From this SciDev.Net story that we found at All Africa, David Njagi And Naomi Antony unpack the new study for us.
Researchers who compared immune cells in the genital tracts of women in Kenya and the United States, found that Kenyan women had more "activated" cells, which are more vulnerable to attack by HIV. Cells can become activated as a reaction to infection.
It is the first time that scientists have shown that immune cells in the genital tract are more activated in African women, though higher activation elsewhere in the body has already been demonstrated. The activation may be an "important additional contributor" to the high infection rates in African women, according to the scientists, led by Craig Cohen, of the University of California, San Francisco, in the United States.
"We believe that these findings should also start to dispel some of the preconceptions and stigma surrounding HIV acquisition among young women in Sub-Saharan Africa," said the authors, writing in the journal AIDS.
The scientists compared CD4 cell counts - an indicator of immune system strength - of women aged 18-24 years in San Francisco, with those from Kisumu, Kenya. They found that Kenyan women had more activated CD4 cells. The researchers controlled for other genital infections and sexual behaviour, which are therefore unlikely to be an explanation of the increased activity.
They say that it is possible that other "systemic" infections, such as malaria, that affect the whole body, might cause the increase. Another possible cause is schistosomiasis and similar infections that occur at other mucosal sites in the body. It is also possible that there is a genetic cause.
"Although it has been suggested that reasons for the discrepancy in HIV seroprevalence include higher prevalence of sexually transmitted infections ... as well as structural and sociocultural factors, for the first time our observations suggest that differences in the genital tract immune milieu may be an important additional contributor," said the team.