This study found that hr-HPV genotypes not included in the currently licensed HPV vaccines are highly prevalent in HIV-positive women from Tanzania and South Africa. As expected, among women with hr-HPV the prevalence of hr-HPV 16 was high (26%).
Despite the high rate of abnormal cytology among women in Tanzania, hr-HPV 18 was uncommon in women with abnormal cytology (4%). In contrast, hr-HPV 18 was significantly more common among South African women with abnormal cytology (21%). We also found significant regional differences in the prevalence of hr-HPV 35; the prevalence of hr-HPV 35 was 8% among Tanzanian women compared to 24% for South African women. In rural Mozambique, Castellsagué et al. also found a high prevalence of hr-HPV 35 (17% among HPV-positive women, and 30% among women with cervical neoplasia [10
]), compared to an hr-HPV 35 prevalence of 5% found by Sanjose in other African women with cervical neoplasia (Algeria, Mozambique, Nigeria, and Uganda) [2
The hr-HPV 52 prevalence found in this study (35% of Tanzanian women and 17% of South African women with any HPV) is vastly different from that in women in The Netherlands (5.5%) [11
]. A study in Pretoria, South Africa reported an hr-HPV 52 prevalence of 6% among women with cervical preneoplasia [12
]. In the general female population in Macao, and northern Taiwan, hr-HPV 52 was the most common genotype found, while in East Asia it was among the top five detected [13
The prevalence of hr-HPV 45 was low in our cohort (), as also found by others in women with preneoplastic lesions [2
]. However, hr-HPV 45 is the third most common HPV type in invasive cervical cancer worldwide. The early presentation of cases of invasive cervical cancer that are positive for hr-HPV 45 might be related to a short time for progression to invasive cancer, with or without transition through the preneoplastic stages, possible correlated to a high early integration rate [2
The strengths of our study include using a standardized HPV type-specific PCR protocol and cytology diagnosis across the two sites. There were differences between the women studied that may have contributed to the different prevalence estimates of hr-HPV types. Tanzanian women were all using ART. In contrast, the women in South Africa were recently diagnosed with HIV and not yet eligible for ART. In HIV positive women there is less HPV clearance due to a lack of an appropriate immune response. The impact of ART in HPV infection and cervical cancer still needs to be defined [16
]. A limitation of this study is that no additional information from the South African women is known about their sexual behavior, and therefore we were unable to explore associations between behaviors and HPV genotype. Roteli-Martins et al. found that young age at first sexual intercourse and increasing number of sexual partners is the main determinant for hr-HPV 16/18 infections [17
For an HPV vaccine to effectively reduce incidence of cervical cancer, it will need to protect against the major hr-HPV infection types progressing to cervical cancer. Because infection types may vary across settings and ethnicities, the impact a vaccine has in preventing cancer in particular settings needs to be considered. In this study, hr-HPV16 was found in 29% of women diagnosed with HSIL; however, hr-HPV 18 was only found in 11%.
Certainly the high prevalence of hr-HPV found here and reported by others, [18
] emphasizes the importance of screening for cervical cancer especially in developing countries with high rates of HIV. Because more than one-third (42%) of women with normal cytology in this study tested positive for an hr-HPV type, as also found by Bruni and others [19
], HPV-based screening tests in this population would be highly inefficient unless coupled with cytology screening of the HPV positive sample.
In summary, the present study showed some differences in the prevalence of HPV genotypes among HIV-positive women in two African countries, and an overall high HPV prevalence. The differences found in hr-HPV genotypes warrant the need to consider different monitoring programmes for cervical preneoplasia, especially in HIV-positive women.