Epidemiology of Cryptococcal antigenemia among HIV infected patients in South-western Nigeria

Abstract

Background: Cryptococcosis is a life-threatening fungal infection that presents diversely with no specific pathognomonic features. Cryptococcal disease is one of the most important opportunistic infections, and a major contributor to early mortality in HIV infected subjects. Cryptococcal antigenemia occurs in Nigeria, but the magnitude of this disease remains unclear. This study was carried out to determine the prevalence of CrAg among HIV seropositive and seronegative individuals attending Adeoyo Maternity Teaching Hospital (AMTH), Yemetu, Ibadan. Methods and materials: This was a case-control study in which 114 cases and 228 controls were recruited. Cases were HIV seropositive individuals while controls were HIV seronegative individuals receiving care at AMTH. Adult male and female (age range: 18–65 years) who agree to participate in the study were recruited. Simple random sampling was used to select subjects. Semi-structured interviewer administered questionnaire was used to collect data from subjects and retrospective review of CD4 count records in HIV infected subjects. Five millilitres venous blood was collected from each participant. Serum Cryptococcal antigen testing was done using CrAg Lateral Flow Assay. Data was analyzed using descriptive statistics and bivariate analysis at 5% level of significance. Results: Mean age of cases was 41.2 ± 10.0 years and 85 (74.6%) were females while mean age of control subjects was 38.9 ± 13.7 years 156 (68.4%) were females. The cumulative prevalence of CrAg was 8.5%. However, the prevalence of CrAg among cases was 11.4% and 7.0% among controls. Age groups 41-50 years and 21-30 years were the most affected among cases and controls respectively. HIV positive subjects were about two times more likely to test positive for CrAg. Individuals with CD4 counts of ≤100cells/μl were 20 times more likely to have positive serum cryptococcal antigen than individuals with CD4 counts >100 cells/μl (OR: 20.3, 95%CI: 5.23-78.9). Conclusion: Cryptococcal antigen was present among both cases and controls; however, the prevalence was higher among cases. Since asymptomatic cryptococcal antigenemia predicts impending cryptococcal infection (pneumonia and meningitis) with probable mortality, screening for CrAg should be part of the routine tests amongst all confirmed HIV seropositive cases