The total case rate for Chlamydia trachomatis infection in 2013 decreased by 1.5 % compared to the rate in 2012; this is the first time since nationwide reporting for chlamydia began that the overall rate of reported cases of chlamydia has decreased. The rate in women decreased 2.4 %, while the rate in men increased 0.8 %. During 2009–2013, the chlamydia rate in men increased 21 %, compared with a 6.2 % increase in women during this period [3]. In 2013, 949,270 cases of chlamydial infection were reported among persons aged 15–24 years of age, representing 68 % of all reported chlamydia cases.

Figure 10.1 shows the rates of reported cases of chlamydia in the USA by year, and Fig. 10.2 shows the rates of chlamydia infection by state in 2013. Figure 10.3 shows the rates of chlamydia by age and gender in 2013.

The larger number of chlamydia cases in women reflects the impact of screening for this infection; however, the increased use and availability of urine testing helps to explain the increased infection rate in men. The lower rate among men also suggests that many of the sex partners of women with chlamydia are not receiving a diagnosis of chlamydia or being reported as having chlamydia [3].

Following a 74 % decline in the rate of reported Neisseria gonorrhea during 1975–1997, overall gonorrhea rates in the USA plateaued for 10 years. After the decline halted for several years, gonorrhea rates decreased further to 98.1 cases per 100,000 population in 2009, the lowest rate since recording of gonorrhea rates began. Since then, the rate of gonorrhea has fluctuated from year to year with an overall trend toward a slight increase. In 2013, the rate of reported gonorrhea was higher in men than in women for the first time since 2000 [3]. This increase may be due to increased disease transmission or may be due to increased detection of cases due to screening high-risk patient populations or to the ease of urine-based diagnostic testing compared to urethral swab testing.

The highest rates of gonorrhea tend to be in the southern and southeastern USA; in 2013, the rate of reported gonorrhea was higher in men than in women for the first time since 2000, corresponding to the similar trend with reported chlamydia. In 2013, as in previous years, men aged 20–24 years had the highest rate of gonorrhea (459.4 cases per 100,000 males) compared with males across other age groups.

After declining throughout the 1990s, the rate of primary and secondary (P&S) syphilis reported in the USA increased each year from 2001 through 2009 and has continued a slower increase from 2010 through 2013 [3]. The increased rates are due almost solely to an increased rate in men; in 2013, men accounted for 91 % of all P&S syphilis cases, and 75 % of these cases are in MSM. In this population, about one-half of MSM patients with syphilis also were infected with HIV, whereas the coinfection rate during the same time was approximately 10 % in men who have sex with women (MSW) and 5 % in women. During 2000–2013, the rate of P&S syphilis among men 20–24 years old increased from 4.3 to 27.7 cases per 100,000, representing the highest rate of P&S syphilis among any age group in men. From the standpoint of STI and sexual health care in men, syphilis has once more become an important disease to consider when assessing patients’ STI risk factors. Figure 10.4 shows the reported cases of syphilis by gender and sexual behavior from 2007 to 2013.

Prevalence data on genital warts due to human papillomavirus (HPV ) were compiled by information via provider diagnosis or by documentation from the physical examination. Gay, bisexual, and other MSM and men who have sex with women only (MSW) were defined by self-report or by reported sex partners. Between 2010 and 2013, among patients in STI clinics who were diagnosed with genital warts, 17.0 % were women, 20.5 % were MSM, and 62.5 % were MSW.

In 2013, the prevalence of diagnosed genital warts among MSM was 3.0 times that of women, and the prevalence among MSW was 4.0 times that of women [3]. During 2010–2013, prevalence of genital warts among MSW increased (6.8–7.4 %), while prevalence among MSM decreased (6.3–5.5 %). The proportion of women diagnosed with genital warts decreased slightly over time, from 1.9 % in 2010 to 1.6 % in 2013. Figure 10.5 shows the rates of genital warts by age and gender.

Herpes simplex virus 2 (HSV2) is essentially ubiquitous in the US population and throughout the world and is an important cause of genital ulcer disease and genital herpes. Genital ulcer disease is associated with an increased risk of acquiring HIV disease, presumably due to exposure of mucosal surfaces that allow increased transmission of infection. Since genital herpes is not a reportable illness, it is impossible to create similarly detailed epidemiologic data and assessments compared to other STIs; the CDC reports only HSV -related physician visits rather than complete case data which is unavailable. Approximately 90 % of patients who are HSV seropositive are unaware of this [3]. Serology for HSV2 is not generally useful in predicting clinical symptoms or transmission, but is often used as a surrogate in place of more specific epidemiologic data. In general, while HSV-2 seroprevalence is increasing, HSV-related physician visits are increasing, possibly due to increased recognition and awareness of infection [3]. Figure 10.6 shows the seroprevalence of HSV2 by age group, ethnicity, and year.

