How dangerous is the Hantavirus, which the woman (65) of actor Gene Hackman died?

Betsy Arakawa (65), the wife of actor Gene Hackman (95), may have died of the consequences of the Hantavirus. The authorities in Santa Fe announced this, almost two weeks after her body was found in the home of the couple in New Mexico. What are the symptoms of this virus and how dangerous is it?

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