RECOVERY OF PASTEURELLA-MULTOCIDA FROM EXPERIMENTALLY-EXPOSED FRESH-WATER SNAILS

We determined how long Pasteurella multocida could survive in experime ntally-exposed freshwater snails. Physa virginea were collected from t he Sacramento National Wildlife Refuge, Glenn County, California (USA) , an enzootic site for avian cholera. Exposure to water containing up to 10(7) P. multocida per mi did not produce observable changes or mor tality in snails. A minimum of 84 P. multocida per snail was necessary for detection among the normal snail bacterial nora. When snails were exposed to P. multocida in vials containing 10(7) bacteria per ml, P. multocida was detected for up to 72 hours in snails. When uninoculate d snails were placed in aquaria containing 10(6) P. multocida per ml, P. multocida was not detected within the snails; further, P. multocida was detected in the water for only 24 hours at this level. Based on t hese results, we propose that P. virginea is not an effective reservoi r for P. multocida.