| laboratory-based surveillance of influenza virus in the united states during the winter of 1977-1978. i. periods of prevalence of h1n1 and h3n2 influenza a strains, their relative rates of isolation in different age groups, and detection of antigenic variants. | influenza a (h3n2) viruses were isolated from outbreaks and epidemics of disease during the period december 1977 to march 1978. for the last two months of this period, h1n1 strains of influenza a were also responsible for epidemics. in some regions (e.g., hawaii) co-circulation of h1n1 and h3n2 strains occurred, whereas in other regions (e.g., wisconsin) isolation of h3n2 strains had almost ceased prior to isolation of h1n1 strains. few influenza b isolates were reported. analysis of the ages of ... | 1979 | 507036 |
| influenza exposure in united states feral swine populations. | swine play an important role in the disease ecology of influenza. having cellular receptors in common with birds and humans, swine provide opportunities for mixed infections and potential for genetic reassortment between avian, human, and porcine influenza. feral swine populations are rapidly expanding in both numbers and range and are increasingly coming into contact with waterfowl, humans, and agricultural operations. in this study, over 875 feral swine were sampled from six states across the ... | 2008 | 18436668 |