**Cervical HPV infections**

High rates of incidence of HPV cervical infection are observed especially in young women. Cumulative incidence of more than 40% after 3 years of follow-up has been demonstrated among university students [5, 6, 37]. The highest incidence rates of cervical HPV infection are observed in young women corresponding to age of sexual intercourse debut. Thereafter, incidence in women tends to decline with age, although second peaks are sometimes observed in older women (such as for prevalence data)[5]. For example, in a cohort of women between 13 and 65 years of age in Bogota in Colombia[37], the cumulative incidence of any HPV after five years of follow-up among women aged 15-19, 20-24, 25-29, 30-44 and more than 45 years were 42.5%, 36.9%, 30.0%, 21.9%, and 12.4%,, respectively. The cumulative incidence after 5 years of follow-up in all age groups was 26.3% and infections rate with HR-HPVs were more frequent than infections with LR genotypes (5.0 cases and 2.0 cases/100 woman-years, respectively). Although some studies observed higher incidence of HR-HPV than LR-HPV, these comparisons depend on the assays used. More recent assays detect more types, many of which fall into the LR category.

#### **Anal HPV infections**

Cumulative incidence of anal HPV infection in a cohort of women of Hawaii (median age: 40 years old) has been evaluated at almost 70% in an average period of 1.3 years of follow-up. The rate of acquisition of anal HPV infection with any genotype was observed at 46.9 cases per 1000 woman-month. The incidence rate of anal HPV infections with HR-HPVs is also higher than with LR-HPV (such as for cervical infection) with estimates reported by Goodman et al (2008) at 19.5 and 8.2/1000 woman-months for an incident anal HR-HPV and LR-HPV, respectively[32]. Lower risk of acquisition of anal HR-HPV in women over 45 years of age have also been observed compared to women under 25 years of age.

#### **Vaginal and vulvar HPV infections**

To our knowledge, there are no estimates on the incidence of vagina and vulvar HPV infection in healthy women.

#### *4.1.3. Special population: HIV-positive women and sex workers*

HIV and HPV infection status has been under the projectors during the last years. In a systemat‐ ic reviewofHIV-positivewomenwithnocytologicalabnormalities,prevalenceofHPVhasbeen evaluated at 36.3% [38], higher than in worldwide estimated prevalence (11.7%)[29].

the higher prevalence in MSM[45]. Another example from a cohort of Italy have settled prevalence of anal HPV infection to 74.8% in MSM[8]. As for the general population of men, the incidence of HPV infection does not seem to drop with age in MSM as the prevalence

Epidemiology of Anogenital Human Papillomavirus Infections

http://dx.doi.org/10.5772/55825

275

Also, it appears that HIV status increases the risk of HPV infection in MSM. For example, a recent systematic review that compared HPV prevalence in MSM according to HIV status has shown that the anal canal prevalence was higher in HIV-positive individuals: (92.6% for HIVpositive compared to 63.9% for HIV negative men) [47]. HR-HPVs were detected in 73.5% of HIV-positive men whereas it was 37.2% in HIV-negative men. The prevalences of HPV-16 and 18 were also higher in HIV-positive men (35.4% compared to 12.5% for HPV-16 and 18.6%

Circumcision has been described to reduce the risk of HPV infections in men. The most recent published meta-analysis shown an inverse association between circumcision and genital HPV prevalence in men with an estimated pooled odds ratio of 0.57 (95% confidence interval: 0.54-0.82)[48]. However, as not many studies have been published on the role of circumcision and HPV infection and as most of them are from observational design, more studies are needed

Although high prevalence of HPV is found in both males and females, most of the HPV infections will be cleared spontaneously. Literature has consistently shown that at least 80 to 90% of cervical HPV infections are transient and are no longer detectable within 1-2 years[49]. HR-HPV infections seem to persist longer than LR-HPV[5]. For example, in cervical swabs of female university students, LR-HPV and HR-HPV infections typically last (in average) 13.4 and 16.3 months, respectively[50]. In a review paper, the median duration (time for 50% of infections to be cleared) of cervical infection reported from published studies ranged from 4

Clearance has also been studied in men. For example, a study on the clearance of HPV infections in penile and scrotum sampling in a cohort of USA men has shown that the median time to clearance of any HPV infection was 5.9 months and that 75% of HPV infections cleared by 12 months[42]. Contrarily to women, LR-HPV and HR-HPV infections durations were almost the same with a median duration of 5.8 months and 6 months respectively. Recent data from a cohort study regrouping men from Brazil, Mexico and USA also supports that median duration of HPV infection is shorter in men than in women with 7.5 months for any HPVs[43].

to 20 months, with a tendency for HPV-16 infections to last a little longer[5].

to confirm the protective role of circumcision with HPV anogenital infections in men.

remains high in all age groups[46].

compared to 4.9% for HPV-18).

