Chlamydia is the common name for infections caused by a bacterium called Chlamydia trachomatis. Risk factors for chlamydia are similar to those for other STIs and include multiple sexual partners, a partner who has had multiple sexual partners, being under age 25, inconsistent use of barrier contraceptives (such as condoms), and a history of STIs. Chlamydia can be transmitted during vaginal intercourse, oral, or anal sex.
The bacterium that causes chlamydia can also cause epididymitis and nongonococcal urethritis (NGU) in men. In fact, chlamydia has been found to cause 50% of all cases of NGU (Kassler & Cates, 1992). NGU may also be caused by the trichomoniasis or herpes organism; however, 40% of the cases of NGU seem to have no direct cause (Baldassare, 1991).
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Incidence Chlamydia is the most commonly reported infectious disease in the United States and is also the most commonly diagnosed bacterial STI in the developed world (Gilson & Mindel, 2001; see Figure 15.7). In 2004 there were 929,462 new cases of chlamydia reported, although experts believe that the majority of cases went unreported (Centers for Disease Control and Prevention, 2005d). It is estimated there are closer to 2.8 million new cases of chlamydia each year (Weinstock et al., 2004). Chlamydia affects all socioeconomic and ethnic groups and is highest among African Americans (see Figure 15.8). Chlamydia rates are also higher in younger women than in younger men (see Figure 15.7). However, this may be because screening programs have been primarily aimed at women. Chlamydia infection in men is underdiagnosed, and ex-
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I I Male Female
perts claim that if men were routinely screened, the rates for men and women would be more similar (Ku et al., 2002). Lesbians also are at risk for chlamydia, although it is most common in heterosexual populations (K. M. Freund, 1992).
Symptoms In approximately 75% of women and 50% of men, chlamydia is asymptomatic (Centers for Disease Control and Prevention, 2005d). Those who do have symptoms usually develop them within 1 to 3 weeks after becoming infected. Even without symptoms, chlamydia is very contagious, which explains why rates are increasing.
Female symptoms can include burning during urination, pain during sexual intercourse, and pain in the lower abdomen. In most women, the cervix is the site of infection with chlamydia, and so cervical bleeding or spotting may occur. Some women do experience a vaginal discharge; however, this is rare and is more likely an indication of another STI (K. M. Freund, 1992). Male symptoms may include a discharge from the penis, burning sensation during urination, burning and itching around the opening of the penis, and a pain or swelling in the testicles. Men may also experience epididymitis (Baldassare, 1991).
In women, the bacteria can move up from the uterus to the Fallopian tubes and ovaries, leading to PID. In fact, infection with chlamydia is thought to be one of the agents most responsible for the development of PID (Teran et al., 2001). Women who are infected with cervical chlamydia and who undergo an elective (or possibly spontaneous) abortion or vaginal birth are also at increased risk of developing pelvic inflammatory disease (Boeke et al., 2005).
Diagnosis Because chlamydia testing is not routine, women who have had unprotected sexual intercourse with several partners should ask their healthcare provider to perform chlamydia tests during their yearly physical examinations, even if they are asymptomatic. A healthcare provider will culture the cervical discharge and examine the cells microscopically or use a blood test. Blood tests are easier, more reliable, less expensive, and offer quicker results (Schachter, 1999). Urine tests are available to screen for chlamydia in men. The Centers for Disease Control and Prevention highly recommends annual screenings for all women between the ages of 20 and 25 and for older women with multiple sex partners.
Treatment Antibiotics are used to treat chlamydia, but, like gonorrhea, chlamydia has become highly resistant. Antibiotics are usually taken for a certain period of time
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vaccine is a preparation that contains disease- causing organisms, or parts of organisms, that cause a person to have immunity against the disease. Our bodies’ immune response to the organisms causes the development of antibodies, which prevent future infections. Many successful vaccines, including smallpox and polio, have been developed throughout history.
As of 2005, the hepatitis A and B vaccinations were the only vaccine available for the prevention of STI complications (Mays et al., 2004). Vaccinations for hepatitis B are administered at birth and are recommended for children throughout the United States, whereas vaccinations for hepatitis A are recommended only in certain areas (Centers for Disease Control and Prevention, 2005c). There are currently a variety of STI vaccines in different stages of development, the most promising of which targets two types of human papillomavirus that have been found to cause 60% to 70% of cervical cancers (Brody, 2005; Harper et al., 2004; Koutsky et al., 2002). In research trials, this vaccination has been found to be 100% effective, and experts are hopeful that it will be available to the public sometime in 2006. After the HPV vaccine is approved for use, a panel of experts at the Centers for Disease Control and Prevention will determine whether it will be a mandatory childhood vaccination (Stein, 2005).
However, there is some controversy over the vaccines for sexually transmitted infections. One involves who should be vaccinated. In the case of the HPV vaccine, should this be given only to girls, because boys are not at risk for developing cervical cancer? Or should boys be given the vaccination because they help spread HPV? Experts believe that both boys and girls should be given the vaccination.
Another controversy involves the fact that STI vaccines will need to be given early in a child’s life, well before the child is sexually active. In fact, the ideal group to be immunized with the HPV vaccine are non-sexually active girls and boys between the ages of 9 and 15 (Taira et al., 2004). Some healthcare advocates believe that the HPV vaccine should be used aggressively to decrease the incidence of cervical cancer (Stein, 2005). However, many conservatives believe that vaccinating young children will promote sexual promiscuity (Phung, 2005; Rubin, 2005; Stein, 2005).
The majority of parents of adolescents find STI vaccination for their children very acceptable (Liddon et al., 2005; Zimet et al., 2005). When parents were asked about the potential for accepting vaccines for genital herpes, the human immunodeficiency virus (HIV), the human papillomavirus (HPV), and gonorrhea for their 8- to 17-year-olds, more than 70% of parents approved (Mays et al., 2004). The HIV vaccination was the most acceptable, followed by vaccines for genital herpes, gonorrhea, and HPV (Mays et al., 2004). Research has also found that the majority of college students would be willing to get STI vaccinations if they were available (Boehner et al., 2003).
The search for STI vaccinations continues today. The National Institute of Allergy and Infectious Diseases has been sponsoring a study for the development of a vaccine for genital herpes, and research on vaccinations for other sexually transmitted infections, including gonorrhea, hepatitis C, and HIV, is ongoing (Harding, 2005; Hoshino et al., 2005; Oxman et al., 2005; Stanberry et al., 2005; Sternberg, 2004a). Later in this chapter we’ll discuss the failure of the first AIDS vaccine to pass clinical trials in 2003. As of 2005, there were over 50 AIDS vaccine trials in progress (Chase, 2005).
(usually at least 7 to 10 days). An infected person’s sexual partners over the 3 months prior to the diagnosis should be referred to a healthcare provider for treatment, whether or not they are experiencing symptoms. This is necessary to avoid reinfection, further complications, and the spread of chlamydia to others (Gilson & Mindel, 2001). Followup examinations are necessary only if a healthcare provider suspects a reinfection (Centers for Disease Control and Prevention, 2002a).
Chancroid
Although a chancroid (SHANK-kroyd) may look similar to a syphilis chancre, the difference lies in its soft edges compared with the hard edges of a syphilis sore. Chancroids are sexually transmitted through the Hemophilus ducreyi bacterium.
Incidence This STI is relatively rare in the United States (see Figure 15.1), but worldwide 7 million cases occur each year (Steen, 2001). The reported cases of chancroid in the United States were approximately 5,000 in 1987, but only 30 in 2004
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