Bayou virus
Bayou virus is the second most common cause of hantavirus pulmonary syndrome in the United States after Sin Nombre.
Bayou virus is the second most common cause of hantavirus pulmonary syndrome in the United States after Sin Nombre. Reservoir: rice rat (Oryzomys palustris) in the southeastern US.
Active and recent clusters
- United States · Four Corners endemic zone — 17 cases, 0 deaths (CFR 0%) · CDC NNDSS, 2026 MMWR week 17 (most recent published). United States reports approximately 15–40 confirmed HPS cases per year, concentrated in the Four Corners region (Sin Nombre virus). Numbers shown are the most recent CDC NNDSS Weekly publication.
Frequently asked
What does Bayou virus cause?
Bayou virus causes hantavirus pulmonary syndrome (HPS) with case fatality typically around 33%. Patients progress from a flu-like prodrome to acute respiratory distress.
Is Bayou virus contagious between people?
No documented person-to-person transmission. Bayou virus spreads via inhalation of aerosolized rodent excreta from its reservoir, Oryzomys palustris (rice rat).
Where does Bayou virus circulate?
Bayou virus circulates primarily in Southeastern United States. Its main reservoir is Oryzomys palustris (rice rat).
Related
Disclaimer. Strain pages are for general information. Diagnosis and treatment decisions must be made with a qualified clinician.