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.
Arbes
Samuel J
SJ
Division of Intramural Research, National Institute of Environmental Health Sciences, National Institute of Health, Research Triangle, NC 27709, USA.
Sever
Michelle
M
Mehta
Jigna
J
Gore
J Chad
JC
Schal
Coby
C
Vaughn
Ben
B
Mitchell
Herman
H
Zeldin
Darryl C
DC
D000485:Allergens / Q000032:analysis* / Q000276:immunology; D000818:Animals; D052179:Antigens, Plant; D016282:Aspartic Acid Endopeptidases / Q000032:analysis* / Q000276:immunology; D002986:Clinical Trials as Topic; D003058:Cockroaches / Q000276:immunology*; D018592:Cross-Over Studies; D005500:Follow-Up Studies; D006798:Housing; D006801:Humans; D007300:Insect Control / Q000379:methods*; D007306:Insecticides / Q000494:pharmacology; D009657:North Carolina; D009994:Osmolar Concentration; D010353:Patient Education as Topic; D011204:Poverty Areas; D014505:Urban Population
D000485:Allergens; D052179:Antigens, Plant; D007306:Insecticides; C105482:allergen Bla g 1; D016282:Aspartic Acid Endopeptidases; C094699:allergen Bla g 2