Nine rodents collected in February in San Timoteo Canyon at the Norton Younglove Reserve have tested positive for hantavirus, Riverside County health officials announced Wednesday.
The rodents were deer mice and western harvest mice, and they were collected in the reserve area between the 60 Freeway and San Timoteo Canyon Road, just west of Beaumont, health officials said in a statement.
The California Department of Public Health confirmed the mice submitted for testing by county Environmental Health officials were infected with the virus, the statement said.
"It is not unusual in Riverside County to find rodents infected with the virus, especially in more rural areas," the county statement said. "County health officials reported the recent discovery only as a means to remind residents that they can take steps to reduce potential exposure.
Between 2001 and 2010, about 13 percent of rodents collected in Riverside County tested positive, which is generally consistent with the average for California, county health officials said.
"There has never been a documented human case of hantavirus pulmonary syndrome originating within Riverside County," the county statement said.
Hantavirus can be transmitted when people inhale tiny droplets contaminated with the virus from deer mouse secretions, such as droppings and urine, according to health officials.
"Infectious rodents do not show signs of illness, so it is important to keep from stirring up materials while cleaning mouse-infested areas around homes, especially in rural areas," the county advised.
Health officials offered steps residents can take to reduce their exposure to hantavirus:
• "Ventilate affected areas the night before cleanup by opening doors and windows.
• "Wear rubber gloves.
• "Apply household disinfectants at maximum recommended concentrations for rodents, rodent droppings, nests, contaminated traps and surrounding area and allow at least 15 minutes contact time before removal.
• "Clean the affected area with sponge or mop. DO NOT SWEEP OR VACUUM.
• "Double-bag the disinfectant-soaked clean-up and rodent materials (newspaper, paper towels, etc.) securely in plastic bags and seal.
• "Before removing gloves, wash gloved hands in disinfectant, and then in soap and water. Thoroughly wash hands with soap and water after removing gloves. Dispose of gloves and clean-up materials with other household waste."
Early warning signs of human infection can include fever, headache, muscle aches, vomiting and abdominal pain, county health officials said.
These symptoms can last a few hours to several days.
"As the illness progresses, the lungs fill with fluid, making breathing difficult," health officials advised. "Respiratory failure can follow rapidly."
Of the 56 human cases identified in California since 1980, 37 percent were fatal, according to the Riverside County Department of Environmental Health.
Anyone concerned about hantavirus should contact their health provider, county health officials said.
Although the Norton Younglove Reserve borders west Beaumont, it has a street address of 30399 Ironwood Ave, Moreno Valley.
For more information on hantavirus and the vector control program, contact the Riverside County Department of Environmental Health in Hemet at (951) 766-9454 or visit www.rivcoeh.org.