To everyone’s surprise, the virus that killed Gene Hackman’s wife Betsy Arakawa in February was found to be hantavirus, an uncommon viral infection spread by rodents.
Arakawa had called a clinic for feeling “congested” and was given an appointment. She did not keep that and was later found dead in her home, along with her husband, the prominent actor.
Later in February, three more deaths from hantavirus were reported from Mammoth Lakes, California. There was also a cluster of hanta isolates in San Diego in 2018.
Outbreaks
The first cluster of deaths was noted in 1993 when there were sudden deaths among healthy young people in the Four Corners area of the southwest. They all died from overwhelming lung infection and respiratory failure.
Hantavirus infections were found in the deer mice (Peromyscus maniculatus) living around the homes of those who were ill. The CDC named this strain Sin Nombre virus.
This case was fascinating because the clues to solving these mysterious deaths came from Navaho elders. They were attuned to patterns in nature and had noted earlier cyclical clusters of deaths. Why? Each cycle followed a year of increased rainfall (an El Niño year). The abundance of rain meant that there was more food available for the deer mice, whose populations exploded. When there were more mice, people living nearby had more exposure to the rodent urine and droppings, and cases would increase. The Navaho elders were at the forefront of linking changes in climate to infections.
Between 1993 and 2022, there were 864 cases of hantavirus reported in the U.S. Almost all the cases were hanta pulmonary infections. The mean age was 39, with 62% male. Most (94%) of the cases occurred west of the Mississippi; 15% were in Hispanic/Latino individuals. The death rate is 34%.
There was another notable cluster in 2012 in people staying in tent cabins in Yosemite. Careful epidemiologic investigation found deer mice nesting in the foam of the tent walls. Three of the ten infected died; others were critically ill.
Notably, two of the infected patients were from the East Coast, where one would not usually think of hantavirus. The first case of infection on the East Coast was in 1993, when a hiker along the Appalachian Trail became critically ill with multi-organ failure. He became infected from mouse droppings or urine in the shelters he had camped at along the trail.
There are other unusual exposures that are often overlooked. I found a hantavirus case in a young construction worker who’s job was laying pipes in the ground near Pittsburgh. There was an outbreak of a related hantavirus, Seoul virus, among people who owned pet Norway rats.
Mice commonly nest in cars or campers and these can cause hantavirus infections. It’s critically important to clean these areas properly and not to aerosolize the droppings or nest materials.
How is hantavirus transmitted?
A variety of mice and rats serve as the host of hantavirus. Even though the rodents may be asymptomatic, they shed the virus in their urine, droppings, and saliva. People commonly become infected by inhaling virus-laden contaminated air.
People can also become infected by touching infected secretions, and then inoculating themselves by touching their nose, mouth, or eyes with contaminated hands. Hanta is not transmitted from person to person.
Who’s at risk?
Hantaviruses are most common in the southwest U.S.; we likely have overlooked them elsewhere simply because we don’t look for it. Anyone exposed to mouse droppings is at risk.
The highest risk for hantavirus infection is when the aerosolized virus is inhaled, so please don’t vacuum or sweep an area contaminated with rodent droppings or secretions unless you have first saturated it with a 1:9 Clorox solution.
Symptoms
Hantavirus presents with nondescript symptoms—“congestion,” muscle aches, fever, headache and fatigue. Symptoms begin 1-8 weeks after exposure. They then often progress to more pulmonary symtoms, with cough, chest tightness, and shortness of breath. Many of those infected develop respiratory failure as their lungs fill with fluid and more than a third die.
How are hantavirus infections diagnosed?
Diagnosing hantavirus is difficult, as most often, it won’t be considered until someone develops respiratory failure. Physicians are under increased time constraints, often limited to 15” for a routine appointment. They are unlikely to take a careful, detailed epidemiologic history during this period.
Diagnosis is made by sending blood samples to the CDC. It’s unknown what their backlog of testing will be now that staffing has been severely cut.
There have been massive firings throughout divisions of Health and Human Services. These included 1300 probationary workers at the CDC, including all 50 first-year officers of the CDC’s Epidemic Intelligence Service. The EIS is the crown jewel of the CDC, and is essential for identifying new pathogens and solving disease outbreaks. Apparently DOGE rescinded these firings. Thousands more jobs (2400, or 18%) were cut last week; it’s unclear what divisions were cut. (Note, I reached out to the CDC for comment; none was received as of the time of publication
Treatment
There is no effective treatment for hantavirus. Patients are given supportive treatment with fluids and oxygen, mechanical ventilation, and blood pressure support for sepsis.
Prevention
The most important public health message is not to aerosolize droppings. When you are cleaning, spray the site and debris thoroughly with a solution of 1 part bleach to 9 part water, wait five minutes, then pick up what is left with a paper towel. Spray and wipe up again. Do not vacuum or sweep up droppings! If you are working in your car engine, disconnect the battery first. You might need a mechanic if filter and air hoses need to be replaced.
Remember to wash your hands thoroughly after cleaning droppings up. If you want to be extra safe, wear a mask while cleaning the area.
Conclusion:
Hantavirus infections are rare. They are likely to occur after winters with abundant rainfall and good crop growth in the spr that will feed mouse populations and enable them to grow.
If you become ill after contact with rodent droppings or after any travel, be sure to tell your physician.
