90-Second Read: Why is Hantavirus so deadly? It’s not what you may think

Andes Hantavirus causes deadly lung failure, but its method of attack differs from other respiratory illnesses. What scientists have gleaned so far is informing how they monitor the more than 150 individuals worldwide currently in quarantine after the recent outbreak of the Andes Hantavirus on the cruise ship MV Hondius. Most patients who die do so either while being admitted to the hospital or within the first 24 hours after admission, Vial and colleagues discovered when reviewing 100 Hantavirus cases treated at eight hospitals in Chile over about eight years. A better understanding of its unusual killing method could point to future treatments Andes Hantavirus has only four proteins yet is a master of manipulating cells and the immune system.

The Hantaviruses grow slowly and kill swiftly, claiming the lives of up to half of people they infect. Forsell and colleagues have tracked Hantavirus antibody levels in blood from about 150,000 participants in the Northern Sweden Health and Disease Study. New treatments won't come soon enough for those affected by the cruise ship outbreak, but he is hopeful that attention to the outbreak will spur research that might benefit the more than 10,000 people estimated to be infected with Hantaviruses worldwide each year. Vial directs the Hantavirus and zoonoses program at the German Clinic at the Universidad del Desarrollo in Santiago, Chile.

But even though New World Hantaviruses cause a severe lung disease called Hantavirus pulmonary syndrome, they don't attack lung cells. An antiviral drug that stops Hantavirus growth in lab dishes didn't work in patients who were developing severe symptoms. Giving people plasma from patients who have recovered from a Hantavirus infection does help when people are just developing symptoms, Vial says. Antibodies that linger for decades in people who have recovered from infections of Puumala virus, an Old World Hantavirus, could also fight Andes virus, says Mattias Forsell, an immunologist at Umeå University in Sweden.

It's a small tool kit, but Hantaviruses make the most of it, evading the immune system while they slowly replicate. Puumala orthohantavirus: prevalence, biology, disease, animal models and recent advances in therapeutics development and structural biology. Though IL-6 is typically made by immune cells and sometimes liver cells, blood vessel cells infected with Hantaviruses also make IL-6, Klingström and colleagues found.