Hantavirus is rare. Here’s why Georgia health officials are watching it.

No cases of hantavirus have been confirmed in the state.

Hantavirus is a disease carried by rodents, including mice and rats, and can be spread by breathing in particles containing their urine or feces. In humans, it can cause fevers, gastrointestinal issues and ultimately respiratory issues, according to the World Health Organization.

Those symptoms began showing in patients aboard the MV Hondius last week, according to the WHO. The ship had set sail from Argentina in early April for an extended exploration of the Atlantic Ocean.

The two Georgia residents were among the passengers and crew members aboard the MV Hondius when an outbreak was discovered. In addition to the deaths and confirmed cases, there are five other suspected cases associated with the cruise.

The state health department and the Atlanta-based Centers for Disease Control and Prevention are both monitoring the in-state residents and the risk level associated with the outbreak. Neither state nor federal health officials have detailed exactly how they are monitoring the two Georgians.

The CDC activated its level 3 emergency protocols, the lowest emergency level, in response to the virus. At that level, the response effort is led by a CDC expert in the particular disease and their staff, rather than employing the agency’s Emergency Operations Center or jump-starting 24/7 response efforts.

Cases of hantavirus transmitted to humans are a rarity, according to Dr. Jodie Guest, the senior vice chair of epidemiology at Emory University’s Rollins School of Public Health.

“Hantavirus by itself is quite unusual,” she said. “It is not a virus that we see much of, particularly in the United States.”

According to the CDC, 890 total cases were reported during a surveillance period that started in 1993. During that period, no cases were reported in Georgia. The CDC had not recorded any cases of hantavirus being spread from person-to-person in the U.S. through the end of their surveillance period in 2023.

Activities that put people at risk of being infected are typically cleaning up rats nests or mousetraps without gloves, being scratched by a rodent or working outside in areas where rodents are likely to live, according to the CDC.

While 40 strains of hantavirus are known, only one — the Andes strain — is known to spread between humans.

“All strains of hantavirus except for this particular strain do not have any human-to-human ability to transfer. And this particular strain does have the ability to do that,” Guest said.

She said a person with hantavirus can spread the disease after the onset of symptoms, such as fatigue, headaches, coughing or trouble breathing. It may take a month for symptoms to occur after someone has been exposed.

If no symptoms are present, the risk of spreading hantavirus is low, even if someone has been exposed, Guest said.

“We do know that the ability to transmit it to another human likely only occurs in the 24 hours of first onset of symptoms,” she said.

As of Friday, roughly 140 people remained on the MV Hondius heading toward the Canary Islands, according to The Associated Press. Authorities planned to evacuate the passengers and crew into isolation. The U.S. agreed to send a plane to the Canary Islands to retrieve 17 Americans citizens aboard the ship.

“At this time, the risk to the American public is extremely low. We urge all Americans aboard the ship to follow the guidance of health officials as we work to bring you home safely,” the CDC said.