Cervical cancer is the second most common female cancer in The Gambia, and there have been few studies carried out on the causative agent, human papillomavirus (HPV) in this country. The Gambia introduced the quadrivalent HPV vaccine for girls between the ages of 9-13 years in the urban area in 2014; nationwide immunization will take place in 2019. This study determined the common circulating oncogenic HPV types in the urban region where most cervical cancer cases were reported. Two hundred and thirty-two women between 20 – 49 years of age from the urban region who attended a polyclinic were recruited for this work.
Endocervical and high vaginal swabs were collected, and a socio-demographic questionnaire was administered to capture potential risk characteristics associated with HPV. Nucleic acid amplification techniques and DNA sequencing were carried out to determine the HPV genotype using PGMY09/11 consensus primers. Phylogenetic analysis was carried out on the Gambian HPV sequences to further confirm the identification of The Gambian HPV genotypes and its relatedness to sequences of the same types from other geographical locations. Microbiological and nucleic acid amplification analyses were used to determine the prevalence of other sexually transmitted pathogens in the participants. Blood samples, endocervical swab, and Pap smear were collected from HIV positive participants and these participants were followed up and re-examined every nine months for 24 months, to determine the persistence of cervical HPV infection, HPV antibodies, and cytological cervical changes. Pseudo-typed neutralisation assays were performed to characterise high-risk HPV antibodies in HIV positive women.
Among the sample population studied, HPV prevalence was found to be 12% (28/232). HPV 52 was the most prevalent (17.9%) genotype detected in cervical samples. The Gambian high-risk HPV genotypes, except for a novel putative HPV 35 genotype, were 98 -100% identical to those submitted in the GenBank database. Prolonged (> 5 years) use of hormone contraceptive was the only variable found to associate statistically with HPV infection. Fifty percent (14/28) of participants infected with HPV were co-infected with Ureaplasma urealyticum/parvum and 25% (7/28) with HIV. HPV sero-prevalence was found to be 51.7% (15/29) in HIV positive participants. HIV positive women had been exposed to multiple HPV types and HPV 52 antibody was more prevalent 24% (7/29). Other high-risk HPV genotypes were found to cause high-grade cervical lesions and cancer in HIV positive women. Future studies to investigate oncogenic HPV genotypes in cervical cancer specimens will be useful in providing evidence for policies and future evaluation of the quadrivalent HPV vaccine in The Gambia.