Survey to estimate prevalence of Leptospira interrogans infection in mature cattle in the United States.

A total of 5,142 kidney tissue samples and 5,111 serum samples from mature cattle in 49 states and Puerto Rico were collected at slaughter. Age of cattle ranged from 1 to 16 years (mean, 6.6 years). Leptospires were isolated from 88 (1.7%) kidney tissues, and 2,493 (49%) sera contained antibodies against 1 or more of 12 Leptospira interrogans serovars. Leptospires were observed by immunofluorescence in 41 (0.8%) kidney tissues. Using agglutinin-absorption tests, 73 (83%) isolates were identified as serovar hardjo, 11 (12.5%) as serovar pomona, and 4 (4.5%) as serovar grippotyphosa. By use of restriction endonuclease analysis studies of chromosomal DNA, all isolates differed from reference serovars but were identical to strains previously isolated from cattle or swine in the United States. Of the serovar hardjo isolates, 85% were identical to restriction endonuclease analysis type (genotype) hardjo-bovis A and 11 (15%) were identical to genotype hardjo-bovis B. Serovar pomona isolates were identical to genotypes kennewicki A (64%) or kennewicki B (36%), and serovar grippotyphosa isolates were identical to the RM 52 strain. Isolation rates were significantly (P less than 0.001) higher for beef cattle than for dairy cattle and were higher (P less than 0.001) for bulls than for cows. Combined culture and immunofluorescence results indicated that 2% of mature cattle were renal carriers of leptospires.

Domestic animal rabies control: an overview.

Models for rabies control, particularly in dogs and cats in urban centers in Western nations, have been based on mandatory regular vaccination and restriction of movement of animals, with removal of unrestricted animals. When this three-component approach has been unsuccessful or only temporarily maintained, especially in developing countries, constraints on implementation and maintenance, rather than the model itself, have been blamed. The ecology of the reservoir animals, the relations of dogs and cats to people, and the development of culturally adaptable approaches to rabies control have received little serious attention. As a part of a rabies control pilot program assisted by the World Health Organization, the city of Guayaquil, Ecuador, was chosen as an urban center of high rabies prevalence in animals and high rabies risk in people. The ecology of dogs and cats was investigated, and the findings were applied in developing a model based on community education, annual house-to-house vaccination campaigns, stabilization of the dog and cat populations, limitation of restriction and removal of animals to focal-outbreak control, and environmental measures to promote population control. Initial implementation has been successful, and longitudinal studies are in place to monitor maintenance of control.