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A comparison was made with the microslide gel diffusion technique, the complement fixation test, cultural isolation, and clinical examination in detecting ram epididymitis caused by Brucella ovis. The results of the gel diffusion method are shown to be similar to those obtained by the complement fixation test and isolation of B. ovis from cultures of semen. The technique offers a reliable diagnostic method adaptable to field use in controlling ovine brucellosis and is more practical.

A serologic, bacteriologic, and histopathologic examination for leptospires was carried out on 89 armadillos (Chaetophractus villosus) from Argentina. Forty-seven per cent of the serum samples yielded positive results when tested by microscopic-agglutination. Predominant agglutination reactions were to the Hebdomadis and Bataviae serogroups. A total of 15 Leptospira isolations (from 16.8 per cent of the animals tested) were obtained from kidney tisse. Nine of the isolates were identified as belonging to the Bataviae group serotypes argentiniensis, paidjan, or bataviae; three other isolates proved to be the Canicola group serotype canicola; two others were Leptospira biflexa strains; and the last isolate was found to be serotype hardjo of the Hebdomadis group. The latter finding represents the first isolation of serotype hardjo from this animal species. Histopathologic examination of kidneys from 11 of the animals yielding pathogenic leptospires permitted a diagnosis of interstitial nephritis. This intersitial nephritis, presenting the characteristic picture of lymphoid infiltration, appeared intense in two animals, moderate in five others, and only slight in the remaining four. These histopathologic findings of chronic nephritis, combined with the high positive serologic and cultural isolation rates, suggest that the armadillo is an important natural reservoir-host for pathogenic leptospirae.

Of 1,065 persons sampled during a house-to-house survey of an area of the Department of Curuzú Cuatiá, Province of Corrientes, Argentina, 21 were seropositive to Brucella canis antibodies by the gel-diffusion test, using a saline-extracted B. ovis surface R antigen. Two positive reactors were similarly identified during a survey of rural schools in the Province of Neuquén, which included 887 persons. The findings are discussed in terms of current knowledge of this recently recognized zoonotic infection.

A serological evaluation was done on the prevalence of bovine leptospirosis in Argentina. In 1,857 serum samples obtained from the major cattle raising areas of the country, 59.1 percent showed leptospiral agglutinins in the microscopic-agglutination test. The most frequent leptospiral antigens showing antibody reactions were the hebdomadis group serotypes, of which 45.8 per cent of the sera reacted to Leptospira hardjo with titres ranging from 1:100 to 1:25,600. Six Leptospira isolations were made from 161 bovine kidneys collected at local abattoirs. Their isolation and subsequent identification as serotype L. hardjo is described. This study reports on L. hardjo in cattle of Argentina for the first time and confirms the need for improved cultural methodology for its isolation.

A focus of B. canis infection was identified in Moreno, Argentina, among the stray dog population by serologic methods and confirmed in a second survey which included cultural isolations. A counterimmunoelectrophoresis technique using a specific rough Brucella surface antigen was applied to the serodiagnosis of canine brucellosis. This method was found to be as effective as the mercaptoethanol tube agglutination test and the gel diffusion test in detecting B. canis antibodies in natural and experimentally infected animals. The results are discussed in terms of the diagnostic significance of the three tests employed.

Three pathogenic leptosipras and 12 saprophytic Leptospira biflexa strains were isolated from 72 apparently normal horse kidneys collected at an abattoir in Argentina. Cross-agglutination reaction patterns of the pathogens showed that they were antigenically homologous with members of the Hebdomadis group. When one of the strains was compared to Hebdomadis serotypes in reciprocal agglutination-absorption tests, it was found to be serologically homologous to serotype hardjo. This is the first known report of an isolation of this serotype from horses. Serological tests were also carried out on randomly collected abattoir sera from 245 horses to determine the prevalence of equine leptospirosis. Significant antibody titers (1:100 or greater) were found in 74.6% of the sera. Predominant reactions occurred with the antigens pomona, hebdomadis group, pyrogenes, tarassovi, and canicola. Agglutination tests performed with antigen prepared with one of the saprophytic biflexa isolates showed seropositive reactions in 99.1% of the equine sera, with agglutination titers ranging from 1:100 to 1:3,200. Absorption of selected horse sera with the saprophytic strain removed the agglutinins to Leptospira interrogans serotypes. This suggests the possibility that L. biflexa strains may act as an antigenic stimulus and account for some of the persistent multiple cross-reaction patterns of equine sera with pathogenic serotypes.

Sera collected during surveys of presumably healthy rural inhabitants of the Provinces of Corrientes and Neuquén, Argentina, were examined for serological evidence of leptospirosis. Significant antibody levels (1:100 or greater) were found in 8.7 per cent of 1,029 sera from residents of Corrientes Province. The most frequent reactions occurred against the serotypes australis, hebdomadis group, pomona, and icterohaemorrhagiae. The predominance of antibodies to the Australis group in the country is new and suggests the emergence of leptospirosis in an unrecognized animal reservoir host. Out of 706 sera collected from rural school students and sera from 71 adults in the Province of Neuquén, only 4 (0.5%) showed leptospiral agglutinin in the microscopic agglutination test and these were only at a 1:100 serum dilution. The higher percentage of reactors in the Corrientes population appears to reflect a more favorable environment and a greater risk of infection.

A serologic survey for leptospirosis in stray dogs from Moreno, Province of Buenos Aires, was carried out. Sera from 143 randomly collected animals were examined by the microscopic agglutination test. A total of 73 (51.0%) of the dogs have had contact with leptospirae. The predominant leptospiral agglutinnins were to serovar canicola (37.0%) and to a lesser degree against the serovar antigens pyrogenes (4.8%) and autumnalis (2.0%). Although a high percentage of seropositive reactions occurred against the serovar antigens ballum, pyrogenes and icterohaemorrhagiae, all the reactions against ballum and icterohaemorrhagiae, and the majority of the reactions to pyrogenes represented the natural coagglutinins frequently associated with serovar canicola. The detection of antibodies to the Autumnalis group in dogs of Argentina could be new and suggest the emergence of canine infections caused by a serovar of this serogroup which should be sought out and identified.