Frequency and pattern of skin- prick aero-allergic sensitizationamong children with asthma inLagos, Nigeria

Abstract

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. CC –BY 4.0

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; Alternaria-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 wa 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.

Keywords: Skin prick test, asthma, allergic sensitisation,  atopy, sub-Saharan Africa