Browsing by Author "Ronoh, Marilyn"

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    Evidence-based modeling of combination control on Kenyan youth HIV/AIDS dynamics
    (plos one, 2020-11-17) Ronoh, Marilyn; Chirove, Faraimunashe; WairimuI, Josephine; Ogana, Wandera
    We formulate a sex-structured deterministic model to study the effects of varying HIV testing rates, condom use rates and ART adherence rates among Adolescent Girls and Young Women (AGYW) and, Adolescent Boys and Young Men (ABYM) populations in Kenya. Attitudes influencing the Kenyan youth HIV/AIDS control measures both positively and negatively were considered. Using the 2012 Kenya AIDS Indicator Survey (KAIS) microdata we constructed our model, which we fitted to the UNAIDS-Kenya youth prevalence estimates to understand factors influencing Kenyan youth HIV/AIDS prevalence trends. While highly efficacious combination control approach significantly reduces HIV/AIDS prevalence rates among the youth, the disease remains endemic provided infected unaware sexual interactions persist. Disproportional gender-wise attitudes towards HIV/AIDS control measures play a key role in reducing the Kenyan youth HIV/AIDS prevalence trends. The female youth HIV/AIDS prevalence trend seems to be directly linked to increased male infectivity with decreased female infectivity while the male youth prevalence trend seems to be directly associated with increased female infectivity and reduced male infectivity.
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    A Mathematical Model of Contact Tracing during the 2014–2016 West African Ebola Outbreak
    (MDPI, 2021-03-12) Ronoh, Marilyn; Burton, Danielle; Lenhart, Suzanne; Edholm, Christina J.; Levy, Benjamin; Washington, Michael L.; Greening, Bradford R. Jr; White, K. A. Jane; Lungu, Edward; Chimbola, Obias; Kgosimore, Moatlhodi; Chirove, Faraimunashe; Machingauta, M. Helen
    The 2014–2016 West African outbreak of Ebola Virus Disease (EVD) was the largest and most deadly to date. Contact tracing, following up those who may have been infected through contact with an infected individual to prevent secondary spread, plays a vital role in controlling such outbreaks. Our aim in this work was to mechanistically represent the contact tracing process to illustrate potential areas of improvement in managing contact tracing efforts. We also explored the role contact tracing played in eventually ending the outbreak. We present a system of ordinary differential equations to model contact tracing in Sierra Leonne during the outbreak. Using data on cumulative cases and deaths, we estimate most of the parameters in our model. We include the novel features of counting the total number of people being traced and tying this directly to the number of tracers doing this work. Our work highlights the importance of incorporating changing behavior into one’s model as needed when indicated by the data and reported trends. Our results show that a larger contact tracing program would have reduced the death toll of the outbreak. Counting the total number of people being traced and including changes in behavior in our model led to better understanding of disease management.
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    MODELING DISPROPORTIONAL EFFECTS OF EDUCATING INFECTED KENYAN YOUTH ON HIV/AIDS
    (journal of biological systems, 2020) Ronoh, Marilyn; OGANA, WANDERA; Chirove, Faraimunashe; Wairimu, Josephine
    We formulate an age and sex-structured deterministic model to assess the effect of increasing comprehensive knowledge of HIV/AIDS disease in the infected Adolescent Girls and Young Women (AGYW) and, Adolescent Boys and Young Men (ABYM) populations in Kenya. Mathematical analysis of infection through sub-network analysis was carried out to trace various infection routes and the veracity of various transmission routes as well as the associated probabilities. Using HIV data in Kenya on our model, disproportional effects were observed when dispensation of comprehensive knowledge of HIV/AIDS was preferred in one population over the other. Effective dispensation of comprehensive knowledge of HIV/AIDS in both the infected AGYW and ABYM populations significantly slows down the infection spread but may not eradicate it.
