The authors have declared that no competing interests exist.
Conceived and designed the experiments: MEA SM MLJ JAB LV SP MO. Performed the experiments: MEA SM MLJ JAB LV SP MO. Analyzed the data: MEA SM MLJ JAB LV SP MO. Contributed reagents/materials/analysis tools: MEA SM MLJ JAB LV SP MO. Wrote the paper: MEA SM MLJ JAB LV SP MO.
Human Papillomavirus (HPV) infection in men may produce cancer and other major disorders. Men play an important role in the transmission of the virus and act as a reservoir. The aim of this study was to determine the HPV-genotypes and their prevalence in a group of men attending a Sexually Transmitted Infection service.
Between July 2002 and June 2011, 1392 balanopreputial, 435 urethral, 123 anal, and 67 condyloma lesions from 1551 men with a mean age of 35.8±11.3 years old (range: 17–87) were collected for HPV-DNA testing.
A fragment of the L1-gene and a fragment of the E6/E7-genes were amplified by PCR. Positive samples were typed by hybridization.
The HPV genome was detected in 36.9% (486/1318) balanopreputial and in 24.9% (101/405) urethral (p<0.0001) swabs from 38.1% (538) of 1469 men. Co-infections were present in 5.4% (80/1469) of cases. HPV was found in 43.9% (373/850) of men younger than 35 vs. 31.7% (187/589) of men aged >35. HPV was found in 59.4% (104) of 165 men with lesions (macroscopic or positive peniscopy), and in 22.8% (61/267) without clinical alterations. HPV was also detected in 71.4% (40/56) men with condylomata and in 58.7% (64/109) of men with positive peniscopy.
HPV prevalence in men was high and decreased with age. HPV was found more frequently in balanopreputial than in urethral swabs. There was a low rate of co-infections. Low-risk HPV vaccine genotypes were the most recurrent especially in younger. Although HPV has been associated with clinical alterations, it was also found in men without any clinical presentation. Inclusion of men in the national HPV vaccination program may reduce their burden of HPV-related disease and reduce transmission of the virus to non-vaccinated women.
Papillomaviruses are the most sexually transmitted viruses. Experimental and epidemiological data imply a causative role for HPVs and they appear to be the second most important risk factor for cancer development in humans, exceeded only by tobacco usage
The most common cause of mortality related to human papillomavirus (HPV) infection is cervical cancer (annually 530.00 cases, with 270.000 deaths). HPV infection is also an important concern for men, due to disease burden and the risk of transmission. HPV is associated with anal cancer (approximately 90%) and a subset of penile (50%) and oral cancers (10–72%)
The aims of this study were: 1) to assess the prevalence of Papillomavirus infection and the circulating genotypes in men who attended a Sexually Transmitted Disease service by examining urethral and paraurethral swabs; 2) to analyze the variables which may play a role in HPV acquisition and persistence; 3) and to determine which would be the best sample to perform this kind of diagnosis; 4) determine the percentages of HPV-infections in men that may be prevented by the bivalent and quadrivalent HPV vaccine.
The HPV genome was detected in 36.9% (486/1318) balanopreputial swabs, and in 24.9% (101/405) urethral swabs (p<0.0001) from 38.1% (560) of 1469 men. In 5.4% (80/1469) of males a mixed infection was found. The incidence of HPV infection found throughout the study period was studied (
In addition, HPV was present in 50.9% (34/67) lesion swabs, and in 49.6% (61/123) anal swabs (p = no significant).
