Assistant Professor of Global Health
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.”
BS, Environmental Engineering, Istanbul Technical University, TurkeyMS, Environmental Technology, Bogazici University, TurkeyMA, Public Affairs, Princeton University, Princeton, NJPhD, Public Affairs, Princeton University, Princeton, NJ
Cost EffectivenessCost-effective Health Programs and PoliciesEconomic EvaluationHealth EconomicsInfectious DiseasesPrevention Interventions
Increased alcohol use during the COVID-19 pandemic: The effect of mental health and age in a cross-sectional sample of social media users in the U.S.
Regional and socioeconomic predictors of perceived ability to access coronavirus testing in the United States: results from a nationwide online COVID-19 survey
Reviewing estimates of the basic reproduction number for dengue, Zika and chikungunya across global climate zonesLiu, Y., Lillepold, K., Semenza, J. C., Tozan, Y., Quam, M. B., & Rocklöv, J.
Journal titleEnvironmental Research
Volume182AbstractBackground: 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.
Severe dengue epidemic, Sri Lanka, 2017Tissera, 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.
Journal titleEmerging Infectious Diseases
Page(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 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
The Mosquito, the Virus, the Climate: An Unforeseen Réunion in 2018DiSera, L., Sjödin, H., Rocklöv, J., Tozan, Y., Súdre, B., Zeller, H., & Muñoz, Ángel G.
Issue8AbstractThe 2018 outbreak of dengue in the French overseas department of Réunion was unprecedented in size and spread across the island. This research focuses on the cause of the outbreak, asserting that climate played a large role in the proliferation of the Aedes albopictus mosquitoes, which transmitted the disease, and led to the dengue outbreak in early 2018. A stage-structured model was run using observed temperature and rainfall data to simulate the life cycle and abundance of the Ae. albopictus mosquito. Further, the model was forced with bias-corrected subseasonal forecasts to determine if the event could have been forecast up to 4 weeks in advance. With unseasonably warm temperatures remaining above 25°C, along with large tropical-cyclone-related rainfall events accumulating 10–15 mm per event, the modeled Ae. albopictus mosquito abundance did not decrease during the second half of 2017, contrary to the normal behavior, likely contributing to the large dengue outbreak in early 2018. Although subseasonal forecasts of rainfall for the December–January period in Réunion are skillful up to 4 weeks in advance, the outbreak could only have been forecast 2 weeks in advance, which along with seasonal forecast information could have provided enough time to enhance preparedness measures. Our research demonstrates the potential of using state-of-the-art subseasonal climate forecasts to produce actionable subseasonal dengue predictions. To the best of the authors' knowledge, this is the first time subseasonal forecasts have been used this way.
Transmission dynamics of dengue and chikungunya in a changing climate: do we understand the eco-evolutionary response?Tozan, Y., Sjödin, H., Muñoz, Ángel G., & Rocklöv, J.
Journal titleExpert Review of Anti-Infective Therapy
Page(s)1187-1193AbstractIntroduction: We are witnessing an alarming increase in the burden and range of mosquito-borne arboviral diseases. The transmission dynamics of arboviral diseases is highly sensitive to climate and weather and is further affected by non-climatic factors such as human mobility, urbanization, and disease control. As evidence also suggests, climate-driven changes in species interactions may trigger evolutionary responses in both vectors and pathogens with important consequences for disease transmission patterns. Areas covered: Focusing on dengue and chikungunya, we review the current knowledge and challenges in our understanding of disease risk in a rapidly changing climate. We identify the most critical research gaps that limit the predictive skill of arbovirus risk models and the development of early warning systems, and conclude by highlighting the potentially important research directions to stimulate progress in this field. Expert opinion: Future studies that aim to predict the risk of arboviral diseases need to consider the interactions between climate modes at different timescales, the effects of the many non-climatic drivers, as well as the potential for climate-driven adaptation and evolution in vectors and pathogens. An important outcome of such studies would be an enhanced ability to promulgate early warning information, initiate adequate response, and enhance preparedness capacity.
Trends and predictors of COVID-19 information sources and their relationship with knowledge and beliefs related to the pandemic: Nationwide cross-sectional studyAli, S. H., Foreman, J., Tozan, Y., Capasso, A., Jones, A. M., & DiClemente, R. J.
