The present study was set to determine the prevalence and determinants of CIN among women in Kisumu County, Kenya. Although continuous monitoring and reporting on prevalence of CIN is essential for estimating the risk of developing cervical cancer and optimizing screening strategy for early detections and treatment [3] this is the first study to comprehensively examine the carriage rate of CIN exclusively in HIV endemic region of western Kenya.
Findings of the study revealed that the overall prevalence of cervical intraepithelial neoplasia (CIN) was 18.4% (95/517) of which high grade CIN2 and above (CIN2+) was 7.54% (39/517) equitable to approximately 32.5 per 100,000 women per year; relatively lower than the national incidence of 40.1 per 100, 000 women per year [2],as well as neighbourhood Uganda (56.2 per 100,000 women per year) [19] and Tanzania (54.0 per 100, 000 women per year) [20]. Although previous estimate had reported higher prevalence of 27.9% severe dysplasia in the same region [21] as well as 21.4% prevalence in Nairobi County [22], our finding was within the range of 3.7% − 22.6% reported around Africa [23] and comparable to 8.2% prevalence report earlier by Mungo et al in the same region [4] suggesting the disease could be widespread locally. This finding is a reflection of high HPV prevalence of 9.1% in the general population [1] as well as 51.1% prevalence among sexually active men of Kisumu County [24] majorly attributed to HPV subtypes 16 and 18 [25]. In this study, hr-HPV subgroup 16 and 18/45 were the most prevalent and major cause of CIN in the region contributing to nearly half of all new cases detected. Higher prevalence of HPV genotype 16 have been reported earlier in the same region [5] as well as in Nairobi [22] thus affirming subtype 16 as key player in CIN prevalence locally.
Analysis of risk determinants revealed that women aged 30 years and below were less likely to test positive for CIN compared to their counterpart above 30 years. However, widows were ten times more likely to test positive compared to their married counterpart. Studies have shown that being married is associated with early diagnosis of CIN and a more favorable prognosis for cervical cancer [26] possibly owing to partner support in regular clinic visit for screening and treatment. In this study, we found age factor and widowhood significantly associated with higher Odds of developing CIN. Similar observations have been recorded by Orang’o and Pinheiro [5, 26] although early onset of CIN among teenagers have also been observed in the region, possibly attributed to changes in diet, lifestyle, obesity, environment and the microbiome all of which interact with genomic and genetic susceptibilities [27]. However, parity and hormonal contraceptive use were found not associated with CIN.
Further analysis of risk factors revealed that women co-infected with HIV were twice more likely to test positive for CIN compared to their HIV-uninfected counterparts suggesting that, co-infection with HIV is independently and significantly associated with higher Odds of developing CIN. Similar observation have been reported by Perez-Gonzalez et al and Sosso et al all noted that HPV infection was common among people living with HIV (PLWH) who were at greater risk of developing CIN [6, 28]. Indeed, PLWH have been shown to experience increased risk of persistent HPV infection including high viral load essential for CIN aetiology [29] more so when co-infection involve multiple HPV genotypes [22]. Few studies have explored the relationship between HSV-2 co-infection and the severity of cervical lesion. In our study, women co-infected with HSV-2 were twice more likely to test positive for CIN compared to their HSV-2-uninfected counterparts suggesting that co-infection with HSV-2 is significantly associated with higher Odds of developing CIN. It’s good to note that HSV-2 co-infection has been incriminated with the initiation of oncogenic processes that are eventually picked by HPV in driving cervical cancer development [30]. Our finding corroborated a systematic review and a meta-analysis by Zhang et al [31] showing that women co-infected with HSV-2 were 3 times more likely to test positive for CIN. Elsewhere, in another systematic review, higher frequency of HSV-2 was observed among women experiencing invasive cervical cancer [30] suggesting a possible association that could potentially be attributed to shared immunological compromise, genetic predisposition, or lifestyle factors. In other studies, it has been suggested that genital HSV-2 infection possibly act in conjunction with HPV infection to increase modestly the risk of cervical intraepithelial neoplasia [32] of which investigation is still in progress.
Women co-infected with Chlamydia trachomatis (CT) were three times more likely to test positive for CIN compared to their CT-uninfected counterparts suggesting that co-infection with CT is equally associated with higher Odds of developing CIN. Again, this was in concurrence with a finding by Lu et al., showing prevalence of 21.8% low grade squamous intraepithelial lesions (LSIL) and 10.8% high grade squamous intraepithelial lesions (HSIL) among women co-infected with CT / HPV [33], and consistent with another study from neighborhood Uganda recording a significant association between CT / HPV co-infection and the development of LSIL [23]. More importantly, studies have shown that co-infection with CT supports HPV persistence by suppressing the functions of Langerhans cells (LCs) pathways which are involved in the regulation of immune responses. Besides, the infection impairs LC functions by reducing the antigen-presenting ability and density of LCs; alter T-cell subsets, resulting in fewer CD4 + and CD8 + T cells and more infiltrating Tregs; decreases the CD4+/CD8 + T cell ratio to below 1; and induces greater T lymphocytes’ apoptosis, hence impairing cell-mediated immunity and accelerating the progression of CIN [33]. In Rome Italy, women co-infected with CT / HPV were found to experience high frequency of high grade cervical lesions compared to their counterparts infected with HPV only [34] suggesting the important role played by CT in cervical carcinogenesis.
It is also good to note that previous local studies have mainly focused on the relationship between cervical cytology results and sexually transmitted pathogens majorly HIV and HPV [5, 22]. Conversely, cervical cytology results do not adequately represent the true picture of the cervix. Instead, cervical biopsy provides the gold standard for assessing cervical abnormalities, highlighting the need for assessing the relationship between sexually transmitted pathogens, HPV infection, and histological findings. In our study, we found a strong association between HIV, CT and HSV-2 co-infection with hr-HPV and prevalence of CIN. This study had some limitations. First, the participants were recruited from a gynecological clinic having been referred from peripheral facilities with either vaginal or cervical abnormalities. This facility-based recruitment coupled with structural inefficiency in some rural setting that conveyed referrals limit the generalization of the study findings.