Last reviewed 2026-05-14
Hantavirus vs Lassa Fever
Hantavirus and Lassa fever are both rodent-borne viral hemorrhagic-style illnesses, but they belong to entirely different virus families, occur on different continents, and have very different treatment options.
Item A
Hantavirus
Family Hantaviridae · Order Bunyavirales
RNA viruses transmitted to humans primarily by inhaling aerosolized rodent excreta. Causes HPS in the Americas and HFRS in Europe and Asia.
More on Hantavirus →Item B
Lassa fever
Family Arenaviridae · Lassa virus (LASV)
Acute viral hemorrhagic fever endemic to West Africa, caused by Lassa virus and transmitted by Mastomys natalensis (multimammate rat). Hundreds of thousands of cases annually.
Side-by-side
| Feature | Hantavirus | Lassa fever |
|---|---|---|
| Virus family | Hantaviridae | Arenaviridae |
| Geographic range | Worldwide; HPS in the Americas, HFRS in Eurasia | West Africa (Nigeria, Sierra Leone, Liberia, Guinea, Benin) |
| Primary reservoir | Various rodents (deer mouse, bank vole, striped field mouse, etc.) | Multimammate rat (Mastomys natalensis) |
| Estimated annual cases | Tens of thousands (China dominates HFRS counts) | ~100,000–300,000 (West Africa) |
| Case fatality rate | HPS 35–40%, HFRS 0.1–15% | ~1% community; 15–20% hospitalized |
| Transmission to humans | Inhalation of aerosolized excreta; Andes virus also human-to-human | Rodent excreta (food contamination, dust) AND human-to-human via bodily fluids |
| Effective antiviral | None licensed; supportive care | Ribavirin (started within 6 days) |
| Vaccine | Inactivated vaccines in Korea/China for HFRS only | None licensed; candidates in clinical trials |
What they share
- ●Both are zoonotic viral illnesses with rodent reservoirs.
- ●Both can produce fever, myalgia, hemorrhagic signs, and multi-organ involvement.
- ●Both are notifiable diseases under WHO International Health Regulations.
- ●Both have characteristic non-specific early symptoms that delay diagnosis.
What sets them apart
- ●Hantavirus is global; Lassa fever is geographically confined to West Africa.
- ●Lassa fever has a proven effective antiviral (ribavirin), particularly when given early. Most hantaviruses do not.
- ●Lassa fever readily spreads between humans through contact with bodily fluids; only Andes hantavirus has any documented human-to-human spread.
- ●Lassa fever is much more common (>100k cases/year) than hantavirus globally.
Bottom line
Travel history is decisive. A patient returning from West Africa with fever, myalgia, and pharyngitis should be evaluated for Lassa fever — and started on ribavirin within 6 days if suspicion is high. A patient returning from rural North America, Patagonia, China, Korea, or northern Europe should be evaluated for hantavirus. These two diseases rarely overlap in real clinical practice.