Journal titleJMIR Public Health and Surveillance
Issue4AbstractBackground: During the COVID-19 pandemic, there is a heightened need to understand health information seeking behaviors to address disparities in knowledge and beliefs about the crisis. Objective: This study assessed sociodemographic predictors of the use and trust of different COVID-19 information sources, as well as the association between information sources and knowledge and beliefs about the pandemic. Methods: An online survey was conducted among US adults in two rounds during March and April 2020 using advertisement-based recruitment on social media. Participants were asked about their use of 11 different COVID-19 information sources as well as their most trusted source of information. The selection of COVID-related knowledge and belief questions was based on past empirical literature and salient concerns at the time of survey implementation. Results: The sample consisted of 11,242 participants. When combined, traditional media sources (television, radio, podcasts, or newspapers) were the largest sources of COVID-19 information (91.2%). Among those using mainstream media sources for COVID-19 information (n=7811, 69.5%), popular outlets included CNN (24.0%), Fox News (19.3%), and other local or national networks (35.2%). The largest individual information source was government websites (87.6%). They were also the most trusted source of information (43.3%), although the odds of trusting government websites were lower among males (adjusted odds ratio [AOR] 0.58, 95% CI 0.53-0.63) and those aged 40-59 years and ≥60 years compared to those aged 18-39 years (AOR 0.83, 95% CI 0.74-0.92; AOR 0.62, 95% CI 0.54-0.71). Participants used an average of 6.1 sources (SD 2.3). Participants who were male, aged 40-59 years or ≥60 years; not working, unemployed, or retired; or Republican were likely to use fewer sources while those with children and higher educational attainment were likely to use more sources. Participants surveyed in April were markedly less likely to use (AOR 0.41, 95% CI 0.35-0.46) and trust (AOR 0.51, 95% CI 0.47-0.56) government sources. The association between information source and COVID-19 knowledge was mixed, while many COVID-19 beliefs were significantly predicted by information source; similar trends were observed with reliance on different types of mainstream media outlets. Conclusions: COVID-19 information source was significantly determined by participant sociodemographic characteristics and was also associated with both knowledge and beliefs about the pandemic. Study findings can help inform COVID-19 health communication campaigns and highlight the impact of using a variety of different and trusted information sources.
A combination intervention addressing sexual risk-taking behaviors among vulnerable women in Uganda: Study protocol for a cluster randomized clinical trialSsewamala, F. M., Sensoy Bahar, O., Tozan, Y., Nabunya, P., Mayo-Wilson, L. J., Kiyingi, J., Kagaayi, J., Bellamy, S., McKay, M. M., & Witte, S. S.
Journal titleBMC Women's Health
Issue1AbstractBackground: Sub-Saharan Africa (SSA) has the highest number of people living with HIV/AIDS, with Nigeria, South Africa, and Uganda accounting for 48% of new infections. A systematic review of the HIV burden among women engaged in sex work (WESW) in 50 low- and middle-income countries found that they had increased odds of HIV infection relative to the general female population. Social structural factors, such as the sex work environment, violence, stigma, cultural issues, and criminalization of sex work are critical in shaping sexually transmitted infection (STI)/HIV risks among WESW and their clients in Uganda. Poverty is the most commonly cited reason for involvement in sex work in SSA. Against this backdrop, this study protocol describes a randomized controlled trial (RCT) that tests the impact of adding economic empowerment to traditional HIV risk reduction (HIVRR) to reduce new incidence of STIs and HIV among WESW in Rakai and the greater Masaka regions in Uganda. Methods: This three-arm RCT will evaluate the efficacy of adding savings, financial literacy and vocational training/mentorship to traditional HIVRR on reducing new incidence of STI infections among 990 WESW across 33 hotspots. The three arms (n = 330 each) are: 1) Control group: only HIVRR versus 2) Treatment group 1: HIVRR plus Savings plus Financial Literacy (HIVRR + S + FL); and 3) Treatment group 2: HIVRR plus S plus FL plus Vocational Skills Training and Mentorship (V) (HIVRR + S + FL + V). Data will be collected at baseline (pre-test), 6, 12, 18 and 24-months post-intervention initiation. This study will use an embedded experimental mixed methods design where qualitative data will be collected post-intervention across all conditions to explore participant experiences. Discussion: When WESW have access to more capital and/or alternative forms of employment and start earning formal income outside of sex work, they may be better able to improve their skills and employability for professional advancement, thereby reducing their STI/HIV risk. The study findings may advance our understanding of how best to implement gender-specific HIV prevention globally, engaging women across the HIV treatment cascade. Further, results will provide evidence for the intervention's efficacy to reduce STIs and inform implementation sustainability, including costs and cost-effectiveness. Trial registration: ClinicalTrials.gov, ID: NCT03583541.
A combination of incidence data and mobility proxies from social media predicts the intraurban spread of dengue in Yogyakarta, IndonesiaRamadona, A. L., Tozan, Y., Lazuardi, L., & Rocklöv, J.