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    Modeling the Effect of HIV/AIDS Stigma on HIV Infection Dynamics in Kenya
    (springer, 2021-03-15) Ronoh, Marilyn; Chirove, Faraimunashe; Correia, Hannah E.; Levy, Ben; Abebe, Ash; Kgosimore, Moatlhodi; Chimbola, Obias; Machingauta, M. Hellen
    Stigma toward people living with HIV/AIDS (PLWHA) has impeded the response to the disease across the world. Widespread stigma leads to poor adherence of preventative measures while also causing PLWHA to avoid testing and care, delaying important treatment. Stigma is clearly a hugely complex construct. However, it can be broken down into components which include internalized stigma (how people with the trait feel about themselves) and enacted stigma (how a community reacts to an individual with the trait). Levels of HIV/AIDS-related stigma are particularly high in sub-Saharan Africa, which contributed to a surge in cases in Kenya during the late twentieth century. Since the early twenty-first century, the United Nations and governments around the world have worked to eliminate stigma from society and resulting public health education campaigns have improved the perception of PLWHA over time, but HIV/AIDS remains a significant problem, particularly in Kenya. We take a data-driven approach to create a time-dependent stigma function that captures both the level of internalized and enacted stigma in the population. We embed this within a compartmental model for HIV dynamics. Since 2000, the population in Kenya has been growing almost exponentially and so we rescale our model system to create a coupled system for HIV prevalence and fraction of individuals that are infected that seek treatment. This allows us to estimate model parameters from published data. We use the model to explore a range of scenarios in which either internalized or enacted stigma levels vary from those predicted by the data. This analysis allows us to understand the potential impact of different public health interventions on key HIV metrics such as prevalence and disease-related death and to see how close Kenya will get to achieving UN goals for these HIV and stigma metrics by 2030.
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    Modeling the effects of insecticides resistance on malaria vector control in endemic regions of Kenya
    (Elsevier Ltd., 2018-12) Wairimu, Josephine; Ronoh, Marilyn; Malonza, David M; Chirove, Faraimunashe;
    We present a model to investigate the effects of vector resistance to control strategies. The model captures the development of resistance as well as loss of resistance in mosquitoes and how these affect the progress in malaria control. Important thresholds were calculated from mathematical analysis and numerical results presented. Mathematical results reveal the existence of the disease free and endemic equilibria whose existence and stability depends on the control reproduction number, Rc. The disease persist when the Rc>1 and dies out when Rc<1. Control strategies use and adherence needs to be highly efficacious to thwart the effects of insecticides resistance. Moreover, it is not enough to just eradicate resistant mosquitoes.
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    Staff Profile: Dr. Marilyn Ronoh
    (2023) Ronoh, Marilyn
    Dr. Marilyn C. Ronoh is a Lecturer and Researcher of Applied Mathematics and Infectious Disease Modelling. She is currently teaching at the University of Embu, Kenya on a full-time basis. She has a BSc. degree in Mathematics, MSc. in Applied Mathematics and PhD in Applied Mathematics (Mathematical Modelling). She is also an alumni of the Organization for Women in Science for the Developing World (OWSD) PhD Fellowship and Mawazo PhD Scholars programme. She has supported the implementation of the Mawazo Learning Exchange (MLEx) programme and the MLEx mentorship programme. Her recent research centered on constructing mathematical models to understand the transmission dynamics of HIV/AIDS among the adolescents and young people in Kenya. She has authored and co-authored published manuscripts in emerging infectious diseases. Currently, she is involved in multidisciplinary and international collaborations, particularly modelling the effectiveness of COVID-19 containment strategies in Kenya and, modelling the social drivers of HIV/AIDS disease. She is also part of the Mathematics in Southern Africa (MASAMU) Advanced Institute Program whose aim is to promote international research collaboration. Outside research, she is a member of the Kenya Women in Mathematics Association (KWIMSA), Organization for Women in Science for the Developing World (OWSD), African Women in Mathematics Association (AWMA) and Southern Africa Mathematical Sciences Association (SAMSA). Dr. Ronoh is passionate about quality education and mentoring children, adolescents and young adults and, showing them the positive side of mathematics.