HIV counselling and testing procedures in areas with high HIV prevalence require reconsideration according to researchers investigating acute HIV infection in Malawi. Their report of the frequency with which acute HIV infections are missed, and the very high viral load levels observed in these individuals, was one of the more alarming presentations at yesterday’s 42nd ICAAC in San Diego.
Thirteen hundred and sixty-one consecutive male attendees at outpatient clinics in Lilongwe, Malawi, with either genital ulcer disease, urethritis, both, or a skin complaint, were entered into a cross-sectional study. All were screened for HIV antibodies (the immune system’s response to HIV infection), and for HIV RNA (genetic material from the virus itself).
Following exposure to HIV, viral load levels within the blood typically reach high quantities before falling back to a lower ‘set-point’. This decrease is accompanied by the production of antibodies to HIV, detectable in standard HIV antibody tests commonly used to diagnose HIV infection. The delay between acquisition of HIV infection and production of antibodies tends to be in the range of two to six weeks in most cases, but can take a little longer for some.
Screening revealed 40.6% of the Malawian men to be HIV-antibody positive, and that 2.1% had acute primary infection. Amongst men with negative antibody tests, 4.8% had positive HIV RNA tests. Acute infection was strongly associated with active genital ulceration, and with inguinal lymphadenopathy (swollen glands in the groin), suggesting these symptoms should alert health care workers in similar settings to counsel patients regarding HIV risk regardless of their HIV antibody status.
Viral load levels were dramatically higher in acutely HIV-infected men than in a comparison group of HIV-positive men without symptoms of sexually transmitted infections. The median HIV viral load level was just under six logs, or one million copies. This includes one antibody-negative individual with a viral load of two billion copies. Given the established relationship between viral load levels and risk of sexual HIV transmission previously reported by Gray and colleagues, these data present a clear indication of the potential for HIV epidemics to be driven by onward transmission from people with acute infection.
You can read more about methods of screening for HIV infection here at aidsmap.com.
Pilcher CD et al. Frequent detection of acute primary HIV infection in men in Malawi: Reconsideration of counselling and testing approaches. 42nd ICAAC
Gray RH et al. Probability of HIV-1 transmission per coital act in monogamous, heterosexual, HIV-1-discordant couples in Rakai, Uganda. Lancet 2001;357:1149-53.