Deadly rodent-borne hantavirus is an emerging disease with pandemic potential

Hantavirus recently made news headlines as the cause of death for Betsy Arakawa, the wife of actor Gene Hackman, but little is commonly known about it other than its connection to rodents.

Virginia Tech researchers have gained a better understanding of this insidious virus by studying its rodent hosts in North America. Using National Science Foundation data, they found three hotspots of hantavirus circulation in wildlife – Virginia, Colorado, and Texas – and identified 15 rodent species as carriers, including six species that had not previously been identified as hosts of the virus. 

The details of their study was published in Ecosphere.

“This project is timely because hantavirus is considered an emerging disease of pandemic potential with symptoms that resemble severe COVID-19 infections,” said Paanwaris Paansri, a Ph.D. student in the Department of Fish and Wildlife Conservation and co-author of the study.

Hantaviruses are a family of viruses that have been identified in regions all over the globe and can reach mortality rates similar to other diseases of high concern, such as nipah and Ebola. In Asia, hemorrhagic fever with renal syndrome is caused by the Hantaan virus, in Europe that syndrome is caused by the Dobrava-Belgrade virus, and in North and South America, hantavirus pulmonary syndrome is caused by Sin Nombre virus and Andes virus — all hantaviruses. Sin Nombre virus was first discovered in New Mexico in 1993. 

Little is known about the ecology of hantaviruses in wildlife except that the pathogen is spread to humans by inhalation of aerosolized excreta, urine, or saliva from asymptomatic rodent hosts, and it can be fatal in humans.

The Virginia Tech team used data from the National Science Foundation’s National Ecological Observatory Network program to gain a better understanding of hantavirus circulation in its sylvatic cycle — the pathogen’s life cycle in wildlife — by examining the environmental influences and geographical distribution of the rodent hosts. The program collected and tested 14,004 blood samples from 49 species at 45 field sites across the United States from 2014-19. 

“In North America, Peromyscus maniculatus, the deer mouse, is the most common carrier but our study also revealed that other rodent species have a higher prevalence of hantavirus, which changes the current paradigm in hantavirus circulation in wildlife,” said Paansri, whose mentor Associate Professor Luis E. Escobar, led the study and is an affiliate with the Fralin Life Sciences Institute. “This new information is expected to help us understand where and when hantavirus is most likely to occur, which is crucial for predicting outbreaks and informing public health officials.”

The discovery of six new rodent species of hantavirus hosts is significant. Some of these newly discovered hosts inhabit regions where traditional hosts, such as the deer mouse or the white-footed mouse (Peromyscus leucopus), are absent, meaning they could be potential reservoirs of the virus in new or overlooked areas. 

“This expands our understanding of the basic biology of the virus and shows that the virus is more adaptable than previously believed,” Paansri said. “This has direct implications for surveillance strategies and risk assessments and can help explain some cases of hantavirus in humans where the main reservoir is absent or rare.”

In addition to expanding the known host species, the researchers were able to gain a better understanding of seasonal trends and effects of seasonal weather shifts. For example, warmer winters and increased precipitation can increase rodent populations and drier conditions can facilitate the generation of contaminated dust containing particulates from rodent excrement and saliva, increasing the risk of transmission to humans.

“Climate change can cause population increases or distributional shifts of rodents, altering the epidemiology of hantavirus,” Paansri said. “These fluctuations can lead to more frequent rodent-human interactions and increase the chance of spillover. We found some evidence that rodent demography and hantavirus prevalence can be predicted months in advance.”

The actual number of human cases of hantavirus infections is largely unknown, according to Paansri, because many infections remain silent, meaning the infected individual may not develop any symptoms or the symptoms could mirror other diseases, such as the common cold or influenza. 

The researchers plan to further explore the extent to which climatic variations influence hantavirus transmission in wildlife and in humans.. 

“We believe that many lessons learned from this study can be generalized to other wildlife diseases, considering that their distribution is global,” Paansri said.

Abdelghafar Alkishe, a Virginia Tech 2022-23 presidential postdoctoral fellow, also worked on this study.

DOI: doi.org/10.1002/ecs2.70209

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