Journal titlePLoS neglected tropical diseases
Issue4AbstractOnly a few studies have investigated the potential of using geotagged social media data for predicting the patterns of spatio-temporal spread of vector-borne diseases. We herein demonstrated the role of human mobility in the intra-urban spread of dengue by weighting local incidence data with geo-tagged Twitter data as a proxy for human mobility across 45 neighborhoods in Yogyakarta city, Indonesia. To estimate the dengue virus importation pressure in each study neighborhood monthly, we developed an algorithm to estimate a dynamic mobility- weighted incidence index (MI), which quantifies the level of exposure to virus importation in any given neighborhood. Using a Bayesian spatio-temporal regression model, we estimated the coefficients and predictiveness of the MI index for lags up to 6 months. Specifically, we used a Poisson regression model with an unstructured spatial covariance matrix. We compared the predictability of the MI index to that of the dengue incidence rate over the preceding months in the same neighborhood (autocorrelation) and that of the mobility information alone. We based our estimates on a volume of 1.302.405 geotagged tweets (from 118.114 unique users) and monthly dengue incidence data for the 45 study neighborhoods in Yogyakarta city over the period from August 2016 to June 2018. The MI index, as a standalone variable, had the highest explanatory power for predicting dengue transmission risk in the study neighborhoods, with the greatest predictive ability at a 3-months lead time. The MI index was a better predictor of the dengue risk in a neighborhood than the recent transmission patterns in the same neighborhood, or just the mobility patterns between neighborhoods. Our results suggest that human mobility is an important driver of the spread of dengue within cities when combined with information on local circulation of the dengue virus. The geotagged Twitter data can provide important information on human mobility patterns to improve our understanding of the direction and the risk of spread of diseases, such as dengue. The proposed MI index together with traditional data sources can provide useful information for the development of more accurate and efficient early warning and response systems.
A prospective study on the impact and out-of-pocket costs of dengue illness in international travelersTozan, Y., Headley, T. Y., Odhiambo Sewe, M., Schwartz, E., Shemesh, T., Cramer, J. P., Eberhardt, K. A., Ramharter, M., Harrison, N., Leder, K., Angheben, A., Hatz, C., Neumayr, A., Chen, L. H., De Pijper, C. A., Grobusch, M. P., & Wilder-Smith, A.
Journal titleAmerican Journal of Tropical Medicine and Hygiene
Page(s)1525-1533AbstractAlthough the costs of dengue illness to patients and households have been extensively studied in endemic populations, international travelers have not been the focus of costing studies. As globalization and humantravel activities intensify, travelers are increasingly at risk for emerging and reemerging infectious diseases, such as dengue. This exploratory study aims to investigate the impact and out-of-pocket costs of dengue illness among travelers. We conducted a prospective study in adult travelers with laboratory-confirmed dengue and recruited patients at travel medicine clinics in eight different countries from December 2013 to December 2015. Using a structured questionnaire, we collected information on patients and their health-care utilization and out-of-pocket expenditures, as well as income and other financial losses they incurred because of dengue illness. A total of 90 patients participated in the study, most of whom traveled for tourism (74%) and visited countries in Asia (82%). Although 22% reported hospitalization and 32% receiving ambulatory care while traveling, these percentages were higher at 39% and 71%, respectively, after returning home. The out-of-pocket direct and indirect costs of dengue illness were US$421 (SD 744) and US$571 (SD 1,913) per episode, respectively, averaging to a total out-of-pocket cost of US$992 (SD 2,052) per episode. The study findings suggest that international travelers incur important direct and indirect costs because of dengue-related illness. This study is the first to date to investigate the impact and out-of-pocket costs of travel-related dengue illness from the patient's perspective and paves the way for future economic burden studies in this population.
Climate change and the rising infectiousness of dengueRocklöv, J., & Tozan, Y.
Journal titleEmerging Topics in Life Sciences
Page(s)133-142AbstractThe disease burden of dengue has been steadily rising over the last half-century due to a multitude of factors, including global trade and travel, urbanization, population growth, and climate variability and change, that facilitate conductive conditions for the proliferation of dengue vectors and viruses. This review describes how climate, specifically temperature, affects the vectors' ability to cause and sustain outbreaks, and how the infectiousness of dengue is influenced by climatic change. The review is focused on the core concepts and frameworks derived in the area of epidemiology of mosquito-borne diseases and outlines the sensitivity of vectorial capacity and vector-to-human transmission on climatic conditions. It further reviews studies linking mathematical or statistical models of disease transmission to scenarios of projected climate change and provides recommendations for future research directions.
Evaluation of a savings-led family-based economic empowerment intervention for AIDS-affected adolescents in Uganda: A fouryear follow-up on efficacy and costeffectivenessTozan, Y., Sun, S., Capasso, A., Wang, J. S. H., Neilands, T. B., Bahar, O. S., Damulira, C., & Ssewamala, F. M.
