Results of laboratory diagnostics of animal leptospirosis by various methods in the Russian Federation for 2021

Abstract

The scientific article presents generalized materials of the results of bacteriological, serological and molecular genetic studies in the diagnosis of animal leptospirosis performed in the state veterinary laboratories of the Russian Federation in 2021. According to the results of the analysis, it was found that populations of productive and unproductive animals are involved in the epizootic process of leptospirosis, the epizootic situation for leptospirosis continues to remain tense. A total of 1 506 785 samples (aborted fetuses, pathological and biological material), as well as 236 water samples were examined for leptospirosis by specialists of the state veterinary laboratories of the Russian Federation during 2021. A total of 9 747 377 studies were performed using classical and molecular genetic methods. 21 530 positive results were obtained (1,4 %). 538 aborted fetuses from 3 types of farm animals (cattle, small cattle and pigs) were studied by bacteriological methods and using PCR. In 98,3 % of cases, the studies were performed using PCR. A total of 9 (1,7) positive results were obtained, including cattle – 3 (1,0), pigs – 6 (2,7 %). The pathological material was examined by bacteriological methods and using PCR of 1263 samples. At the same time, 98,8 % of all studies were carried out by the molecular genetic method. A total of 40 positive results were obtained (3,2 %), including 4 cases in cattle (1,7 %), 1 in small cattle (6,7), 32 in pigs (3,6), 2 in dogs (50,0), and 1 in other animal species (1,1 %). Using PCR, 7674 blood samples were examined, 15 positive results were obtained (0,2 %), including the leptospir genome was detected in cattle in 8 cases (0,3), in pigs and other animal species, respectively, in 4 cases (0,1 %) and 3 (1,8 %). 1 404 076 blood serum samples were received for serological diagnostics, 45 897 ELISA studies were conducted, and 9 598 535 samples were taken in the classical microagglutination reaction (PMA). Specific antibodies to leptospira were detected in 21 148 samples (1,5 %). The largest number of seropositive animals was found among horses – 2744 samples (4,1), cattle – 14 104 (2,5) and pigs – 2848 (0,5 %). 93 099 urine samples were examined to identify leptospira-bearing animals. The percentage of identified patients was: horses 0,2 %; cattle – 0,3 %; small cattle – 4,4; other species – 0,1 (cats, furbearing animals, zoo animals, other species). A total of 318 (0,3 %) positive results were obtained. 99,6 of the studies were performed by dark-field microscopy, 0,4 % by PCR. In the study of 113 semen samples from cattle and 22 samples from boars, leptospir DNA was not found. Bacteriological studies of 236 samples of water from open reservoirs gave a negative result. It should be noted that the reliability of the diagnosis of leptospirosis in animals largely depends on the quality of sampling materials, storage conditions of samples, compliance with temperature conditions, time of delivery of samples to the laboratory for testing, the level of equipment of laboratories with modern equipment and diagnostic drugs, as well as on the professional competencies of a particular doctor.