Yesim Tozan
Yesim Tozan
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Associate Professor of Global and Environmental Health
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Professional overview
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Dr. Yesim Tozan’s research centers on health decision science and priority setting, and explores the costs and cost-effectiveness of health care interventions using decision analytic models and the issues of health care resource allocation in low- and middle-income countries. Her main focus has been infectious disease prevention and control with an emphasis on dengue and malaria. Dr. Tozan is currently leading a health economics work package in a European Union-funded research project on dengue surveillance and control with field sites in Sri Lanka and Thailand. She is also leading a prospective multi-center study on the cost of dengue illness in international travelers utilizing a network of travel clinics in Europe, the US, the Middle East and Australia. Most recently, she has been working on economic evaluation of artemisinin-based combination therapies for the treatment of uncomplicated childhood malaria using data from multi-site randomized clinical trials in Africa and Asia. Dr. Tozan was a task force associate for the UN Millennium Project’s Task Force on HIV/AIDS, Malaria, Tuberculosis and Access to Essential Medicines and was lead author of the malaria task force report entitled “Coming to grips with malaria in the new millennium.”
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Education
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BS, Environmental Engineering, Istanbul Technical University, TurkeyMS, Environmental Technology, Bogazici University, TurkeyMA, Public Affairs, Princeton University, Princeton, NJPhD, Public Affairs, Princeton University, Princeton, NJ
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Areas of research and study
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Cost EffectivenessCost-effective Health Programs and PoliciesEconomic EvaluationHealth EconomicsInfectious DiseasesPrevention Interventions
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Publications
Publications
Moving towards universal coverage with malaria control interventions : Achievements and challenges in rural Burkina Faso
AbstractDe Allegri, M., Louis, V. R., Tiendrébeogo, J., Souares, A., Yé, M., Tozan, Y., Jahn, A., & Mueller, O. (n.d.).Publication year
2013Journal title
International Journal of Health Planning and ManagementVolume
28Issue
1Page(s)
102-121AbstractThis paper reports on a study, which assessed coverage with malaria control interventions in rural Burkina Faso, namely insecticide-treated mosquito nets (ITN) ownership, intermittent preventive treatment (IPTp) for pregnant women and artemisinin-based combination therapy (ACT) for under-five children. The study also addressed the distributional impact of such interventions, with specific reference to equity. The study used data from a representative household survey conducted on 1106 households in the Nouna Health District in 2010. Findings indicated that 59% of all households owned at least one ITN, 66% of all pregnant women received IPT at least once and 34% of under-five children reporting a malaria case were treated with ACT. Multivariate logistic regression revealed that higher socio-economic status, ownership of at least one radio and living in a village within a Health and Demographic Surveillance System were significantly positively associated with ITN, IPTp and ACT coverage. ITN coverage was higher among households in villages, which had previously hosted an ITN trial and/or the most favourable arm of a trial. Comparing current findings with previous estimates suggests that the country has made substantial progress towards scaling up malaria control interventions but that current coverage rates are still far from achieving the universal coverage targets set by the Roll Back Malaria Partnership. In addition, current coverage patterns reveal the existence of multiple inequities across groups, suggesting that current policies are inadequate to achieve equitable scaling up. Future planning of malaria control interventions ought to take into consideration current inadequacies and lead to programmes better designed to overcome them.Novel tools for the surveillance and control of dengue : findings by the dengueTools research consortium
AbstractWilder-Smith, A., Tissera, H., AbuBakar, S., Kittayapong, P., Logan, J., Neumayr, A., Rocklöv, J., Byass, P., Louis, V. R., Tozan, Y., Massad, E., & Preet, R. (n.d.).Publication year
2018Journal title
Global Health ActionVolume
11Issue
