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Allergen sensitization in Mexico associated with age, climate

Patients with allergic rhinitis living in tropic and subtropic Mexico showed an association between age and climate, but no relationship was determined with a specific rhinitis symptom phenotype in a recent study.

In a nationwide prospective study, investigators reviewed questionnaire results of 529 patients (mean age, 21.8 years; 48.2% male) with confirmed allergic rhinitis (AR), aged 2 to 68 years, from 26 study centers across six climatic zones in Mexico. Patients completed surveys on rhinoconjunctivitis symptoms and underwent double blind skin prick tests (SPT) with 16 common allergens, including house dust mites (56%), cat (22%), cockroach (21%) and pollen from Bermuda grass (26%), ash (24%) and oak (23%).

Results from SPT showed that nationally patients tested positive for mites (proportion, 0.599; 95% CI, 0.55-0.64), tree pollens (0.442; 95% CI, 0.4-0.48), grass pollens (0.338; 95% CI, 0.3-0.38), weed pollens (0.265; 95% CI, 0.23-0.3) and molds (0.113; 95% CI, 0.09-0.14). Across all regions, most patients displayed perennial (82.2%), intermittent (56.6%) and moderate-severe (84.7%) AR.

Eighty-seven percent of patients living in tropical climates were sensitized to house dust mites, while patients who lived in central agricultural areas were more susceptible to grass and tree pollen. Children and adolescents showed greater sensitization to mites than adults in tropical (P<.0005) and subtropical (P<.05) regions, while adults were more sensitive to tree pollens (P<.0001) and weed pollens (P<.0005).

“In patients with AR symptoms living in the subtropics, SPT sensitization patterns are different from those found in Europe and the US,” the researchers concluded. “Sensitization patterns are not clearly linked to any specific AR symptom phenotype, but they do vary according to age (child-adolescent vs. adult) and climate zone.

“Hence, in our population, sensitization to a certain allergen is not linked to either intermittent or persistent AR, or to mild or moderate-severe AR.”

Disclosure: The researchers report no relevant financial disclosures.