The cruise ship docked in Argentina was meant to be the beginning of an extended vacation. Rather, it evolved into something more akin to a warning. Some of the passengers died before the ship finished its journey after contracting the Andes virus, a kind of hantavirus spread by rodents. As is often the case, the story quickly made its way through the news cycle before being overshadowed by reports on earnings and elections. However, a small team of researchers at the University of California, Davis quietly published something that should have a much longer shelf life while editors moved on.
Their study, which was published in npj Viruses in the middle of April, lacks the dramatic quality of disaster films. This paper is used for modeling. It uses machine learning systems to map out areas where dangerous arenaviruses may emerge over the next 20 to 40 years based on climate projections, rodent habitat data, and human population density. The conclusions are cautious, somber, and a little frightening. Diseases like Guanarito, Junin, and Machupo that are currently on the periphery of public awareness have the potential to spread to communities that have never had to consider them.
The lead author, Pranav Kulkarni, stated unequivocally that most public health officials are unaware of these diseases. More than anything else in the paper, that sentence remained with me. We often think of climate change in terms of weather, such as hotter summers, stronger storms, and water seeping up the coast. Because it doesn’t take good pictures, the slower, stranger work of climate change—the way it upends ecosystems and forces animals into new neighborhoods—gets less attention.
Hemorrhagic fevers caused by arenaviruses have a five to thirty percent fatality rate. No approved treatments are available. That’s all there is to Argentina’s licensed Junin vaccine, which might provide some cross-protection against Machupo. Outbreaks have historically been sporadic and rural because the viruses reside in rodents that farm workers occasionally come into contact with. However, neither borders nor epidemiology textbooks are readable by rodents. They carry their cargo with them when their habitats change.
To allow other researchers to examine the data, the Davis team created AtlasArena, a public, open-source platform. That particular detail is important. This team appears to recognize that public health, by definition, requires the public, whereas many climate-health studies remain hidden behind institutional walls or lengthy methodology sections. It remains to be seen if health organizations in nations like Chile, Brazil, or even the southern United States will truly use the tool. Instead of planning for the next crisis, bureaucracies typically prepare for the last one.
One could argue that this study is proof positive that climate change poses a health risk, and in some respects it is. Seldom has the relationship between increasing temperatures, changing rainfall patterns, and the geographic distribution of rodent-borne illness been outlined with such precision. Reporters covering the outbreak have been correct to point out that further research is necessary because the connection between the hantavirus on the cruise ship and climate change is still less clear. However, it is getting more difficult to ignore the larger trend.
As this develops, it’s difficult to ignore how frequently the climate change warnings come in the form of brief, technical papers that ought to have made headlines. Everyone has been given a map showing potential outbreak locations by the UC Davis team. The part that no one can model is whether or not anyone in a position to act will actually look at it.
