German cockroach allergen levels in North Carolina schools: comparison of integrated pest management and conventional cockroach control.

Cockroach suppression is fundamental to cockroach allergen mitigation in infested homes. The effects of various cockroach control strategies on cockroach populations and allergen concentration have not been examined in schools. This study was conducted to compare the effectiveness of integrated pest management (IPM) and conventional pest control in controlling German cockroach (Blattella germanica L.) infestations and concentrations of the cockroach allergen Bla g 1 in public school buildings. Two school districts included six schools that used conventional pest control and one district included seven schools that used IPM to control pests. Cockroach traps were deployed to assess the level of infestation, settled dust samples were collected in food service areas, classrooms, and other school areas, and the Bla g 1 allergen was quantified by ELISA. Both cockroach counts and Bla g 1 concentrations were dependent on the pest control approach, with highly significant differences between IPM-treated schools and conventionally treated schools in both the cockroach mean trap counts (0 versus 82.6 +/- 17.3 cockroaches/trap/wk, respectively) and in the amount of Bla g 1 in dust samples (2.8 +/- 0.3 versus 30.6 +/- 3.4 U/g dust). Cockroaches and Bla g 1 were primarily associated with food preparation and food service areas and much less with classrooms and offices. Our data extend recent findings from studies in homes, showing that cockroach allergens can be reduced by cockroach elimination alone or by integrating several tactics including education, cleaning, and pest control. IPM is not only effective at controlling cockroaches but also can lead to long-term reductions in cockroach allergen concentrations, resulting in a healthier environment for students and school personnel.

Cockroach allergen reduction by cockroach control alone in low-income urban homes: a randomized control trial.

BACKGROUND: We previously reported significant reductions in cockroach allergen concentrations in urban homes by reducing cockroach infestations. OBJECTIVE: To determine the effectiveness of pest control performed by professional entomologists, compared with commercial companies, in reducing cockroach allergen. METHODS: This 3-arm randomized controlled trial enrolled 60 cockroach-infested homes in North Carolina. Homes were randomly assigned to a control group or 1 of 2 treatment groups. Treatment 1 had insecticide baits placed by entomologists from North Carolina State University. Treatment 2 received pest control from a randomly assigned commercial company. Vacuumed dust sampling and cockroach trapping were conducted at 0, 6, and 12 months. Dust samples were analyzed by ELISA. RESULTS: In treatment 1 homes, there were significant reductions in geometric mean trap counts compared with control and treatment 2 homes at 12 months. Relative to control, significant 12-month reductions in Bla g 1 were evident in treatment 1 homes at all sampled sites, except bedroom floor. From baseline to month 12, geometric mean Bla g 1 concentrations (U/g) decreased from 64.2 to 5.6 in kitchen, 10.6 to 1.1 in living room, 10.7 to 1.9 on bedroom floor, and 3.6 to 2.3 in bed. Treatment 2 homes showed no significant 12-month allergen reductions versus control. CONCLUSION: Reductions in Bla g 1 in cockroach-infested homes can be achieved by reducing infestations; however, the magnitude of allergen reduction is dependent on the thoroughness and effectiveness of cockroach eradication efforts. CLINICAL IMPLICATIONS: Elimination of cockroaches is an effective method for reducing exposure to cockroach allergen.

Cockroach allergen biology and mitigation in the indoor environment.

For nearly a half century, cockroaches have been recognized as a major cause of asthma morbidity in the urban, inner-city environment. Several cockroach-produced allergens have been identified and characterized, and a few have been produced as recombinant proteins. Recent research has moved beyond clinical, patient-based investigations to a more entomological perspective that addresses the production, physiological regulation, and developmental expression of cockroach allergens, thus providing insight into their functional biology and their relationship to current cockroach control strategies. Although successful removal of cockroach allergens from the infested environment has been difficult to accomplish with remedial sanitation, large-scale reductions in cockroach allergens below clinically relevant thresholds have recently been realized through suppression of cockroach populations. Here we review the current understanding of cockroach allergen biology and the demographics associated with human exposure and sensitization. We also critically evaluate allergen mitigation studies from an entomological perspective, highlighting disparities between successful and failed attempts to lessen the cockroach allergen burden in homes.

Expression, production and excretion of Bla g 1, a major human allergen, in relation to food intake in the German cockroach, Blattella germanica.

