Frequency and pattern of skin-prick aero-allergic sensitization among children with asthma in Lagos, Nigeria

Abstract

Background: Among children with asthma, aero-allergen sensitisation (AS) results in poorer outcomes, necessitating allergen control. However, the spectrum of AS in childhood asthma in Nigeria is not well-known. We describe the prevalence and pattern of skin-prick AS among children with asthma seen at the paediatric allergy clinic of the Lagos State University Teaching Hospital, Ikeja, Lagos, Nigeria. Methods/Material: Retrospective review of routinely-collected data of asthmatic children who had skin-prick test (SPT) at the Paediatric Allergy clinic, conducted with a 9-allergen-extracts kit comprising house-dust mite (HDM) [subtypes: Dermatophagoides pteronysinnus (Der p), Dermatophagoides farina (Der f ), Blomia tropicalis (Blo t)]; Cockroach, Aspergillus fumigatus, cat, dog, Alternaria alternata and grass-mix. AS was defined as wheal diameter ≥ 3 mm above saline control (0 mm), with histamine wheal ≥ 3 mm (after 15-minute observation), to at least one antigen. Results: Between January 2019 and May 2021, fifty-eight children (60.3% boys) aged 2-17 years [median (range; IQR)= 7.0 (2.0, 17.0; 5.0)] had SPT. AS was present in 86.2% (n=50/58), comprising allergy to: HDM [82.1% (n=46/56) (Der f-67.9%; Blo t: 64.3%; Der p: 51.8%]; cockroach ( 3 9 . 3 %, 2 2 / 5 6 ); m o u l d s (Aspergillus-3.6%, 2/56; Alter-naria-1.8%, 1/55) and pet (cat-1.8%, 1/56; dog-1.8%, 1/56). About two-thirds (65.5%, 38/58) were polysensitised but there was no cross-sensitisation between HDM and cockroach allergy [kappa (95% CI)=-0.004(-0.18, 0.17)]. Conclusions: AS, especially to HDM and cockroach, was common among asthmatic children; a previously-unreported high prevalence of Blomia tropicalis allergy was notable. HDM and cockroach control may be important in our patients.