Experts are sounding the alarm over the spread of a virus seldom seen in the US that comes from mice, the same virus that killed actor Gene Hackman’s wife.
Betsy Arakawa was found dead in the Santa Fe home she shared with her husband, and the mysterious circumstances surrounding their passing gripped the nation’s attention for weeks.
Mr Hackman was later determined to have died of heart disease, while Ms Arakawa, a classical pianist, died of hantavirus, a rare but severe respiratory illness spread through exposure, typically inhalation, to rodent droppings.
The hantavirus was first identified in South Korea in 1978 when researchers isolated the virus from a field mouse. The virus is rare in the US, with fewer than 50 cases reported yearly. For reference, there are roughly 2,000 cases of West Nile Virus reported in the US annually.
This is partly because the US has fewer rodent species than Asian countries. Hantaviruses in the US primarily circulate in fewer rodent species compared to Asia and Europe, where multiple rodent species act as hosts.
Virginia Tech researchers found that while deer mice are still the primary reservoir for hantaviruses in North America, the virus circulates more widely than previously thought – detecting antibodies in six additional rodent species where hantavirus was not documented before.
The findings suggest that hantaviruses may circulate among a broader range of rodents, though human infection risk is still highest in areas with high deer mouse populations, especially in Southwestern states.
Betsy Arakawa was found dead in the Santa Fe home she shared with her husband, Gene Hackman, and the mysterious circumstances surrounding their passing gripped the nation’s attention for weeks
Hantaviruses, which kill around 50 percent of patients, are a group of viruses found worldwide and can cause deadly diseases with fatality rates comparable to serious illnesses like Ebola, which has a death rate ranging from about 60 to as much as 90 percent, depending on the strain.
Hantaviruses, which are spread to people when they inhale aerosolized fecal matter, urine, or saliva from infected rodents, cause distinct diseases based on their geographic regions.
In Asia, the Hantaan virus causes hemorrhagic fever with kidney disease, while in Europe, the same condition is linked to the Dobrava-Belgrade virus.
In the Americas, hantavirus pulmonary syndrome is caused by the Sin Nombre virus and the Andes virus.
The Sin Nombre virus was first identified in New Mexico in 1993.
The Virginia Tech team analyzed data from the National Science Foundation’s National Ecological Observatory Network to better understand how hantavirus spreads in the wild.
They focused on how environmental factors and geographic patterns affect the rodent species that carry the virus.
Arakawa was infected with hantavirus which caused a deadly build-up of fluid in her lungs, known medically as hentavirus pulmonary syndrome (HPS). Hackman died of heart disease
Seventy-nine percent of positive blood samples came from deer mice species, which cause around 90 percent of all hantavirus cases in the US
Between 2014 and 2019, the program gathered and tested 14,004 blood samples from 49 different species at 45 locations across the US to test for levels of hantavirus antibodies.
Seventy-nine percent of positive blood samples came from deer mice species, which cause around 90 percent of all hantavirus cases in the US.
These species showed the highest infection rates in their blood at three percent based on 116 positive samples, which was to be expected.
But, researchers found that some rodent species, like Peromyscus truei and Microtus pennsylvanicus, had a higher percentage of hantavirus infections than deer mice – between 4.3 and 4.9 percent.
Paanwaris Paansri, a Ph.D. student in the Department of Fish and Wildlife Conservation and co-author of the study, said: ‘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.’
At the same time, these numbers can be misconstrued to pose a greater threat than actually exists.
They are based on much smaller sample sizes: only nine out of 184 P. truei and 33 out of 768 M. pennsylvanicus tested positive. Meanwhile, 116 out of 3,919 deer mice were infected.
When the sample is small, even a few positive cases can skew the percentage to appear high.
The above shows hantavirus cases recorded in the US
The vast majority of human cases are traced back to two or three key deer mouse species, and there is no evidence these species sustain outbreaks or significantly increase human risk.
Still, according to Mr Paansri, these findings reveal that the virus is more flexible than scientists once thought, broadening what they know about its basic biology.
Virginia had the highest infection rate among rodents, with nearly eight percent of 99 samples testing positive for hantavirus – 3.8 times the national average of around two percent.
Colorado had the second-highest infection rate, followed by Texas, both known risk regions for the virus, with average positive blood samples more than twice as high as the national average.
The team’s findings could influence how public health officials monitor and evaluate hantavirus risk and help clarify human cases in areas where the usual rodent host is uncommon or missing.
Mr Paansri said: ‘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.
‘We believe that many lessons learned from this study can be generalized to other wildlife diseases, considering that their distribution is global.’
