Research

Dr. Alexander “Sasha” Keyel, a post-doctoral researcher in the Department of Atmospheric and Environmental Sciences (DAES) and the NYSDOH Wadsworth Center., spoke to us about a recent publication regarding West Nile Virus in NY.

What the main objectives of the project?

West Nile virus (WNV) has caused more than 46,000 diagnosed cases in the United States, with over 2000 human deaths (1999–2016) according to the CDC. When we think of diseases transmitted by mosquitos it is important to realize that climate and other environmental factors affect the abundance of mosquitos and the percentage of the mosquitos infected with a virus like the West Nile Virus. Mosquito traps have been deployed to monitor the spread of WNV in mosquito populations throughout the state of New York and Connecticut since 2000. The number of human cases has also been monitored and recorded by the state Department of Health since the first cases were identified in NY in 1999. We are analyzing data in connection with climate data to quantify the relationship between temperature and hydroclimatic conditions (e.g. rainfall and soil moisture). Novel machine learning data analysis methods play a large role in our research. The data and statistical methods allow us to study year-to-year fluctuations in the occurrences of human WNV cases and identify relationships between climate and other environmental factors. Our ultimate objective in this study was to develop predictive models that give us estimates how the numbers of human WNV disease cases are going to change in a warmer future climate.

What made you interested in researching this topic?

In 2015, a group of faculty members from the Department of Atmospheric and Environmental Science and the scientists at the Wadsworth Center (who are faculty members of the School of Public Health) met to discuss opportunities for collaborations on the question how climate change is going to affect spread of infectious diseases the Northeast US. I was interested in this type of interdisciplinary research, because as a climate scientist I have been studying regional impacts of climate change in terms of changes in temperature and precipitation for the Hawaiian Islands. And for that region I had also opportunity to collaborate with ecologists and epidemiologists to investigate the future changes in native bird populations in connection with avian malaria (malaria virus that, unfortunately, is projected to decimate a large fraction of the endemic bird population in Hawaii). Seeing how important it is to provide climate change scenario data and to communicate the uncertainty in the scenarios to the ecologists/ epidemiologists reminded me of the importance to learn to communicate my climate research results across scientific Research 6

disciplines. In that process I was learning about the biological processes and I was actually surprised how challenging it is to understand cause-effect relations in these complex natural systems. Now with the human health component included, things got even more complicated; but as scientists we like new complicated puzzles and try to put a few pieces together that fit and give us some more insight into the full system.

What were the main outcomes of the project?

One lesson I learned during this research is that the complex processes that determine the reproduction of the virus, the infection rates in the mosquitos, and contact rates between mosquitos and humans all this results in a narrow optimal temperature range where the WNV can be most ‘effectively’ transmitted and cause human infections. Some regions of NY and CT are already close to the optimal conditions in the present climate. Future warming is going to increase the summer temperatures to levels above this optimum temperature range. In short, in some regions it’s likely getting too warm for the mosquitos and the virus and it can lead to a reduced WNV risk. Our model predicts that the counties at present with the highest WNV case numbers will see lower numbers in future. On the other hand, many of the counties in NY and CT with currently low WNV cases are likely to experience climatic conditions in future that are more conducive for the spread of WNV. For those regions we expect a higher risk for WNV infections. It should be pointed out that we are ignoring the changes in population density, landscape, human behavior in these scenarios. Planning for and adaption in connection with future climate change should therefore also pay attention to changes in infectious diseases like WNV.

Which of the UN Sustainable Development Goals do you feel are most addressed?

Most directly our research addresses Goal 3 Ensure healthy lives and promote well-being for all with relevance to Goal 15 Life on Land (Sustainably manage forests, combat desertification, halt and reverse land degradation, halt biodiversity loss) and Goal 13 Climate Action (since it reveals potential harmful impacts of climate change).