Millions warned to beware of frightening rodent disease as two Americans test positive

Experts are sounding the alarm over the spread of a rare deadly virus after two Americans tested positive this week.

Hantavirus, the disease that killed Gene's Hackman's wife Betsy Arakawa, is a rare but severe respiratory illness spread through exposure, typically inhalation, to rodent droppings.

The hantavirus, which kills 30 to 50 percent of people infected, was first identified in South Korea in 1978 when researchers isolated the virus from a field mouse. It is rare in the US, with fewer than 50 cases reported yearly.

But now two cases have been confirmed in Nevada - bringing the US' total count to 864 cases since 1993.

Health experts are warning the public to be extra vigilant as warmer weather arrives, especially around areas such as sheds, barns, trailers, garages, and cabins where deer mice may have nested in the cold weather and left droppings.

Early symptoms of hantavirus include fever, fatigue and muscle aches, and may later progress to headaches, chills, and nausea, vomiting and diarrhea.

Hantavirus can also cause hantavirus pulmonary syndrome (HPS), with patients often experiencing a tightness in the chest, as the lungs fill with fluid.

HPS can be deadly and 38 percent of people who develop respiratory symptoms die from the disease.

Melissa Bullock, Nevada State Medical Epidemiologist, told local 2 News Nevada: 'We urge people to be aware of any signs of rodent activity and to take precautions to reduce the risk of exposure to hantavirus.

'Anyone who has been in contact with rodents, nests or droppings and subsequently develops symptoms consistent with hantavirus pulmonary syndrome should see a health care provider immediately.'

No details are known about the two people who have tested positive.

To reduce risk of exposure, state health officials recommend airing out spaces where mice droppings could be, avoid sweeping droppings, use disinfectant and wipe up debris, and wear gloves and a mask.

Hantaviruses are a group of viruses found worldwide that are spread to people when they inhale aerosolized fecal matter, urine, or saliva from infected rodents.

The rarity of hantavirus in the US is partly because the country has fewer rodent species that the illness can circulate amongst, compared to Asia and Europe, where multiple rodent species act as hosts.

However, Virginia Tech researchers found that while deer mice are still the primary reservoir for hantaviruses in North America, the virus is now circulating more widely than previously thought, with antibodies detected in six additional rodent species where they had not been documented before.

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.

Between 2014 and 2019, the program gathered and tested 14,004 blood samples from 49 different mouse 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.

But, researchers found that other rodent species had a higher percentage of hantavirus infections than deer mice – between 4.3 and five percent.

The vast majority of human cases are traced back to two or three key deer mouse species, but the study's 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 samples testing positive for hantavirus – four 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.'