**4. Co-infection of HPV and** *Chlamydia trachomatis*

It has been confirmed in different studies that HPV can be part of a co-infection with *Chlamy‐ dia trachomatis*. This is important since sexually transmitted diseases and there association with the development of cancerous and precancerous lesions has been shown in several studies. In Honduras, in women aged 18–35 years, the prevalence of *Chlamydia trachomatis* and HPV was found to be 6% and 28%, respectively; 19 genotypes were detected – proving to be the most common were HPV-5 and 11 [41]. In a previous study of our working group we found that of 77 patients with squamous intraepithelial lesions 13% had a co-infection with HPV and *Chlamydiatrachomatis*;46%onlyHPVinfectionand13%only*Chlamydiatrachomatis*infection[42].

In another study, it was found that patients with *Chlamydia trachomatis* and HPV had a prevalence of 74 %. However, only 13% of patients were negative to HVP and positive to *Chlamydia trachomatis* [43]. In the case of sexually transmitted infections *Chlamydia trachoma‐ tis* was found in 50% and HPV in 30% [44]. Other studies show that *Chlamydia trachomatis* infection is associated with multiple HPV genotypes and changes in signaling mechanisms in cancer and precancerous lesions [45, 46].

As mentioned in the above paragraphs the relationship between infection of HPV and *Chlamydia trachomatis* is confirmed, however, few studies exist regarding infertility in men with high prevalence. It has been found that men who have HPV present *Chlamydia trachomatis* 82.8% compared to a negative HPV of 17.2% [47]. In another study a prevalence of HPV in the semen of men with conjugal infertility was of 38.5 %, meanwhile the prevalence of *Chlamydia trachomatis* with HSV (types 1 and 2) was 9.6 % [48].

There are few studies showing the association of the two pathogens as co-factors with male infertility, however, there are multiple studies showing their coexistence, so it is important to know how each of these pathogens affects infertility.
