Two Deadly Syndromes, One Viral Family
The same broad family of viruses, the hantaviruses, can unfold into two very different nightmares in the human body. In parts of Asia and Europe it presents as hemorrhagic fever with renal syndrome (HFRS), a disease that attacks the kidneys and causes internal bleeding. In the Americas, it more often appears as hantavirus pulmonary syndrome (HPS), a condition that fills the lungs with fluid and can kill within hours.
Old World vs New World
Hantaviruses are divided loosely into “Old World” and “New World” types. Old World hantaviruses dominate in Asia and Europe and are responsible for HFRS. New World hantaviruses, found in North and South America, are usually behind HPS, also called hantavirus cardiopulmonary syndrome (HCPS).
These two forms share a similar beginning: after an incubation period of about 2–4 weeks, people develop vague, flu-like symptoms — high fever, chills, headache, backache, abdominal pain, nausea, and vomiting. But then their paths diverge.
When Kidneys Fail: HFRS
In HFRS, the disease pivots into a hemorrhagic crisis. Bleeding starts under the skin, blood pressure drops, and internal bleeding spreads throughout the body. The kidneys begin to fail, leading to serious complications and, in some cases, death. A milder European form, nephropathia epidemica, still brings fever, headache, gastrointestinal upset, blurred vision, and impaired kidney function.
When Lungs Flood: HPS
In HPS, after a similar early phase, a deadly second act begins. Over a few days, the patient suddenly develops progressive coughing, severe shortness of breath, and a racing heart as fluid rapidly collects in the lungs. At the same time, lymphoid organs, key parts of the immune system, become impaired. Many deaths result from cardiovascular shock soon after these severe symptoms appear.
Although HCPS is usually linked to New World hantaviruses, there is a twist: in rare cases the Puumala virus in Europe has also caused an HCPS-like illness, blurring the geographic lines.
One Mechanism, Different Outcomes
Beneath these different clinical pictures lies a shared mechanism: low platelet counts and leaky blood vessels. Platelets help blood clot, and when they drop, bleeding is more likely. At the same time, blood vessels become unusually permeable, allowing fluid to seep into tissues — into the lungs in HPS, and with widespread internal bleeding and kidney injury in HFRS.
A Sobering Risk
The numbers tell their own story. About 100,000 cases of HFRS occur every year worldwide, with a fatality rate of roughly 12%. HPS is rarer — about 1,000 documented cases since 1993 — but far deadlier, killing about 40% of those infected.
Two faces, one viral family: whether it is the kidneys or lungs that fail first, hantaviruses reveal how fragile our circulatory system is when blood vessels themselves turn against us.