Three deaths in California have been linked to arenavirus, a rare virus never before acquired by humans in North America.

In April, a 14-year-old female who died in Alameda County was confirmed to have contracted the virus. Arenavirus is also suspected in the death of a 52-year-old Riverside woman in June of last year, and in a 30-year-old female from Orange County who died in June of this year. The three cases were not considered to be related, officials said.

Arenavirus is believed to be transmitted to humans through inhalation of dust contaminated with the urine, feces, or saliva of infected rodents. The victims had complained of flu-like symptoms before being hospitalized with high fevers, respiratory distress, internal bleeding, and fluid buildup in their lungs.

The California Department of Health Services has issued a statewide alert to physicians to be on the lookout for similar symptoms.

Human cases have been observed in the United States only from travelers returning from overseas, and laboratory personnel accidentally exposed while doing research.

The arenavirus strain found in California is called Whitewater Arroyo virus, named after the place it was found in woodrats four years ago in New Mexico.

Few laboratories in the United States are equipped to test for the virus. California health officials are reportedly scrambling to establish the tests.