Prediction of dermatophyte culture by clinical features: Saving time and cost in resource-poor settings

Abstract

Background: Tinea capitis is common among children worldwide. Confirmation of diagnosis for early commencement of therapy and control has continued to be a major challenge in resource-poor settings. Patients and Methods: This cross-sectional study recruited 185 children in the rural community of Osogbo, Nigeria. Two thirds of the study population were children aged 5 to 8 years. Clinical history was documented and scalp scrapping of scales and hairs was obtained for microscopy and culture. Two sided fisher exact test was employed in the bivariate analysis. Results: The mean ± SD age for the culture positive and the negative children were 7.2 ± 2.2 years and 7.8 ± 2.7 years respectively. Dermatophyte culture positivity was found in 123 (66.5%) of the children. For the culture-positive children, the positive predictive values were high at 95%, 91%, 88%, and 87% and negative predictive values were low at 16%, 24%, 18% and 0% respectively for adenopathy, alopecia, pruritus, and scalp scaling as single symptom and sign respectively. For various combinations of any two symptoms, positive predictive values ranged from 73-82%, for three symptoms 81% and for four symptoms 77%. The combinations also demonstrated higher negative predictive values 67 -86% for two, 64% for three and 78% for four symptoms, the absence of which diagnosis could be held in doubt. Similarly, positive likelihood ratios were 2.7, 1.5,1.1, and 1.0 for adenopathy, alopecia, pruritus, and scalp scaling respectively. The positive likelihood ratios ranges from 1.6 -2.8 for various combinations of two cardinal symptoms; highest for adenopathy and alopecia, and 2.0 for three symptoms and 1.8 for all the four symptoms. Conclusions: Among pre adolescent children, culture positivity is well predicted when adenopathy and alopecia are present or in combination with scalp scaling. Consequently, control of infection may be further enhanced with omission of culture and early commencement of treatment.

Prevalence of Tinea Capitis among Children in Osogbo, Nigeria, and the Associated Risk Factors

“…This is not very different from the study by Amen and Okolo (2004), which found a strong link between dermatophytosis and domestic animals [21]. A similar study also found that the overwhelming majority of the children who had tinea capitis had unlimited close contact with goats, sheep, and dogs that roam around and are not kept in closed pens [23]. The practice of rearing free-range and stray animals around the home and neighborhoods, which subsequently leads to the easy transmission of zoophilic tinea capitis, is further fostered in the cultural belief that the rearing of animals, especially free-range animals, keeps away evil from their owners [11].…”