1AbstractBackground: Dengue fever persists as a major global disease burden, and may increase as a consequence of climate change. Along with other measures, research actions to improve diagnosis, surveillance, prevention, and predictive models are highly relevant. The European Commission funded the DengueTools consortium to lead a major initiative in these areas, and this review synthesises the outputs and findings of this work conducted from 2011 to 2016. Research areas: DengueTools organised its work into three research areas, namely [1] Early warning and surveillance systems; [2] Strategies to prevent dengue in children; and [3] Predictive models for the global spread of dengue. Research area 1 focused on case-studies undertaken in Sri Lanka, including developing laboratory-based sentinel surveillance, evaluating economic impact, identifying drivers of transmission intensity, evaluating outbreak prediction capacity and developing diagnostic capacity. Research area 2 addressed preventing dengue transmission in school children, with case-studies undertaken in Thailand. Insecticide-treated school uniforms represented an intriguing potential approach, with some encouraging results, but which were overshadowed by a lack of persistence of insecticide on the uniforms with repeated washing. Research area 3 evaluated potential global spread of dengue, particularly into dengue-naïve areas such as Europe. The role of international travel, changing boundaries of vectors, developing models of vectorial capacity under different climate change scenarios and strategies for vector control in outbreaks was all evaluated. Concluding remarks: DengueTools was able to make significant advances in methods for understanding and controlling dengue transmission in a range of settings. These will have implications for public health agendas to counteract dengue, including vaccination programmes. Outlook: Towards the end of the DengueTools project, Zika virus emerged as an unexpected epidemic in the central and southern America. Given the similarities between the dengue and Zika viruses, with vectors in common, some of the DengueTools thinking translated readily into the Zika situation.Opportunities and challenges for innovative and equitable healthcare
AbstractTozan, Y., Ecker, D. J., Aiello, C. D., Arron, J. R., Bennett, C. F., Bernard, A., Breakefield, X. O., Broderick, T. J., Callier, S. L., Canton, B., Chen, J. S., Fishburn, C. S., Garrett, B., Hecht, S. M., Janowitz, T., Kliegman, M., Krainer, A., Louis, C. U., Lowe, C., … Hayden, M. R. (n.d.).Publication year
2024Journal title
Nature reviews. Drug discoveryAbstract~Opportunities and challenges for innovative and equitable healthcare
AbstractEcker, D. J., Aiello, C. D., Arron, J. R., Bennett, C. F., Bernard, A., Breakefield, X. O., Broderick, T. J., Callier, S. L., Canton, B., Chen, J. S., Fishburn, C. S., Garrett, B., Hecht, S. M., Janowitz, T., Kliegman, M., Krainer, A., Louis, C. U., Lowe, C., Sehgal, A., … Hayden, M. R. (n.d.).Publication year
2024Journal title
Nature Reviews Drug DiscoveryVolume
23Issue
5Page(s)
321-322AbstractAn unprecedented number of potentially disruptive therapeutic technologies are under development. Forward-looking policies, incentives and infrastructure are needed to harness these advances to provide effective and globally equitable healthcare.Pre-referral rectal artesunate treatment of childhood malaria in the community: Training manual and for community health workers to assess danger signs, provide emergency pre-referral treatment and refer treated children to a health facility
AbstractTozan, Y., & Gomez, M. (n.d.).Publication year
2012Abstract~Predicting the dengue cluster outbreak dynamics in Yogyakarta, Indonesia : a modelling study
AbstractRamadona, A. L., Tozan, Y., Wallin, J., Lazuardi, L., Utarini, A., & Rocklöv, J. (n.d.).Publication year
2023Journal title
The Lancet Regional Health - Southeast AsiaAbstractBackground: Human mobility and climate conditions are recognised key drivers of dengue transmission, but their combined and individual role in the local spatiotemporal clustering of dengue cases is not well understood. This study investigated the effects of human mobility and weather conditions on dengue risk in an urban area in Yogyakarta, Indonesia. Methods: We established a Bayesian spatiotemporal model for neighbourhood outbreak prediction and evaluated the performances of two different approaches for constructing an adjacency matrix: one based on geographical proximity and the other based on human mobility patterns. We used population, weather conditions, and past dengue cases as predictors using a flexible distributed lag approach. The human mobility data were estimated based on proxies from social media. Unseen data from February 2017 to January 2020 were used to estimate the one-month ahead prediction accuracy of the model. Findings: When human mobility proxies were included in the spatial covariance structure, the model fit improved in terms of the log score (from 1.748 to 1.561) and the mean absolute error (from 0.676 to 0.522) based on the validation data. Additionally, showed only few observations outside the credible interval of predictions (1.48%) and weather conditions were not found to contribute additionally to the clustering of cases at this scale. Interpretation: The study shows that it is possible to make highly accurate predictions of the within-city cluster dynamics of dengue using mobility proxies from social media combined with disease surveillance data. These insights are important for proactive and timely outbreak management of dengue. Funding: Swedish Research Council Formas, Umeå Centre for Global Health Research, Swedish Council for Working Life and Social Research, Swedish research council VINNOVA and Alexander von Humboldt Foundation (Germany).Predictors of Depressive Symptoms and Post Traumatic Stress Disorder Among Women Engaged in Commercial Sex Work in Southern Uganda
