Medicine: Mouse Fever

At the height of the Korean War in 1951, hundreds of G.I.s were struck by a malady characterized by fever and bleeding from the mouth, nose and internal organs. Nothing medics did seemed to help. Most of the soldiers eventually recovered, and the mysterious ailment was later identified as epidemic hemorrhagic fever. But Army doctors were unable to find either the cause of the disease or how it was transmitted.

Now, after years of patient investigation supported by funds from the U.S. Army, a South Korean medical researcher may have solved the mystery of a disease that last year afflicted thousands of Asians, including at least 800 South Koreans. Dr. Lee Ho Wang says that the dangerous ailment is caused by an elusive virus borne by a tiny Korean field mouse that lives in mountainous areas. If Lee’s discovery is confirmed, it should not only help doctors make a faster diagnosis of the disease but also pave the way for the development of a vaccine against it.

Russian doctors who wrote the first comprehensive reports on the disease —after a 1913 outbreak in Vladivostok —suspected a rodent-borne virus, but neither they nor later researchers were ever able to isolate the culprit. Lee himself made little progress until 1971, when a member of his team assigned to catch rodents for research was suddenly felled by hemorrhagic fever. The lab was immediately quarantined and work interrupted for several months, but the incident made Lee even more certain that the carrier was indeed a rodent. During seven years, the research team collected more than 2,400 mice and other rodents, examined countless human and animal organs and isolated no fewer than 16 unknown viruses.

Disease Agent. Finally, Lee made the crucial connection. He took viral material from a Korean subspecies of the mouse known as Apodemus agrarius and mixed it with blood serum from patients recuperating from hemorrhagic fever. The blood proved to contain antibodies—protective proteins developed by the body’s immune system in response to invading foreign substances —that matched and combined with the viral material from the mouse. There were no such linkups when Lee did the same with the blood of people who had never suffered from hemorrhagic fever. Thus the mouse virus was almost certainly the cause of the disease.

How is the disease transmitted? Because hemorrhagic fever peaks in May and October, the dry seasons in South-Korea, Lee suspects the virus lives in the droppings of Apodemus agrarius and attacks humans when they stir up dust and inhale virus-laden particles.