Pox and Haemoproteus sp. infections in a mute swan are reported. Experimental study of the swan pox isolate indicated that geese were susceptible, but chickens, ducks, and pigeons were resistant to the virus. The distinctive feature of pox infection in the swan was the invasive proliferation deep into the subcutaneous tissues of the face and beak, producing facial deformity and swelling.

The deer from Tyler County, Texas, had heavy infestations of ticks (Amblyoma americanum) and were infected by the hemoprotozoan (Babesia cervi). These two factors may be responsible for the unthrifty condition and low reproductive ability of the deer from Tyler County.

Leptospiras isolated from creek water in Iowa at the site of human leptospirosis exposure could not be identified by a reference laboratory but the 31 isolates were placed into 12 serologic groups using serologic cross reactions and agglutinin absorption techniques. Reactions of the isolates to 8-azaguanine and copper sulfate suggest that they belong to the nonpathogenic or saprophytic complex. Cloning procedures failed to detect any leptospires that could be classified as pathogenic or parasitic but did indicate that some isolations from water contained serologically heterogenous populations of leptospires. The possible significance of these results is discussed.

Environmental studies were conducted to determine survival potential of leptospires in a farm creek. The creek was the swimming site involved in two previous outbreaks of human leptospirosis. Finding infected mammals in the area and the isolation of pathogenic leptospires from the water supported the theory that an endemic foci existed.

Precipitation was sufficient to cause numerous floodings of the creek and surface run-off was evident. The water temperature data indicates that for several months each year the temperature range was adequate for survival of pathogenic leptospires. Saprophytic water leptospires were found during the total year. Although the pH of the creek water ranged from 6.9 - 8.7 the majority of samples were slightly alkaline and considered adequate for maintenance of leptospires. Several nutrients were found in the water including NH₃, B₁, B₁₂, considered essential for leptospiral growth.

If infected mammals are shedding leptospires, it is likely that the creek environmental conditions herein determined are usually adequate for survival. The creek water becomes a vehicle and an ecologic foci for transmission of leptospires to animals and man.

Serologic tests for leptospiral antibodies were conducted on 3236 sera from white-tailed deer killed in Pope County, Illinois from 1957 through 1968. Antibodies were detected to Leptospira pomona in 162 (5.0%) samples. The percentage of reactors was significantly less in female deer and in fawns of both sexes. The distribution of reactors in the county showed a reactor incidence (reactors/1000 deer tested) of 103 in areas with lower deer densities and higher cattle densities. The incidence in areas with more deer and fewer cattle ranged from 14 to 44.

The incidence of leptospirosis due to L. pomona and L. hardjo in 900 cattle at the Dixon Springs Agricultural Center was evaluated annually by the microscopic agglutination test during a 15-year period.

The L. pomona reactor rate ranged from 5 percent in 1954 to 58 percent in 1955 during the period from 1953 to 1958 when the cattle were not vaccinated. Abortions were observed during 1955 and 1960.

The L. pomona reactor rate ranged from 15 percent to 28 percent between 1959 and 1964 when half of the cattle were vaccinated and declined to 0.5 percent to 5 percent when all of the cattle were vaccinated with L. pomona bacterin.

An infection of L. pomona vaccinated cows occurred in 1968 as indicated by a MA titer response of 1:100. No clinical signs were associated with the infection. The infection may have been caused by an endemic infection in a few carrier cattle or from infected wildlife. The skunk had previously been shown to be an active shedder.

The L. hardjo reactor rate ranged from 29 percent to 56 percent during the period from 1958 to 1966 when the cattle were not vaccinated and 33 percent during 1967 and 1968 when half of the cattle were vaccinated.

Data obtained on losses occurring among various species of waterfowl due to avian cholera were analyzed statistically. Coots, gulls, rodents and rabbits were inoculated with suspensions of Pasteurella multocida.