If HPV infection is analyzed according to age, HPV was found in 48.7% (98/201) individuals younger than 25, in 42.4% (275/649) of individuals in the 25–35 range, in 31.7% (111/350) in the 36–45 range, and in 31.8% (76/239) individuals over 45 (p<0.0001). Mixed infections were detected in 9.2% (9/98) men younger than 25, in 16% (44/275) men in the 25–35 range, in 13.5% (15/111) men in the 35–45 range and in 15.8% (12/76) men over 45 years (
On the other hand in
Low-risk genotypes (HPV-6, HPV-11, or the absence of the E6/E7 fragment) were detected in 47.1% (317/674) of patients, as opposed to 41.2% (278/674) of individuals who exhibited high-risk genotypes. High-risk genotypes are more frequent in men younger than 25 years old. However the most frecuent genotype in men younger than 25 was HPV 6 (p = 0.0013) .The involved genotype distribution by age groups was analyzed (
<36 years | >35 years | TOTAL | p | |
Number of HPV | 449 | 225 | 674 | |
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HPV-6 | 119 (26.5%) | 36 (16%) | 155 (23%) | 0.0025 |
HPV-11 | 68 (15.4%) | 30 (13.3%) | 98 (14.5%) | n.s |
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HPV-16 | 79 (17.6%) | 50 (22.2%) | 129 (19.1%) | n.s |
HPV-18 | 18 (4%) | 7 (3.1%) | 25 (3.7%) | n.s |
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n.s |
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0.018 |
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HPV-31 | 16 (3.6%) | 8 (3.5%) | 24 (3.6%) | n.s |
HPV-33 | 11 (2.4%) | 5 (2.2%) | 16 (2.4%) | n.s |
HPV-35 | 4 (1.8%) |
2 (1.9%) |
6 (1.8%) | n.s |
HPV-45 | 6 (1.3%) | 6 (1.3%) | ||
HPV-52 | 8 (3.6%) |
1 (0.9%) |
9 (2.7%) | n.s |
HPV-58 | 18 (4%) | 13 (5.8%) | 31 (4.6%) | n.s |
HPV-66 | 6 (2.7%) |
4 (3.7%) |
10 (3.1%) | n.s |
HPV-NT | 14 (3.1%) | 8 (3.6%) | 22 (8.3%) | n.s |
Vaccinal genotypes, notably those with low oncogenic risk were more frequent than non-vaccinal types, except in men older than 45 years old.
As for mixed infections,
The mixed infection rate of positive samples was 14.3% (80/560) and was not related with age (
On the other hand, 15.9% (89/560) of patients presented HPV-16 and/or HPV-18 without other genotypes. And 40% (224/560) presented HPV-6 and/or HPV-11 and/or HPV-16 and/or HPV-18 without other genotypes.
The relationship between HPV infection and several factors associated to it or its progression is shown in
Infection factors (HPV+) | YES | NO | p |
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4/8 (33.3) | 158/264 (37.4%) | ns |
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89/86 (50.8%) | 133/138 (49%) | ns |
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86/164 (34.4%) | 97/157 (38.2%) | ns |
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Single | 119/179 (39.9%) | ||
Divorced | 17/26 (39.5%) | 0.05 | |
Married | 35/112 (23.8%) |
Progression factors (E6/E7+) | YES | NO | |
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32/62 (34%) | 20/43 (31.7%) | ns |
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28/70 (28.6%) | 24/36 (40%) | ns |
The results of macroscopic penis examinations were known for 151 men; 56 featured alterations compatible with condylomata at the time of exploration, and HPV was detected in 71,4% (40/56); however, only 16,8% (16/95) out of males with negative exploration were HPV positive (p<0.0001). After performing a peniscopy, HPV was present in 58.7% (64) out of 109 patients with lesions compared to 26.6% (45) of 172 patients without lesions (p<0.0001).
Of all the studied variables, only marital status was related to the infection: single and divorced men have a higher viral infection rate than married men (p = 0.05).
While much is known about the natural history of cervical HPV infection and its consequences, including cervical intraepithelial neoplasia and cervical cancer, relatively little is known about the natural history of genital HPV infection and diseases in men. In part this reflects difficulties in penile sampling and visual assessment of penile lesions. Although HPV is transmitted sexually and infects the genitals of both sexes, the cervix remains biologically more vulnerable to malignant transformation than the penis or anus in men. However, as more precise and sensitive methods become available and wider studies are performed, the number of HPV-associated pathologies has also increased
The HPV infection rate increased steadily throughout the years of the study in the male population in our area. In the first years of the study (2002–2005), it was 28.3% to 43% in 2007–2009. This rate remained stable in the latest years after solving some issues related to sample types and sample gathering, and improving the assessment of individuals with a potential pathology. The 36.3% incidence rate in men attending a STI clinic is close to the highest values described
Data on infection incidence take into account the results of the urethral and paraurethral swabs. As other authors have already described, paraurethral swabs exhibited a greater diagnostic performance, which facilitates the performance of this type of studies, since these samples can be easily obtained
In this study, swabs obtained from anal lesions or penile condylomata were also processed. The performance of these types of samples was lower than expected (50%), but it must be taken into account that no biopsies were carried out. Biopsies would be the preferred samples to perform an etiologic diagnosis of lesion samples
No evident influence of age on infection rate has been found in the published literature on HPV infection in men
The more frequent viral genotypes in the male population were the vaccinal genotypes, notably HPV-6 and HPV-11, a fact already mentioned by other authors
According to these results, male vaccination with the tetravalent vaccine would be more effective than with the bivalent one, since it could reduce the risk of anal-genital warts, which, although not a severe pathology, do cause significant psychological morbility.
