House dust mite sensitive asthma: preliminary study on its incidence and seasonal prevalence under the Egyptian environmental conditions

ABSTRACT

The authors tried to trace incidence and seasonal prevalence of allergic bronchial asthma in relation to common aeroallergens in Egypt. The subjects consisted of patients coming to allergy clinic from urban and rural areas around Cairo. Among unselected asthmatics, the house dust mite allergy occurred more common followed by house dust. Among selected patients who were clinically sensitive to house dust, there was a higher incidence of positive skin reactions with extracts of house dust mite D. pteronyssinus, a finding which might suggest a strong correlation between mite allergens and house dust allergy under our Egyptian indoor environmental conditions.The IFA tests revealed that sera of patients sensitive to house dust mite D. pteronyssinus gave positive reactions to D. pteronyssinus and T. putrescentiace with varying degrees. This positive reaction to both antigens of Dermatophagoides and Tyrophagus might be either due to the presence of common antigens related to allergens sharing in the two mites or due to sensitization of patients by antigens from both mites patients who had positive prick tests to house dust mite D. pteronyssinus had worsening of symptoms in mid autumn and to a lesser extent during summer. It was also obvious that there was delayed rise in onset of severe symptoms which occurred, at least about two months later from peaks of live mite abundance. This was seemingly due to the disintegrated dead mites and the accumulated faecal pellets which might maximize environment pollution with mite allergens. The authors discussed their finding with those of others and introduced new suggestions