AbstractNabunya, P., Byansi, W., Damulira, C., Bahar, O. S., Jennings Mayo-Wilson, L., Tozan, Y., Kiyingi, J., Nabayinda, J., Braithwaite, R., Witte, S. S., & Ssewamala, F. M. (n.d.).Publication year
2021Journal title
Psychiatry ResearchVolume
298AbstractThis study examined the factors associated with depressive symptoms and post traumatic depressive disorder (PTSD) among economically vulnerable women engaged in commercial sex work (WESW) in southern Uganda. Baseline data from a longitudinal cluster randomized study involving 542 self-identified WESW (18-55 years), recruited from 19 HIV hotspots were analyzed. Hierarchical linear regression modelling was utilized to estimate individual, family-level and economic-level predictors of depressive symptoms and PTSD. Family cohesion, sex work stigma, HIV status, financial distress, household assets, number of children and number of household income earners, were associated with PTSD. Similarly, family cohesion, number of people in the household, HIV status, sex work stigma, financial distress, and household assets, were associated with depressive symptoms. Women engaged in commercial sex work are at a higher risk of HIV and poor mental health outcomes. Sex work stigma and financial distress elevate levels of depressive symptoms and PTSD, over and above an individual's HIV status. Family and economic-level factors have the potential to mitigate the risk of poor mental health outcomes. As such, integrating stigma reduction and economic strengthening components in the programming targeting WESW—a key population, may be critical to address their mental health outcomes.PrEP acceptability and initiation among women engaged in sex work in Uganda : Implications for HIV prevention
AbstractWitte, S. S., Filippone, P., Ssewamala, F. M., Nabunya, P., Bahar, O. S., Mayo-Wilson, L. J., Namuwonge, F., Damulira, C., Tozan, Y., Kiyingi, J., Nabayinda, J., Mwebembezi, A., Kagaayi, J., & McKay, M. (n.d.).Publication year
2022Journal title
EClinicalMedicineVolume
44AbstractBackground: Women engaged in sex work (WESW) are disproportionately affected by HIV. In Uganda, HIV prevalence among WESW is estimated at 37%, accounting for 18% of all new infections in the country. WESW experience poverty, gender-based violence, and other issues that reduce their power and limit their ability to negotiate condom use. Female-controlled strategies, including pre-exposure prophylaxis (PrEP), may afford women more transmission protection, but barriers to access and use persist. This cross-sectional study examined baseline PrEP acceptability and initiation among WESW recently enrolled in a randomized clinical trial in Uganda to test the impact of a combination HIV risk reduction and economic empowerment intervention on sexual risk outcomes (clinicaltrials.gov, NCT03583541). Methods: A total of 542 WESW from 19 high HIV-prevalent geographical areas were enrolled in the Kyaterekera study between June 2019 and March 2020. Women were eligible for the study if they: (1) were age 18 or over; (2) reported engagement in transactional sex (a sex act in exchange for pay) in the past 30 days; and (3) reported engagement in one or more episodes of unprotected sex in the past 30 days. Women completed a baseline assessment, were tested for HIV and other sexually transmitted infections (STIs) at enrollment, and were connected with antiretroviral therapy (ART), STI treatment, or PrEP, based on need and interest. Descriptive statistics examined baseline data on PrEP acceptability and initiation. Independent variables (i.e. years in sex work, recent sexual coercion, perceived HIV and sex work stigmas, harmful alcohol use, barriers to medical care, and social support) were derived from the empirical literature and women's self-report. Bivariate analysis was performed to test associations between main effects of these variables. Using binomial logistic regression, predictive models were evaluated for two distinct outcomes—PrEP acceptability and PrEP initiation/uptake. Findings: At baseline, 59% of women (n = 322) tested HIV negative. Among WESW testing negative, 11% (n = 36) were already PrEP enrolled. Most women reported willingness to use PrEP (n = 317; 91%). Slightly over half of WESW not already on PrEP agreed to initiate PrEP (n = 158; 55%). Logistic regression models demonstrate that acceptability of or willingness to use PrEP was significantly associated with fewer years engaged in sex work (AOR= ·18, 95% CI 0·05-·66, pPrereferral rectal artesunate for treatment of severe childhood malaria : A cost-effectiveness analysis
