Schistosome Infection During HIV Seroconversion Slows Adverse Outcomes

blood fluke
blood fluke
The investigators believe that schistosome infection at the time of HIV-1 acquisition may delay disease progression of HIV-1.

People who have schistosome infection at the time of HIV-seroconversion develop adverse HIV outcomes more slowly than those who do not have schistosome infection, according to a study published in PLOS Neglected Tropical Diseases.

Previous research has indicated that the presence of schistosome infection increased the risk for HIV and raising HIV viral concentrations. As a result, researchers investigated the effect of a schistosome infection on HIV. They hypothesized that the presence of schistosome parasites at the time of acquiring the HIV-1 infection would negatively impact the antiviral immune response and cause HIV to progress twice as fast or lead to death when compared with people who did not have a schistosome infection at the time of HIV-1 seroconversion.

Using a large cohort from the TAZAMA project, which is based on longitudinal HIV-testing data from northwest Tanzania, study investigators identified individuals who became HIV-1-seropositive between September 2006 and February 2016. To be included in the study, participants also needed to have a dried blood spot or serum available for schistosome infection testing.

Researchers analyzed the results of participants who had seroconverted to HIV-1 (N=172). Using a competing risk analysis, the researchers evaluated differences in reaching CD4 counts of <350 cells/μL or death in participants with (n=43) and without (n=129) schistosome infections. Surprisingly, an 82% reduction in risk was observed for people who had the schistosome infection (subHazard Ratio = 0.18 [95% CI, 0.068-0.500], P =.001), even after adjusting for demographic, clinical, and time-dependent covariates.

Study limitations included approximations of seroconversion dates and the inability to test for viral loads and additional related markers.

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Researchers concluded their study by noting that “schistosome infection at the time of HIV-1 acquisition may delay HIV-1 disease progression. Complementary findings from a variety of other studies of HIV-1/helminth co-infections strengthen the likelihood that this result is not spurious. Plausible mechanisms by which schistosome infection could delay HIV-1 disease progression include induction of Th17 or T reg cells or disrupting the Th17/Treg ratio. This work highlights the need for additional studies to examine these immunological interactions between the two pathogens on a longer-term scale.”

This study was supported by the NIH and a Kellan Junior Faculty Fellowship from Weill Cornell Medicine.


Colombe S, Machemba R, Mtenga B, et al. Impact of schistosome infection on long-term HIV/AIDS outcomes [published on July 2, 2018]. PLOS Neglected Tropical Diseases. doi: 10.1371/journal. pntd.0006613