4 Californians being monitored for hantavirus exposure, officials say

Four Californians were exposed to the Andes strain of the hantavirus and are being monitored by public health officials, the California Department of Public Health announced Monday, May 11.

Out of the four people exposed, two of the residents were on the MV Hondius cruise ship and are currently being quarantined in Nebraska with the other Americans who were evacuated and returned stateside, according Erica Pan, the director and state public health officer for CDPH.

The CDPH did not release the counties of origin of these two people being quarantined.

The other two people exposed to the virus are currently being monitored by the Santa Clara and Sacramento counties' public health departments, according to Pan.

The Santa Clara County resident was a passenger on the MV Hondius who disembarked early and returned to California, before the outbreak was recognized, according to Pan.

Pan noted that the Sacramento County resident was briefly exposed to the virus by a passenger from the ship while traveling on an aircraft in South Africa. The resident sat within two seats of an ill patient for at least 15 minutes, according to Pan.

The Sacramento County resident was quickly removed from the flight after it was determined that they had been exposed. The resident has since returned to Sacramento County and is being monitored for symptoms.

Pan noted that although these two Californians were exposed to the hantavirus, they were allowed to return to California since neither resident was showing symptomatic behaviors.

Pan said "none" of the confirmed cases from the outbreak "are from California."

'They are very different situations.' COVID vs. hantavirus

The California Department of Public Health acknowledged that many Californians have been vocal regarding their concerns that this could turn into another pandemic like in 2020, but Pan reassured residents that this was a "very different situations."

"With this virus, hantavirus, there's decades of experience in South America with this particular virus, whereas when COVID-19 (happened), when we first heard about those cruise ship outbreaks, it was a brand new virus," Pan said.

"I also want to emphasize, (that) decades of experience in South America managing Andes hantavirus have shown that it has only been associated with rare human-to-human transmission after close and prolonged contact with a sick and infected person."

She noted that, unlike COVID-19, which spreads through respiratory droplets and aerosol particles from an infected person, a person would need to be in close proximity to a symptomatic patient with hantavirus in order to contract the virus.

What is hantavirus?

Hantavirus typically spreads through contact with the urine, feces, or saliva of infected rodents, and human-to-human transmission is uncommon.

The strain at the center of the outbreak has been confirmed as the Andes virus, which is believed to spread person-to-person, according to the World Health Organization.

"Exposure typically occurs during activities such as cleaning buildings with rodent infestations, though it may also occur during routine activities in heavily infested areas," according to the World Health Organization.

Those who are infected with hantavirus typically experience headache, dizziness, chills, fever, myalgia, and gastrointestinal problems, such as nausea, vomiting, diarrhea, and abdominal pain, followed by the sudden onset of respiratory distress and hypotension, according to health officials. Symptoms typically appear between two and four weeks after initial exposure.

"Hantavirus infections are relatively uncommon globally," according to the World Health Organization.

Human cases are most common in rural settings, "such as forests, fields, and farms, where rodents are present, and opportunities for exposure are greater," health officials said.

3 infected with hantavirus die in cruise ship outbreak

The ship, which had nearly 150 people on board from 23 nations, departed from Argentina on April 1 and made multiple stops across the Atlantic Ocean, including mainland Antarctica, South Georgia, Nightingale Island, Tristan da Cunha, Saint Helena, and Ascension Island, according to the World Health Organization.

"The extent of passenger contact with local wildlife during the voyage, or prior to boarding in Ushuaia, remains undetermined," health officials said.

Since its departure, three people — a Dutch couple and a German national — have died in the outbreak, according to health officials.

How did the hantavirus outbreak start?

The WHO has said it believes the hantavirus outbreak stemmed from a Dutch couple on board the MV Hondius who both later died from their infections.

Prior to boarding the ship, the couple had gone on a bird-watching trip through Argentina, Chile and Uruguay, Dr. Tedros Adhanom Ghebreyesus, director-general of the WHO, said at a May 7 briefing.

The couple's bird-watching trip included visits to sites where "the species of rat that's known to carry hantavirus was present," he said.

Dr. Maria Van Kerkhove, director of WHO's department of epidemic and pandemic management, said at a May 5 briefing that the MV Hondius also stopped at many islands up the coast of Africa where others may have come in contact with the virus.

"We do believe that there may be some human-to-human transmission that's happening among the really close contacts – the husband and wife, people who've shared cabins, etcetera," Van Kerkhove said.

(This story was updated to refresh headlines.)

Previous reporting from USA TODAY reporters Melina Khan and Daniella Segura was used in this story.

Noe Padilla is a Northern California Reporter for USA Today. Contact him at [email protected], follow him on X @1NoePadilla or on Bluesky @noepadilla.bsky.social. Sign up for the TODAY Californian newsletter or follow us on Facebook at TODAY Californian.