AbstractTozan, Y., Tozan, Y., Klein, E. Y., Darley, S., Panicker, R., Laxminarayan, R., & Breman, J. G. (n.d.).Publication year
2010Journal title
The LancetVolume
376Issue
9756Page(s)
1910-1915AbstractSeverely ill patients with malaria with vomiting, prostration, and altered consciousness cannot be treated orally and need injections. In rural areas, access to health facilities that provide parenteral antimalarial treatment is poor. Safe and effective treatment of most severe malaria cases is delayed or not achieved. Rectal artesunate interrupts disease progression by rapidly reducing parasite density, but should be followed by further antimalarial treatment. We estimated the cost-effectiveness of community-based prereferral artesunate treatment of children suspected to have severe malaria in areas with poor access to formal health care. We assessed the cost-effectiveness (in international dollars) of the intervention from the provider perspective. We studied a cohort of 1000 newborn babies until 5 years of age. The analysis assessed how the cost-effectiveness results changed with low (25), moderate (50), high (75), and full (100) referral compliance and intervention uptake. At low intervention uptake and referral compliance (25), the intervention was estimated to avert 19 disability-adjusted life-years (DALYs; 95 CI 16-21) and to cost I$1173 (95 CI 1050-1297) per DALY averted. Under the full uptake and compliance scenario (100), the intervention could avert 967 DALYs (884-1050) at a cost of I$77 (73-81) per DALY averted. Prereferral artesunate treatment is a cost-effective, life-saving intervention, which can substantially improve the management of severe childhood malaria in rural African settings in which programmes for community health workers are in place. The Disease Control Priorities Project; Fogarty International Center; US National Institutes of Health; and the Peter Paul Career Development Professorship, Boston University.Prereferral rectal artesunate for treatment of severe childhood malaria: a cost-effectiveness analysis
AbstractKlein, E. Y., Darley, S., Panicker, R., Laxminarayan, R., Breman, J. G., & Tozan, Y. (n.d.).Publication year
2010Journal title
The LancetVolume
376Issue
9756Page(s)
1910-1915Abstract~Prevalence and predictors of HIV and sexually transmitted infections among vulnerable women engaged in sex work : Findings from the Kyaterekera Project in Southern Uganda
AbstractKiyingi, J., Nabunya, P., Bahar, O. S., Mayo-Wilson, L. J., Tozan, Y., Nabayinda, J., Namuwonge, F., Nsubuga, E., Kizito, S., Nattabi, J., Nakabuye, F., Kagayi, J., Mwebembezi, A., Witte, S. S., & Ssewamala, F. M. (n.d.).Publication year
2022Journal title
PloS oneVolume
17Issue
9 SeptemberAbstractIntroduction Women engaged in sex work (WESW) have an elevated risk of the human immunodeficiency virus (HIV) and sexually transmitted infections (STI). Estimates are three times higher than the general population. Understanding the predictors of HIV and STI among WESW is crucial in developing more focused HIV and STI prevention interventions among this population. The study examined the prevalence and predictors of HIV and STI among WESW in the Southern part of Uganda. Methodology Baseline data from the Kyaterekera study involving 542 WESW (ages 18–55) recruited from 19 HIV hotspots in the greater Masaka region in Uganda was utilized. HIV and STI prevalence was estimated using blood and vaginal fluid samples bioassay. Hierarchical regression models were used to determine the predictors of HIV and STI among WESW. Results Of the total sample, 41% (n = 220) were found to be HIV positive; and 10.5% (n = 57) tested positive for at least one of the three STI (Neisseria gonorrhoeae, Chlamydia trachomatis and Trichomonas vaginalis) regardless of their HIV status. Older age (b = 0.09, 95%CI = 0.06, 0.13, p≤0.001), lower levels of education (b = -0.79, 95%CI = -1.46, -0.11, p≤0.05), fewer numbers of children in the household (b = -0.18, 95%CI = -0.36, -0.01), p≤0.05), location (i.e., fishing village (b = 0.51, 95%CI = 0.16, 0.85, p≤0.01) or small town (b = -0.60, 95% CI = -0.92, -0.28, p≤0.001)), drug use (b = 0.58, 95%CI = 0.076, 1.08, p≤0.05) and financial self-efficacy (b = 0.05, 95%CI = -0.10, 0.00, p≤0.05), were associated with the risk of HIV infections among WESW. Domestic violence attitudes (b = -0.24, 95%CI = -0.42, -0.07, p≤0.01) and financial distress (b = -0.07, 95%CI = -0.14, -0.004, p≤0.05) were associated with the risk of STI infection among WESW. Conclusion Study findings show a high prevalence of HIV among WESW compared to the general women population. Individual and family level, behavioural and economic factors were associated with increased HIV and STI infection among WESW. Therefore, there is a need for WESW focused HIV and STI risk reduction and economic empowerment interventions to reduce these burdens.Prevalence and predictors of HIV and sexually transmitted infections among vulnerable women engaged in sex work : Findings from the Kyaterekera Project in Southern Uganda
