Economic Valuation of Coccidioidomycosis (Valley Fever) Projections in the United States in Response to Climate Change

Coccidioidomycosis, or valley fever, is an infectious fungal disease currently endemic to the southwestern United States. Symptoms of valley fever range in severity from flu-like illness to severe morbidity and mortality. Warming temperatures and changes in precipitation patterns may cause the area of endemicity to expand northward throughout the western United States, putting more people at risk for contracting valley fever. This may increase the health and economic burdens from this disease. We developed an approach to describe the relationship between climate conditions and valley fever incidence using historical data and generated projections of future incidence in response to both climate change and population trends using the Climate Change Impacts and Risk Analysis (CIRA) framework developed by the U.S. Environmental Protection Agency. We also developed a method to estimate economic impacts of valley fever that is based on case counts. For our 2000-15 baseline time period, we estimated annual medical costs, lost income, and economic welfare losses for valley fever in the United States were $400,000 per case, and the annual average total cost was $3.9 billion per year. For a high greenhouse gas emission scenario and accounting for population growth, we found that total annual costs for valley fever may increase up to 164% by year 2050 and up to 380% by 2090. By the end of the twenty-first century, valley fever may cost $620,000 per case and the annual average total cost may reach $18.5 billion per year. This work contributes to the broader effort to monetize climate change-attributable damages in the United States. Significance StatementValley fever is a disease that is most common in the hot and arid regions of the southwestern United States and already costs billions of dollars in disease treatment and lost worker productivity, with consequences that include premature death. The purpose of our work was to estimate the impact that climate change may have on the total costs to society from valley fever. We found that there will likely be a tripling of valley fever cases in the future and that the average cost per case will increase, causing total yearly costs to rise from $3.9 billion per year (2000-15 estimate) to $18.5 billion per year by 2090. Our estimations of the future number of valley fever cases and total costs may help to inform public health decision-makers to begin monitoring the number of disease cases and prepare appropriate medical supplies.