Journal titlePloS one
Issue12AbstractBackground Children who have lost a parent to HIV/AIDS, known as AIDS orphans, face multiple stressors affecting their health and development. Family economic empowerment (FEE) interventions have the potential to improve these outcomes and mitigate the risks they face. We present efficacy and cost-effectiveness analyses of the Bridges study, a savings-led FEE intervention among AIDS-orphaned adolescents in Uganda at four-year follow-up. Methods Intent-to-treat analyses using multilevel models compared the effects of two savings-led treatment arms: Bridges (1:1 matched incentive) and BridgesPLUS (2:1 matched incentive) to a usual care control group on the following outcomes: self-rated health, sexual health, and mental health functioning. Total per-participant costs for each arm were calculated using the treatment-on-the-treated sample. Intervention effects and per-participant costs were used to calculate incremental cost-effectiveness ratios (ICERs). Findings Among 1,383 participants, 55% were female, 20% were double orphans. Mean age was 12 years at baseline. At 48-months, BridgesPLUS significantly improved self-rated health, (0.25, 95% CI 0.06, 0.43), HIV knowledge (0.21, 95% CI 0.01, 0.41), self-concept (0.26, 95% CI 0.09, 0.44), and self-efficacy (0.26, 95% CI 0.09, 0.43) and lowered hopelessness (-0.28, 95% CI -0.43, -0.12); whereas Bridges improved self-rated health (0.26, 95% CI 0.08, 0.43) and HIV knowledge (0.22, 95% CI 0.05, 0.39). ICERs ranged from $224 for hopelessness to $298 for HIV knowledge per 0.2 standard deviation change. Conclusions Most intervention effects were sustained in both treatment arms at two years post-intervention. Higher matching incentives yielded a significant and lasting effect on a greater number of outcomes among adolescents compared to lower matching incentives at a similar incremental cost per unit effect. These findings contribute to the evidence supporting the incorporation of FEE interventions within national social protection frameworks.
Evaluation of intensified dengue control measures with interrupted time series analysis in the Panadura Medical Officer of Health division in Sri Lanka: a case study and cost-effectiveness analysisLiyanage, P., Rocklöv, J., Tissera, H., Palihawadana, P., Wilder-Smith, A., & Tozan, Y.
Journal titleThe Lancet Planetary Health
Page(s)e211-e218AbstractBackground: Dengue has become a major public health problem in Sri Lanka with a considerable economic burden. As a response, in June, 2014, the Ministry of Health initiated a proactive vector control programme in partnership with military and police forces, known as the Civil-Military Cooperation (CIMIC)programme, that was targeted at high-risk Medical Officer of Health (MOH)divisions in the country. Evaluating the effectiveness and cost-effectiveness of population-level interventions is essential to guide public health planning and resource allocation decisions, particularly in resource-limited health-care settings. Methods: Using an interrupted time series design with a non-linear extension, we evaluated the impact of vector control interventions from June 22, 2014, to Dec 29, 2016, in Panadura, a high-risk MOH division in Western Province, Sri Lanka. We used dengue notification and larval survey data to estimate the reduction in Breteau index and dengue incidence before and after the intervention using two separate models, adjusting for time-varying confounding variables (ie, rainfall, temperature, and the Oceanic Niño Index). We also assessed the cost and cost-effectiveness of the CIMIC programme from the perspective of the National Dengue Control Unit under the scenarios of different levels of hospitalisation of dengue cases (low [25%], medium [50%], and high [75%])in terms of cost per disability-adjusted life-year averted (DALY). Findings: Vector control interventions had a significant impact on combined Breteau index (relative risk reduction 0·43, 95% CI 0·26 to 0·70)and on dengue incidence (0·43, 0·28 to 0·67), the latter becoming prominent 2 months after the intervention onset. The mean number of averted dengue cases was estimated at 2192 (95% CI 1741 to 2643), and the total cost of the CIMIC programme at 2016 US$271 615. Personnel costs accounted for about 89% of the total cost. In the base-case scenario of moderate level of hospitalisation, the CIMIC programme was cost-saving with a probability of 70% under both the lowest ($453)and highest ($1686)cost-effectiveness thresholds, resulting in a net saving of $20 247 (95% CI −57 266 to 97 790)and averting 176 DALYs (133 to 226), leading to a cost of −$98 (−497 to 395)per DALY averted. This was also the case for the scenario with high hospitalisation levels (cost per DALY averted −$512, 95% CI −872 to −115)but with a higher probability of 99%. In the scenario with low hospitalisation levels (cost per DALY averted $690, 143 to 1379), although the CIMIC programme was cost-ineffective at the lowest threshold with a probability of 77%, it was cost-effective at the highest threshold with a probability of 99%. Interpretation: This study suggests that communities affected by dengue can benefit from investments in vector control if interventions are implemented rigorously and coordinated well across sectors. By doing so, it is possible to reduce the disease and economic burden of dengue in endemic settings. Funding: None.
