Browsing by Author "Muthoka, Kapten"

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    ‘Addressing HPV vaccine hesitancy: unveiling concerns and building trust’ perspectives of adolescent girls and parents in Kisumu County, Kenya
    (eCancer Global Foundation, 2024-08-05) Ochomo, Edwin Onyango; Tonui, Philiph; Muthoka, Kapten; Amboka, Sayo; Itsura, Peter; Orang’o, Elkanah Omenge; Rosen, Barry; Loehrer, Patrick; Cu-Uvin, Susan; Medicine, School of Medicine
    Introduction: Human papillomavirus (HPV) causes cervical cancer, and HPV vaccination is highly effective in preventing vaccine-targeted HPV infection. However, low HPV vaccination coverage in Kisumu County, Kenya, at about 10% for the first dose, highlights the critical issue of vaccine hesitancy, particularly in low and middle-income countries. Methods: This study explores the concerns, myths and barriers to HPV vaccine uptake among adolescent girls (aged 10-14) enrolled at human immune-deficiency virus comprehensive care clinics and their parents in Kisumu County. Focused group discussions were conducted with 48 participants. Results: Content analysis revealed limited knowledge about the HPV vaccine and widespread misconceptions regarding its safety and efficacy. Financial constraints, injection fears and negative clinic experiences emerged as additional barriers. Conclusion: The findings emphasise the role of effective communication strategies, including engaging parents through written materials and involving them in decision-making, to dispel myths, provide accurate information and encourage HPV vaccination. Collaborative efforts with community stakeholders are crucial to improve vaccine coverage and ultimately reduce the cervical cancer burden.
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    Association of Plasma Aflatoxin With Persistent Detection of Oncogenic Human Papillomaviruses in Cervical Samples From Kenyan Women Enrolled in a Longitudinal Study
    (BMC, 2023-06-06) Tong, Yan; Tonui, Philip; Orang’o, Omenge; Zhang, Jianjun; Maina, Titus; Muthoka, Kapten; Groopman, John; Smith, Joshua; Madeen, Erin; Ermel, Aaron; Loehrer, Patrick; Brown, Darron R.; Biostatistics, School of Public Health
    Background: Cervical cancer is caused by oncogenic human papillomaviruses (HR-HPV) and is common among Kenyan women. Identification of factors that increase HR-HPV persistence is critically important. Kenyan women exposed to aflatoxin have an increased risk of HR-HPV detection in cervical specimens. This analysis was performed to examine associations between aflatoxin and HR-HPV persistence. Methods: Kenyan women were enrolled in a prospective study. The analytical cohort for this analysis included 67 HIV-uninfected women (mean age 34 years) who completed at least two of three annual study visits and had an available blood sample. Plasma aflatoxin was detected using ultra-high pressure liquid chromatography (UHPLC)-isotope dilution mass spectrometry. Annual cervical swabs were tested for HPV (Roche Linear Array). Ordinal logistic regression models were fitted to examine associations of aflatoxin and HPV persistence. Results: Aflatoxin was detected in 59.7% of women and was associated with higher risk of persistent detection of any HPV type (OR = 3.03, 95%CI = 1.08-8.55, P = 0.036), HR-HPV types (OR = 3.63, 95%CI = 1.30-10.13, P = 0.014), and HR-HPV types not included in the 9-valent HPV vaccine (OR = 4.46, 95%CI = 1.13-17.58, P = 0.032). Conclusions: Aflatoxin detection was associated with increased risk of HR-HPV persistence in Kenyan women. Further studies, including mechanistic studies are needed to determine if aflatoxin synergistically interacts with HR-HPV to increase cervical cancer risk.
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    A community-based approach to cervical cancer prevention in western Kenya: An AMPATH feasibility project
    (Sage, 2022-05-23) Orang’o, Omenge; Tonui, Philip; Muthoka, Kapten; Kiptoo, Stephen; Maina, Titus; Agosa, Mercy; Ermel, Aaron; Tong, Yan; Brown, Darron; Medicine, School of Medicine
    Objectives: Centralized programs have been ineffective in reducing the burden of cervical cancer among Kenyan women. A community-based pilot study was initiated to screen Kenyan women for cervical cancer and to vaccinate their children against human papillomavirus (HPV). Methods: Women were educated about cervical cancer prevention at community meetings. Women then provided self-collected vaginal swabs for oncogenic HPV testing using the Roche Cobas Assay. All women were then referred to the local clinic for Visual Inspection with Acetic Acid (VIA). Women were offered the quadrivalent HPV vaccine for their children if and when it became available for the study. Results: Women in western Kenya were invited to participate in community meetings. A total of 200 women were enrolled: 151 (75.5%) were HIV-uninfected and 49 (24.5%) were HIV-infected; the median age for all women was 42 years. High-risk (HR)-HPV types were detected in 49 of swabs from all 200 participants (24.5%) including 20.5% of HIV-uninfected women and 36.7% of HIV-infected women (P = .022). VIA was performed on 198 women: 192 had normal examinations and six had abnormal examinations. Five cervical biopsies revealed two cases of CIN 2 and one CIN 3. Although all mothers were willing to have their children (N = 432) vaccinated, the HPV vaccine could not be delivered to Kenya during the study period. Conclusions: Kenyan women were willing to attend community meetings to learn about prevention of cervical cancer, to provide self-collected vaginal swabs for HPV testing, to travel to the Webuye Clinic for VIA following the collection of swabs, and to have their children vaccinated against HPV. HR-HPV was prevalent, especially in HIV-infected women. As a result of this pilot study, this community-based strategy to prevent cervical cancer will be continued in western Kenya.
