Prevalence of Wuchereria bancrofti Microfilariae and its Association with HIV Among Filarial Antigenemia Positive Individuals in Kyela District, Tanzania.

Abstract

Wuchereria bancrofti is a filarial nematode causing a chronic debilitating infection known as lymphatic filariasis (LF). It accounts for 90% of all lymphatic filariasis cases worldwide. The disease is characterized by clinical manifestations of lymphoedema of the lower limbs (elephantiasis) and hydrocele that leads to severe morbidity of the infected person. The previous study described increased susceptibility to Human immunodeficiency virus (HIV) in individuals infected with W. bancrofti, as measured by circulating filarial antigen (CFA) a marker which released is by the adult filarial worms. During that study microfilaria test wasn’t done which would have been help to discriminate between patent and latent infection and the link to HIV susceptibility. Main objective of this study was to determine prevalence of W. bancrofti microfilariae and its association with HIV among CFA positive individuals who were annually followed up for five years. The present study was retrospective laboratory based that used bio-banked blood samples collected from people living in Kyela district who were CFA positive but HIV negative at baseline. A nonprobability purposive sampling technique was used to select a total 396 bio-archived blood samples. DNA was extracted and W. bancrofti microfilaria chitinase gene was detected by using Polymerase Chain Reaction (PCR). Statistical analysis was done using Pearson test, where p value <=0.005 was considered significant. Out of 396 samples, 350 were analyzed, of which 12/350 (3.4%) were positive for W. bancrofti microfilaria chitinase PCR. Among them 9/350 (2.6%) were samples collected from female and 3/350 (1.7%) from males (Pearson correlation, p=0.062). During the four-year follow-up period (1085 person-years), 22 individuals became HIV infected, resulting in an overall HIV incidence of 2.0 per 100 person-years. The incidence of HIV in W. bancrofti MF chitinase positive subjects was significantly higher than of MF chitinase negative study subjects (8.7 vs 1.8 cases per 100 person years, p=0.014). Multivariable log link binary regression was used to determine the association, when adjusted for age, sex and economic status, the risk of HIV infection was about 5 times higher in MF infected individuals than those without MF, despite active W. bancrofti infection (IRR 4.58; 95% CI: 1.37 – 15.4, p=0.009). As observed that MF positivity increased the risk to HIV infection, therefore MF screening and treatment should be considered as one of the prevention and control strategy in areas endemic to HIV and filariasis.