What makes the Ebola virus so frightening is its speed. In a matter of days, it can pump out enough copies of itself to overtake the immune system. But the Hemopurifier, a specially designed cartridge that attaches to a dialysis machine, can tip the balance back in the body’s favor: its lectin filter attracts Ebola viruses and sucks them from the blood as it flows through. It’s been used only once, on a patient in Germany, but it did the trick—effectively curing his Ebola infection. In the future, doctors hope similar tech could be used on viruses like hepatitis.