As climate changes rodent habitats, hemorrhagic fever viruses could reach countries not currently at risk
Rodents in South America could be poised to spread the disease to new locations.
Warming temperatures and changes in precipitation patterns could push some South American rodents to settle in new areas. Such changes in suitable habitat may increase the risk that rodents infected with a group of deadly bleeding viruses called arenaviruses could trigger a deadly outbreak among residents of areas not previously in the line of fire, researchers report April 15 in npj virus.
“That’s what’s concerning,” says Pranav Kulkarni, a veterinary epidemiologist at the University of California’s Weill School of Veterinary Medicine. “These diseases are not on the radar of public health officials. »
A virus transmitted by rodents is currently making headlines: Andes virus, a type of hantavirus, has become ill several passengers on board a cruise ship who began his journey in Argentina. Some patients have died.
But hantaviruses are just one of many pathogens that rodents can transmit to humans. Arenaviruses — a family that includes the virus that causes Lassa fever in parts of Africa – are another. These viruses can trigger severe hemorrhagic fevers with mortality rates ranging from 5 to 30 percent.
Arenaviruses that have caused sporadic outbreaks in South America include Guanarito virus, Junin virus, and Machupo virus. There are no approved treatments. A vaccine against the Junin virus, which may also provide some protection against the Machupo virus, is authorized in Argentina.
Farmworkers working in areas with infected rodents are usually at greatest risk, Kulkarni says. But as Earth’s climate changes, these creatures could move to new areas, bringing viruses with them. “If there’s going to be a high-impact arenavirus outbreak,” Kulkarni says, “this could be the candidate.”
Kulkarni and colleagues performed computer simulations incorporating habitat suitability for six rodent species known to carry one of three viruses. The calculations also took into account future climate projections and population density. The team found that the risk of viral transmission from rodents to humans would increase over the next 20 years in areas of the continent that are currently not at risk.
The Guanarito virus, for example, is currently present in central Venezuela. But by 2060, the virus could spread to parts of Colombia, Guyana, Suriname and Brazil. The risk linked to the Junin virus could move from the grasslands of Argentina to other regions of the country as well as Paraguay and Bolivia. And the Machupo virus, currently present in Bolivia, could in the future also infect people in Brazil, Paraguay and Peru.
The resulting risk maps “set the stage,” says Greg Glass, a disease ecologist at the University of Florida in Gainesville, who was not involved in the work. “This allows people to use these maps to set up studies to see if these species are there or not.”
For Glass, checking current cards should be the next step. It is possible that the simulations suggest circulation in regions where rodents are not actually carrying the virus. But if the simulations “say it shouldn’t be there, but you find it…that’s a bigger mistake” that could cost lives, he says.
Changes in temperature and changes in precipitation were among the climatic factors leading to changes in rodent populations in the simulations. Human activities such as agriculture and urbanization have also played a role. But the simulations focused on long-term changes, Kulkarni says. “What we would really like to do is look at short-term weather changes, short-term changes in certain climate disturbances and how that affects risk from week to week or month to month.”
Some changes could already be happening. Hantavirus cases are increasing in Argentina, Carlos del Rio, a virologist and infectious disease doctor at Emory University in Atlanta, said at a news conference. a press briefing on May 7. “The main cause is climate change. Argentina is becoming more and more tropical.”
Some of the rodents included in the study can also transmit hantaviruses, Kulkarni says. The yellow pygmy rice rat (Oligoryzomys flavescens), for example, transmits not only the Junin virus but also certain strains of hantavirus. Although the pygmy yellow rice rat is not a known reservoir of the Andean strain of hantavirus responsible for the cruise ship outbreak, it is possible that other rodents and pathogens may also expand their ranges as the climate changes.
“Climate change is a reality,” Del Rio said. “And that has a significant impact on infectious diseases.”
