Arenavirus in California



Three deaths in California during the past 14 months have been linked to an arenavirus, a rare virus never before acquired by humans in North America, State Health Director Diana M. Bontà, R.N., Dr.P.H., announced today. The discovery followed an extensive investigation by the California Department of Health Services (DHS) and the University of Texas Medical Branch (UTMB) into the unexplained deaths of a 52-year-old female who died in June 1999 in Riverside County, a 14-year-old female who died in April 2000 in Alameda County and a 30-year-old woman who died in June 2000 in Orange County. UTMB has one of the few laboratories in the country equipped to test for arenaviruses.

In the 14-year-old patient, arenavirus has been confirmed and in the two others, the virus is highly suspected based on initial laboratory tests. Further testing is under way. The three individuals were each hospitalized with fever and respiratory distress. Two of them also had severe liver disease and bleeding consistent with viral hemorrhagic fever.

Like hantavirus, which causes a rare, but often fatal respiratory disease, arenaviruses are believed to be transmitted to humans through inhalation of dust contaminated with the urine, feces or saliva of infected rodents. Human infection with arenavirus is also likely to be very uncommon. Arenavirus infection has been documented in rodents in Southern California in recent years.

"Viral hemorrhagic fever associated with arenaviruses has never been documented in the United States except among overseas travelers and laboratory personnel exposed accidentally while doing research," Bontà explained. DHS was prompted to send specimens to UTMB because of clinical and autopsy findings suggestive of viral hemorrhagic fever and a history of rodent contact in the Riverside County patient. The virus was detected in all three patients through testing for virus genes. In addition, virus isolation was used to confirm infection in the 14-year-old. There is no evidence that these cases are related.

In parts of Africa and South America, several arenaviruses are known which cause mild to severe infection characterized by fever, headache and occasionally severe bleeding or nervous system problems. Lassa fever and the South American viral hemorrhagic fevers are examples of human illnesses caused by such arenaviruses.

The antiviral drug ribavirin has been successfully used in the treatment of other arenavirus infections. Studies are under way to learn more about this virus and medicines that may be effective. Individuals can protect themselves from diseases carried by rodents by taking some relatively simple precautions both in the home and while outdoors:

  • 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 rodent infestation. Wet the area thoroughly with a disinfectant like bleach and use gloves to clean up. Contact local public health officials for recommendations about safely cleaning rodent-infested areas.
  • Cabins and buildings that haven't been occupied for some time should be aired out. If possible, buildings should not be used if there are signs of rodent infestation until properly cleaned.
  • When sleeping outdoors, avoid campsites near rodent droppings, burrows or nests.

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