The German cockroach, Blattella germanica (Linnaeus) (Dictyoptera: Blattellidae), produces several potent human allergens, one of which, Blattella germanica allergen 1 (Bla g 1), is produced in the midgut and excreted in faeces. We tested with descriptive and experimental approaches the hypothesis that Bla g 1 production is related to food intake in adult males and females of the German cockroach. Bla g 1 mRNA expression in the female midgut (assayed by real time quantitative polymerase chain reaction), her Bla g 1 content (assayed by enzyme-linked immunosorbent assay), and the female's faeces production and its Bla g 1 content tracked a cyclic pattern in relation to the gonadotrophic cycle. All four measures rose as food intake increased, declined before oviposition in relation to diminishing food intake, and remained low while the female carried an egg case for 20 days. After her first clutch of embryos hatched, the female resumed feeding, and faeces and Bla g 1 production increased concomitantly. Both Bla g 1 mRNA expression and Bla g 1 protein levels remained low in experimentally starved females. However, when starved females were allowed to feed, Bla g 1 production elevated and the gonadotrophic cycle resumed. Bla g 1 mRNA expression also increased six-fold in response to feeding compared to starved females. By contrast, there were no apparent cycles in the pattern of Bla g 1 production in males, reflecting their low and non-cyclic food intake. Our results therefore demonstrate that Bla g 1 production in B. germanica is modulated in relation to food intake.

Gene expression and tissue distribution of the major human allergen Bla g 1 in the German cockroach, Blattella germanica L. (Dictyoptera: Blattellidae).

Exposure and sensitization to cockroach allergens is an important risk factor for allergic disease in humans. Despite a recent burgeoning of clinical and socioeconomic studies regarding environmental pervasiveness and human exposure to cockroach allergens, little is known about the basic biology of these proteins. The purpose of this study was to ascertain gene expression patterns and the tissue distribution of Blattella germanica allergen 1 (Bla g 1), a perennial indoor environmental allergen, thought to be involved in digestion in cockroaches. We also investigated the relative potential contribution of different life stages of the German cockroach to environmental Bla g 1. Enzyme-linked immunosorbent assay was used to quantify the Bla g 1 contents of feces and various anatomical tissues, and Northern blot analysis was used to elucidate tissue-specific expression of Bla g 1. Results showed that the Bla g 1 protein is most prevalent in the midgut, and the Bla g 1 gene is exclusively expressed by midgut cells. Although Bla g 1 is produced by both sexes and all life stages of the German cockroach, adult females produce and excrete significantly more Bla g 1 in their feces than males or nymphs, even when corrected for body mass or mass of voided feces. Our results show that the concentration of Bla g 1 in feces of adult females is 6- to 7- and 30-fold higher than in adult males and nymphs, respectively, probably because females process more food than other life stages of the German cockroach.

Laboratory evaluation of boric acid-sugar solutions as baits for management of German cockroach infestations.

Boric acid dust has a long history as an insecticide in urban pest management, and it has been shown to be an effective alternative to conventional neurotoxic insecticides. However, dust formulations require specialized equipment and are difficult to apply, whereas gel and paste formulations contain large amounts of boric acid and tend to be less efficacious than other insecticide baits. The purpose of this study was to evaluate the effectiveness of borate solutions as baits against the German cockroach. Several borate-sugar combinations were evaluated in choice and no-choice assays in the laboratory. Mortality was recorded for 15 d and expressed as lethal time90, the time taken to kill 90% of the cockroaches. Results showed that boric acid was more effective than sodium tetraborate or disodium octaborate tetrahydrate and that aqueous solutions containing mixtures of 0.5-2% boric acid and any of several inexpensive sugars, including fructose, glucose, maltose, and sucrose as a phagostimulant, at molar concentrations of 0.05-1.0, can provide rapid and effective kill of German cockroaches, Blattella germanica (L.).

Water solutions of boric acid and sugar for management of German cockroach populations in livestock production systems.

Pest management in confinement swine production relies primarily on calendar-based applications of broad-spectrum insecticides. However, regulatory restrictions imposed by the U.S. Food Quality Protection Act of 1996, the large financial obligation of pesticide registration, and development of insecticide resistance have led to a renewed search for alternative control methods. Boric acid dust has long served as an insecticide in urban pest management and has been shown an effective alternative for use in sensitive environments such as swine production. However, dust formulations are difficult to apply and require specialized equipment. The purpose of this study was to evaluate the efficacy of liquid baits containing boric acid for the control of German cockroaches in a commercial swine nursery. Bait, consisting of 1 or 2% boric acid and 0.5 M sucrose, was deployed in 21 bait delivery tubes per room. Results of a 2-yr study showed significant reductions in cockroach populations. When baits were withdrawn in the summer, the cockroach population increased significantly faster than when the baits were removed during the winter. These data indicate that liquid formulations of boric acid effectively reduce the burden of cockroach infestation in swine production. This approach should have applications in structures in other urban and agricultural environments.