Incidence of Guillain-BarréSyndrome (GBS) in Latin America and the Caribbean before and during the 2015-2016 Zika virus epidemic: A systematic review and meta-analysisCapasso, A., Ompad, D. C., Vieira, D. L., Wilder-Smith, A., & Tozan, Y.
Journal titlePLoS neglected tropical diseases
Issue8AbstractBackground A severe neurological disorder, Guillain-Barrésyndrome (GBS) is the leading cause of acute flaccid paralysis. Enhanced surveillance of GBS in Latin America and the Caribbean (LAC) following the 2015-2016 Zika virus (ZIKV) epidemic presents an opportunity to estimate, for the first time, the regional incidence of GBS. Methods and findings For this systematic review and meta-analysis, we searched nine scientific databases and grey literature from January 1, 1980 to October 1, 2018. Sources with primary data on incident GBS cases in LAC within a well-defined population and timeframe, published in English, Spanish, Portuguese, or French, were included. We calculated the annual GBS incidence rates (IRs) and 95% confidence intervals (CIs) for each source based on published data. Following an assessment of heterogeneity, we used random-effects meta-analysis to calculate the pooled annual IR of GBS. The study is registered with PROSPERO, number CRD42018086659. Of the 6568 initial citation hits, 31 were eligible for inclusion. Background annual GBS IRs in Latin America ranged from 0.40 in Brazil to 2.12/100,000 in Chile. The pooled annual IR in the Caribbean was 1.64 (95% CI 1.29-2.12, I2<0.01, p = 0.44). During the ZIKV epidemic, GBS IRs ranged from 0.62 in Mexico to 9.35/100,000 in Martinique. GBS increased 2.6 (95% CI 2.3-2.9) times during ZIKV and 1.9 (95% CI 1.1- 3.4) times during chikungunya outbreaks over background rates. A limitation of this review is that the studies included employed different methodologies to find and ascertain cases of GBS, which could contribute to IR heterogeneity. In addition, it is important to consider that data on GBS are lacking for many countries in the region. Conclusions Background IRs of GBS appear to peak during arboviral disease outbreaks. The current review contributes to an understanding of the epidemiology of GBS in the LAC region, which can inform healthcare system planning and preparedness, particularly during arboviral epidemics.
Using big data to monitor the introduction and spread of Chikungunya, Europe, 2017Rocklöv, J., Tozan, Y., Ramadona, A., Sewe, M. O., Sudre, B., Garrido, J., De Saint Lary, C. B., Lohr, W., & Semenza, J. C.
Journal titleEmerging Infectious Diseases
Page(s)1041-1049AbstractWith regard to fully harvesting the potential of big data, public health lags behind other fields. To determine this potential, we applied big data (air passenger volume from international areas with active chikungunya transmission, Twitter data, and vectorial capacity estimates of Aedes albopictus mosquitoes) to the 2017 chikungunya outbreaks in Europe to assess the risks for virus transmission, virus importation, and short-range dispersion from the outbreak foci. We found that indicators based on voluminous and velocious data can help identify virus dispersion from outbreak foci and that vector abundance and vectorial capacity estimates can provide information on local climate suitability for mosquitoborne outbreaks. In contrast, more established indicators based on Wikipedia and Google Trends search strings were less timely. We found that a combination of novel and disparate datasets can be used in real time to prevent and control emerging and reemerging infectious diseases.
Economic burden of caregiving for persons with severe mental illness in sub-Saharan Africa: A systematic reviewAddo, R., Agyemang, S. A., Tozan, Y., & Nonvignon, J.
Journal titlePloS one
Issue8AbstractBackground Over the past two decades, the focus of mental health care has shifted from institutionalisation to community-based programs and short hospital stays. This change means that there is an increased role for caregivers, mostly family members, in managing persons with mental illness. Although there is evidence to support the benefits of deinstitutionalisation of mental health care, there are also indications of substantial burden experienced by caregivers; the evidence of which is limited in sub-Saharan Africa. However, knowledge of the nature and extent of this burden can inform the planning of mental health services that will not only benefit patients, but also caregivers and households. Objective To systematically review the available evidence on the economic burden of severe mental illness on primary family caregivers in sub-Saharan Africa. Methods A comprehensive search was conducted in Pubmed, CINAHL, Econlit and Web of Science with no date limitations up to September 2016 using keywords such as "burden", "cost of illness" and "economic burden" to identify relevant published literature. Articles were appraised using a standardised data extraction tool covering themes such as physical, psychological and socioeconomic burden. Results Seven papers were included in the review. Caregivers were mostly family members with a mean age of 46.34, female and unemployed. Five out of seven studies (71%) estimated the full economic burden of severe mental illness on caregivers. The remainder of studies just described the caregiver burden. All seven papers reported moderate to severe caregiver burden characterised by financial constraint, productivity loss and lost employment. The caregiver’s level of income and employment status, severity of patient’s condition and duration of mental illness were reported to negatively affect the economic burden experienced by caregivers. Conclusion There is paucity of studies reporting the burden of severe mental illness on caregivers in sub-Saharan Africa. Further research is needed to present the nature and extent of this burden to inform service planning and policymaking.
