syndromes, geography and clinical course
HPS vs HFRS
| Feature | HPS | HFRS |
|---|---|---|
| Full name | Hantavirus Pulmonary Syndrome | Hemorrhagic Fever with Renal Syndrome |
| Hemisphere | New World (Americas) | Old World (Eurasia) |
| Pathogens | Sin Nombre, Andes, Bayou, Black Creek Canal, Choclo, Laguna Negra | Hantaan, Puumala, Seoul, Dobrava-Belgrade, Tula |
| Reservoirs | Sigmodontine rodents (deer mice, rice rats, cotton rats) | Murid rodents (Apodemus, Myodes, Rattus) |
| Primary organ | Lungs (capillary leak, pulmonary oedema) | Kidneys (interstitial nephritis, AKI) |
| Hallmark course | Prodrome → cardiopulmonary phase → diuretic → convalescent | Febrile → hypotensive → oliguric → polyuric → convalescent |
| CFR (range) | ≈ 10–40% | < 0.5% (PUUV) to ≈ 15% (HTNV/DOBV) |
| Ribavirin benefit | Not established | Modest if started early (HTNV) |
The two clinical syndromes caused by hantaviruses split along New World / Old World lines, with very different pathogens, reservoirs and prognoses.
HPS — Hantavirus Pulmonary Syndrome — Americas. Caused by sigmodontine-rodent-borne hantaviruses, HPS is dominated by a capillary-leak syndrome in the lungs. After a 3–7 day flu-like prodrome, patients can decompensate respiratorily within hours. The case-fatality ratio for the two flagship pathogens (Sin Nombre and Andes virus) is roughly 30–40% even with modern intensive care. Treatment is supportive — early intubation, judicious fluid management (over-resuscitation worsens lung oedema), vasopressors, and ECMO at experienced centres.
HFRS — Hemorrhagic Fever with Renal Syndrome — Eurasia. Caused by murid-rodent-borne hantaviruses, HFRS is a five-phase illness: febrile, hypotensive, oliguric, polyuric, and convalescent. Severity scales with the pathogen — Puumala virus ("nephropathia epidemica") in Fennoscandia kills fewer than 0.5% of patients, while Hantaan and Dobrava-Belgrade can produce 10–15% case-fatality with bleeding, shock, and acute kidney injury requiring dialysis. Ribavirin started within the first six days has a modest mortality benefit for severe HFRS, an effect not replicated for HPS.
Why the split? The reservoir genera diverged tens of millions of years ago, and the hantaviruses co-evolved with their hosts. The result is two distinct viral lineages with subtly different receptor and tropism profiles — and two distinct clinical syndromes in their human spillover.
Both syndromes are notifiable to public health in most jurisdictions with surveillance capacity. Both share the same prevention strategy: avoid contact with rodents and their excreta, and use the CDC "open up, air out, wet down" protocol when cleaning rodent-infested spaces.