Cockroaches bugs are a medical threat to people in two ways. As incidental carriers of microorganisms, they spread a variety of human diseases, by transferring microorganisms wherever they go, causing food spoilage and associated intestinal disorders. Cockroaches also produce antigens from their bodies and excretions, and these are important triggers for asthma and other allergies.
Species and Distribution
Cockroaches are a diverse group of insects with some 4,000 species worldwide. Sixty-nine species are known to exist in the U.S., and fewer that 10 species regularly infest homes.
The most common are the ubiquitous German cockroach, Blatella germanica; species belonging to the genus Periplaneta (usually the American and Smoky-brown cockroaches, P. americana and fuliginosa, respectively); – the brown-banded cockroach, Supella longipalpa; and the Oriental cockroach, Blatta orientalis. The German and brown-banded cockroaches are found almost exclusively inside dwellings. The others are more commonly found out-of-doors and enter homes and multi-family dwellings from the outside.
Cockroaches can be found anywhere in homes, but usually where food, water and shelter are abundant. Kitchens, cabinets, and appliances are primary living and breeding quarters for cockroaches. Large outdoor-living species may also aggregate at entries from the outside.
Nocturnal cockroaches forage intensely for food and water, and seek mates when human occupants generally are not present. Crawling unhindered over a variety of surfaces in the home, including those harboring harmful microorganisms on their legs and antennae, transferring them back to other surfaces as they move about.
This incidental transfer of microorganisms is likely to contaminate foods and produce spoilage and cause gastrointestinal illness in people. While such effects are not well documented, many studies have identified a variety of human pathogens from cockroaches, including bacteria, viruses, fungi and protozoan.
Cockroaches multiply rapidly, especially with adequate heat and humidity. They molt up to six times from egg to adult. The remnants of repeated molting, excretions and dead roaches eventually produce a biological dust of protein particles capable of becoming airborne. Recent research has associated this debris from some cockroach species with antibodies responsible for allergies, including asthma, which can be life threatening. Medical reports indicate that up to 60% of asthmatics have allergic reactions to cockroaches, which are second only to house dust mites in an ability to trigger allergies. Alarmingly, the incidence of asthma is on the increase, particularly in low-income families in cities and among children. Cockroach control is now commonly found in medical recommendations for asthma management, since roaches contribute to an estimated billion dollar per year medical problem.
Nearly any activity that reduces cockroach numbers will reduce food contamination and allergens (substances that cause allergies). Minimizing food and water access is important for curtailing cockroach populations. Keeping food sealed in plastic bags or in the refrigerator, not allowing dirty dishes or pet food to remain out overnight, and fixing dripping faucets are useful steps. Frequent vacuuming with a well filtered vacuum cleaner and disposal of dead cockroaches will minimize airborne allergens. General cleanliness is a necessary start for effective roach control. Numerous products are available in nearly any retail outlet for consumer control of cockroaches. Read labels carefully to determine which product is right for the job and follow use directions. Some products come in combination as roach and ant products, commonly roach and ant aerosols and liquids. Others come in fogger, fumigator and bait form. Effective control usually requires direct spray of ant and roach aerosols or liquids on roaches seen in the area. If infestations are heavy, a first step in good roach control is use of an aerosol fogger system or a fumigating type device. These products work for two to three hours and will basically eliminate the roach population in the residence. This can be followed with spot treatment with an ant and roach aerosol or trigger sprayer and placing baits where roaches have been noticed, especially in bathrooms and under sinks or near water sources. Roach bait products include baits designated for large roaches, small roaches and even baits with egg stopping claims to control the next generation of roaches.