Aug. 4, 2000 -- Three California residents have died of infection with a rare new type of virus carried by rats. Known as the Whitewater Arroyo virus, it is similar to deadly viruses found in South America. The California cases are the first to occur naturally in the U.S.
The new virus was first reported in 1996 among the type of pack rats known as white-throated wood rats. Laboratory studies suggest it is the cause of the mysterious deaths of a 52-year-old Riverside County woman in June 1999; a 14-year-old Alameda County girl in April 2000; and a 30-year-old Orange County woman in June 2000. All were hospitalized with fever and difficulty breathing. Two of the patients had severe liver disease and bleeding.
"We don't want the public to be alarmed; we think this is very rare," Lea Brooks, spokesperson for the California Department of Health Services in Sacramento, tells WebMD. "These are very severe and unusual illnesses. We have a lot of focus on prevention."
The California cases do not appear to represent an outbreak. The deaths, which took place over a 14-month period in two widely separated regions, appear to be completely unconnected. In the wake of the deaths, California public health authorities are stepping up surveillance efforts and warning residents to avoid contact with rats and other rodents and their droppings.
Like the hantavirus -- another rare but dangerous virus, carried by deer mice -- people get infected by breathing dust contaminated with the urine, feces, or saliva of infected rodents. Human-to-human transmission can occur through contact with blood or other excretions containing virus particles, but this rarely happens outside health care settings and can be prevented by the use of normal hospital gowns and gloves.
T.G. Ksiazek, PhD, DVM, is acting chief of the special pathogen branch of the CDC's disease assessment section. He says that while all three known cases were fatal, it is too soon to know exactly how deadly the new virus will turn out to be. "Whenever something new pops up, the first cases you find are the most serious," he says.
Public health officials are urging people to take these simple but effective precautions:
- Do not touch or feed wild rodents or any other wild animals.
- Properly dispose of trash and clutter. Move woodpiles away from residences.
- Prevent rodents from entering residences by blocking holes. Control rodents with spring-loaded (snap) traps.
- Store food and garbage in rodent-proof containers. Pet food should not be left outside.
- Avoid creating dust when cleaning buildings with signs of rodents. Wet the area thoroughly with bleach and use gloves to clean up. Contact local health officials for recommendations about safely cleaning rodent-infested areas.
- Cabins and buildings that haven't been lived in for some time should be aired out. If possible, do not use buildings with signs of rodents until they have been cleaned properly.
- When sleeping outdoors, avoid campsites near rodent droppings, burrows, or nests.