AbstractKiyingi, J., Nabunya, P., Bahar, O. S., Mayo-Wilson, L. J., Tozan, Y., Nabayinda, J., Namuwonge, F., Nsubuga, E., Kizito, S., Nattabi, J., Nakabuye, F., Kagayi, J., Mwebembezi, A., Witte, S. S., & Ssewamala, F. M. (n.d.).Publication year
2022Journal title
PloS oneVolume
17Issue
9 SeptemberAbstractIntroduction Women engaged in sex work (WESW) have an elevated risk of the human immunodeficiency virus (HIV) and sexually transmitted infections (STI). Estimates are three times higher than the general population. Understanding the predictors of HIV and STI among WESW is crucial in developing more focused HIV and STI prevention interventions among this population. The study examined the prevalence and predictors of HIV and STI among WESW in the Southern part of Uganda. Methodology Baseline data from the Kyaterekera study involving 542 WESW (ages 18–55) recruited from 19 HIV hotspots in the greater Masaka region in Uganda was utilized. HIV and STI prevalence was estimated using blood and vaginal fluid samples bioassay. Hierarchical regression models were used to determine the predictors of HIV and STI among WESW. Results Of the total sample, 41% (n = 220) were found to be HIV positive; and 10.5% (n = 57) tested positive for at least one of the three STI (Neisseria gonorrhoeae, Chlamydia trachomatis and Trichomonas vaginalis) regardless of their HIV status. Older age (b = 0.09, 95%CI = 0.06, 0.13, p≤0.001), lower levels of education (b = -0.79, 95%CI = -1.46, -0.11, p≤0.05), fewer numbers of children in the household (b = -0.18, 95%CI = -0.36, -0.01), p≤0.05), location (i.e., fishing village (b = 0.51, 95%CI = 0.16, 0.85, p≤0.01) or small town (b = -0.60, 95% CI = -0.92, -0.28, p≤0.001)), drug use (b = 0.58, 95%CI = 0.076, 1.08, p≤0.05) and financial self-efficacy (b = 0.05, 95%CI = -0.10, 0.00, p≤0.05), were associated with the risk of HIV infections among WESW. Domestic violence attitudes (b = -0.24, 95%CI = -0.42, -0.07, p≤0.01) and financial distress (b = -0.07, 95%CI = -0.14, -0.004, p≤0.05) were associated with the risk of STI infection among WESW. Conclusion Study findings show a high prevalence of HIV among WESW compared to the general women population. Individual and family level, behavioural and economic factors were associated with increased HIV and STI infection among WESW. Therefore, there is a need for WESW focused HIV and STI risk reduction and economic empowerment interventions to reduce these burdens.Private Payer-Negotiated Rates for FDA-Approved Head and Neck Cancer Immunotherapy and Chemotherapy Agents
AbstractTozan, Y., Talwar, A., Kim, S., Yu, S., Samant, S., Tozan, Y., & Givi, B. (n.d.).Publication year
2023Journal title
Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck SurgeryVolume
169Issue
4Page(s)
954-961AbstractTo quantify the price that private payers pay hospitals for head and neck squamous cell carcinoma (HNSCC) treatments and identify hospital-level factors associated with price variation.Private Payer-Negotiated Rates for FDA-Approved Head and Neck Cancer Immunotherapy and Chemotherapy Agents
AbstractTalwar, A., Kim, S., Yu, S., Samant, S., Tozan, Y., & Givi, B. (n.d.).Publication year
2023Journal title
Otolaryngology - Head and Neck SurgeryAbstractObjective: To quantify the price that private payers pay hospitals for head and neck squamous cell carcinoma (HNSCC) treatments and identify hospital-level factors associated with price variation. Study Design: Cross-sectional study. Setting: Price transparency files. Methods: Files from the top 50 hospitals in otolaryngology according to the US News and World Report were analyzed between December 2021 and June 2022. This study analyzed the following Food and Drug Administration-approved HNSCC therapies: pembrolizumab, nivolumab, cetuximab, cisplatin, carboplatin, and paclitaxel. Results: Twenty-four (48%) hospitals reported prices for at least 1 medication in our sample. Newer biologics were significantly more expensive than traditional chemotherapeutic agents. Given approved medication regimens, all biologics in our sample have similar annual costs. Price markups over acquisition costs ranged between 109% (pembrolizumab, nivolumab) and 530% for carboplatin. Across hospitals, prices varied the most for paclitaxel, the cheapest medication in our sample, and prices varied the least for pembrolizumab the most expensive medication in our sample. Hospital 340B status and geographic location in the northeast/west are associated with lower price markups. Conclusion: Price nondisclosure remains a significant problem among hospitals. Newer biological medications are more expensive when compared to traditional chemotherapeutic agents. Prices vary significantly across hospitals, with lower price markups observed in 340B hospitals as well as hospitals located in the geographic northeast and west. It remains to be seen if price transparency will lead to more uniform pricing or lower costs of treatments.Quantifying the lagged effects of climate variables on malaria risk in Eastern Uganda: A case study in Iganga-Mayuge population cohort (an HDSS)
