Why School IPM: Health Issues: Pests

Allergens

The US Government reports a trend of increasing cases of asthma {4}. A series of studies have identified cockroaches as human allergens and have furthermore linked these allergens to asthma. The following bulleted items are briefly reviewed in the literature and do not by any means constitute a thorough search.

• Rodents
• Flies
• Cockroaches

Cockroaches / byproducts as human allergens: these allergies linked to asthma

A host of studies recognize cockroaches and their byproducts as strong indoor allergenic agents {11, 35, 38, 40}. The potential role of cockroach allergens in asthma development was first suggested by Bernton et al. {12} and subsequent studies have linked asthma to allergens associated with cockroaches {15, 18, 22, 24, 27, 28}.

Sensitivity to cockroaches linked to Infestation levels

Kang et al. {29} linked cockroach hypersensitivity with the rate of cockroach infestations in human habitats. Since the prevalence of asthma in children been increasing steadily {13, 29}, the need to control cockroaches is more important than ever. 

Cockroaches identified as a key factor of asthma in children

Children in the inner city have higher levels of exposure to cockroach allergens than most {32}, and this increased exposure to cockroach allergens is one key factor responsible for the higher prevalence of asthma in poor urban areas {15}.

Not surprisingly, a significant reduction in exposure to cockroach allergens can be achieved only through extermination of resident cockroach populations. In a recent study by Sarpong et al. {43}, repeated measure of cockroach allergen levels in floor dust samples taken from an urban dormitory were similar despite weekly vacuum cleaning. However, when regular vacuuming was combined with cockroach extermination, the level of cockroach allergens fell 5.5 times. Currently available pesticides have been shown to reduce cockroach populations by 85 to 100% and maintain reductions for at least 3 months {25}. Unfortunately, cockroaches are behaviorally, physiologically, and genetically adaptable, and it is unlikely that a single approach to their control will be effective through time {26}. Therefore, it is important to implement integrated pest management approaches, that do not rely on indiscriminate insecticide applications as a sole tool for cockroach control.

Diseases Associated with Rodents

Rodents and insects have been implicated in the transmission of various diseases. Rats and mice are carriers of rare but deadly microorganisms such as plague and the hanta virus. Insects are also associated with diseases and food contaminants. 

Diseases Associated with Flies

There is a direct correlation between dysentery in people and the extremely large populations of house flies. Other types of major health risks include tuberculosis, yaws, leprosy, myiasis, and poliomyelitis {1}. Although there is little definitive proof that flies transmit diseases, there is ample evidence suggesting they are capable of mechanically picking them up. In fact, a compilation of two articles reviewing the human pathogens associated with the house fly lists 2 viruses, 30 types of bacteria, 10 protozoa, 6 platyhelminths and 3 species of nematodes {17, 23}. 

Diseases Associated with Cockroaches

Cockroaches produce odorous secretions that can affect the flavor of various foods and have also been implicated in the transmission of diseases. Disease-producing organisms such as bacteria, protozoa, and viruses have been found in cockroach bodies. Different forms of gastroenteritis (food poisoning, dysentery, diarrhea, etc.) appear to be the principal diseases transmitted by these cockroaches. These disease-causing organisms are carried on the legs and bodies of cockroaches, and are deposited on food and utensils as cockroaches forage.

In addition, there is ample evidence implicating cockroaches in the transmission of hospital acquired diseases {14, 16, 21, 19, 20, 34}.