Most people don’t recognize the serious impact allergies to cockroaches have on the American health-care system. When you ask a person what they think of cockroaches, their likely answer is a reflection of the places cockroaches live — they are dirty and indicate poor sanitation. If you follow up the question by asking them what the public health implications are of a cockroach infestation, they may respond that cockroaches spread disease. However, allergies to cockroaches (and other insect and vertebrate pests like mice and rats) are much more of an issue than their role in spreading human pathogens.
In urban areas, one in four children are known to be affected by asthma, and of those, 23 to 60 percent will show sensitization to cockroach allergen. As a comparison, in one study of inner-city children, 37 percent were allergic to cockroaches, 35 percent to dust mites and 23 percent to cats.
WHERE IS IT? Cockroach allergen is a protein found in the feces, saliva and bodies of cockroaches. For some people, exposure to the feces, saliva and bodies of cockroaches causes their immune system to go into overdrive, causing symptoms such as itchy skin, rashes, watery eyes and persistent asthma. For people who are allergic to cockroaches, exposure to them can result in hospitalizations. In fact, children who are allergic to cockroaches, when exposed to them, are 3.3 times more likely to be hospitalized than their non-allergic peers.
Although sensitization to cockroach allergens can be found anywhere where cockroach infestations exist, inner-city homes often have a higher prevalence of cockroach allergens. Levels of pest allergens vary between cities. A recent nationwide study found that almost 50 percent of children’s bedrooms in some cities had a high level of detectable cockroach allergen in dust samples. Another study found that 98 percent of sampled homes in Gary, Ind., had detectable cockroach allergen compared to 57 percent of homes in New Orleans. In Chicago and New York, more than 50 percent of homes had a concentration of cockroach allergen known to aggravate children’s asthma symptoms.
The problem is not only found in homes, it is also present in schools, workplaces and restaurants. In an analysis of dust samples taken from schoolrooms in Detroit; Houston; and Birmingham, Ala.; all three cities had school rooms with levels of cockroach allergen exceeding proposed sensitization thresholds. The school samples had significantly higher levels of pest allergens compared to students’ homes sampled in the same city. For individuals with sensitivity to cockroach allergens, exposure to areas with a cockroach infestation can trigger an asthmatic response.
PMPs are in the unique position to offer cockroach control as a potential treatment for asthma symptoms. In 2010, the Indoor Allergy and Air Pollution Committee of the American Academy of Allergy, Asthma and Immunology released a report about research conducted on pest and allergen exposure and abatement in inner-city asthma. The report discusses how exposure to cockroaches is common in the inner city and how exposure is associated with allergen sensitization and asthma. Most importantly, the report discusses the link between professional IPM-based cockroach control and its effect on asthma.
USING IPM. Integrated Pest Management is effective in reducing cockroach allergen and pesticides. A successful cockroach IPM program consists of careful assessment of the presence and location of roaches, removal of food sources through proper food storage and cleaning, educating residents, repairing structural defects that allow roaches access, application of gel bait and other pesticides as needed, and monitoring until roaches are eliminated.
Research shows in homes with an IPM program, exposure to cockroaches is reduced. In a controlled study, professional cleaning, cockroach baiting and insecticide treatment, and HEPA filters were used to reduce cockroach allergen inside of homes. This method was linked to a decrease in wheezing, decrease in nighttime asthma symptoms and fewer missed school days in treated homes.
IPM-based cockroach control can reduce allergen levels. However, simply controlling cockroaches indiscriminately with pesticides can actually worsen asthmatic symptoms. For instance, 15 percent of inhabitants in New York City public housing report using illegal pesticides or pesticides in a manner inconsistent with their labels. Pesticide exposure is associated with a higher prevalence of hypersensitivity allergic reactions, chronic bronchitis and possibly decreased lung function.
Conversely, Purdue University entomologists and commercial pest control companies exterminated cockroaches in public housing units. Units treated by the entomologists had prolonged reductions in cockroach allergen compared to those treated by the commercial companies. In order to reduce cockroach allergens, PMPs must have a thorough knowledge of cockroach biology and factors that contribute to allergen presence in homes.
Continuous efforts to eliminate the cockroaches and allergens must continue in order for positive health benefits to continue. Even if cockroaches are gone, allergen levels can remain in the home if dead roaches and feces remain. For most asthma patients, removing cockroaches from the home is just part of treatment. The key to keeping cockroach allergens out of homes is to prevent the establishment of an infestation in the first place.
Photos by Keith Willingham, Western Exterminator Company, Anaheim, Calif.
The author holds a master of public health degree and is an assistant vector ecologist at the Orange County (Calif.) Vector Control District. E-mail her at email@example.com.
Efficacious Insect and Rodent Pest Allergen Reduction Techniques
The allergen reduction tactics listed below have been show to successfully reduce allergen levels and should be considered an important part of cockroach IPM strategies.
Environmental (indoor and outdoor):
• Remove attractants
• Landscaping and vegetation management (prune trees and ornamentals)
• Ventilation, temperature and moisture control
• Trash removal and well-placed Dumpster site
• General housekeeping
• Detailed cleaning
• Sealing (caulking, metal mesh, expandable spray foams and gels)
• Clutter reduction
• Storage practices
• Disposal frequency
• Traps (e.g., sticky, snap, curiosity and light)
• Biological agents and pheromones
• Predators and parasites
• Freeze, heat or steam
• Insecticides and rodenticides
• Formulations (e.g., baits)
• Insect growth regulators
• Legal housing codes (development and enforcement)
• City housing and environmental commissions
Source: American Academy of Allergy, Asthma & Immunology Report, Sheehan, et. al. 2010. Pest and allergen exposure and abatement in inner-city asthma: A Work Group. J Allergy Clin Immunol. March; 125(3): 575–581.