Sexually Transmitted Infections in the Tropics

The burden of sexually transmitted infections (STIs) on the health and well-being of the population in the developing world is considerable. The World Health Organization (WHO) estimates that there are 340 million new cases of curable STIs in the world each year; 174 million new cases of trichomoniasis, 92 million new cases of Chlamydia infection, 62 million cases of gonorrhea, and 12 million new cases of syphilis (Table 1). Approximately three quarters of these infections are in countries encompassing tropical regions of the world in Latin America, sub-Saharan Africa, and South and Southeast Asia. The prevalence of viral STIs is even higher; infection with Herpes simplex virus-2 (HSV-2) is the most common STI worldwide and as many as 50% of sexually active individuals will be infected with human papillomavirus (HPV) during their life. The prevalence of STIs is considerably greater than many classical tropical diseases and it is unfortunate that they do not receive more attention and resources from international programs and donor groups. The public health impact of these diseases extends well beyond the immediate effects and morbidities of infection. STIs have been implicated in facilitating acquisition and transmission of HIV, in pregnancy complications such as pre-term births, low birth weight infants, stillbirth, neonatal death and blindness, in the inducement of cervical and prostate cancers, and in increased risk of pelvic inflammatory disease and infertility. Failure to diagnose and treat STIs at an early stage thus increases the already substantial burden these conditions impose on the populations of developing countries. Although effective diagnostic tests and treatments are available for these STIs, they are often unavailable or inaccessible in resource-limited tropical settings. As a consequence, syndromic management of STIs remains the option of choice for individual case management. The inadequate public health response coupled to ongoing socioeconomic and demographic trends have led to an epidemic of STIs in many countries in the developing world. The development of antimicrobial resistance is an ongoing problem and new agents are often much more expensive, increasing the burden of control. The economic costs of these diseases and their infection sequelae place a considerable burden on national health budgets and household income. In developing countries, STIs are among the top five reasons for which adults seek medical care. Due to the prevalence and public health implications of STIs in the tropics a discussion of STIs should be included in any compilation of tropical medicine. This chapter will cover sexually transmitted infections caused by Trichomonas vaginalis (trichomoniasis), Chlamydia trachomatis (chlamydia and lymphogranuloma venereum), Neisseria gonorrhoeae (gonorrhea), Treponema pallidum (syphilis), Haemophilus ducreyi