**5. Natural history**

*5.1.1. Clearance*

*4.2.4. Circumcision and genital HPV infections*

**5.1. Clearance and persistence of HPV infection**

More attention was also paid to sex workers in the last years. For example, in a study made in China, prevalence of any HPV genotype was estimated at 38.9% in this population[39]. A recent study in Spain also demonstrated a higher incidence and a higher risk of persistence of HR-HPV infection in sex workers compared to the general population (incidence of 3.98 per 100 women-years relatively to 26.81 per 100 women-years)[40].

#### **4.2. Anogenital HPV infections in men**

#### *4.2.1. Prevalence*

Depending of the anatomic sites (coronal sulcus, glans, prepuce, shaft, urethra, scrotum, perianal area, anus, semen or urine) that is analysed, HPV prevalence (any genotypes) can vary from 1% to 84% among the general population of men and from 2% to 93% in high-risk men (such as STI clinic attendees, HIV-positive males, and male partners of women with HPV infection or abnormal cytology)[41]. For example, the site specific prevalences of HPV infection in male were estimated between 6.5%-50% in corona and/or glans, 5.6%-51.5% in penile shaft, 24%-50% in prepuce, 7.1%-46.2% in scrotum, and 8.7%-50% in urethra [27]. Contrarily to what is reported in women, HPV prevalence is relatively stable across age groups in men [41, 42]. Prevalence of anal HPV infection in men who have sex with women has been reported to range between 0% and 32.8% [27]. It is important to consider, however, that a high variability in the prevalence estimates may occurred in man due to the variability of sites tested or to the type of specimen used for which the detection method is not completly optimized (such as urine).

#### *4.2.2. Incidence*

Few studies have reported HPV infections incidence in men. Cumulative incidence calculated with penile and scrotal sampling, in a cohort of USA men aged between 18-44 years old (mean age: 29.7 years) was 29.3% after a follow-up of 12 months[42]. Incidence rate in this cohort for any HPV genotype infection was 29.4 per 1000 men-months. Incidence rates of HPV-6, 11, 16, and 18 infections were 2.8, 0.5, 4.8, and 0.8 per 1000 men-months, resectively.

#### *4.2.3. Special population: Men who have Sex with Men (MSM) and HIV-positive men*

HPV infection is strongly associated with the number of lifetime female sexual partners in men who have sex with women (MSW) and also with the number of male anal-sexual partners in men who have sex with men (MSM) [43]. For MSM, prevalence of any HPV genotype was estimated at 18.5% on the penis, 17.1% on the scrotum, 33.0% on the perineal/perianal region, 42.4% in the anal canal, and 48.0% at any site. The prevalence of HPV infection is high among young sexually active MSM, with the anal canal being the most common site of infection[44]. A study comparing the anal canal HPV prevalence in MSW (12.2%) to MSM (47.2%), confirmed the higher prevalence in MSM[45]. Another example from a cohort of Italy have settled prevalence of anal HPV infection to 74.8% in MSM[8]. As for the general population of men, the incidence of HPV infection does not seem to drop with age in MSM as the prevalence remains high in all age groups[46].

Also, it appears that HIV status increases the risk of HPV infection in MSM. For example, a recent systematic review that compared HPV prevalence in MSM according to HIV status has shown that the anal canal prevalence was higher in HIV-positive individuals: (92.6% for HIVpositive compared to 63.9% for HIV negative men) [47]. HR-HPVs were detected in 73.5% of HIV-positive men whereas it was 37.2% in HIV-negative men. The prevalences of HPV-16 and 18 were also higher in HIV-positive men (35.4% compared to 12.5% for HPV-16 and 18.6% compared to 4.9% for HPV-18).

### *4.2.4. Circumcision and genital HPV infections*

Circumcision has been described to reduce the risk of HPV infections in men. The most recent published meta-analysis shown an inverse association between circumcision and genital HPV prevalence in men with an estimated pooled odds ratio of 0.57 (95% confidence interval: 0.54-0.82)[48]. However, as not many studies have been published on the role of circumcision and HPV infection and as most of them are from observational design, more studies are needed to confirm the protective role of circumcision with HPV anogenital infections in men.