In the present study, to 2007 a 3.1% of mixed infections were detected. The prevalence of multiple-type HPV has been reported to be between 2.1% and 34.8% in men
The individuals from this study that would have benefit by the bivalent vaccine will be 15.9% and by the quadrivalent vaccine 40%.
The virus was more frequently detected in those men showing a clinical presentation compatible with HPV infection than in those who did not. In these cases, however, the percentage of HPV found was not higher than 51%. Obtaining cellular samples by exfoliation of the keratinized epithelium was difficult in those instances, thus compromising the diagnosis
The risk of contagion is related to sexual behaviour (number of sexual partners, both throughout life and simultaneous), sexual intercourse with risk groups (prostitution), polygamy, having suffered other STDs and parenteral drug use. In our study, none of these factors seemed to be involved in the increase of the HPV infection rate, with the exception of marital status: single or divorced individuals were associated to a higher HPV infection rate. These males also exhibit a sexual behaviour different to that of married men.
Although many males get infected with HPV, most of such infections do not develop into cancer. It is thus probable that other co-factors, such as tobacco usage, alcohol intake and coinfection with other sexually transmitted diseases play a role in the pathologic process. No relationship between these co-factors and the presence of oncogenic genotypes was established in this study.
On this study, urethral and paraurethral swabs are not collection simultaneously, and clinical and pathological data were reviewed only from 151 patients due to the medical history confidentiality. These limitations could have any influence in the data.
To sum up, although HPV infection do have worse consequences for women, men play an active role in it, as the high incidence rates found demonstrate. Men are involved in its reservoir and transmission, and the virus may end up causing major disorders and severe consequences. The high prevalence in this collective suggests the need of more exhaustive assessments, even though most individuals do not feature high-risk oncogenic viruses. Most countries have only included girls in their national vaccinations programs
Between June 2002 to June 2011, HPV genome detection was performed prospectively in 1551 males (mean age: 35.8±11.38 years old, range: 17–87 years old) which were attended in the Sexually-transmitted Infections Service of the Hospital Monte Naranco (Oviedo, Asturias; North of Spain). From them 1318 paraurethral swabs, 405 urethral swabs, 123 anal and 67 condyloma lesions were recovered.
Clinical data together with HPV infection-related risk factors (marital status, a history of STDs, alcohol intake, tobacco usage, and parenteral drug abuse) were gathered from 515 patients. From them, in 151 macroscopic penis data, and in 286 peniscopy data were also recovered.
Half the volume of the samples was homogenized and concentrated by centrifugation at 6000 rpm (1800 g) for 5 min and supernatant removed. Then, 200 µl of lysis solution (10 mM Tris-HCL pH 8.3, 50 mM potassium chloride, 2.5 mM magnesium chloride, 0.5% Igepal, 0.5% Tween 20 and 10 µg of proteinase K) was added, mixed and incubated for 45 min at 56°C, then for 10 min at 96°C to inactivate proteinase K, and finally stored at −20°C until it was analyzed. The quality of extracted DNA was checked by PCR amplification of the β-globin gene (the primer forward
Standard protocol of PCR with MY11/MY09 primers (site-directed L1 fragment of HPV)
Another PCR was performed with a pair of primers against the E6/E7 fragment (onco1-sense-
Positive specimens from different HPV types were used as positive controls. The reaction mixtures containing no DNA, water, and DNA from human leucocytes were used as negative controls.
All positive specimens for L1 fragment were tested by hybridization assays using type-specific probes for HPV types 6 (MY12:
From 2007 were added probes against HPV types 35 (
To avoid prevalence bias, only the first specimen positive for HPV DNA from a given sample was considered Prevalence rates of four age groups were used. Statistical tests (Chi-square test, Fisher's test, Student's t-test, etc.) were performed using GraphPad InStat version 3.00 for Windows 95 (GraphPad Software, San Diego, CA) following the manufacturer's instructions.
All experiments were performed in compliance with relevant laws and institutional guidelines and in accordance with the ethical standards of the Declaration of Helsinki. Information concerning the research project was provided to all participants, and all signed a free and informed consent from approved by Ethical committee of Clinical Investigation of the HUCA.
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