Patch testing and contact allergens in Ethiopia – results of 514 contact dermatitis patients using the European baseline series

Abstract

Patch testing is essential to diagnose allergic contact dermatitis. Dermatologists in many countries use a baseline (standard) series covering the major allergens responsible for allergic contact dermatitis in their population, with the addition of relevant allergens for the individual patient. However, a baseline series has not yet been developed for Ethiopia. Our objective in this study is to identify common contact allergens to form the basis of a future baseline series in Ethiopia. We patch tested 514 subjects with dermatitis according to the recommended procedure using the European baseline series for 1 year. 52.7% of the tested subjects showed positive reaction for at least one allergen tested. The top five contact allergens identified were nickel sulfate, fragrance mix I, cobalt chloride, p-tert-butylphenolformaldehyde (PTBP) resin and potassium dichromate. Positive reactions to nickel and PTBP were commoner in females. PTBP positivity was strongly associated with foot eczema. Positive test reactions were commoner in cement workers, notably to potassium dichromate, which was also a commoner allergen in patients presenting with hand dermatitis. There were no reactions to several allergens, including neomycin, benzocaine, budesonide, primin and quaternium-15. Comparable patch test results with other countries have been shown and the European baseline series can be used as a baseline series in Ethiopia with some modification.