The common STIs produce generally predictable clinical syndromes; the presenting features and symptoms of these infections differ from men to women, and a review of the key clinical features of these disorders specific to men can help physicians maintain an appropriate index of suspicion for STIs in patients with various presenting complaints.

During sexual intercourse or other contact, STIs are typically transmitted at the site of breaks in mucosal surfaces that are exposed to STI-causing organisms [4]. Women have a greater exposed mucosal surface than do men, and these surfaces are subjected to greater trauma, which in part explains the increased risk women have for STIs.

Men’s physical examination to evaluate for evidence of STIs is easier and less invasive than in women, in whom the vagina and cervix must be visualized. Despite this, the ready availability of urine-based STI testing may limit the actual physical examination of men for STIs, particularly in “express treatment” STI clinics that rely heavily on urine-based testing and forego the clinical examination. One study found an increased rate of missed STI diagnoses in men presenting to an STI clinic with symptoms (10.4 %) compared to the group of asymptomatic patients (2.6 %) and the group of patients presenting after identification of an STI in a sexual contact (4.5 %) [5]. This suggests that even when a diagnosis of urethritis seems evident based on history and can be confirmed on urine testing, a physical examination is still important to identify other or unsuspected STIs or genital infections, such as balanitis, scabies, epididymitis, penile warts, or genital herpes, as well as a disseminated gonococcal infection and the small proportion of primary syphilis cases [5].

The clinical syndromes for STIs in men include the following: urethritis, presenting with urethral discharge or irritation; genital ulcer disease; HPV causing genital warts; and disorders presenting with irritative voiding. Table 10.2 lists the most common clinical syndromes and causative organisms for STIs in men.

Interventions to prevent STIs depend upon an accurate assessment of a man’s STI risks as well as on epidemiologic and clinical understanding of the disorders involved. Clinical recommendations regarding behavioral counseling, screening, and other preventive health measures are often recommended for men considered to be at “high risk” for STIs, and it is critical to effectively assess these risk factors in men in primary care practices, urgent or emergency care, or STI clinic settings. As with women, STI risk factors include modifiable risks (e.g., sexual behavior) and non-modifiable risk factors (e.g., ethnicity, demographics); STI risk assessment for men should also address the patient’s social context including work and/or living arrangements as possible risk factors that can guide preventive health interventions. Table 10.3 lists modifiable and non-modifiable as well as contextual STI risk factors for men; many of these are the same risk factors as for women.

Additional behavioral and contextual risk factors have been investigated; for example, in one study, first leaving the parental home, poor self-regulation or planning skills, emotional distress and hostility, poor attitudes toward condom use, and alcohol binge drinking predicted unprotected sexual contact in rural African American men, but not in women [11]. These factors suggest that obtaining a detailed and patient-centered social history, including an understanding of patient beliefs regarding sexual behavior and STI risks, represents an important area for determining a patient’s overall STI risk profile.

A number of scoring systems and risk calculators (including online scoring systems or cell phone “apps” such as http://​www.​stdriskcalculato​r.​com/​ or http://​www.​medindia.​net/​patients/​calculators/​hiv-risk-calculator.​asp) have been developed in an attempt for providers or patients themselves to quantify their degree of STI risk [12]. However, the studies on which such scoring systems have been conducted vary widely in their patient population, baseline STI risk, methods and outcomes assessment, and other factors. As such it is nearly impossible to determine a useful quantitative risk profile for various STI risk factors, and attempts to calculate or quantify such risks have not performed well outside very limited settings.

Physicians and other health-care providers should, instead of attempting to quantify STI risk, simply be aware of the multiple possible risk factors that patients might have for STIs and should try to elicit these details in their history-taking. Assessing an individual patient’s overall STI risk becomes more of a subjective global risk assessment based on the patient’s unique social and medical history, rather than a more quantifiable or scientific risk estimate.

Male circumcision has long been felt to have a protective effect against acquiring STIs, particularly HIV and particularly in MSM. Different studies have had variable results, largely as a result of varying patient populations and varying sexual practices. A meta-analysis of 15 studies of over 500,000 MSM [13] found that the odds of being HIV positive were lower in circumcised than in non-circumcised MSM, but the difference was not statistically significant; this study also found that there was no evidence of a protective effect against other STIs.

This study noted that earlier trials showing a protective effect from circumcision were conducted before the advent of highly active antiretroviral therapy (HAART) for chronic HIV disease and that changes in sexual behavior and/or disease transmission may limit the actual current protective effect of circumcision. Also, it is possible that male circumcision can still provide an aggregate protective effect in areas where STI prevalence is high and circumcision prevalence is low (<50 %).

Applying a knowledge of STI epidemiology, clinical features, and risk factors depends on eliciting a medical and sexual health history from the patient. Obtaining the sexual history requires the physician to take extra time to ensure that the environment and the physician communication are optimal to protect patient privacy and confidentiality, so that the most effective history and counseling can be conducted. Effective history-taking and communication can be thought of in the following steps: