At a glance
- Reservoir
- Deer mouse (Peromyscus maniculatus)
- Geography
- Most of the continental United States and Canada
- Disease
- Hantavirus Pulmonary Syndrome (HPS)
- Case fatality
- Approximately 35–40%
- Person-to-person spread
- Not documented
- First identified
- 1993, during the Four Corners outbreak in the U.S. Southwest
A virus discovered in retrospect
Sin Nombre was identified in 1993 after a cluster of previously healthy young adults in the Four Corners region of the U.S. Southwest died of acute respiratory failure. CDC investigators traced the outbreak to deer mice and a then-unknown hantavirus. Subsequent serological studies found stored tissue samples from earlier deaths that, in retrospect, had been HPS — the disease had been present for decades, undiagnosed.
Clinical signature
Sin Nombre HPS is defined by a brief flu-like prodrome followed by abrupt onset of pulmonary edema and cardiogenic shock. Distinguishing laboratory findings include thrombocytopenia, an elevated hematocrit, and a left-shifted leukocytosis with immunoblasts on peripheral smear — a constellation experienced clinicians can recognize within hours.
Ecology drives outbreaks
Years with abundant winter precipitation in the Southwest produce pinyon nut booms, which feed deer mouse population surges, which precede HPS clusters. The relationship is well documented and forms the basis of seasonal CDC advisories.