The Amazonas state in northern Brazil is an area with a high incidence rate of cervical cancer14. Most previous studies have investigated the prevalence of cervical abnormalities and HPV infections in urban populations (REF). Consequently, the knowledge regarding these conditions in women living in remote indigenous communities is still largely lacking. Here, the prevalences of epithelial cell abnormalities and HPV infections were investigated in 123 women living in 9 remote riverine communities of the Amazon basin. These communities are characterized by a low level of education with almost half the women (48%) not being able to read or write or only having finished elementary school.
A relatively high rate of cervical abnormalities was found with almost 10% of the women displaying cytological alterations (Table 2.). This rate is similar to what has previously been reported from the Brazilian state of Paraná where 10.7% of the women had cellular atypia (REF NR 22). Lower prevalences, ranging between 2.1% to 3.3%, have however been described in other areas of Brazil (Rocha et al 2013, REF NR 17 and Coser et al 2013). Moreover, cytology also showed a large percentage (81.3%) of reactive changes associated with inflammation, a prevalence that corroborates the results obtained in other studies from Amazonian communities in Brazil 7, 23. Microscopic examination showed signs of infection with Candida spp and/or bacterial vaginosis. However since the presence of other sexually transmitted diseases (STDs), also known to cause local inflammation e.g. chlamydia (ref IARC and Lehtinen et al 2011) and herpes simplex virus infections (IARC) was not investigated, other causes cannot be excluded. Other STDs e.g. Trichomonas vaginalis and Gardnerella vaginalis have also been associated with HPV and cervical lesion progression (Amorin et al), hence, future studies should include screening for additional co-infecting agents.
Differences in reported frequencies of cervical abnormalities and/or HPV infections as well as in the types of circulating viruses emphasize the importance of assessing regional as well as population heterogeneities in order to develop suitable disease prevention programs. Hence, direct detection and typing of HPV using molecular techniques is often used as a supplement to cytology for routine cervical cancer screening (Levi et al 2019). Overall HPV prevalences ranging between 14.3% and 65.2 % have previously been reported in Brazil and elsewhere in South America (Clifford et al 2005, South America, SanJose et al 2007), Rocha et al, Coser et al, Lippman et al 2010, Fonseca et al, Fernandes et al 2013). Here, 31 of the 122 (25.4%) investigated women were infected with HPV, 6 (19.4%) of them were positive for HPV 16; ere14.3% of the Rio Madeira women and 23.5% of the Rio Negro women, thus making type 16 the most commonly detected. This is similar to what had previously been reported (Fernandes et al 2013, Lippman 2010, Coser et al, REF18). In addition, HPV 31, 45 and 53 were also frequently detected while HPV 18 was less common with only two women being positive.
Using a DNA microarray, in total 22 different HPV types; 14 high-risk HPV (16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59 and 66) and 8 low-risk HPV (6, 42, 43, 44, 54, 61, 72 and 81) were differentiated; 17 types among the Rio Madeira women and 13 types among the Rio Negro women. Regional diversity in the circulating HPV types has previously been described; six HPV types were identified in Manaus, Brazil (Castro et al 2011, 14 in the city of Coari, Brazil (Rocha et al) while more than 60 were detected in the Amazonian rainforest (Fonseca et al 2015). Here, cervical intraepithelial lesions were related to HPV 43, 53 and 72 (LSIL), and HPV 39, 51 and 61 (HSIL). Furthermore, one woman with ASC-US was infected with HPV 61. Even though none of the women infected with HPV 16/18 presented with atypia, the high prevalence of HPV 16, 31 and 45 infections in the study populations highlights the importance and correspondingly the probable health gains of introducing HPV vaccination in these remote regions.
In addition to HPV, there are other risk factors predisposing to the development and progression of cervical dysplasia such as multiple sexual partners, early sexarche, HIV infection, other STDs, multiparity, smoking and taking oral contraceptives. Here, eight cases of cervical intraepithelial lesions with no HPV present were identified. Besides the above-mentioned factors contributing to the atypia the possibility that rare HPV types, not tested for here, are circulating in the region (REF Fonesca et al 2015), can however not be excluded. In addition, 27 cases of high- and low-risk HPV infection without the manifestation of cervical intraepithelial lesions were identified. These infections are likely to resolve spontaneously. Nonetheless, affected women should be continuously monitored for disease progression.
The association between social and behavioural factors and HPV prevalence was investigated. The women's age was associated with the prevalence of HPV infection (p = 0.006), with infections being more common in women aged 25 years or less and 50 years or more when compared to women aged 26 to 49 years. Similar age-dependent patterns have previously been described 29,. The higher prevalence in older women could possibly be due to reactivation of latent infections due to the gradual loss of type-specific immunity or changes in the pattern of sexual behaviour over the age 30.
In total 8,1% of the women were smokers. There are divergences in the literature regarding smoking and increased susceptibility to HPV infections; however, it has been implicated as a cofactor associated for the development of high-risk lesions (HSIL) and cervical carcinoma (REF). Furthermore, smoking appears to increase cervical and systemic susceptibility to general infections and HPV 6,24. Here, however, the relationship between smoking and the prevalence of HPV infections was not statistically significant (Table 5.). Similarly, condom use was not significantly associated with HPV prevalence. Even though the overall condom use was rather low here (13.1%), the results corroborates the literature which states that sexual contamination can only be avoided through complete sexual abstinence, since condoms do not guarantee full protection and the virus can still be transmitted via non-penetrative sex. In addition, different variables influence condom use such as age, number of sexual partners, knowledge of correct use, accessibility, partner age and the ability to negotiate condom use with partner. 25,26
Furthermore, the sexarche was not significantly associated with HPV prevalence,, thus contradicting literature which considers early sexual initiation as a factor related to a larger number of sexual partners, favouring the acquisition of STDs and early pregnancy 32. In addition, as shown previously, early onset of sexual activity and teenage pregnancy increase the risk of developing cervical cancer 33. Furthermore, the literature states that having multiple sexual partners is a risk factor for contracting HPV 35, 36. Here, the Rio Negro women had significantly more sex partners than the Rio Madeira women (average 6 vs. 1, p<0.001), there was however no significant association between the number of lifetime sexual partners and the prevalence of HPV (Table 5.). Furthermore, more single women were infected with HPV compared to married women in this study, but the difference was not significant. Previous studies have also associated high parity as a factor for cervical carcinogenesis 37, 38. Here, HPV was more prevalent in women that never have had children compared to multiparous women; the difference was however not significant and likely associated with that these women were younger.