A peer educator discusses how to prevent HIV/AIDS and other sexually transmitted diseases with young people in a poor neighborhood of Manila. Photo courtesy of WHO
Increased investment in research and development for new vaccines is key to halting the spread of genital herpes, gonorrhea, chlamydia, syphilis and trichomoniasis, according to a new special issue of the journal Vaccine, co-edited by the World Health Organization (WHO) and the United States’ National Institute of Allergy and Infectious Diseases (NIAID), National Institute of Health (NIH).
Gonorrhea has developed resistance to many of the common antibiotics used as treatment. Antimicrobial resistance for other STIs, though less common, also exists, making prevention and prompt treatment critical.
“Sexually transmitted infections are a massive health challenge,” says Dr. Marleen Temmerman, director of the Department of Reproductive Health and Research at WHO. “First, they are extremely common—more than a million new infections occur every day. Second, most infections don’t show any symptoms so people don’t know they are infected. Third, gonorrhea, one of the major diseases, is becoming increasingly resistant to the medicines currently available to treat it.”
More than 500 million sexually transmitted infections (STIs) are estimated to occur worldwide every year triggering a range of sexual, reproductive, and maternal-child health problems. These include:
- Increased risk of HIV: STIs such as herpes can increase the risk of HIV acquisition three-fold or more.
- Mother-to-child transmission of syphilis can result in stillbirth, neonatal death, low-birth-weight and prematurity, and congenital deformities.
- HPV infection causes 530 000 cases of cervical cancer each year.
- STIs such as gonorrhea and chlamydia are major causes of pelvic inflammatory disease, adverse pregnancy outcomes and infertility.
Some countries have made efforts to control STIs by promoting healthier sexual behaviours, including increasing condom use, and improving access to testing and treatment. Most high-income countries, for example, offer accurate diagnostic tests for STIs. However, in low- and middle-income countries, diagnostic tests are largely unavailable. Where testing is available, it is often expensive and geographically inaccessible; and patients often need to wait a long time (or need to return) to receive results. As a consequence, follow up can be impeded and care or treatment can be incomplete. Moreover, because many people do not demonstrate any symptoms, they do not go to get tested.
Additional barriers to STI control exist as well. No medications are available to cure genital herpes, a lifelong viral infection that is fuelling the HIV epidemic. Gonorrhoea has developed resistance to many of the common antibiotics used as treatment. Antimicrobial resistance for other STIs, though less common, also exists, making prevention and prompt treatment critical. Control of chlamydia infections has been difficult, and costly, even in countries with longstanding chlamydia screening programmes, and repeat infections after treatment are common.
“Widespread immunization with safe and effective vaccines could revolutionize the way we tackle STIs,” says Dr. Jean-Marie Okwo-Bele, director of the Department of Immunization Vaccines and Biologicals at WHO. “The good news is that the introduction of vaccines to prevent both hepatitis B and human papillomavirus shows that it can be done.”
In May 2012, the World Health Assembly endorsed the Global Vaccine Action Plan, which calls for research to develop new vaccines to extend the life-saving benefits of vaccination to all people. In April 2013 WHO and NIAID convened a Technical Consultation on STI Vaccine Development and Introduction. Meeting participants focused on development of new, effective vaccines against the five most common STIs—herpes simplex virus (HSV), Chlamydia trachomatis (chlamydia), Neisseria gonorrhoeae (gonorrhoea), Trichomonas vaginalis (trichomoniasis) and Treponema pallidum (syphilis)—and developed a road map: Vaccines against sexually transmitted infections: The way forward. This road map lays out a number of concrete next steps in the areas of basic science, epidemiology, clinical research, regulatory oversight and public health planning that will be necessary to bring these vaccines to fruition. Moreover, the road map document represents the initial consensus between WHO, US-NIAID and other partners present at the meeting to work jointly toward the goal of adding new vaccines to our tool-box for the fight against some of the world’s most neglected diseases.