Different strains: There are a large number of different varieties of influenza virus that have natural affinity for different species. Bird flu and swine flu are two such strains. The animal viruses occasionally acquire the ability to infect humans.
Answered 7/11/2012
5.7k views
A doctor has provided 1 answer
3 doctors weighed in across 2 answers
A doctor has provided 1 answer
A doctor has provided 1 answer
90,000 U.S. doctors in 147 specialties are here to answer your questions or offer you advice, prescriptions, and more.
Ask your question