Epidemiology and immunology of helminth-HIV interactions

Helminths and HIV-1 use multiple mechanisms to avoid or deviate immune responses, and these mechanisms may interact with important consequences for the epidemiology of each infection. In this review, we summarize recent immunological and epidemiological advances in the understanding of HIV-1-helminth co-infections.

Considering the extent of geographical overlap of these chronic infections, there has been so far surprisingly limited and inconsistent evidence of important interactive effects, either from epidemiological studies examining associations between helminth infection indicators and HIV disease parameters, or from studies that have dissected the immune mechanisms triggered by each pathogen in isolation and investigated their interaction. Systematic reviews have found inconsistent evidence for a beneficial effect of anthelmintic treatment of helminth-HIV-1 co-infected individuals on viral load or CD4 cell counts. It is not certain that co-infection with HIV-1 and helminths will always be more detrimental to the host than either single infection alone, or that intervening against co-infections will have only beneficial effects.

A consensus on the implications of co-infection on de-worming and vaccination policies has not yet emerged. Well powered randomized trials in HIV-1-infected individuals with defined helminth infections are required to determine the benefits of anthelmintic interventions.