The relation between population size of the individual waterfowl species and the respective mortality rates was not statistically sigificant. No correlation could be found for the average weights and the death rates occurring in each species. The widgeon duck, white-fronted goose and coot had higher losses from avian cholera than other waterfowl. Gulls were more resistant to P. multicoda than the coot, and the laboratory rat was completely resistant whereas the Norway rat was susceptible.

Nasal pharyngeal swabs were taken from 400 waterfowl and 37 feral pigeons (Columba livia) and cultured for the presence of Pasteurella multocida, the causative agent of fowl cholera. Blood samples were also taken from these birds and tested for antibodies for P. multocida. Pasteurella multocida was not isolated from any of the birds. However, two of the waterfowl had antibodies for P. multocida. The nasal pharynges of 50 Canada geese (Branta canadensis) were also cultured for Pasteurella anatipestifer, the causative agent of anatipestifer infection. Pasteurella anatipestifer was isolated from 4 of these geese. Experimental inoculation of mallards (Anas platyrhynchos) demonstrated that they are susceptible to anatipestifer infection.

The brains of 1,634 wild animals trapped for pelts were examined for rabies by the fluorescent antibody procedure. Twenty-one of 268 striped skunks and 2 of 52 spotted skunks examined were positive for rabies. Thirteen hundred twenty three animals including 7 badgers, 65 coyotes, 365 foxes, 1 weasel, 377 mink, 52 muskrats, 208 opossums, 219 racoons and 1 wolf were negative.

Studies show that duck plague virus elicits comparable clinical and pathologic responses in domestic White Pekin ducks (Anas platyrhynchos domesticus), wild mallard ducks (Anas platyrhynchos), and Canada geese (Branta canadensis). All these birds were infected by oral inoculation or contact exposure. The antibody response was similar in both duck species. Clinical signs were ruffled feathers, increased lachrymation, nasal secretion, diarrhea, and reddening of the cloacal mucosae. The mortality rate was high in Pekin ducks and Canada geese, while mallard ducks were more resistant. Serums from birds that survived infection had a relatively high antibody level. The pathologic changes were qualitatively comparable in all three waterfowl species and were characterized by generalized congestion, hemorrhages in the serous and mucous membranes and necrosis of the gastrointestinal mucosae as well as the liver. Intranuclear inclusion bodies having staining characteristics of DNA viruses were found in the hepatic cells and epithelium of the esophageal and cloacal mucosae. These inclusions and other pathologic alterations might be valuable in diagnosing duck plague in wild waterfowl.

Studies of arbovirus infections of snowshoe hares in central Alberta were carried out in 1961 through 1967, in an attempt to determine which arboviruses were importantly associated with the hare population. These studies were carried out during a period of marked decline of the hare population. Neutralizing antibodies to California encephalitis virus and Silverwater virus were present in the population throughout the study with prevalence ranging from 59% to 97% and from 0% to 68%, respectively. Antibody prevalence rates to western equine encephalomyelitis virus were generally low except for two epizootics during the spring and early summers of 1963 and 1965, when rates of over 80% were observed. The significance of these findings is discussed. Data are presented which show a rapid, significant decline in neutralizing antibody prevalence which suggests that hares convalescent from these arbovirus infections experienced higher mortality than did uninfected animals.

The relationship between the California encephalitis (CEV) group of arboviruses and a snowshoe hare population near Rochester (54N, 113W), Alberta has been studied since 1961. The neutralizing antibody prevalence to the CEV group of viruses in adult hares was high, 58% to 95%, during the 6 years of snowshoe hare population decline, when the population dropped from over 600 hares per square mile to 3 hares per square mile. In the 2 years of population recovery thus far observed, the antibody prevalence has been low, 0% to 43%. The prevalence rates in juveniles have been lower than in the adults throughout the study. At least 2 strains of the virus group are present and a total of 7 isolations from Aedes mosquitoes and 1 from a snowshoe hare have been made, representing the northern most known limit of the CEV froup in North America. Experimental viremia studies with the Montana snowshoe hare strain of virus resulted in titers up to 10⁴ mouse LD₅₀ per ml. of whole blood and viremia lasted up to 3 days with an increase in length of viremia with age.

