H5N1 Virus Isolated from Infected Farm Worker Lethal in Mice and Ferrets

An H5N1 virus isolated from the eye of an infected farm worker was “lethal in mice and ferrets infected in a high-containment laboratory environment.” NIH has the news.

The investigators in the study “also found that the virus isolated from the worker, who experienced mild inflammation of the cornea (conjunctivitis), could be transmitted through the air between separated ferrets and might be capable of binding to and replicating in human respiratory tract cells.”

The virus had a mutation “frequently seen in avian influenza viruses that replicate in mammals, typically making virus replication more efficient.” The study also found two antiviral drugs the virus is susceptible to.

The researchers infected ferrets with a high dose of the virus; “all infected ferrets died within 5 days and scientists found huTX37-H5N1 virus in all the tissues sampled, with high levels in the respiratory system. In a prior study, the researchers had infected ferrets with a bovine H5N1 virus and, although it caused severe disease, lethality was limited.” Between 17% and 33% of nearby ferrets also became infected when housed about five centimeters away from already-infected ferrets.

The study authors stress that “based in these observations, every effort should be made to contain HPAI H5N1 outbreaks in dairy cattle to limit the possibility of further human infections.”