STD Control: A Public Health Priority

During the 20th century, improvements in sanitation and hygiene, reduced crowding, and the development of antimicrobials and vaccines have greatly reduced infectious disease morbidity in industrialized countries. In developing countries, smallpox has been eradicated, polio eliminated from the Western Hemisphere, and child survival prolonged through the expanded use of childhood vaccines, and improved management of diarrhea and acute respiratory infections of children. However, there is growing concern about the persistence, emergence or reemergence of a host of other infectious disease threats. Sexually transmitted infections, including HIV, figure prominently among these emerging infectious diseases. The number of microbial pathogens identified as causes of STD, and the morbidity attributable to STD, relative to that caused by other infectious diseases, have continued to increase throughout the 20th century. In fact, recent analyses show that STDs collectively rank among the five most important causes of years of healthy productive life lost in developing countries.

Changes in human behavior and ecology, including socioeconomic factors and related economic development policies, the population explosion and the demographic transition (with rapid increases in the number of adolescents and young adults), rural-to-urban migration, war and attendant sociocultural disruption all have led to epidemic increases in STDs. Sexually transmitted pathogens are increasingly being linked to various common disease syndromes and new sexually transmitted pathogens (such as HIV) are emerging, causing new sexually transmitted diseases (like AIDS). Unrestrained population growth and urbanization leave every reason to expect the continued emergence of new STD pathogens and syndromes into the next century. In addition, improved diagnostic methods have led to the identification of previously unrecognized pathogens.

The World Health Organization estimates that the global incidence in 1995 of new cases of selected curable STDs onorrhea, chlamydial infection, syphilis and trichomoniasis as 333 million. The global prevalence of active or latent infection with the common chronic viral STDs such as genital herpes simplex virus, genital HPV, hepatitis B virus and, increasingly, HIV, could be estimated in the billions of cases, since in some populations the majority of adults become infected with one or more of these pathogens. The consequences of being infected with an STD can be divided into two categories: complications and sequelae seen in STDs other than HIV/AIDS, and those directly related to HIV/AIDS. Social and economic consequences of these conditions as well as the direct health costs need to be considered. The most serious health consequences of STDs, other than HIV/AIDS, tend to occur in women and newborn children. Complications in women include cervical cancer, pelvic inflammatory disease with resulting infertility, chronic pain, ectopic pregnancy and related maternal mortality. In developing countries maternal complications directly related to untreated STDs are a major cause of infant and maternal morbidity and mortality. Complications in newborns include congenital syphilis, gonococcal infection of the conjunctivae potentially blinding condition and perinatal hepatitis B infection.

The Role of STDs in Increasing Sexual Transmission of HIV

The impact of other STDs on sexual transmission of HIV was initially suspected on the basis of epidemiologic studies, showing that persons with an ulcerative or nonulcerative STD appear more susceptible to acquiring HIV infection. Subsequent studies showed that urethral and endocervical inflammation caused by non-ulcerative STDs increases genital shedding of HIV-infected cells, and thus probably increases infectivity of the person with HIV infection.

It is important to emphasize that interventions that reduce risky sexual behaviors or result in increased condom use, can prevent most, if not all, important STDs; whereas those designed to improve only early detection and curative treatment of STDs can reduce transmission only of those specific diseases that are cured or suppressed.