Current epidemiology of atopic dermatitis in south-eastern Nigeria

Atopic dermatitis (AD) is a common pruritic, eczematous skin disorder that runs a chronic and relapsing course. In Nigeria, it is currently on the increase, particularly amongst infants, and has created cost burdens for families. It occurs in association with a personal or family history of asthma, allergic rhinitis and conjunctivitis. Major and minor criteria exist as guidelines for arriving at a diagnosis of AD, and surveys from Western countries have shown that these features, in particular the minor features, vary with ethnicity and genetic background and can be used to aid diagnosis. African dermatologists have also voiced concern that the much used Hanifin criteria for diagnosis of AD may need some adaptation for use in Africa.

To document the features and disease outcomes of AD seen amongst dermatology hospital patients in Enugu, south-eastern Nigeria, with a view to reflecting current features amongst Nigerian Blacks.

A prospective study of AD patients seen over a 2-year period at a tertiary referral dermatology clinic (University of Nigeria Teaching Hospital, Enugu, Nigeria) was carried out. A total of 1019 patients aged between 4 weeks and 57 years were included in the study.

The prevalence of AD was 8.5%, which is much higher than the prevalence of AD reported in various parts of Nigeria 15 years ago. AD occurred before the age of 10 years in 523 (51.3%) patients, whilst 250 (24.5%) had onset after 21 years. The earliest age of onset in infants was in the first 6 weeks of life, and this was found in 129 patients (12.7%). Education and occupation of household heads were the most significant (P < 0.001) factors associated with seeking proper health care for the child's AD. Four hundred and forty-one (43.3%) patients presented with subacute atopic eczema and 326 (32%) patients with severe impeteginized eczema. Four hundred and twenty-five patients (41.7%) had at least one first-degree family member with AD (16.7%), allergic rhinitis (10.3%), asthma (14.6%) and allergic conjunctivitis (2.1%), while 55 (13.3%) of controls had a positive family history (P < 0.01) of allergy. A personal history of AD only, without concomitant respiratory allergies, was seen in 486 (47.7%) patients. The face was affected in 431 (42.3%) patients. Inverse distribution of a flexural rash was observed over the extensor aspect of the joints: the elbow in 502 patients (49.3%), the wrist joint in 183 patients (17.9%) and the knee joints in 354 patients (34.7). The commonly observed minor features included xerosis in 719 patients (71%), papular lichenoid lesions in 547 patients (54.1%), infraorbital folds in 498 patients (49.2%), palmar hyper linearity in 524 patients (51.8%) and raised peripheral blood eosinophils in 519 patients (51%), particularly for those with severe AD. Fissured heels, forehead lichenification, orbital darkening, nail pitting, sand paper-like skin lesions on the elbows/knees/lateral malleolli, knuckle dermatitis of the hands, palmar erythema and pitted keratolysis occurred more uncommonly as minor features. Infective complications were very common and included bacterial infections (folliculitis, impetiginized dermatitis and pyodermas) in 425 (41.7%) patients, fungal infections in 377 (37%) patients, parasitic infections (scabies) in 90 (8.8%) patients and viral infection (herpes simplex and molluscum contagiosum) in 29 (2.9%) patients. Thirteen of these atopics were also HIV positive. Aggravating factors most commonly reported included heat intolerance, excessive sweating, humidity, grass intolerance, thick woollen clothing and drug reactions. Only three patients had food intolerance. Three hundred and ten patients (30.4%) recalled their AD being worse in the hot humid periods and 383 (37.6%) could not recall any periods of relief or remission.

The prevalence of AD amongst south-eastern Nigerian Blacks is on the increase, as in other areas, although it is still lower here than in other parts of the world. Many conventional minor features were found, but some occurred less frequently than in other countries, which may be attributed to ethnicity. Further studies will be required to confirm the ethnic differences in these features of AD amongst Nigerians and other Africans, to clarify the features of AD that are peculiar to Africans.