Epidemiological study of swine influenza virus as a component of the respiratory disease complex of feeder calves.

A survey of 177 paired calf sera collected during the years 1978-1981 showed that 3.4% of the calves had prior experience with swine influenza virus. Six calves positive by the single radial hemolysis test (SRH) were also positive by the virus neutralization test (VN) in chicken embryos, and one calf reacted with all three tests (hemagglutination-inhibition (HI), SRH, and VN). The SRH and HI tests available cannot adequately provide the information necessary in a survey of this sort. The HI test is subject to too many variations to enable the data to be used with any degree of confidence. The SRH test lacks accepted standarization for performing the test with cattle sera. Therefore, the VN test is necessary for confirmatory results.