[Evaluation of exposure and sensitization to house dust mites among rhinitis patients in the steppe environment of Inner Mongolia].

Objective: To evaluate the correlation of exposure and sensitization to house dust mites among rhinitis patients, and the consistency of skin prick test (SPT) and serum specific IgE (sIgE) in the detection of sensitization in a steppe environment of inner Mongolia.

Methods: Three hundreds and fourteen patients with rhinitis symptoms were recruited in this study in a hospital setting at Xilinhot City, inner Mongolia. All patients underwent medical history investigation, anterior rhinoscopy, and allergen tests in vivo (SPT) and in vitro (sIgE). Dust samples were collected from mattresses in patient's bedroom. The concentrations of group I major allergen of Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f) were measured by enzyme linked immunosorbent assay (ELISA). Statistical analysis was performed using a SPSS 17.0 software (t test, χ(2) test and so on).

Results: Among a total of 314 patients, the prevalence of positive SPT for Der p and Der f was 5.7% and 22.0%, respectively; and the prevalence of positive sIgE for Der p and Der f was 9.2% and 7.6%, respectively. Sensitization rates for house dust mites (Der p and/or Der f) were lower than those of pollens. The pollen allergen with the highest positive rate was mugwort (SPT, 51.9%; sIgE, 47.1%). Diagnostic tests using SPT as the gold standard for sensitization showed that the positive likelihood ratio of sIgE was 4.27 for Der p and 10.64 for Der f, and the Kappa value was 0.20 for Der p and 0.35 for Der f, respectively. A total of 276 dust samples collected from patient's mattresses were measured. The concentrations of Der p 1 and Der f1 were detectable in 2 (0.7%) and 4 (1.4%) mattress samples, respectively. There was positive correlation between the exposure levels of Derp 1 and the SPT positive reaction to Der p (r(s) = 0.156, P = 0.01), but no significant correlation was found between the exposure levels of Der p 1 and the sIgE positive reaction to Der p (r(s) = 0.116, P = 0.055). There was no significant correlation between the exposure levels of Der f 1 and the SPT as well as sIgE positive reaction to Der f 1(r(s) = 0.05, P = 0.931; r(s) = 0.07, P = 0.245).

Conclusions: In the steppe environment of inner Mongolia, exposure to house dust mites are very low, and the Der p and Der f are not the major allergens in patients with allergic rhinitis. Also, it was not a simple dose-response relationship between exposure and sensitization to house dust mites. In such a specific environment, there is lower consistency between the results of SPT and sIgE in the detection of sensitization to house dust mites. Therefore, it is recommended that the allergen testing in vivo and in vitro should be combined for clinical diagnosis.