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    Detection of types of HPV among HIV-infected and HIV-uninfected Kenyan women undergoing cryotherapy or loop electrosurgical excision procedure
    (Wiley, 2020-11) Orang’o, Elkanah O.; Emont, Jordan P.; Ermel, Aaron C.; Liu, Tao; Omodi, Victor; Tong, Yan; Itsura, Peter M.; Tonui, Philip K.; Maina, Titus; Ong’echa, John M.; Muthoka, Kapten; Kiptoo, Stephen; Moormann, Ann; Hogan, Joseph; Loehrer, Patrick J.; Brown, Darron; Cu-Uvin, Susan; Medicine, School of Medicine
    Objective: To assess the baseline types of HPV infection among HIV-positive and HIV-negative women in western Kenya undergoing cryotherapy or loop electrosurgical excision procedure (LEEP) for cervical intraepithelial neoplasia. Methods: A prospective observational study was conducted of baseline HPV characteristics of women undergoing visual inspection with acetic acid (VIA) and cryotherapy or LEEP. After a positive VIA in HIV-positive and HIV-negative women, data on demographics, CD4 count, and use of antiretroviral therapy and a cervical swab were collected. HPV typing was performed using the Roche Linear Array. Results: Of 175 participants, 86 (49.1%) were HIV-positive and had a higher prevalence of low-risk HPV types (odds ratio [OR] 5.28, P=0.005) compared with HIV-negative women. The most common high-risk (HR)-HPV types in HIV-positive women were HPV 16 (13.9%) and HPV 18 (11.1%). HIV-positive women requiring LEEP were more likely to have HR-HPV types (OR 6.67, P=0.012) and to be infected with multiple HR-HPV types (OR 7.79, P=0.024) compared to those undergoing cryotherapy. Conclusion: HIV-positive women requiring LEEP versus cryotherapy had a higher prevalence of any HR-HPV type and multiple HR-HPV types. There were no such differences in HPV types identified among HIV-negative women.
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    Longer duration of anti-retroviral therapy is associated with decreased risk of human papillomaviruses detection in Kenyan women living with HIV
    (Sage, 2021-11) Ermel, Aaron; Tong, Yan; Tonui, Phillip; Omenge, O’rango; Muthoka, Kapten; Wong, Nelson; Titus, Manai; Kiptoo, Stephen; Loehrer, Patrick J.; Brown, Darron R.; Medicine, School of Medicine
    Objective: A longitudinal study was conducted among women living with HIV in Kenya to determine if duration of anti-retroviral (ART) usage altered detection and persistence of oncogenic (high-risk) human papillomaviruses (HR-HPV). Methods: Women living with HIV without cervical dysplasia were enrolled at a cervical cancer screening clinic. Three cervical swabs, HIV viral loads, and CD4 cell counts were obtained at enrollment and at two annual visits. HPV genotyping was performed on swabs (Roche Linear Array). Linear regression models assessed effects of ART duration on HR-HPV detection and persistence. Results: Seventy-seven women, median age 38 years, completed three study visits and were included in the analysis. The mean time from HIV diagnosis to enrollment was 9.6 years (SD 3.9 years). The mean ART duration was 6.2 years (SD 3.1 years). Most women had undetectable HIV viral loads and CD4 cell counts above 500 cells/L. Each additional year of ART use reduced the likelihood of detection of HR-HPV by 10-15% and persistent detection of A9 HR-HPV by 20%. Conclusion: Among Kenyan women living with HIV, longer duration of ART use was associated with significantly reduced risk of all detection and persistent detection of HR-HPV.
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    Persistence of oncogenic and non-oncogenic human papillomavirus is associated with human immunodeficiency virus infection in Kenyan women
    (SAGE, 2020-07-28) Tong, Yan; Tonui, Philip; Ermel, Aaron; Orang’o, Omenge; Wong, Nelson; Titus, Maina; Kiptoo, Stephen; Muthoka, Kapten; Loehrer, Patrick J; Brown, Darron R; Medicine, School of Medicine
    Objectives: Cervical cancer is caused by persistent infection with oncogenic, or “high-risk” types of human papillomaviruses, and is the most common malignancy in Kenyan women. A longitudinal study was initiated to investigate factors associated with persistent human papillomavirus detection among HIV-infected and HIV-uninfected Kenyan women without evidence of cervical dysplasia. Methods: Demographic/behavioral data and cervical swabs were collected from HIV-uninfected women (n = 82) and HIV-infected women (n = 101) at enrollment and annually for 2 years. Human papillomavirus typing was performed on swabs (Roche Linear Array). Logistic regression models of human papillomavirus persistence were adjusted for demographic and behavioral characteristics. Results: HIV-infected women were older and less likely to be married and to own a home and had more lifetime sexual partners than HIV-uninfected women. All HIV-infected women were receiving anti-retroviral therapy at enrollment and had satisfactory CD4 cell counts and HIV viral loads. One- and two-year persistent human papillomavirus detection was significantly associated with HIV infection for any human papillomavirus, high-risk human papillomavirus, International Agency for the Research on Cancer-classified high-risk human papillomavirus, and non-oncogenic “low-risk” human papillomavirus. Conclusion: Persistent detection of oncogenic and non-oncogenic human papillomavirus was strongly associated with HIV infection in Kenyan women with re-constituted immune systems based on satisfactory CD4 cell counts. In addition to HIV infection, factors associated with an increased risk of human papillomavirus persistence included a higher number of lifetime sex partners. Factors associated with decreased risk of human papillomavirus persistence included older age and being married. Further studies are needed to identify the immunological defects in HIV-infected women that allow human papillomavirus persistence, even in women receiving effective anti-retroviral therapy. Further studies are also needed to determine the significance of low-risk human papillomavirus persistence in HIV-infected women.