Hantavirus pulmonary syndrome associated with Monongahela virus, Pennsylvania

The first two recognized cases of rapidly fatal hantavirus pulmonary syndro me in Pennsylvania occurred within an 8-month period in 1997. Illness in th e two patients was confirmed by immunohistochemical techniques on autopsy m aterial. Reverse transcription-polymerase chain reaction analysis of tissue from one patient and environmentally associated Peromyscus leucopus (white -footed mouse) identified the Monongahela virus variant. Physicians should be vigilant for such Monongaheta virus-associated cases in the eastern Unit ed States and Canada, particularly in the Appalachian region.