Novel tools for the surveillance and control of dengue: findings by the dengueTools research consortiumWilder-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.
Journal titleGlobal Health Action
Issue1AbstractBackground: 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  Early warning and surveillance systems;  Strategies to prevent dengue in children; and  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.
Economic cost and quality of life of family caregivers of schizophrenic patients attending psychiatric hospitals in GhanaOpoku-Boateng, Y. N., Kretchy, I. A., Aryeetey, G. C., Dwomoh, D., Decker, S., Agyemang, S. A., Tozan, Y., Aikins, M., & Nonvignon, J.
Journal titleBMC health services research
Volume17AbstractBackground: Low and middle income countries face many challenges in meeting their populations' mental health care needs. Though family caregiving is crucial to the management of severe mental health disabilities, such as schizophrenia, the economic costs borne by family caregivers often go unnoticed. In this study, we estimated the household economic costs of schizophrenia and quality of life of family caregivers in Ghana. Methods: We used a cost of illness analysis approach. Quality of life (QoL) was assessed using the abridged WHO Quality of Life (WHOQOL-BREF) tool. Cross-sectional data were collected from 442 caregivers of patients diagnosed with schizophrenia at least six months prior to the study and who received consultation in any of the three psychiatric hospitals in Ghana. Economic costs were categorized as direct costs (including medical and non-medical costs of seeking care), indirect costs (productivity losses to caregivers) and intangible costs (non-monetary costs such as stigma and pain). Direct costs included costs of medical supplies, consultations, and travel. Indirect costs were estimated as value of productive time lost (in hours) to primary caregivers. Intangible costs were assessed using the Zarit Burden Interview (ZBI). We employed multiple regression models to assess the covariates of costs, caregiver burden, and QoL. Results: Total monthly cost to caregivers was US$ 273.28, on average. Key drivers of direct costs were medications (50%) and transportation (27%). Direct costs per caregiver represented 31% of the reported monthly earnings. Mean caregiver burden (measured by the ZBI) was 16.95 on a scale of 0-48, with 49% of caregivers reporting high burden. Mean QoL of caregivers was 28.2 (range: 19.6-34.8) out of 100. Better educated caregivers reported lower indirect costs and better QoL. Caregivers with higher severity of depression, anxiety and stress reported higher caregiver burden and lower QoL. Males reported better QoL. Conclusions: These findings highlight the high household burden of caregiving for people living with schizophrenia in low income settings. Results underscore the need for policies and programs to support caregivers.
Household costs of hospitalized dengue illness in semi-rural ThailandTozan, Y., Ratanawong, P., Sewe, M. O., Wilder-Smith, A., & Kittayapong, P.
Journal titlePLoS neglected tropical diseases
Issue9AbstractBackground: Dengue-related illness is a leading cause of hospitalization and death in Thailand and other Southeast Asian countries, imposing a major economic burden on households, health systems, and governments. This study aims to assess the economic impact of hospitalized dengue cases on households in Chachoengsao province in eastern Thailand. Methods: We conducted a prospective cost-of-illness study of hospitalized pediatric and adult dengue patients at three public hospitals. We examined all hospitalized dengue cases regardless of disease severity. Patients or their legal guardians were interviewed using a standard questionnaire to determine household-level medical and non-medical expenditures and income losses during the illness episode. Results: Between March and September 2015, we recruited a total of 224 hospitalized patients (<5 years, 4%; 5–14 years, 20%, 15–24 years, 36%, 25–34 years, 15%; 35–44 years, 10%; 45+ years, 12%), who were clinically diagnosed with dengue. The total cost of a hospitalized dengue case was higher for adult patients than pediatric patients, and was US$153.6 and US$166.3 for pediatric DF and DHF patients, respectively, and US$171.2 and US$226.1 for adult DF and DHF patients, respectively. The financial burden on households increased with the severity of dengue illness. Conclusions: Although 74% of the households reported that the patient received free medical care, hospitalized dengue illness cost approximately 19–23% of the monthly household income. These results indicated that dengue imposed a substantial financial burden on households in Thailand where a great majority of the population was covered by the Universal Coverage Scheme for health care.
