Background Human T cell Lymphotropic Virus Type I (HTLV-I) associated infective dermatitis, first described by Sweet in Jamaican children, is a pattern of eczema characterized by exudation, crusting around the nostrils, ears and scalp with eventual appearance of a generalized fine papular rash. More recently LeGranade and co-workers have proposed major and minor criteria in establishing the diagnosis of HTLV-I associated infective dermatitis (HAID). HTLV-I has been aetiologically linked to Adult T cell leukaemia/lymphoma (ATLL) and tropical spastic paraparesis (TSP). HAID is not only a marker of childhood infection with HTLV-I but may be a harbinger of more serious HTLV-I associated diseases later on in life such as ATLL or TSP. The pathogenesis of HAID is poorly understood so are the histopathological features of this entity. The effects of co-infection with human immunodeficiency virus- 1 (HIV-1) are inconclusive. HAID is described in Sub Saharan Africa, Senegal but no data is published on this entity in Southern Africa, characterizing the clinical, laboratory features and the histopathology of this entity. Aims and Objectives 1) To describe the clinical and histological features of HTLV-I associated infective dermatitis in KZN, South Africa 2) To determine the virological characteristics of HTLV-I in KZN, South Africa 3) To assess for HTLV-I / HIV co-infection Methods This was a prospective study of all patients with HAID who presented to King Edward VIII hospital (KEH), outpatient department over a period of 42 months. These were patients who fulfilled the clinical criteria of HAID. Enrolled patients were subjected to a confirmatory HTLV-I serology testing. Demographic data was obtained from all HTLV-I seropositive patients. Their clinical examination included dermatological, neurological and pathological examination. A blood count, immunoglobulin levels, serum protein electrophoresis measuring albumin levels and globulin fractions were measured. For bacteriological assessment skin swabs were taken from the affected sites with stool samples examined for parasites, ova and cysts. The HIV-1 status together with HIV-1 viral load were determined on those enrolled. The CD4 count, CD8 counts and CD4/CD8 ratio were also calculated. Skin biopsies were taken for histological examination. PCR for HTLV subtyping was performed on a subset of the cohort. Results Demography Of the 60 patients recruited, 33 fulfilled criteria for HAID. The majority of patients fell between age categories of 6 to lOyears. The male to female ratio was 1:1. There were more females in the adult group than there were within the childhood group. All of the patients in our cohort were African. Clinical features The lesions were erythematous, scaly, exudative, and crusted in all cases. The distribution of lesions was as follows: scalp (77.4%), retroauricular areas (71%), the axilla (65%) and paranasal areas (58%) were the sites more commonly affected. Nasal crusting was not a significant feature in this series. Bacteriology Culture was positive for Staphylococcus aureus (S. aureus) in 90%, with streptococcal group of organisms found in 68% of the skin swabs taken from the lesional skin. Haematological Our patients were mildly anaemic as has been shown in previous studies. They had a mean Hb of 11.5g/dl. In 12 of the 14 patients tested, the erythrocyte sedimentation rate (ESR) was elevated. Serum protein electrophoresis and levels of Immunoglobulin A, G and M were raised. The mean CD4 count in the entire group was elevated at 1730 cells/fil, CD8 was 1299 cells/ul Histopathology The major histological findings were as follows: 38% demonstrated a superficial and deep perivascular inflammatory infiltrate, 28% had a superficial and deep perivascular inflammatory infiltrate together with a lichenoid dermatitis, 12.9% had features of superficial and deep inflammatory infiltrate with an interface dermatitis, 6.4% revealed features of seborrhoeic dermatitis. Genotyping Our patients were infected with the strains belonging to the Cosmopolitan, A Subtype (HTLV-Ia). Complications Complications were low in this series with the commonest being scabies in 6(18.1%), corneal opacities in 3(8.6%), 2(6 %) with HAM/TSP. No parasitic worm infestations were isolated. HIV/HTLV-I co-infection Of the 33 patients, 9 (30 %) were co-infected with HIV. The mean viral load in this group was 52 000 copies/ml. Their mean CD4 count was also elevated at 1505cells/^il with a CD8 of 1704 cells/Mi and a CD4/CD8 ratio of 1.15. Discussion Thirty three of the 60 patients enrolled met the diagnosis for HAID according to the established criteria. The mean age in this series was 17 years (range: 8 months-46 years)however; almost a third (30.3%) were children under 12 years, reinforcing the entity as a childhood infective condition. There was an equal male female distribution in the childhood group and a female predominance in the adult group. Clinically patients presented with infected erythematous, scaly lesions mainly on the scalp, neck and post- auricular area. The clinical features were in keeping with other series worldwide. The complication rate was low in our cohort. S. aureus was the predominant organism in both anterior nares and lesional skin. The most common histological pattern was superficial and deep perivascular inflammatory infiltrate. The subtype in our series was the Cosmopolitan Subtype A (HTLV-Ia) as opposed to subtype B in Japan. We share with Brazil a common subtype. A subset of our patients (30%) was co-infected with HIV. The CD4 cell count in this subgroup was lower than the entire group but this was not statistically significant. The histological patterns found in this subgroup infected with HIV were similar to the rest of the group except for a more intense eosinophilic infiltrate in these skin biopsy specimens. Conclusion HTLV-I associated infective dermatitis is distinct entity which affects the African population of KwaZulu Natal, South Africa. It is predominantly a disease of childhood with an equal female to male ratio in children. The clinical features are an exudative, erythematous scaly rash most commonly found involving the scalp, axillae, paranasal and retroauricular areas. HTLV-I positivity is essential for the diagnosis; the Cosmopolitan Subtype A is commonest in South Africa. The commonest histological pattern is a superficial and deep perivascular infiltrate in 38%. A subset, 30%, was co-infected with HIV. / Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2008.