As an Atlantic cruise ship remains isolated off the South African coast due to a deadly hantavirus outbreak, the world watches with anticipation to learn more about this uncommon but dangerous infectious disease.
While rare, hantaviruses are a genus of viruses primarily transmitted from rodents to humans. Only one strain, known as Andes virus, has been documented to potentially spread from person to person, although such transmission is rare and typically requires close contact.
“There is no concrete evidence that there is human-to-human transmission for most hantaviruses,” said Safder Ganaie, Ph.D., an assistant professor of molecular genetics and microbiology in the University of Florida College of Medicine and a member of the UF Emerging Pathogens Institute. His lab studies hantaviruses at the cellular level and researches therapeutic interventions. “It’s not nearly as airborne as influenza or other common respiratory viruses.”
Hantaviruses are not new. Ganaie notes their discovery dates to the Korean War in the 1950s. The World Health Organization classified them in 1987, but it wasn’t until a 1993 outbreak in the United States’ Four Corners that hantavirus pulmonary syndrome—the condition that killed Betsy Machiko Arakawa Hackman, Gene Hackman’s wife—was discovered, splitting the virus into two subgroups: Old World, which can cause renal failure, and New World, which can cause pulmonary failure.
How it spreads
Transmission occurs primarily through inhaling aerosolized rodent excrement. John Lednicky, Ph.D., EPI member and research professor at the UF College of Public Health and Health Professions, describes the mechanism.
“Rats jump on ships or are carried onto them in cargo, they poop and pee, air currents aerosolize it, carry it, and it can get in the lungs, causing serious pulmonary illness,” said Lednicky. The U.S. Centers for Disease Control and Prevention identifies Andes virus as the most commonly found and deadly variant in South America, where Lednicky warns “very dangerous versions of hantavirus are proliferating.”
A common misconception is that hantavirus spreads like the flu. “You have to inhale virus-carrying particles released when rodent-contaminated materials are disturbed, and even then, the virus only survives on surfaces for a few days,” Ganaie said. “Aerosolized viruses, like measles virus or influenza, stay in the air much longer and transmit more easily than hantaviruses.”
Rodent bites are not a common route of transmission. “It’s the inhalation that is the major route,” said Ganaie. While many assume risk is limited to dirty environments, Ganaie cautions otherwise: “Even clean homes and cabins can pose a risk; if rodents are present, the virus may be as well.” Ultimately, the transmission requires the disturbance of this contaminated material in poorly ventilated areas.
Symptoms and diagnosis
Early symptoms, such as fever, muscle aches, headache, nausea, vomiting and diarrhea, are easy to mistake for other illnesses. “The symptoms are very non-specific, especially in the beginning,” said Amy Vittor, M.D., Ph.D., an associate professor of infectious disease at the UF College of Medicine and the EPI’s biomedical officer. The danger lies in what follows. Someone with a New World hantavirus can rapidly fall into pulmonary or heart failure within a matter of days after initial symptoms appear.
Diagnosis is made through antibody blood tests or viral genetic testing, though results can take days to weeks. Fatality rates range from 1% to 15% for Old World strains, while New World strains carry a fatality rate of up to 50%, even with treatment.
Treatment
“Luckily, there isn’t nothing,” Vittor said of treatment options. The most effective intervention is ECMO, or extracorporeal membrane oxygenation, which temporarily takes over heart and lung function to give the body a break. “This decreases mortality from 50% down to 20%. Unfortunately, ECMO requires a well-resourced Intensive Care Unit.”
Doctors must also avoid over-administering fluids, as the body’s low blood pressure can cause fluid to accumulate in the lungs. According to Vittor, steroids should not be used, as they can disrupt the delicate balance of inflammation needed for an immune response in a hantavirus infection.
Researchers around the world are working on antiviral treatments, but none have been approved yet in the U.S. For now, the main treatment is helping the body get through the illness. Advanced life support can improve survival in severe cases. Early diagnosis and prompt initiation of supportive care are key to improving outcomes.
If you care about heart health, please read studies about how vitamin D influences cholesterol levels, and what we know about egg intake and heart disease.
For more health information, please see recent studies about best supplements for heart disease prevention, and wild blueberries can benefit your heart and brain.
Written by Sydney Burge, University of Florida.