AbstractTozan, Y. (n.d.).Publication year
2025Journal title
Am J Trop Med HygAbstract~Regional and socioeconomic predictors of perceived ability to access coronavirus testing in the United States : results from a nationwide online COVID-19 survey
AbstractAli, S. H., Tozan, Y., Jones, A. M., Foreman, J., Capasso, A., & DiClemente, R. J. (n.d.).Publication year
2021Journal title
Annals of EpidemiologyVolume
58Page(s)
7-14AbstractPurpose: Access to COVID-19 testing remained a salient issue during the early months of the pandemic, therefore this study aimed to identify 1) regional and 2) socioeconomic predictors of perceived ability to access Coronavirus testing. Methods: An online survey using social media-based advertising was conducted among U.S. adults in April 2020. Participants were asked whether they thought they could acquire a COVID-19 test, along with basic demographic, socioeconomic and geographic information. Results: A total of 6,378 participants provided data on perceived access to COVID-19 testing. In adjusted analyses, we found higher income and possession of health insurance to be associated with perceived ability to access Coronavirus testing. Geographically, perceived access was highest (68%) in East South Central division and lowest (39%) in West North Central. Disparities in health insurance coverage did not directly correspond to disparities in perceived access to COVID-19 testing. Conclusions: Sex, geographic location, income, and insurance status were associated with perceived access to COVID-19 testing; interventions aimed at improving either access or awareness of measures taken to improve access are warranted. These findings from the pandemic's early months shed light on the importance of disaggregating perceived and true access to screening during such crises.Reviewing Dengue : Still a Neglected Tropical Disease?
AbstractHorstick, O., Tozan, Y., & Wilder-Smith, A. (n.d.).Publication year
2015Journal title
PLoS neglected tropical diseasesVolume
9Issue
4AbstractDengue is currently listed as a “neglected tropical disease” (NTD). But is dengue still an NTD or not? Classifying dengue as an NTD may carry advantages, but is it justified? This review considers the criteria for the definition of an NTD, the current diverse lists of NTDs by different stakeholders, and the commonalities and differences of dengue with other NTDs. We also review the current research gaps and research activities and the adequacy of funding for dengue research and development (R&D) (2003–2013). NTD definitions have been developed to a higher precision since the early 2000s, with the following main features: NTDs are characterised as a) poverty related, b) endemic to the tropics and subtropics, c) lacking public health attention, d) having poor research funding and shortcomings in R&D, e) usually associated with high morbidity but low mortality, and f) often having no specific treatment available. Dengue meets most of these criteria, but not all. Although dengue predominantly affects resource-limited countries, it does not necessarily only target the poor and marginalised in those countries. Dengue increasingly attracts public health attention, and in some affected countries it is now a high profile disease. Research funding for dengue has increased exponentially in the past two decades, in particular in the area of dengue vaccine development. However, despite advances in dengue research, dengue epidemics are increasing in frequency and magnitude, and dengue is expanding to new areas. Specific treatment and a highly effective vaccine remain elusive. Major research gaps exist in the area of integrated surveillance and vector control. Hence, although dengue differs from many of the NTDs, it still meets important criteria commonly used for NTDs. The current need for increased R&D spending, shared by dengue and other NTDs, is perhaps the key reason why dengue should continue to be considered an NTD.Reviewing estimates of the basic reproduction number for dengue, Zika and chikungunya across global climate zones
AbstractLiu, Y., Lillepold, K., Semenza, J. C., Tozan, Y., Quam, M. B., & Rocklöv, J. (n.d.).Publication year
2020Journal title
Environmental ResearchVolume
