Research in context
Evidence before the study
We searched PubMed on April 15, 2016, for studies published in English using the search terms “lymphatic filariasis”, “Wuchereria bancrofti”, and “HIV” with no restrictions on publication date. We found few manuscripts describing co-infections of both diseases, which have been cited and discussed in this manuscript. Helminth infections have been suggested as one of the factors driving the HIV/AIDS epidemic in sub-Saharan Africa. However, not many studies have examined the interaction of W bancrofti, a mosquito-transmitted filarial nematode, and HIV, and all of them have focused on already co-infected individuals. A cross-sectional study in north Tanzania suggested a higher HIV prevalence in W bancrofti-positive individuals, but a follow-up study of the same group did not provide evidence for an interaction of lymphatic filariasis with HIV. Recent reports from India, Zimbabwe, and south Tanzania did not show any difference in lymphatic filariasis prevalence or circulating filarial antigen levels in HIV-positive compared with HIV-negative individuals. However, none of the published reports focused on the effect of lymphatic filariasis on HIV transmission.
Added value of the study
The risk for HIV infection is determined by multiple factors, most of which are behavioural. This study describes an increased HIV infection risk caused by a helminth infection (lymphatic filariasis). Our findings open up new opportunities for prevention, especially in the high-HIV-risk group of young adults in developing countries. Furthermore they support the primarily laboratory-based hypothesis that an immune-activated host is more receptive for HIV infection, which if investigated further might improve our understanding of the physiopathology during primary HIV infection.
Implications of all the available evidence
The adult worm of W bancrofti lives for 10–12 years in the lymphatic system and is not killed by single-dose treatment. By contrast, it takes up to 10 years of annual mass treatment to produce a lasting reduction in lymphatic filariasis prevalence in an affected area. Lymphatic filariasis eradication programmes in the past decade have focused on the reduction of transmission but made only limited efforts to cure W bancrofti infection, although recently an active therapy has become available. Lymphatic filariasis, together with other helminth infections, belongs to the 17 neglected diseases as defined by WHO. Our findings add another argument to push neglected diseases, in this case filarial infection, into the focus of global strategies, as they create not only morbidity but in addition generate an increased risk of acquiring HIV.