ALBUQUERQUE, N.M. — A suspected rodent-borne illness has led to an outbreak on a cruise ship, resulting in three deaths and several illnesses.
The illness, identified as hantavirus, has been confirmed in one case. The World Health Organization is conducting detailed investigations into the outbreak, which includes further lab testing.
Outbreaks of gastrointestinal and respiratory illnesses are not uncommon on cruise ships, where people are in close quarters for extended periods. These outbreaks are often caused by highly contagious germs, like norovirus.
According to the U.S. Centers for Disease Control and Prevention, 23 gastrointestinal outbreaks occurred on cruise ships docking at U.S. ports last year, with norovirus responsible for 18 of them.
Hantavirus, however, is not commonly linked with cruise ships and does not spread easily between individuals.
Research indicates hantaviruses have existed for centuries, with outbreaks recorded in Asia and Europe. In the Eastern Hemisphere, it is associated with hemorrhagic fever and kidney failure. In the early 1990s, a new group of hantaviruses was identified in the southwestern United States, causing what is now known as hantavirus pulmonary syndrome.
The disease gained public attention last year when the wife of late actor Gene Hackman, Betsy Arakawa, died from a hantavirus infection in New Mexico.
The virus is spread by rodents and, more rarely, people
Hantavirus primarily spreads through contact with rodents or their urine, saliva, or droppings, especially when the material is disturbed, becomes airborne, and is inhaled. People are generally exposed to hantavirus around homes, cabins, or sheds, particularly when cleaning enclosed areas with poor ventilation or where mouse droppings are present.
The WHO notes that although rare, hantaviruses can also spread directly between individuals.
The U.S. CDC started monitoring the virus following a 1993 outbreak in the Four Corners region, where Arizona, Colorado, New Mexico, and Utah meet.
An observant physician with the Indian Health Service first identified a pattern of deaths among young patients, according to Michelle Harkins, a pulmonologist at the University of New Mexico Health Sciences Center who has studied and treated the disease for years.
Most U.S. cases occur in Western states. Harkins notes that New Mexico and Arizona are particular hot spots, likely due to increased mouse-human encounters in rural settings.
The illness starts with flu-like symptoms
The infection can quickly escalate and become life-threatening. Experts say initial symptoms include fever, chills, muscle aches, and possibly a headache.
“Early in the illness, you really may not be able to tell the difference between hantavirus and having the flu,” said Dr. Sonja Bartolome of UT Southwestern Medical Center in Dallas.
Symptoms of hantavirus pulmonary syndrome typically appear one to eight weeks after contact with an infected rodent. As the disease advances, patients may experience chest tightness as the lungs fill with fluid.
The other syndrome caused by hantavirus, hemorrhagic fever with renal syndrome, usually develops one to two weeks after exposure.
Fatality rates differ depending on the hantavirus strain. Hantavirus pulmonary syndrome is fatal in about 35% of those infected, while hemorrhagic fever with renal syndrome has a death rate ranging from 1% to 15%, according to the CDC.
A lot of unknowns about the illness and treatment
There is no specific treatment or cure, but early medical intervention can improve survival chances.
Despite extensive research, many questions remain unanswered, said Harkins, including why the severity varies among individuals and how antibodies develop. Researchers, including Harkins, have been tracking patients over long periods to seek a treatment.
“There are a lot of mysteries,” Harkins noted, emphasizing the importance of rodent exposure in the transmission.
To prevent infection, it is best to limit contact with rodents and their droppings. Protective gloves and a bleach solution should be used for cleaning up rodent droppings. Public health experts advise against sweeping or vacuuming, which can release virus particles into the air.
Different versions of hantavirus documented in different countries
The term hantavirus encompasses a wide family of viruses, with different strains existing in various countries. Most do not spread from person to person, except possibly a version found in South America — a focus of suspicion since the cruise originated in Argentina, said Angela Luis, a hantavirus researcher at the University of Montana.
A thorough investigation will be essential to determining what exactly occurred and could help resolve whether it spreads among people, Luis suggested.
“My guess is we’re going to learn a lot from this,” Luis said.
— Susan Montoya Bryan
