A Methodological Framework for Economic Evaluation of Operational Response to Vector-Borne Diseases Based on Early Warning Systems

Despite significant advances in improving the predictive models for vector-borne diseases, only a few countries have integrated an early warning system (EWS) with predictive and response capabilities into their disease surveillance systems. The limited understanding of forecast performance and uncertainties by decision-makers is one of the primary factors that precludes its operationalization in preparedness and response planning. Further, predictive models exhibit a decrease in forecast skill with longer lead times, a trade-off between forecast accuracy and timeliness and effectiveness of action. This study presents a methodological framework to evaluate the economic value of EWS-triggered responses from the health system perspective. Assuming an operational EWS in place, the framework makes explicit the trade-offs between forecast accuracy, timeliness of action, effectiveness of response, and costs, and uses the net benefit analysis, which measures the benefits of taking action minus the associated costs. Uncertainty in disease forecasts and other parameters is accounted for through probabilistic sensitivity analysis. The output is the probability distribution of the net benefit estimates at given forecast lead times. A non-negative net benefit and the probability of yielding such are considered a general signal that the EWS-triggered response at a given lead time is economically viable. In summary, the proposed framework translates uncertainties associated with disease forecasts and other parameters into decision uncertainty by quantifying the economic risk associated with operational response to vector-borne disease events of potential importance predicted by an EWS. The goal is to facilitate a more informed and transparent public health decision-making under uncertainty.

Artificial intelligence to predict West Nile virus outbreaks with eco-climatic drivers

Background

In Europe, the frequency, intensity, and geographic range of West Nile virus (WNV)-outbreaks have increased over the past decade, with a 7.2-fold increase in 2018 compared to 2017, and a markedly expanded geographic area compared to 2010. The reasons for this increase and range expansion remain largely unknown due to the complexity of the transmission pathways and underlying disease drivers. In a first, we use advanced artificial intelligence to disentangle the contribution of eco-climatic drivers to WNV-outbreaks across Europe using decade-long (2010-2019) data at high spatial resolution.

Methods

We use a high-performance machine learning classifier, XGBoost (eXtreme gradient boosting) combined with state-of-the-art XAI (eXplainable artificial intelligence) methodology to describe the predictive ability and contribution of different drivers of the emergence and transmission of WNV-outbreaks in Europe, respectively.

Findings

Our model, trained on 2010-2017 data achieved an AUC (area under the receiver operating characteristic curve) score of 0.97 and 0.93 when tested with 2018 and 2019 data, respectively, showing a high discriminatory power to classify a WNV-endemic area. Overall, positive summer/spring temperatures anomalies, lower water availability index (NDWI), and drier winter conditions were found to be the main determinants of WNV-outbreaks across Europe. The climate trends of the preceding year in combination with eco-climatic predictors of the first half of the year provided a robust predictive ability of the entire transmission season ahead of time. For the extraordinary 2018 outbreak year, relatively higher spring temperatures and the abundance of Culex mosquitoes were the strongest predictors, in addition to past climatic trends.

Interpretation

Our AI-based framework can be deployed to trigger rapid and timely alerts for active surveillance and vector control measures in order to intercept an imminent WNV-outbreak in Europe.

Funding

The work was partially funded by the Swedish Research Council FORMAS for the project ARBOPREVENT (grant agreement 2018-05973).

A Prospective Study on the Impact and Out-of-Pocket Costs of Dengue Illness in International Travelers

Although 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 human travel 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.

Systemic resilience to cross-border infectious disease threat events in Europe

Recurrent health emergencies threaten global health security. International Health Regulations (IHR) aim to prevent, detect and respond to such threats, through increase in national public health core capacities, but whether IHR core capacity implementation is necessary and sufficient has been contested. With a longitudinal study we relate changes in national IHR core capacities to changes in cross-border infectious disease threat events (IDTE) between 2010 and 2016, collected through epidemic intelligence at the European Centre for Disease Prevention and Control (ECDC). By combining all IHR core capacities into one composite measure we found that a 10% increase in the mean of this composite IHR core capacity to be associated with a 19% decrease (p = 0.017) in the incidence of cross-border IDTE in the EU. With respect to specific IHR core capacities, an individual increase in national legislation, policy & financing; coordination and communication with relevant sectors; surveillance; response; preparedness; risk communication; human resource capacity; or laboratory capacity was associated with a significant decrease in cross-border IDTE incidence. In contrast, our analysis showed that IHR core capacities relating to point-of-entry, zoonotic events or food safety were not associated with IDTE in the EU. Due to high internal correlations between core capacities, we conducted a principal component analysis which confirmed a 20% decrease in risk of IDTE for every 10% increase in the core capacity score (95% CI: 0.73, 0.88). Globally (EU excluded), a 10% increase in the mean of all IHR core capacities combined was associated with a 14% decrease (p = 0.077) in cross-border IDTE incidence. We provide quantitative evidence that improvements in IHR core capacities at country-level are associated with fewer cross-border IDTE in the EU, which may also hold true for other parts of the world.

Household costs of hospitalized dengue illness in semi-rural Thailand

Background

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.

Dengue, an arbovirus infection with an explosive epidemic potential, is a major public health problem in Thailand and other developing countries in subtropical and tropical regions. Dengue illness often leads to school and work absenteeism, medical and non-medical expenditures, and foregone income. A growing literature shows that these illness related costs pose a severe economic burden on households, health care systems, and governments. We conducted a prospective cost-of-illness study to assess the costs and impact of hospitalized pediatric and adult dengue cases on households in a highly endemic area in eastern Thailand. We found that the total cost of a hospitalized dengue case accounted for about 19–23% the monthly household income. Although direct medical costs were covered for a majority of hospitalized dengue patients by the Thai Universal Coverage Scheme for health care, direct non-medical and indirect costs were of great economic significance to households. These hidden costs of dengue illness are likely to increase given the shift in the mean age of dengue cases in Thailand and other endemic countries in the region. High household costs of dengue illness justify efforts to improve the coverage of preventive and control measures against dengue in endemic areas.