>Recent infection with herpes simplex virus - 2 (HSV-2) substantially increases the risk of also being infected with HIV, even when HSV - 2 does not cause any apparent symptoms, according to US research conducted in India and published in the May 15 th edition of the Journal of Infectious Diseases.
An editorial in the same edition of this journal says that the findings of this study justify a large trial to see if the use of the anti-HSV drug aciclovir can reduce the transmission of HIV in resource-limited countries.
The association between genital ulcers and the risk of being infected with HIV has been understood since the late 1980s. A large number of studies were published in late 2002 looking at the role of HSV-2 in HIV transmission and HIV disease progression (see links below).
In this study investigators wished to see if there was any relationship between incident HSV - 2 infection (infection within the last 12 months) and the risks of HIV infection. The study involved 2,732 HIV-negative patients attending a sexual health clinic in Pune, India, between 1993 and 2000. Patients were followed-up for an average of eleven months, and visited the clinic an average of three times.
At baseline 1,175 patients (43%) tested positive for HSV - 2 antibodies. Of these, 44% had no history of genital ulcers. During the course of the study, a further 217 patients seroconverted for HSV - 2. Younger women, sex workers, people living away from home, and people with HIV were found to be at greater risk of acquiring HSV - 2 infection.
A total of 224 patients were detected with recent HIV infection, of whom 28 also had recent HSV - 2 infection, and in the majority of instances the two infections were diagnosed at the same visit to the clinic. The investigators also found that exposure to more recent HSV - 2 infections substantially increased the risk of also being infected with HIV, with a hazard ratio (HR) of 1.67 (95% CI, 1.22-2.30) for people who acquired HSV - 2 from somebody who had had the infection for over twelve months. This increased to 1.92 (95% CI, 1.15-3.21) for people exposed to HSV - 2 from a person who had had the infection for between six months and a year. The risk was highest for people who were infected by people with very recent HSV - 2 exposures (under six months) with a HR of 3.81 (95% CI, 1.81-8.03).
Unsurprisingly, the investigators also found a strong link between visible genital ulcers caused by HSV - 2 and recent HIV infection, with a five-fold increased risk of being infected with HIV. Asymptomatic chronic HSV - 2 increased the risks of being infected with HIV two-fold.
?The findings of this study demonstrate that individuals who experience incident HSV-2 infections are at the greatest risk of HIV-1 acquisition?, comment the investigators.
The investigators also note that although most recent HSV-2 infections have no clinical symptoms, there is frequent shedding of HSV-2, which allows a "portal of entry by mucosal disruption" for HIV. In addition, infection with HSV-2 could make people with HIV more infectious, leading to more musocal shedding of HIV.
Targeted use of anti-HSV therapy could "have an impact of the risk of HIV-1 acquisition in contexts in which the prevalence of HSV-2 infection is high" conclude the investigators.
An editorial in the same edition of the journal supports this suggestion and praises this study as `superb`. It goes on to suggest that anti-HSV therapy could prove a useful tool in controlling the spread of HIV, particularly in resource limited countries. Cost would not pose a significant barrier. Generic aciclovir, standard treatment for acute and chronic HSV - 2, costs approximately 20 US cents a day, or US $73 a year, and has a good safety and resistance profile.
The editorial calls for a large study to be designed which would randomise people who HSV-positive to receive aciclovir or a placebo to determine if it reduces HIV infection by reducing the symptoms of HSV-2 - even those symptoms which can only be detected on a microscopic level.
In addition, in both resource-rich and poor countries providing aciclovir to people who are infected with both HIV and HSV-2 could reduce HIV transmission, particularly in patients who are not receiving HAART and have relatively high HIV viral loads.
Further information on this website
Herpes simplex - overview
Herpes - factsheet
Herpes virus shedding increases HIV infectivity too - news story
Herpes suppression leads to lower HIV viral load, says study - news story
Recent infection with genital herpes increases chance of HIV seroconversion - news story
Aciclovir - overview
Reynolds SJ et al. Recent herpes simplex virus type 2 infection and the risk of human immunodeficiency virus type 1 acquisition in India. Journal of Infectious Diseases, 187: 1513 - 1521, 2003.
Wald A et al. How does herpes simplex virus 2 influence human immunodeficiency virus infection and pathogenesis?Journal of infectious Diseases, 187: 1509 - 1512, 2003.