Newcastle disease virus (NDV) hemagglutination inhibition (HI) antibody titers of 1:20 or greater were detected in 80 of 200 serums from adult female and 9 of 35 adult male mallard breeders tested from three commercial game farm flocks in Wisconsin and Illinois. Six of 106 serums from mallard ducklings also were considered to be reactors. Almost half (49) of 100 swan serums from five aviculturist flocks in Michigan had HI antibody titers of 1:20 or greater. The possible significance of these findings regarding waterfowl management practices was discussed.

The first known case of rangiferine brucellosis caused by Brucella suis biotype 4 in a sled dog has been proven by isolation of the organism from the naturally infected animal. The infection was undoubtedly contracted from eating raw, infected barren-ground caribou, Rangifer tarandus granti, in which the disease is enzootic. Limited experience with infections in sled dogs suggests that the disease may run a comparatively mild course in them. Serological evidence indicating the natural occurrence of the disease in wolves, Canis lupus, also is reported for the first time.

Comparison of bot-infested and bot-free chipmunks collected during 1966–1969 revealed no significant differences in rate of infestation among sex-age classes. Splenomegaly and thymic involution were associated with bot infestation, and adrenal weights were greater in bot-infested adult females. Parasitized animals of all sex-age classes tended to be larger than non-parasitized individuals, and reproductive organs were heavier in infested adults of both sexes. Evidence of bot-induced mortality was not found, but results indicate the possibility of differential loss of bot-infested animals from the population.

North American elk (Cervus canadensis) were susceptible to experimental bluetongue virus (BTV) infection although clinical signs were mild or inapparent. A viremia of significant magnitude and duration occured in all five experimental elk following subcutaneous inoculation. Elk developed BTV antibody by the second or third week after exposure and antibody was still present in the sera of all animals at the termination of the experiment at 6 or 7 months. The possible role of elk in the epizootiology of bluetongue was discussed.

The development of the larval stages of Ophiotaenia gracilis Jones, Cheng and Gillespie, 1958, was experimentally demonstrated to occur in the copepod Eucyclops agilis. Eggs were recovered from worms found in naturally infected bullfrogs in Colorado. This is the first report of this parasite in Colorado.

Twenty-four hours after ingestion of the embryonated egg, procercoids were seen in the hemocoel of the copepod. Calcareous bodies appeared 9 days after infection. The larvae developed a cercomer by the 13th day of infection and lost it on the 16th day. Measurements and illustrations are given for the developmental stages.