[pronut-hiv] Genital schistosomiasis increases HIV risk for Zimbabwean women

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Genital schistosomiasis increases HIV risk for Zimbabwean women 

Genital lesions caused by the waterborne parasite schistoma haemotobium
increased the risk of acquiring HIV infection threefold in women living
in rural Zimbabwe, according to findings from a study conducted by
Norwegian and Zimbawean researchers published in the February 28th
edition of the journal AIDS. 

The schistoma parasite can be acquired by bathing in water infested
with the parasite, or by drinking this water. Schistosomiasis infection
is predominantly a rural problem in Africa and Asia. Although the
infection is known to cause genital tract lesions, no study had
previously assessed whether schistosomiasis increases the risk of HIV
infection in a similar way to genital lesions caused by sexually
transmitted infections such as herpes. 

Norwegian and Zimbabwean researchers carried out a cross-sectional
study in rural north-western Zimbabwe, recruiting 527 women through a
local clinic in Mupfure. 

Forty-six per cent were found to have genital schistosomiasis at
baseline, 29% were HIV-positive and 65% were positive for HSV-2
antibodies. HIV infection was more common in women with schistosomiasis
lesions (41% vs 26%, p=0.008). Multivariate analysis showed that women
with S.haematobium infection in the genitals were almost three times
more likely to be HIV-positive (odds ratio 2.9, p=0.03). 

Seven out of 224 women who were HIV-negative at baseline subsequently
acquired HIV during one year of follow-up, an incidence of 3.1% ( six of
seven had received praziquantel treatment for schistosomiasis at
baseline and all had evidence of S. haematobium infection at baseline).
However there was no significant difference in S. haematobium infection
at baseline between the seroconverters and those who remained
HIV-negative. 

The authors suggest that genital schistosomiasis increases the risk of
HIV infection because it causes genital lesions and `sandy patches`
(areas that bleed easily) in the female genitals. S. haematobium also
induces higher expression of the CCR5 receptor on the surface of
T-cells, increasing the risk that those cells will become infected by
HIV, and the parasite attracts immune system cells vulnerable to HIV
infection into the surrounding tissue. 

They say that prospective studies are needed to confirm whether genital
S. haemotobium infection indeed poses a risk factor for HIV
transmission, and in addition, the effect of female genital
schistosomiasis as a risk factor for HIV transmission to men needs to be
explored. 

Reference 

Kjetland EF et al. Association between genital schistosomiasis and HIV
in rural Zimbabwean women. AIDS 20: 593-600, 2006.