Forests can help diminish the number of dengue cases in Costa Rica

Abstract Approximately 3.9 billion people are at risk of infection with dengue fever, a group of viruses transmitted by mosquitos.1,2 In 2019 Central America has suffered a strong dengue epidemic.3 Costa Rica has almost doubled the number of dengue cases between in the first 24 epidemilogical weeks of 2019 regarding the same period in the previous year.4 In the Americas, forest cover is thought to diminish anthropogenic habitats for mosquito larvae, as well as increase the presence of their predators.5,6 Here we estimate the marginal effects of increasing forest cover on dengue prevalence, using econometric models to relate hospital admission records and forest cover maps from 2001 and 2011. We find that increasing the percentage of forest cover significantly decreased both the number of hospital admissions for dengue and the probability of an outbreak. Using the same models, we predict that increasing forest cover by one percentage point would have avoided between 85 to 103 dengue hospital admissions per year. This represents savings between USD 21,500 to 295,000 per year, depending on the severity of dengue cases. Our study shows that forest conservation can be a public health investment that increases welfare both by avoiding sickness and by reducing associated health care expenditures. Understanding the contribution of nature to diminish the risk of disease outbreaks turn even more urgent and important under the COVID-19 global pandemic the world has faced in 2020.7,8