Epidemiology and prevalence of onychomycosis in HIV-positive individuals

Patients who are human immunodeficiency virus (HIV) positive are predisposed to the development of infections including tinea pedis and onychomycosis. While smaller studies have been reported, there has been no large study evaluating the prevalence of onychomycosis in HIV-positive individuals, or comparing the development of onychomycosis in a typical temperate area with that in a typical tropical area.

HIV-positive individuals were evaluated at five clinics: four in Ontario, Canada and one in Sao Paulo, Brazil. The subjects were asked questions to determine the epidemiology of onychomycosis in HIV-positive individuals. The feet were examined and nail material was obtained for mycologic examination to determine the causative organism of onychomycosis.

A total of 500 subjects were examined (415 men and 85 women; age (mean +/- SE), 39 +/- 0.4 years; 400 Canadian, 100 Brazilian). The racial origins of the Canadian patients were: Caucasian, 83.8%; Asian, 4.3%; African-American, 8.1%; Hispanic, 3.3%; American Indian, 0.3%. The Brazilian origins were: Caucasian, 68.7%; African, 18.1%; mixed race, 13.3%. Abnormal appearing nails and mycologic evidence of onychomycosis were present in 200 (40.0%) and 116 (23.2%), respectively, of 500 subjects. The prevalence of onychomycosis in the Canadian and Brazilian samples was 24.0% (96 of 400) and 20.0% (20 of 100), respectively. The projected prevalence of onychomycosis in HIV-positive individuals in Canada was 19.9% (95% CI: 16.0-23.9%) after taking into account the age and sex distribution of HIV-positive individuals in the population. When nails appeared clinically abnormal, the prevalence of onychomycosis was 50.5% (Canada, 51.3%; Brazil, 45.5%). For comparison, published data indicate that the prevalence of onychomycosis in immunocompetent individuals living in Canada is 6.9%. The clinical presentation of onychomycosis for the whole sample (n=500) was: distal and lateral subungual onychomycosis (DLSO), 20.0%; white superficial onychomycosis (WSO), 3.6%; proximal subungual onychomycosis (PSO), 1.8% (Canadian and Brazilian samples: DLSO 21.2% vs. 15.0%, WSO 3.3% vs. 5.0%, and PSO 1.5% vs. 3.0%). The distribution of the causative fungal organisms was: dermatophytes: Candida species: nondermatophyte molds, 73:2:2 (Canadian and Brazilian samples: dermatophytes 95.5% vs. 90.9%, Candida species 3.0% vs. 0%, and nondermatophyte molds 1.5% vs. 9.0%). The use of protease inhibitors, reverse transcriptase inhibitors, or oral antifungal agents did not make a significant difference in the prevalence of onychomycosis for both the Canadian and Brazilian groups. Patients with onychomycosis were aware of their abnormal appearing nails (chi2(1)=69.7, P<0.001), embarrassed by the appearance of their nails (chi2(1)=29.7, P<0.001), and took measures to hide their nails from other individuals. A higher proportion of individuals with onychomycosis experienced discomfort compared with those without the disease (chi2(1)=9.0, P=0.003). Also, individuals who experienced pain in the nail unit were more likely to have onychomycosis (risk odds ratio (ROR), 2.2; 95% CI: 1.0-4.7, P=0.05).

The prevalence of onychomycosis in HIV-positive individuals in the sample of 500 patients was 23.2%. In the Canadian (n=400) and Brazilian (n=100) samples, the corresponding figures were 24% and 20%, respectively, with the predominant causative organisms being dermatophytes. The projected prevalence of onychomycosis in HIV-positive Canadians is 19.9%. Predisposing factors include a CD4 count of approximately 370, a positive family history of onychomycosis, a history of tinea pedis, and walking barefoot around pools. Onychomycosis can be symptomatic, a source of embarrassment, and a potential cause of morbidity.