Suffering from a sexually transmitted disease, with no symptoms, but still contagious

„If it itches or burns, go and see your doctor.“ This is the message behind a campaign launched by the Federal Office of Public Health requesting people with a sexually transmitted disease to get themselves tested. „This statement is not wrong as such, but it is not quite right either,“ says Dominique Braun, consultant in the Department of Infectious Diseases and Hospital Epidemiology at the University Hospital Zurich. As he and his colleagues have found in a current study, homosexual men are very often infected with sexually transmitted diseases, but the infection „does usually not present with symptoms.“

In the study just published in the renowned medical journal Clinical Infectious Diseases, approximately 200 HIV-infected homosexual men were tested for sexually transmitted diseases. These men were diagnosed in the early phase of an HIV infection and underwent effective HIV treatment. This meant that, as far as their HIV infection was concerned, they were no longer regarded as infectious. Within the prospective screening phase of about 1.5 years, one in three of these men became infected with one or more sexually transmitted infections, most commonly with chlamydia (50%), more rarely with gonorrhea (25%) and syphilis (19%), and very rarely with hepatitis C (4%). These infections were most often found in the rectum, but also in the throat and urethra. „Compared with other studies in Western Europe of this group of people, the number of diagnosed infections is extraordinarily high,“ says Professor Huldrych Günthard from the Department of Infectious Diseases and Hospital Epidemiology. However, up to 70 percent of those infected showed no symptoms whatsoever.

Sex without condoms as a risk factor

„If someone is only tested on the basis of symptoms, these carriers are not discovered, no treatment is put in place and they carry on transmitting the disease,“ says infectiologist Braun. This means it is often difficult to decide which people should be tested for sexually transmitted diseases if there are no symptoms. The authors of the study therefore looked for risk factors that could predict presence of a sexually transmitted infection. Multiple sexual partners are among the determined risk factors, as is sex without condoms or the use of drugs such as ecstasy, GHB or cocaine. „We recommend that homosexual men to whom these risk factors apply get themselves tested for sexually transmitted diseases every three months, even if they have no symptoms,“ says Dominique Braun. If symptoms such as burning or pain in the genital area are present, they should also undergo a test, as these symptoms strongly indicate a sexually transmitted disease.

The fact that sexually transmitted diseases in men do not trigger symptoms in most cases is a new discovery. Until now, testing for sexually transmitted diseases was recommended if there were typical symptoms. The study results are „highly relevant“ against the background of the current epidemic of sexually transmitted diseases in homosexual men, says Huldrych Günthard. However, a drastic rise in sexually transmitted diseases such as syphilis, gonorrhea and chlamydia is also being seen in the heterosexual population.

The Zurich Primary HIV Infection Study is dedicated to acute HIV infection. The study led by Prof Huldrych Günthard in Zurich was started in 2002. The University of Zurich supports the research. The study participants are also enrolled in the globally well-known Swiss HIV cohort study (

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