Hantavirus is a virus that is transmitted by rodents and causes infection in humans.
The mini-epidemic of hantavirus infection that erupted in the Southwest in 1993 was an ominous new variation of an old theme.
In other parts of the world, rodent-borne hantaviruses have been causing sporadic outbreaks of high fever, hemorrhages, and sometimes kidney failure for most of this century. Over the past 40 years, four strains of hantavirus have been blamed for periodic outbreaks of illness characterized by flu-like symptoms, fevers, and kidney problems.
But this outbreak was different: instead of the 5 to 30 percent fatality rates seen in the past, about 60 percent of people who were stricken in the U.S. died of respiratory failure within days. The first hantavirus deaths were reported in New Mexico in May 1993, in the remote Four Corners area where Arizona, Colorado, Utah and New Mexico meet on the high plains.
The cause of the disease was quickly identified as a novel member of the family of hantaviruses, originally named for the river (Hantaan) in South Korea where the prototype was discovered. The Hantaan serotype viruses cause severe hemorrhagic fever with kidney involvement and are found in Korea, China, and eastern Russia.
The new disease (discovered in the Southwest U.S.) is called the hantavirus pulmonary syndrome. The name for the new pathogen is the Muerto Canyon (Sin Nombre, Four Corners) virus, for the location in New Mexico where it was isolated.
Rodents are the primary reservoir for all hantaviruses, shedding virus from saliva, urine and feces. People acquire infection most often by inhalation of rodent excreta; person-to-person transmission does not occur.
The virus can reside not only in rats but also in more socially acceptable animals such as chipmunks and squirrels. Crowding and other external pressures can cause animal behavior and breeding habits to change in ways that ultimately affect humans. Rodent populations in the U.S. and Europe have swelled over the past several years and exceptionally wet winters have increased their food supplies. Such abundance inspires rodents of all kinds to raise bigger families, so more of them are available to colonize campsites, barns, or weekend cabins.
Depending on the type of hantavirus, symptoms may be mild.
The hantavirus pulmonary syndrome begins as a nonspecific illness with fever, followed by rapid progression to a shock-like state with respiratory distress and blood abnormalities.
Diagnosis is made and clinically supported by immunological lab tests.
People who live in areas where hantavirus illnesses have occurred should take precautions to rodent-proof their homes and make outdoor areas as inhospitable to rodents as possible. People who live in areas not yet touched by hantavirus should avoid contact with rodents and be cautious about cleaning up their nests or droppings.
Public health officials emphasize that most tourist activities pose little or no risk, and that travelers need not worry about visiting areas where hantavirus has cropped up. Campers, however, should seek advice locally about avoiding native rodents.
Ribavirin, an antiviral drug, may be of some benefit. But what appears to help most is being hospitalized early, monitored carefully, and treated with life-sustaining fluids and medications that help normalize heart rate and breathing.
What are the chances of being infected with hantavirus?
What causes the disease and how is it transmitted?
What precautions should be taken to avoid infection?
What are the signs and symptoms?
When should a doctor be seen?
What treatment is currently available?
Is it safe to go camping in this area?
Since infection is thought to occur by inhalation of rodent wastes (excreta), prevention is aimed toward eradication of rodents in houses and avoidance of exposure to rodent excreta in rural settings.