182AbstractBackground: Globally, dengue, Zika virus, and chikungunya are important viral mosquito-borne diseases that infect millions of people annually. Their geographic range includes not only tropical areas but also sub-tropical and temperate zones such as Japan and Italy. The relative severity of these arboviral disease outbreaks can vary depending on the setting. In this study we explore variation in the epidemiologic potential of outbreaks amongst these climatic zones and arboviruses in order to elucidate potential reasons behind such differences. Methodology: We reviewed the peer-reviewed literature (PubMed) to obtain basic reproduction number (R0) estimates for dengue, Zika virus, and chikungunya from tropical, sub-tropical and temperate regions. We also computed R0 estimates for temperate and sub-tropical climate zones, based on the outbreak curves in the initial outbreak phase. Lastly we compared these estimates across climate zones, defined by latitude. Results: Of 2115 studies, we reviewed the full text of 128 studies and included 65 studies in our analysis. Our results suggest that the R0 of an arboviral outbreak depends on climate zone, with lower R0 estimates, on average, in temperate zones (R0 = 2.03) compared to tropical (R0 = 3.44) and sub-tropical zones (R0 = 10.29). The variation in R0 was considerable, ranging from 0.16 to 65. The largest R0 was for dengue (65) and was estimated by the Ross-Macdonald model in the tropical zone, whereas the smallest R0 (0.16) was for Zika virus and was estimated statistically from an outbreak curve in the sub-tropical zone. Conclusions: The results indicate climate zone to be an important determinant of the basic reproduction number, R0, for dengue, Zika virus, and chikungunya. The role of other factors as determinants of R0, such as methods, environmental and social conditions, and disease control, should be further investigated. The results suggest that R0 may increase in temperate regions in response to global warming, and highlight the increasing need for strengthening preparedness and control activities.RTS, S/AS01 malaria vaccine and child mortality
AbstractMüller, O., Tozan, Y., & Becher, H. (n.d.).Publication year
2015Journal title
The LancetVolume
386Issue
10005Page(s)
1736Abstract~Self-Reported Adherence to Antiretroviral Therapy (ART) Among Women Engaged in Commercial Sex Work in Southern Uganda
AbstractKiyingi, J., Nabunya, P., Kizito, S., Nabayinda, J., Nsubuga, E., Bahar, O. S., Jennings Mayo-Wilson, L., Namuwonge, F., Nattabi, J., Magorokosho, N., Tozan, Y., Witte, S. S., & Ssewamala, F. M. (n.d.).Publication year
2022Journal title
AIDS and BehaviorAbstractWe examined the correlates of self-reported adherence to antiretroviral therapy (ART) among women engaged in commercial sex work (WESW) in Uganda. We used baseline data from a longitudinal study, which recruited 542 WESW in Southern Uganda. We used nested regression models to determine the individual and family, and economic level correlates of self-reported adherence. Study findings show that older age (OR = 1.07, 95% CI = 1.013, 1.139), secondary education (OR = 2.01, 95% CI = 1.306, 3.084), large household size (OR = 1.08, 95% CI = 1.020, 1.136), high family cohesion (OR = 1.06, 95% CI = 1.052, 1.065), and high financial self-efficacy (OR = 1.07, 95% CI = 1.006, 1.130) were associated with good self-reported adherence to ART. Married women (OR=-0.39, 95% CI = 0.197, 0.774), depression (OR = 0.85, 95% CI = 0.744, 0.969), alcohol use (OR = 0.72, 95% CI = 0.548, 0.954), ever been arrested (OR = 0.58, 95% CI = 0.341, 0.997), and high household assets ownership (OR = 0.48, 95% CI = 0.313, 0.724) were associated with poor self-reported adherence to ART. Findings suggest a need to adopt a multi-level approach to address gaps in ART adherence among WESW.Severe dengue epidemic, Sri Lanka, 2017
AbstractTissera, H. A., Jayamanne, B. D., Raut, R., Janaki, S. M., Tozan, Y., Samaraweera, P. C., Liyanage, P., Ghouse, A., Rodrigo, C., de Silva, A. M., & Fernando, S. D. (n.d.).Publication year
2020Journal title
Emerging Infectious DiseasesVolume
26Issue
4Page(s)
682-691AbstractIn 2017, a dengue epidemic of unexpected magnitude occurred in Sri Lanka. A total of 186,101 suspected cases and 440 dengue-related deaths occurred. We conducted a comprehensive analysis of this epidemic by comparing national surveillance data for 2017 with data from the preceding 5 years. In all Sri Lanka districts, dengue incidence in 2017 increased significantly over incidence during the previous 5 years. Older schoolchildren and young adults were more clinically symptomatic than those at extremes of age. Limited virologic surveillance showed the dominant circulating variant was dengue virus type 2 cosmopolitan genotype in the most affected district. One quarter of total annual cases were reported 5 weeks after the southwest monsoon started. Changes in vector abundance were not predictive of the increased incidence. Direct government expenditures on dengue control activities in 2017 were US $12.7 million. The lessons learned from this outbreak are useful for other tropical nations facing increasing dengue incidence.Social and Psychological Mediators of Sexual and Physical Male-Perpetrated Intimate Partner Violence Against Young African American Women : The Role of Alcohol Use and Drinking Context
