Guanine, mite, and cockroach allergens in Costa Rican homes

Abstract

Previous studies of schoolchildren in Costa Rica have shown an asthma prevalence of 23% and a high level of sensitization, particularly to mite allergens. As a continuation of these studies, some 400 dust samples were collected from various places in Costa Rica, and parts of these were analyzed for specific mite and cockroach allergens, as well as for the number of mites and amount of guanine. Guanine was quantified by a diazo, as well as an HPLC method, which were found to be highly correlated. The concentrations of guanine by the diazo method, Der p 1, Der f 1, and the number of mites were higher in bed dust than in bedroom floor dust, and it was possible to quantify mite allergens and guanine in almost all bed-dust samples. The mean levels were 2-3 times higher than the proposed risk level for elicitation of symptoms in mite-sensitive asthmatics. Bed and bedroom floor dust contained more guanine and mite allergen in humid (> 2000 mm rain) than in drier places (P < 0.05), but the number of mites in bed and bedroom floor dust was higher in less humid places (P = 0.01). The guanine content in bedroom floor dust was higher in areas with a temperate climate than in areas with a warmer climate (P < 0.001, Bartlett's chi square [BCS]), as was the number of mites (P < 0.01, Kruskal-Wallis [KW], 0.04, BCS) and the Der p 1 concentration (P = 0.01, BCS; P = 0.02, KW). The Der f 1 concentration in bedroom floor dust was higher in a warmer than in a temperate climate (P < 0.001, BCS). More guanine and mites were found in urban than in rural bed dust (P = 0.03, KW). Dust samples from the metropolitan area (temperate climate) of Costa Rica contained higher levels of guanine (P < 0.01) and Der p 1 (P = 0.07) than the coastal areas, but very little Der f 1. In these samples, guanine and Der p 1 allergen were closely related, and 2 micrograms of the allergen was equivalent to 0.49 mg of guanine. Two-thirds of bed and floor samples collected on cotton filters contained Bla g 2 allergen at mean levels of 1.6 and 2.1 units/g dust, respectively. Cockroach allergen was, however, absent in all bed samples from the metropolitan area, but did occur in very high concentrations in the coastal bed dust samples collected with tighter polyester filters. In conclusion, the concentration of guanine and Der p 1 was very high in the bed dust of Costa Rican homes. Some factors, such as humidity, small houses for large families, and type of bedding, probably favored the heavy mite infestation, which is probably related to the widespread occurrence of bronchial asthma in this country.

Arthropod Allergens and Human Health

“…Allergy to cockroaches was first reported in 1964 by Bernton & Brown in New York (36), who showed that 40% of their asthmatic patients were sensitive to cockroaches. Since that time, many studies have shown that among exposed populations in the United States, China, Costa Rica, Hong Kong, Malaysia, Taiwan, Japan, and Europe, the sensitivity to cockroaches ranges from 23-60% (45,88,126,127,159,160,179,227,238,240,280). Among patients with atopic rhinitis, atopic dermatitis, and asthma, the prevalence of sensitivity to cockroach allergens in Italy, France, and Brazil is reported to be 12.5, 24.5, and 55%, respectively (37, 201, 223).…”

Dust mite allergens: Ecology and distribution

“…Data from South America [34][35][36][37][38][39][40], the Caribbean [41,42], and Southeast Asia [43][44][45] show that D. pteronyssinus and Blomia tropicalis are the predominant species, but D. farinae is present in low numbers. A survey of 41 dwellings in Upper Silesia, Poland [46], found most to be infested with both D. farinae and D. pteronyssinus.…”

The High Prevalence of Rhinitis, Rhinoconjunctivitis, and Eczema in Costa Rican Schoolchildren Studied with the ISAAC Protocol

“…In our study, the prevalence of rhinitis was reported to be higher during the rainy season, from May to October, probably due to high humidity, causing high mite and cockroach concentrations in homes, especially in the beds (16), as well as the presence of an usually rich variety of pollens and molds in Costa Rica, at that time of the year. Viral infections increase in prevalence during the rainy season and possibly the asthmatic and rhinitic symptoms are related to them.…”

“…The most prevalent IgE antibodies were directed against the mite Dermatophagoides farinae, cockroach, dog, and housedust allergens. 16 In a previous investigation of Costa Rican schoolchildren, aged 5-17 years, we found that allergic rhinitis was present in 32.8% and atopic dermatitis in 14.2% of the children with asthma, as compared with 17.3% and 12.9% of the nonasthmatics. 24 SOTO-QUIRÓS ET AL.…”

“…20 The varying prevalences of atopic dermatitis in the Latin American region and other Spanish speaking countries may be related to genetic differences, 11,18 but the heavy exposure to mites and cockroaches among the populations we studied may also be an important factor. 16 Other factors unrelated to atopy, such as dry skin in early infancy, may influence the occurrence of atopic dermatitis. 21 Perinatal factors like low parity, febrile infections in pregnancy, and use of contraceptives before pregnancies have also been suggested to increase the risk of allergic disorders among children.…”