Hantavirus Strikes Again

“The virus that killed Betsy Arakawa, the wife of Gene Hackman, is a relatively rare but devastating threat without a vaccine, treatment or cure.” Evan Bush, NBC News, March 7, 2025

“A third case of Hantavirus Pulmonary Syndrome, each of which has been fatal, is tragic and alarming. We don’t have a clear sense of where this young adult may have contracted the virus.” Dr. Tom Boo, Mono County public health officer, April 4, 2025

Hantaviruses—a family of RNA viruses—are pathogens that can cause serious illnesses and death.  On April 4, 2025, California health officials confirmed that three adults had died of a hantavirus infection in the town of Mammoth Lakes. These deaths occurred a little over a month after Betsy Machiko Arakawa Hackman, the wife of famed movie actor Gene Hackman, died of hantavirus pulmonary syndrome in the couple’s home in Santa Fe, New Mexico.

Upon reading this, you might ask, “What is hantavirus, and do I need to worry about getting it?” In this week’s post, I provide a brief overview of hantaviruses, a highly lethal group of zoonotic pathogens, and suggest steps to take to avoid contracting them.

Discovery of hantavirus. Dr. Ho-Wang Lee, a Korean virologist, is credited with the discovery of Hantavirus. In 1976, in the area near the Hantaan River in South Korea, there was an outbreak of cases of  hemorrhagic fever with renal syndrome (HFRS). Dr. Lee and his team isolated a virus from the lungs of a field mouse, hence establishing the zoonotic (rodent-borne) nature of virus and identified the Hantaan virus, the prototype virus of the Hantavirus genus, as the cause of HFRS.

What is hantavirus pulmonary syndrome?  Hantavirus pulmonary syndrome (HPS) is a severe and potentially deadly disease that affects the lungs. The main hantaviruses that cause HPS are the Sin Nombre virus (North America) and the Andes virus (South America).

The Sin Nombre virus was discovered in the Four Corners region of the U.S. in 1993 where there was an outbreak of fatalities due to HPS. The virus was originally named Muerto Canyon Hantavirus. It was then renamed Four Corners Hantavirus. But, due to objections from the Navajo nation and to avoid further offense, the virus was renamed again and called Sin Nombre virus which is Spanish for “without a name.”

The Andes virus was discovered in 1995 in Argentina and later that same year in Chile. In subsequent years, small clusters of HPS have been reported in Europe and Turkey caused by the Puumala orthohantavirus. (Ten cases were identified between 2002 and 2023.)

The main cellular targets of these viruses are the vascular endothelial cells and macrophages. Damage to the endothelium in the lungs causes fluid leakage resulting in HPS.

It’s all about rodents. Hantaviruses are carried by rodents, particularly rats, mice and voles. In North America, the western deer mouse is responsible for transmitting the Sin Nombre virus. In South America where Andes virus is the most common cause of HPS, the Long-tailed pygmy mouse is the most common animal reservoir.

Transmission of the virus to humans occurs mainly through inhalation of aerosols that contain rodent saliva, urine, or feces. Transmission can also occur, however, through contaminated food, bites, and scratches. The virus is not transmitted by person-to-person contact.

Signs and symptoms. Hantavirus can cause flu-like symptoms which usually start to show one to eight weeks after contact with an infected rodent. The early symptoms of HPS can include fatigue, fever and muscle aches. About half of all patients also experience headaches, dizziness, chills, abdominal pain and abdominal problems such as nausea, vomiting and diarrhea.

Four to ten days after the initial phase of illness, the late symptoms of HPS appear. These  include coughing and shortness of breath. Patients might also experience tightness in the chest, as the lungs fill with fluid.

HPS can be deadly. Of those who develop respiratory symptoms, 38% die from the disease; death usually occurs 2-10 days after the onset of illness.

The majority of HPS cases in the U.S. occur west of the Mississippi River. According to the Centers for Disease Control and Prevention (CDC), at the end of 2022, 864 cases of hantavirus disease were reported in the U.S.

Treatment. There is no specific treatment for hantavirus infections. Patients should receive supportive care, including intubation, mechanical ventilation, and supplemental oxygen as needed. The CDC recommends that people who suspect they have hantavirus should “see a physician immediately and mention potential rodent exposure.”

Reducing risk. Reducing your risk of exposure to the hantavirus is the key to preventing HPS. Anything that fosters contact with rodents should be avoided. Eliminate or minimize contact with rodents in your home, cabin, workplace, or campsite. The CDC recommends sealing holes and gaps in your garage or home to keep rodents from entering these spaces and placing traps in and around your home to decrease rodent infestation.  If you are cleaning out a cabin or home, wear gloves and a N95 mask and use a wet paper towel to clean up droppings rather than a vacuum or broom which can stir up the aerosols.

In addition, there are newer technologies, such as the WellAir Defend NV400, that remove airborne pathogens. This filtration device is 99.9% effective at inactivating airborne pathogens like SARS-CoV-2, MRSA, and fungi, making it ideal for hospitals, clinics, and schools. It is unclear, however, whether it removes air contaminated with rodent saliva, urine, and feces. Therefore, whether it is worthwhile to invest in such a product to prevent HPS is not known.

Role of climate change in hantavirus infections. A link of hantavirus infection to climate change has been suspected since the turn of the 20th century. (See, “Hantaviruses and climate change,” Clinical Microbiology and Infection, June 2009). Rodents are the primary reservoirs for the virus. Their population densities are affected by changes in temperature, precipitation and food availability.

The 1993 hantavirus outbreak in the Four Corners region is an example of how climate-related factors can amplify hantavirus risks. That outbreak followed a 20-fold increase in rodent populations due to increased rainfall from the 1992-1993 El Nino.  Similarly, elevated temperatures in West Central Europe have driven higher seed production and higher vole population growth which have been linked to increased outbreaks of Puumala hantavirus.

In a recent study from Virginia Tech, researchers identified new rodent carriers of the disease and identified environmental factors that influence distribution of the disease. (Astorga, F., et al “Hantavirus in rodents in the United States: Temporal and special trends and reports of new hosts,” Ecosphere, March 16, 2025.) In an interview, Paanwaris Paansri, one of the researchers, said, “Climate change can cause population increases or distributional shifts of rodents, altering the epidemiology of hantavirus. These fluctuations can lead to more frequent rodent-human interactions and increase the chance of spillover.”

Climate change transforms entire ecosystems. It alters the habitats of disease vectors like rodents. It changes patterns of disease transmission and raises the risk of zoonotic infections like Hantavirus. It is the number one human health problem today.