AbstractCapasso, A., Pahl, K., Tozan, Y., & DiClemente, R. J. (n.d.).Publication year
2025Journal title
Journal of Interpersonal ViolenceAbstractProblem alcohol use is prevalent among women who experience male-perpetrated intimate partner violence (IPV). However, the pathways by which this occurs remain poorly understood and understudied among African American women. This study sought to examine context-specific social and psychological mediators of this association. Using structural equation modeling (SEM), we tested a conceptual framework predicting problem alcohol use within 3 months of experiencing physical and/or sexual IPV. The sample included 508 young African American women (median age 21, interquartile range 19–22 years). A modified SEM met prespecified global and local fit index criteria. The model identified four indirect paths from IPV to problem alcohol use. Three of the paths were through the endorsement of drinking contexts: negative coping, social drinking, and intimate drinking. Negative coping and social drinking emerged as the most salient pathways (β =.431, 95% CI [0.107, 0.754]; β =.472 [0.103, 0.841], respectively). A fourth path operated via depressive symptomatology and negative coping. The model predictors explained 35% of the variance in problem alcohol use; findings were consistent with full mediation of IPV and problem drinking. These findings increase the understanding of problem alcohol use among African American women who experience IPV and identify modifiable context-specific risk factors for problem alcohol use. Interventions to reduce problem drinking could incorporate trauma-informed counseling, as part of integrated IPV and substance use care, to reduce depressive symptomatology and enhance drinking refusal skills in response to situational drinking.Social and psychological mediators of sexual and physical male-perpetrated intimate partner violence against young African American women and problem alcohol use: the role of intimate and social drinking context
AbstractTozan, Y. (n.d.).Publication year
2025Journal title
J Interpers ViolenceAbstract~Social determinants approaches to public health : from concept to practice
AbstractTozan, Y. (n.d.).Publication year
2011Abstract~Social media as a recruitment platform for a nationwide online survey of COVID-19 knowledge, beliefs, and practices in the United States : Methodology and feasibility analysis
AbstractAli, S. H., Foreman, J., Capasso, A., Jones, A. M., Tozan, Y., & Diclemente, R. J. (n.d.).Publication year
2020Journal title
BMC Medical Research MethodologyVolume
20Issue
1AbstractBACKGROUND: The COVID-19 pandemic has evolved into one of the most impactful health crises in modern history, compelling researchers to explore innovative ways to efficiently collect public health data in a timely manner. Social media platforms have been explored as a research recruitment tool in other settings; however, their feasibility for collecting representative survey data during infectious disease epidemics remain unexplored.OBJECTIVES: This study has two aims 1) describe the methodology used to recruit a nationwide sample of adults residing in the United States (U.S.) to participate in a survey on COVID-19 knowledge, beliefs, and practices, and 2) outline the preliminary findings related to recruitment, challenges using social media as a recruitment platform, and strategies used to address these challenges.METHODS: An original web-based survey informed by evidence from past literature and validated scales was developed. A Facebook advertisement campaign was used to disseminate the link to an online Qualtrics survey between March 20-30, 2020. Two supplementary male-only and racial minority- targeted advertisements were created on the sixth and tenth day of recruitment, respectively, to address issues of disproportionate female- and White-oriented gender- and ethnic-skewing observed in the advertisement's reach and response trends.RESULTS: In total, 6602 participant responses were recorded with representation from all U.S. 50 states, the District of Columbia, and Puerto Rico. The advertisements cumulatively reached 236,017 individuals and resulted in 9609 clicks (4.07% reach). Total cost of the advertisement was $906, resulting in costs of $0.09 per click and $0.18 per full response (completed surveys). Implementation of the male-only advertisement improved the cumulative percentage of male respondents from approximately 20 to 40%.CONCLUSIONS: The social media advertisement campaign was an effective and efficient strategy to collect large scale, nationwide data on COVID-19 within a short time period. Although the proportion of men who completed the survey was lower than those who didn't, interventions to increase male responses and enhance representativeness were successful. These findings can inform future research on the use of social media recruitment for the rapid collection of survey data related to rapidly evolving health crises, such as COVID-19.