Abatement of cockroach allergens (Bla g 1 and Bla g 2) in low-income, urban housing: month 12 continuation results.

BACKGROUND: In the first 6 months of this previously published, randomized trial, the combined intervention of occupant education, insecticide bait application, and professional cleaning significantly reduced cockroach numbers and Bla g 1 allergen levels in inner-city homes. OBJECTIVE: This continuation study investigated whether the cockroach allergen reductions achieved by month 6 could be maintained through month 12 with insecticide application alone. METHODS: Because we had agreed to place insecticide bait in control homes at the conclusion of the first study, intervention and control homes were treated with insecticide bait at months 6 and 9. No other intervention was conducted in either arm. Vacuumed dust and swab samples were collected at month 12. Twenty-one of the 31 original homes completed the 12-month study. RESULTS: Among the original intervention homes, Bla g 1 concentrations remained essentially unchanged from months 6 to 12. However, among the crossed-over control homes, the geometric mean Bla g 1 concentrations (Units per gram of dust) decreased from 287 to 14.4 for kitchen floors (95% reduction), from 28.8 to 5.6 for living room floors/sofas (81% reduction), from 26.7 to 4.7 for bedroom floors (82% reduction), and from 7.2 to 2.4 for beds (67% reduction). At month 12, Bla g 1 concentrations did not significantly differ between intervention and crossed-over control homes (P >.64 at each location). Similar results were seen for the allergen Bla g 2. CONCLUSIONS: Reductions in cockroach allergen concentrations achieved through the combined intervention of occupant education, insecticide application, and professional cleaning can be maintained with continued cockroach control. Surprisingly, and in contrast to other studies, insecticide application alone significantly lowered allergen concentrations in the crossed-over control homes. This unexpected result is being tested further in another randomized trial.

Boric acid dust as a component of an integrated cockroach management program in confined swine production.

Boric acid dust treatments were evaluated as a tool for the integrated management of the German cockroach, Blattella germanica (L.), in commercial confined swine production. The efficacy of boric acid dust was comparable to that of an organic residual insecticide, cyfluthrin, which is commonly used to control cockroaches in this environment. Fall treatments suppressed the cockroach population for longer durations than treatments in the Spring. Boric acid dust is an effective, inexpensive, and low risk (to animal and human health, and the environment) alternative for the management of cockroaches in livestock production systems.

Abatement of cockroach allergen (Bla g 1) in low-income, urban housing: A randomized controlled trial.

BACKGROUND: Clinically relevant reductions in exposure to cockroach allergen, an important risk factor for asthma in inner-city households, have proven difficult to achieve in intervention trials. OBJECTIVE: This study investigated a method for the abatement of cockroach allergen in low-income, urban homes. The goal was to reduce mean Bla g 1 concentrations below the previously proposed thresholds for allergic sensitization and asthma morbidity. METHODS: A prerandomized, nonmasked trial with 16 intervention and 15 control homes was conducted. Study inclusion was based on 50 to 500 cockroaches trapped in a 3-day period. The interventions consisted of occupant education, placement of insecticide bait, and professional cleaning. Vacuumed dust and multiple swab samples were collected at 0, 1, 2, 4, and 6 months in intervention homes and at 0 and 6 months in control homes. Room maps containing cockroach and allergen data were used to guide and monitor the interventions. RESULTS: From 0 to 6 months among intervention homes, geometric mean Bla g 1 concentrations (U/g dust) decreased from 633 to 24 on kitchen floors (96% reduction), from 25 to 4.3 on living room floors/sofas (83% reduction), from 46 to 7.3 on bedroom floors (84% reduction), and from 6.1 to 1.0 in bedroom beds (84% reduction). These reductions, with the exception of that on the bedroom floor (P =.06), were statistically significant relative to changes in control homes. CONCLUSIONS: Substantial reductions in cockroach allergen levels can be achieved in inner-city homes. In this study, allergen levels were reduced below the sensitization threshold (2 U/g) in beds, arguably the most relevant site for exposure, and below the asthma morbidity threshold (8 U/g) on bedroom floors and living room floors/sofas. The level on kitchen floors, although reduced 96%, remained above the asthma morbidity threshold. Future studies will test the intervention's effectiveness in asthma prevention trials.