Earlier this week the World Health Organization issued a global warning to travelers who might have come into contact with the deadly hantavirus while staying in Yosemite National Park in California. So far, three* people have died and at least half a dozen more have been sickened by the virus, which causes pulmonary distress. The outbreak is unusual in that cases of the virus are usually solitary and most have come from the high desert areas in or near New Mexico.
Most victims likely picked up the infection while staying in insulated tent cabins that were infested with mice, which carry the disease. The U.S. National Park Service estimates that as many as 10,000 people might be at risk of having been exposed to the disease since early June. And it has urged anyone who stayed in the "Signature Tent Cabins" in Yosemite’s Curry Village to be vigilant about looking for flulike symptoms, which can signal the onset of the illness. The virus can take as long as six weeks to incubate.
The infection was initially described in New Mexico about 20 years ago. It is exceedingly rare, with only about 600 documented cases in the U.S. But it is extremely deadly, killing more than one in three people who contract it.
The deer mice (Peromyscus) and other rodents that have been known to carry the disease, however, are by no means limited to high desert or mountainous areas and can be found throughout North America. So does that mean hantavirus could spread to other parts of the country?
To find out, we spoke with Charles Chiu, director of the Abbott Viral Diagnostics and Discovery Center and an associate professor of medicine and infectious diseases at the University of California, San Francisco. He explains what we know about hantavirus and what he and his colleagues are rushing to figure out in light of this latest outbreak.
[An edited transcript of the interview follows.]
What, exactly, is hantavirus?
Hantavirus is a very rare virus that's spread through contact with rodents. In the western U.S., it causes hantavirus pulmonary syndrome, a devastating pneumonia. There is also another disease associated with hantavirus, which is rarely found in the U.S. but is more often found in Central and South America: hantavirus hemorrhagic fever with renal syndrome.
How is the respiratory form of hantavirus spread?
It is acquired through contact with rodents, most commonly by inhaling dust that's contaminated with rodent droppings or urine. Less often, it can occur from a bite from a rodent. The main rodent that spreads this is the deer mouse.
Was hantavirus likely around before its formal description in the early 1990s?
The evolutionary data suggest that it's been around for hundreds or thousands of years. This is not a common infection, and probably a large factor in this is that there are no documented cases of human-to-human infection, so it's not contagious.
Hantavirus is usually thought of as an illness from desert areas of the Southwest, like New Mexico. Is this the first time it has sickened people in another region?
It was originally described in the Four Corners region of New Mexico in the high desert. But more than half of the states have reported cases. The cases have all been associated with wild rodents, which have been detected in every state.