By Faiza Ilyas
KARACHI: A population-based survey of HPV (human papillomavirus) which is a sexually transmitted infection and carries a major risk of causing cervical cancer has found its prevalence very low in a densely populated locality of Karachi.
Over 900 women residing in Orangi participated in the survey, a collaborative project of Aga Khan University Hospital (AKUH), International Agency for Research on Cancer (IARC) based in France and Sindh Government Qatar Hospital (SGQH), Orangi.
The study – the first large-scale population-based survey on HPV infection in Pakistan – will be published soon. It found the HPV prevalence in Orangi at less than three per cent.
Dr Syed Ahsan Raza, a senior instructor and epidemiologist at the AKUH who was the principal investigator of the survey, described the findings as “striking” given the fact that the HPV prevalence in Karachi was lower not only than what it is in the other countries surveyed by the IARC, but also compared to the neighbouring Asian countries – Nepal (8.6per cent), Tamil Nadu, India, (17 per cent), China (15-18 per cent in three provinces) and 10 times lower compared to the high-risk areas in Asia and Africa (35 per cent in Mongolia and 51 per cent in Guinea).
“The HPV prevalence (in the Karachi locality) was found to be even lower than what it is in Iran and Algeria. It is difficult to explain the actual reasons for this difference. However, the extent of sexual promiscuity in those areas, perhaps, could provide some insight into the reasons,” says Dr Raza.Results from Karachi, he said, had to be interpreted cautiously compared to the rest of the country. “In fact, there were some suggestions of slightly higher prevalence among non-Urdu speakers. However, given the fact that the survey was conducted in one of the largest cities of Pakistan and in an area where there is representation of different ethnic groups, it is reasonable to believe that the HPV prevalence is not as high as seen in other parts of Asia.”
For the survey, a group of midwives was initially trained to go door-to-door and create awareness about cervical cancer in order to convince women to participate in the survey. The midwives were also trained in carrying out gynaecological examinations at the Qatar Hospital.
A census of 10,000 households was done to collect name and age of every woman resident of the locality. Due to certain socio-cultural constraints, however, unmarried women were not included in the study.
Cervical samples were obtained from women between the age of 15 and 59 years from May 2007 to March 2008. The HPV type testing was performed on samples at the Vrije University Medical Centre, Amsterdam.
One of the most common STIs (sexually transmitted infections), the HPV infects the epidermis and mucous membranes of humans. Approximately, 130 HPV types have been identified. About 30 to 40 HPV types are typically transmitted through sexual contact. Some sexually transmitted HPV types may cause genital warts.
According to the study, cervical cancer is the third most commonly reported cancer in women after breast and oral cavity cancer. At the moment, no cervical screening programme exists in the country nor is there any data on HPV infection in the general population. Little information is available on HPV-associated cervical cancer in the country.
The study points out that the public awareness programmes on STIs in Pakistan in the past have been hampered by the social restriction attached to discussing female sexuality. Even in high-risk groups, women are hesitant to undergo regular gynaecological examination or medical check-ups, it says.
According to the findings, a total of 17 different HPV types were identified. HPV was 2.8 per cent overall with 22.7 per cent and 2.2 per cent among women with and without cervical abnormalities, respectively.
Significant associations with HPV positivity were observed in a working woman having two or more than two sexual partners, an age difference of 10 and above with husband, extramarital affairs of husband and his absence from home more than seven nights a month.
Higher HPV was also found among illiterate women (as compared to women who reported secondary education); and women who were separated or divorced (compared to married women in monogamous marriages).
HPV prevalence was relatively constant across all the age groups. HPV 16 was the most common type.
The proportion of women using any kind of contraceptive was 43.4 per cent. There was no suggestion of higher HPV prevalence among younger women.
Fourteen per cent of women in the study were working women and three-fold elevated risk of HPV positivity was seen in 90 per cent of those women who were either employed as factory workers or were domestic workers.“The low prevalence of HPV infection is consistent with a country of low cervical cancer risk,” it concludes.
According to Dr Raza, the findings of very low prevalence in Karachi will help decide whether or not to prioritise cervical cancer prevention programmes in Pakistan where the burden of other infectious diseases is very high.