A serologic study was conducted to investigate the exposure of captive and free-flying Canada geese (Branta canadensis) to five arboviruses, chlamydiae and Mycoplasma gallisepticum. Of more than 1200 serums screened in the metabolic-inhibition test (MIT), no serums neutralized eastern encephalitis virus (EEV), less than 1% neutralized western (WEV) or Venezuelan (VEV) encephalitis viruses, 2% neutralized St. Louis encephalitis virus (SLEV), and 29% neutralized California encephalitis virus (CEV). Supplementary serologic procedures indicated that a nonspecific inhibitor probably caused inhibition of CEV in the MIT.

Fifty-six per cent of 197 serums had hemagglutination-inhibition titers of 1:80 or higher against M. gallisepticum and were considered “positive”. Two hundred and eight serums were negative for complement-fixing antibody against chlamydiae.

Between November, 1966 and November, 1968 serum samples from 725 wild vertebrates from south Florida were examined for antibody to Venezuelan encephalitis virus by the hemagglutination-inhibition test. Antibodies to Venezuelan encephalitis were found in 29 sera from the cotton mouse, Peromyscus gossypinus, the cotton rat, Sigmodon hispidus, the rice rat, Oryzomys palustris, the black rat, Rattus rattus, and the white-tailed deer, Odocoileus virginianus. Recent circulation of Venezuelan encephalitis virus in habitats other than documented enzootic foci warrants extensive ecological studies in areas adjacent to the Everglades National Park.

Aspergillosis was diagnosed as the cause of mortality during an epizootic in which 32 of 140 captive herring gulls (Larus argentatus) died. The cause of disease was attributed to the individual or cumulative stresses of capture, transportation, confinement, and a nutritional deficiency allowing subclinical levels of Aspergillus fumigatus fungi present in the gulls at the time of capture to produce overt disease.

A cycle of prevalence of Q-fever antibodies in sheep is confirmed, and possible relationships between sheep, wild mammals and birds in the ecology of Q-fever are exhibited. Carnivores and carrion-eaters, including coyotes (Canis latrans), turkey vultures (Cathartes aura), grey foxes (Urocyon cinereoargenteus), and hawks [Red-tailed hawk (Buteo borealis) and Sparrow hawk (Falco sparverius)] have serological evidence of Q-fever indicating exposure relative to their food habits. Herbivorous mammals and birds have evidence of Q-fever exposure relative to their relationship with sheep: species that share the same pastures as the sheep have a higher percentage with Q-fever antibodies than species inhabiting the protective underbrush or species that are more independent of the activities of livestock. A detailed study of 5 representative wildlife species, including the deer mouse (Peromyscus maniculatus), black - tailed jackrabbit (Lepus californicus), Columbian black-tailed deer (Odocoileus hemionus columbianus), ground squirrel (Citellus beecheyi), and the common red-wing blackbird (Agelaius phoeniceus) indicated that the blackbird has a peak prevalence of antibodies before that of sheep, the black-tailed jackrabbit and the ground squirrel seem to parallel sheep in cyclic responses, and the peak prevalence of Q-fever antibodies in the deer mouse occurs after the peak response in sheep. Deer responses appear to be unrelated to sheep responses.

In each of three successive years male yellow perch (Perca flavescens) examined from South Bay, Lake Huron were found to have testicular tumors. From a total of 2630 males examined 190 were tumor-bearing. Similar tumors were observed also in yellow perch from Lakes Erie and Ontario.

A furunculosis epizootic during May 1968 decimated the yellow bass population in Clear Lake, Iowa. Loss in body weight during the previous year and reduced fecundity suggested that inadequate nutrition resulting from over-population was a causal factor.

