THE EPIDEMIC POTENTIAL OF BRAZILIAN MYXOMA VIRUS (LAUSANNE STRAIN) FOR THREE SPECIES OF NORTH AMERICAN COTTONTAILS

Regnery, David C. (Dept. Biological Sciences, Stanford Univ., Stanford, Calif. 94305). The epidemic potential of Brazilian myxoma virus (Lausanne strain) for three species of North American cottontails. Amer J Epidem 94: 514–519, 1971.—Three species of North American cottontails (Sylvilagus audubonii, S. floridanus, and S. nuttallii) developed prominent tumors after being infected with Brazilian (Lausanne strain) myxoma virus. One Audubon cottontail was infected with an Australian attenuated derivative (KM13) of Brazilian myxoma virus. Only primary tumors were observed in S. audubonii and in S. floridanus, but in S. nuttallii extensive secondary tumor formation followed either inoculation or mosquito transfer. One S. nuttallii died 22 days after infection, the other was sacrificed 29 days after infection at which time it was in a moribund condition. Mosquitoes (Aedes aegypti) acquired enough virus by probing the tumors to facilitate transfer to susceptible Oryctolagus. On the basis of the results of these experiments it seems possible that Brazilian myxoma virus could become established in some S. audubonii or S. nuttallii populations. The virus could reduce the population density of S. nuttallii.