Men having sex with men (MSM) are at risk of infection from human papillomavirus (HPV) and should have regular anal pap smears, a medical expert advised on Wednesday.

A study by the Thai Red Cross Aids Research Centre shows that, among men, anal HPV infection which can lead to anal cancer is a high risk, compared with men having sex with women.

Thai couple Tanakorn Sittiamthong, right, and Nonthawat Charoengaysornsin kiss during a contest to break the Guinness World Record for longest continuous kiss as part of Valentine's Day celebrations at Pattaya last year. (EPA Photo)

Dr Nittaya PhanuphakPungpapong, deputy chief of theThai Red Cross AIDS Research Centre, estimated that 85% of HIV-positive Thai MSM carry some form of HPV, with 58% infected by high risk types of HPV. The infection with high risk HPV types can leads to anal cancer.

HPV is a known cause of cervical cancer and genital warts in women, but it also can cause of ano-genital warts and anal cancer in men, and then lead to anal cancer. It can be prevented by a quadrivalent HPV vaccine

In Thai MSM who do not have HIV, the infection rate of HPV is still 58%. Anal HPV infection is much higher in HIV-positive MSM than in those who do not have HIV.

She recommends that risk groups should take an "anal pap smear" which can screen for abnormal cells in the anus, and may give early warning of possible pre-cancerous or cancerous anal lesions.

Associate Professor Mongkol Benjapibal from Division of Gynaecologic Oncology at Siriraj Hospital, also noted that HPV vaccinations of males can reduce HPV infection rates because men are carriers of HPV.

He said a study of young men showed that vaccine can prevent up to 78% of anal cancer cases. HPV vaccination is safe and shows a 91% efficiency rate in men.Only quadrivalent HPV vaccine is currently approved by Thai Food and Drug Administration for males.

To stop the spread of HPV in Australia, for instance, school boys have begun receiving this vaccine to protect against cancers and diseases caused by HPV.