Drugs for HIV, the virus causing AIDS, have existed for more than two decades. Therapies have been continually refined and the standard approach in the West is now a combination therapy involving various antiretroviral substances. The rationale behind this idea is that the constantly changing virus finds it harder to develop resistances against three or more drugs administered simultaneously.
Less resistance to new drugs
At the beginning of the year, Huldrych Günthard (University Hospital Zurich) and his colleagues from the Swiss HIV Cohort Study showed (*) that new combination therapies are better at keeping viruses in check than the therapies used ten years ago. For the older therapies, resistant viruses developed on average 2.6 times per 100 patient-years (i.e. 100 patients over the course of one year, 50 over the course of two years) while resistance to the newer therapies developed only 1.5–1.9 times. Researchers believe that this improvement is not only the result of greater drug effectiveness – patients also tend to take the drugs more regularly because they have less side-effects.
Dramatic spread of hepatitis C
The continual improvement of combination therapies reduces the risk of HIV transmission. Recently published results of the Swiss HIV Cohort Study (**) suggest that this leads to a false sense of security in certain patients. Figures show that hepatitis C has spread rapidly among HIV-positive gay men during the last few years. While the rate of infection among heterosexuals has remained low (on average 0.4 infections per 100 patient-years), it has risen drastically among homosexuals: 4.1 persons are infected per 100 patient-years. This rate is 18 times higher than the one recorded in 1998.
Researchers point to the inconsistent use of condoms as the greatest risk factor. While the fear of AIDS has understandably diminished, there may be a tendency now to neglect other sexually transmitted illnesses. „Caution is still called for,“ says Günthard.
(*) von Wyl V, Yerly S, Böni J, Shah C, Cellerai C, Klimkait T, Battegay M, Bernasconi E, Cavassini M, Furrer H, Hirschel B, Vernazza PL, Ledergerber B, Günthard HF; Swiss HIV Cohort Study (2012). Incidence of HIV-1 drug resistance among antiretroviral treatment-naive individuals starting modern therapy combinations. Clin Infect Dis. 54:131-40
(**) Wandeler G, Gsponer T, Bregenzer A, Günthard HF, Clerc O, Calmy A, Stöckle M, Bernasconi E, Furrer H, Rauch A; Swiss HIV Cohort Study (2012). Hepatitis C Virus Infections in the Swiss HIV Cohort Study: A Rapidly Evolving Epidemic. Clin Infect Dis. 55:1408-1416
(Available as a PDF from the SNSF; e-mail: email@example.com)
The Swiss HIV Cohort Study
Established in 1988, the Cohort Study aims to generate knowledge about HIV infection and AIDS as well as to improve the care given to patients. All Swiss hospitals specialising in HIV (Basel, Berne, Geneva, Lausanne, Lugano, St. Gallen and Zurich) have collected and analysed data from over 16,000 HIV-positive persons. Currently, more than 8,400 persons are taking part in the Swiss HIV Cohort Study. Almost a third of them are women.
Prof. Dr. med. Huldrych Günthard
Klinik für Infektionskrankheiten und Spitalhygiene
Tel.: +41 (0)44 255 34 50
The text of this press release is available on the website of the Swiss National Science Foundation at: www.snsf.ch > Media > Press releases