Mitigating Diseases Transmitted by Aedes Mosquitoes: A Cluster-Randomised Trial of Permethrin-Impregnated School UniformsKittayapong, P., Olanratmanee, P., Maskhao, P., Byass, P., Logan, J., Tozan, Y., Louis, V., Gubler, D. J., & Wilder-Smith, A.
Journal titlePLoS neglected tropical diseases
Issue1AbstractBackground: Viral diseases transmitted via Aedes mosquitoes are on the rise, such as Zika, dengue, and chikungunya. Novel tools to mitigate Aedes mosquitoes-transmitted diseases are urgently needed. We tested whether commercially insecticide-impregnated school uniforms can reduce dengue incidence in school children. Methods: We designed a cluster-randomised controlled trial in Thailand. The primary endpoint was laboratory-confirmed dengue infections. Secondary endpoints were school absenteeism; and impregnated uniforms’ 1-hour knock-down and 24 hour mosquito mortality as measured by standardised WHOPES bioassay cone tests at baseline and after repeated washing. Furthermore, entomological assessments inside classrooms and in outside areas of schools were conducted. Results: We enrolled 1,811 pupils aged 6–17 from 5 intervention and 5 control schools. Paired serum samples were obtained from 1,655 pupils. In the control schools, 24/641 (3.7%) and in the intervention schools 33/1,014 (3.3%) students had evidence of new dengue infections during one school term (5 months). There was no significant difference in proportions of students having incident dengue infections between the intervention and control schools, with adjustment for clustering by school. WHOPES cone tests showed a 100% knock down and mortality of Aedes aegypti mosquitoes exposed to impregnated clothing at baseline and up to 4 washes, but this efficacy rapidly declined to below 20% after 20 washes, corresponding to a weekly reduction in knock-down and mosquito mortality by 4.7% and 4.4% respectively. Results of the entomological assessments showed that the mean number of Aedes aegypti mosquitoes caught inside the classrooms of the intervention schools was significantly reduced in the month following the introduction of the impregnated uniforms, compared to those collected in classrooms of the control schools (p = 0.04) Conclusions: Entomological assessments showed that the intervention had some impact on the number of Aedes mosquitoes inside treatment schools immediately after impregnation and before insecticidal activity declined. However, there was no serological evidence of protection against dengue infections over the five months school term, best explained by the rapid washing-out of permethrin after 4 washes. If rapid washing-out of permethrin could be overcome by novel technological approaches, insecticide-treated clothes might become a potentially cost-effective and scalable intervention to protect against diseases transmitted by Aedes mosquitoes such as dengue, Zika, and chikungunya. Trial Registration: ClinicalTrials.gov NCT01563640
Using remote sensing environmental data to forecast malaria incidence at a rural district hospital in Western KenyaSewe, M. O., Tozan, Y., Ahlm, C., & Rocklöv, J.
Journal titleScientific reports
Issue1AbstractMalaria surveillance data provide opportunity to develop forecasting models. Seasonal variability in environmental factors correlate with malaria transmission, thus the identification of transmission patterns is useful in developing prediction models. However, with changing seasonal transmission patterns, either due to interventions or shifting weather seasons, traditional modelling approaches may not yield adequate predictive skill. Two statistical models,a general additive model (GAM) and GAMBOOST model with boosted regression were contrasted by assessing their predictive accuracy in forecasting malaria admissions at lead times of one to three months. Monthly admission data for children under five years with confirmed malaria at the Siaya district hospital in Western Kenya for the period 2003 to 2013 were used together with satellite derived data on rainfall, average temperature and evapotranspiration(ET). There was a total of 8,476 confirmed malaria admissions. The peak of malaria season changed and malaria admissions reduced overtime. The GAMBOOST model at 1-month lead time had the highest predictive skill during both the training and test periods and thus can be utilized in a malaria early warning system.
A spatial hierarchical analysis of the temporal influences of the el niño-southern oscillation and weather on dengue in Kalutara District, Sri LankaLiyanage, P., Tissera, H., Sewe, M., Quam, M., Amarasinghe, A., Palihawadana, P., Wilder-Smith, A., Louis, V. R., Tozan, Y., & Rocklöv, J.
Journal titleInternational journal of environmental research and public health
Issue11AbstractDengue is the major public health burden in Sri Lanka. Kalutara is one of the highly affected districts. Understanding the drivers of dengue is vital in controlling and preventing the disease spread. This study focuses on quantifying the influence of weather variability on dengue incidence over 10 Medical Officer of Health (MOH) divisions of Kalutara district. Weekly weather variables and data on dengue notifications, measured at 10 MOH divisions in Kalutara from 2009 to 2013, were retrieved and analysed. Distributed lag non-linear model and hierarchical-analysis was used to estimate division specific and overall relationships between weather and dengue. We incorporated lag times up to 12 weeks and evaluated models based on the Akaike Information Criterion. Consistent exposure-response patterns between different geographical locations were observed for rainfall, showing increasing relative risk of dengue with increasing rainfall from 50 mm per week. The strongest association with dengue risk centred around 6 to 10 weeks following rainfalls of more than 300 mm per week. With increasing temperature, the overall relative risk of dengue increased steadily starting from a lag of 4 weeks. We found similarly a strong link between the Oceanic Niño Index to weather patterns in the district in Sri Lanka and to dengue at a longer latency time confirming these relationships. Part of the influences of rainfall and temperature can be seen as mediator in the causal pathway of the Ocean Niño Index, which may allow a longer lead time for early warning signals. Our findings describe a strong association between weather, El Niño-Southern Oscillation and dengue in Sri Lanka.
