What is hantavirus? What to know as cases raise concern

Recent headlines about hantavirus have sparked concern and comparisons to the early days of COVID-19, but infectious disease experts say the risk to the public in the United States remains very low.

“Hantavirus is a group of viruses that are usually transmitted from animals to humans,” says Jorge Robledo, MD, an infectious disease physician at Loma Linda University Health. “In the case of hantavirus, the virus is most commonly carried by rodents, specifically deer mice here in the U.S.”

Unlike COVID-19, hantavirus is not primarily spread through person-to-person contact. In the United States, people typically become infected after exposure to rodent urine, droppings, or saliva, especially in enclosed areas where particles can become airborne and inhaled. 

Experts say exposures most commonly happen in outdoor or rural settings such as cabins, campsites, sheds, or wooded mountain areas where deer mice may live.

“Usually we see it in patients after cleaning a cabin or being in an outdoor setting like camping,” Robledo says. “When droppings or urine become aerosolized, people can inhale the virus.” 

How hantavirus differs from COVID-19

Recent headlines surrounding a hantavirus outbreak tied to the Andes strain in South America aboard a cruise ship have raised concerns, but Robledo says the strain found in the United States is different.

“The strain we usually see here in the U.S. is called the Sin Nombre virus,” Robledo says. “The Andes strain, which has been associated with human-to-human transmission, has not been reported in the U.S.” 

According to Robledo, hantavirus cases in California are extremely rare. State health data has reported fewer than 100 cases statewide since the 1980s, with only a handful reported in San Bernardino and Riverside counties over the past several decades. 

“Overall, the risk for our population here in San Bernardino and Riverside County is really low,” Robledo says.

Robledo says recent headlines have created confusion about how hantavirus spreads. The cruise ship outbreak involved the Andes strain found in South America, which differs from the strain seen in the U.S. and has been linked to limited human-to-human transmission in close-contact environments. The U.S. strain, known as the Sin Nombre virus, has not been shown to spread person-to-person, according to the Centers for Disease Control and Prevention.

How to protect yourself

If entering a cabin, garage, shed, or other enclosed area that may contain rodent droppings, experts recommend opening windows for at least 30 minutes, avoiding sweeping or vacuuming droppings, spraying affected areas with disinfectant or bleach solution, and using gloves and a face mask while cleaning.

Robledo also emphasizes that the virus in the U.S. is primarily linked to deer mice found in wooded or mountain areas, not typical household mice.

While experts continue monitoring global cases closely, Robledo says there is no indication that hantavirus poses the same widespread threat as COVID-19. As of now, confirmed cases of the Andes strain linked to the recent outbreak have only been identified among passengers aboard the cruise ship.

What symptoms to watch for

If you have potentially been exposed to rodent droppings or contaminated areas, it is recommended to monitor your symptoms as early signs could mimic the common cold. 

Early hantavirus symptoms can resemble the flu and may include fever, chills, muscle aches, fatigue, nausea, vomiting, and diarrhea. Symptoms can develop anywhere from one to six weeks after exposure.

“When patients start developing a cough or shortness of breath, they should seek medical care immediately,” Robledo says. “That can be a sign the illness is progressing.”

There is currently no specific antiviral treatment for hantavirus. Treatment focuses on managing symptoms and supporting breathing and oxygen levels in severe cases.

To learn more about infectious diseases or to schedule an appointment with a Loma Linda University Health provider, visit LLUH Infectious Diseases page.