A new microsporidian parasite from the muscular tissue of the body wall of the Piute sculpin from Lake Tahoe is described. The name Plistophora tahoensis is suggested in recognition of the habitat of the host and the uniqueness of the fauna of the lake. Fresh spores were ovoidal and measured 6.05 ± 0.14 by 3.03 ± 0.11 microns for spore length and width, respectively. Fixed and stained spores were somewhat smaller. The polar filament measured 140.9 ±3.8 microns which was 23.28 times the mean spore length. Cysts, which measured 0.4 to 0.9 mm long, were present in the abdominal body wall between the points of insertion of the pelvic fins. The macroscopic cysts were composed of several smaller cysts derived from infected muscle bundles. Cysts displaced the muscles and weakened the body wall. Uninucleate, binucleate, and multinucleate schizogonic stages were recognized. Sporogony resulted in the development of a sporonts measuring 15–24 microns which produced 20 to 48 spores.

New Jersey bullfrogs, Rana catesheiana, were found to be heavily infested with filarial worms of the genus Foleyella Seurat 1917. A technique was devised to rapidly screen amphibians for the infection. The results of a state-wide survey are presented and a possible life cycle is suggested. Preliminary transmission studies indicated the mosquito, Culex territans, to be a natural vector.

Fecal samples were collected from white-tailed deer, Odocoileus virginianus, in Pennsylvania, Texas, and Wisconsin. Four species of Eimeria which have not been reported previously from white-tailed deer were found. Two new species, E. virginianus and E. madisonensis are described, while E. mccordocki and E. odociolei are compared with their original descriptions from mule deer, Odocoileus hemionus. Oocysts of E. virginianus are elongate ovoid to ellipsoidal with micropyle. They have a rough outer wall and measure 42.3 to 55.0 by 26.2 to 42.0_μ, mean 49.2 by 32.6. Oocysts of E. madisonensis are nearly round with a smooth outer wall and measure 14.0 to 19.1 by 12.8 to 16.3_μ, means 16.1 by 15.5. Eimeria mccordocki and E. odocoilei were found in deer from all three states, E. virginianus, in deer from Pennsylvania and Wisconsin, and E. madisonensis, only from Wisconsin deer.

Wildlife rabies invaded Ontario in 1954 along the coasts of Hudson and James Bays. During the period 1954 to 1958, rabies was carried into southern Ontario by red foxes (Vulpes vulpes), and in 1958–59 a severe epizootic of rabies occurred. From 1961 to 1969 rabies has remained endemic in southern Ontario. The red fox and striped skunk (Mephitis mephitis) are the main wildlife vectors, and account for 43% and 16% of the total rabies cases respectively. Of the domestic species, cattle make up 22%, dogs 7%, and cats 5%. The remaining 7% are in several other wild and domestic species. An annual cycle of rabies occurs each year, with a peak in December and a low in June. Three year cycles of red fox rabies occur in areas of good red fox habitat. During the initiation of the fall-winter rabies peak, the red fox is the species most commonly involved.

Because of the importance of the red fox as a rabies vector, a sample of 244 rabid red fox heads was collected over a one year period to study the sex-age structure of the rabid population. Animals were sexed by the sex chromatin technique and aged by counting tooth cementum layers. Forty percent of the heads showed evidence of ferocious contact as indicated by bites or cuts. Females showed a significantly higher rate of ferocious contact in March during the time of parturition. Animals from high rabies areas showed significantly more evidence of ferocious contact than did animals from areas of isolated cases. Thirty-four percent of the rabid red foxes had attacked porcupines (Erethizon dorsatum) as evidenced by porcupine quills in their muzzles. This species is usually avoided by normal red foxes.

During the increase in rabies in late summer and early fall, juvenile males were the predominant sex-age class in the rabid sample. This increase in rabies corresponds to the time of dispersal and reproductive maturation in juvenile males.

The peak of red fox rabies is in March. Yearling females were the most common sex-age class during this time, which also corresponds to the time of parturition. The oldest rabid red foxes were 4 years old. The results of the study indicate apparent relationships between the susceptibility of red foxes to rabies and various physiological changes which occur at different times of the year.