Characteristics of and factors associated with dengue vector breeding sites in the City of Colombo, Sri LankaLouis, V. R., Montenegro Quiñonez, C. A., Kusumawathie, P., Palihawadana, P., Janaki, S., Tozan, Y., Wijemuni, R., Wilder-Smith, A., & Tissera, H. A.
Journal titlePathogens and Global Health
Page(s)79-86AbstractIntroduction: Dengue has emerged as a major public health problem in Sri Lanka. Vector control at community level is a frequent and widespread strategy for dengue control. The aim of the study was to assess Aedes mosquito breeding sites and the prevention practices of community members in a heavily urbanized part of Colombo. Methods: A cross-sectional entomological survey was conducted from April to June 2013 in 1469 premises located in a subdistrict of the City of Colombo. Types of breeding sites and, where found, their infestation with larvae or pupae were recorded. Furthermore, a questionnaire was administered to the occupants of these premises to record current practices of dengue vector control. Results: The surveyed premises consisted of 1341 residential premises and 110 non-residential premises (11 schools, 99 work or public sites), 5 open lands, and 13 non-specified. In these 1469 premises, 15447 potential breeding sites suitable to host larvae of pupae were found; of these sites18.0% contained water. Among the 2775 potential breeding sites that contained water, 452 (16.3%) were positive for larvae and/or pupae. Schools were associated with the proportionally highest number of breeding sites; 85 out of 133 (63.9%) breeding sites were positive for larvae and/or pupae in schools compared with 338 out of 2288 (14.8%) in residential premises. The odds ratio (OR) for schools and work or public sites for being infested with larvae and/or pupae was 2.77 (95% CI 1.58, 4.86), when compared to residential premises. Occupants of 80.8% of the residential premises, 54.5% of the schools and 67.7% of the work or public sites reported using preventive measures. The main prevention practices were coverage of containers and elimination of mosquito breeding places. Occupants of residential premises were much more likely to practice preventive measures than were those of non-residential premises (OR 2.23; 1.49, 3.36). Conclusion: Schools and working sites were associated with the highest numbers of breeding sites and lacked preventive measures for vector control. In addition to pursuing vector control measures at residential level, public health strategies should be expanded in schools and work places.
Costs of Dengue Control Activities and Hospitalizations in the Public Health Sector during an Epidemic Year in Urban Sri LankaThalagala, N., Tissera, H., Palihawadana, P., Amarasinghe, A., Ambagahawita, A., Wilder-Smith, A., Shepard, D. S., & Tozan, Y.
Journal titlePLoS neglected tropical diseases
Issue2AbstractBackground: Reported as a public health problem since the 1960s in Sri Lanka, dengue has become a high priority disease for public health authorities. The Ministry of Health is responsible for controlling dengue and other disease outbreaks and associated health care. The involvement of large numbers of public health staff in dengue control activities year-round and the provision of free medical care to dengue patients at secondary care hospitals place a formidable financial burden on the public health sector. Methods: We estimated the public sector costs of dengue control activities and the direct costs of hospitalizations in Colombo, the most heavily urbanized district in Sri Lanka, during the epidemic year of 2012 from the Ministry of Health’s perspective. The financial costs borne by public health agencies and hospitals are collected using cost extraction tools designed specifically for the study and analysed retrospectively using a combination of activity-based and gross costing approaches. Results: The total cost of dengue control and reported hospitalizations was estimated at US$3.45 million (US$1.50 per capita) in Colombo district in 2012. Personnel costs accounted for the largest shares of the total costs of dengue control activities (79%) and hospitalizations (46%). The results indicated a per capita cost of US$0.42 for dengue control activities. The average costs per hospitalization ranged between US$216–609 for pediatric cases and between US$196–866 for adult cases according to disease severity and treatment setting. Conclusions: This analysis is a first attempt to assess the economic burden of dengue response in the public health sector in Sri Lanka. Country-specific evidence is needed for setting public health priorities and deciding about the deployment of existing or new technologies. Our results suggest that dengue poses a major economic burden on the public health sector in Sri Lanka.