The new H3N2 strain of swine influenza virus is spreading quickly through U.S. hog operations and now accounts for about half the flu cases reported, according to veterinarians speaking at a recent tele-news conference. Dr. Rick Sibbel, Ankeny, Iowa, a technical service veterinarian with Schering-Plough Animal Health Corporation, pointed to a recent survey of 129 Iowa herds conducted by researchers at Iowa State University. H3N2 appears to have spread fairly quickly. It1s also possible the H3N2 strain has been in the pig population and became infective among pigs across several regions about the same time, he speculated.
Correct diagnosis is crucial.
The vaccine has already been updated and contains two H3N2 isolates to help assure it will provide the broadest possible protection, Dr. Sibbel said. NVSL1s Dr. Swenson also emphasized the importance of testing before vaccinating for H3N2 because it is difficult if not impossible to clinically differentiate H1N1 from H3N2. I know of one 3,600-head herd vaccinated for H3N2, but it turned out to be H1N1. Once the presence of H3N2 has been confirmed, the vaccination plan should be devised carefully, the veterinarians said. That part of the program helps minimize the subpopulation effect that occurs with this disease.