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CHAPTER 1
Sexually Transmitted Infections: Why are they Important?
Kevin A Fenton1and Karen E Rogstad2
1Centers for Disease Control and Prevention, Atlanta, USA
2Department of Sexual Health and HIV, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
OVERVIEW
- There are more than 30 different sexually transmissible bacteria, viruses and parasites
- A million people acquire HIV or another STI every day
- There are 33.4 million people with HIV worldwide, with 2.7 million new HIV infections and 2 million HIV-related deaths annually (1998 data)
- STIs (excluding HIV) are the second most common cause of healthy life lost in 15- to 44-year-old women
- STIs cost $16 billion annually to the health care system
- Preventing a single HIV transmission would save £0.5–1 million in health benefits and costs
What are sexually transmitted infections?
Sexually transmitted infections (STIs) are infections that are spread primarily through person-to-person sexual contact. There are more than 30 different sexually transmissible bacteria, viruses, and parasites (Table 1.1). Several, in particular HIV and syphilis, can also be transmitted from mother to child during pregnancy and childbirth, and through blood products and tissue transfer.
In general, the viral STIs (including sexually transmitted HIV and hepatitis A, B, and C) are more prevalent, often causing lifelong infections, frequently asymptomatic in their early phases, and may result in serious long-term sequelae including chronic morbidity or even mortality. In contrast, the bacterial and protozoal STIs are generally curable, and often asymptomatic. The causative organisms may cause a spectrum of genitourinary symptoms, including urethral discharge, genital ulceration, and vaginal discharge with or without vulval irritation.
STIs are among the most commonly diagnosed infectious diseases in many parts of the world. More than a million people acquire HIV or another STI every day, and there are 450 million new cases of curable STIs occurring in adults each year. There is marked variation in the prevalence and incidence of infections throughout the world, and even within countries (Figure 1.1 and Table 1.2).
Why are STIs important?
Being diagnosed with an STI can have a tremendous physical, emotional, and psychological toll on individuals. Symptoms are unpleasant and may cause considerable pain, and have systemic complications. HIV and hepatitis B and C may have an aggressive course leading to lifelong morbidity and death. Some human papillomavirus (HPV) types are a cause of cervical, penile, anal, and oropharyngeal cancer (Table 1.3). Chlamydia and gonorrhoea are both the most serious, and also most preventable, threats to women’s fertility worldwide. The World Bank estimated that STIs (excluding HIV) were the second most common cause of healthy life lost after maternal morbidity in 15- to 44-year-old women (Figure 1.2).
Effects on pregnancy, neonates, and children
STIs can lead to miscarriage, intrauterine growth retardation, and in utero death. They can also cause neonatal illness and death, and long-term sequelae. The consequences of congenital herpes and HIV are well recognised in developed nations. However, the magnitude of the congenital syphilis burden, globally, rivals that of HIV infection in neonates yet receives little attention. Congenital syphilis results in serious adverse outcomes in up to 80% of cases and is estimated to affect over 1 million pregnancies annually.
Effects on partners
STIs are also important to sexual partners, who may have asymptomatic infection. Partner notification is a key strategy for identifying and treating sexual partners for most STIs (see Chapter 2). The diagnosis of an acute STI may indicate that a partnership is non-monogamous, with negative impacts on relationships. For some couples who are discordant for infections such as HIV or herpes, there are long-term implications such as whether to have unprotected sex and psychological issues.
Stigma
The stigma and fear of STIs cannot be over-emphasised. There is significant psychological morbidity associated with being diagnosed with an STI which ranges from mild distress to severe anxiety and depression. Stigma can result in people living with HIV and other STIs being rejected, shunned, and discriminated against by partners, family, and community, and being victims of physical violence. Stigma not only makes it more difficult for people trying to come to terms with and manage their illness, but it also interferes with attempts to fight the disease more generally. On a national level, stigma can deter governments from taking fast, effective action against STI epidemics.
Table 1.1 Main sexually transmitted pathogens and the diseases they cause.
Source: World Health Organization, 2007.
| Bacterial infections |
| Neisseria gonorrhoea | GONORRHOEA Men: urethral discharge (urethritis), epididymitis, orchitis, infertility.
Women: cervicitis, endometritis, salpingitis, pelvic inflammatory disease, infertility, preterm rupture of membranes, peri-hepatitis. Both sexes: proctitis, pharyngitis, disseminated gonococcal infection. Neonates: conjunctivitis, corneal scarring and blindness |
| Chlamydia trachomatis | CHLAMYDIAL INFECTION Men: urethral discharge (urethritis), epididymitis, orchitis, infertility.
Women: cervicitis, endometritis, salpingitis, pelvic inflammatory disease, infertility, preterm rupture of membranes, peri-hepatitis; commonly asymptomatic. Both sexes: proctitis, pharyngitis, Reiter’s syndrome. Neonates: conjunctivitis, pneumonia |
| Chlamydia trachomatis (strains L1–L3) | LYMPHOGRANULOMA VENEREUM Both sexes: u... |
