Inhaling mouse urine. One presumes inadvertently. Often exposure occurs cleaning mice infected areas
Fevers, severe myalgias followed by non-cardiac pulmonary edema, volume contraction with hemoconcentration, lactic acidosis, shock, and death.
A hint is immature myelocytes and immunoblasts on the differential and low platelets.
Supportive. Steroids do nothing (PubMed) so don't give them. I know you want to. Resist.
Besides the four corners of the US, there are strains of Hanta viruses in mice all over the world.
The big outbreak in the US SW years ago may have been due in part to El Nino. More rain lead to more grain lead to more mice lead to more Hanta (PubMed).