 41-47.

4. Rosenstreich DL, Eggleston P, Kattan M, et al: The role of cockroach allergy and exposure to cockroach allergen in causing morbidity among inner-city children with asthma. N Engl J Med 1997; 336: 1356-1360.

5. Roth LM, Willis ER: The medical and veterinary importance of cockroaches. Smithsonian Miscellaneous Collection, Vol. 134 (#10), 1957.

6. Rueger ME, Olson TA: Cockroaches as vectors of food poisoning and food infection organisms. J Med Entomol 1969; 6: 185-192.

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