Estudo sorológico e molecular da infecção por Leptospira spp. em pequenos ruminantes no Semiárido Nordestino, Brasil.

Abstract

The leptospirosis is an infectious and contagious disease caused by bacteria of the genus Leptospira spp. widespread in Brazil. Small ruminants are susceptible to infection generating economic losses as it determines reproductive failures in these animals, as well as problems in public health as it is an important zoonosis. The aim of this work was to detect Leptospira spp. DNA, determine the frequency of specific antibodies and proceed to the isolation of the agent in goats and sheep slaughtered in different slaughterhouses in the State of Paraiba, in the semi-arid region of the Brazilian Northeast. 1049 animals were used originated from 19 municipal slaughterhouses, being 500 goats and 549 sheep. To verify the presence of anti-Leptospira spp antibodies the microscopic agglutination test (MAT) was used, using 24 serovars as antigens and the cut-off point 1:100. Samples of kidneys and urine were used for the molecular detection (PCR) and bacteriological cultivation of leptospires in 49 woolless sheep. The frequency of seropositive animals for leptospirosis in the 49 woolless sheep was of 8.2% (4/49). The number of sero-reactive animals among the 1000 analyzed goats and sheep was 82 (8.2% IC 95% = 7.0-10.5%), in which 26/500 (5.2% ; IC95% = 3.5- 7.5%) were goats and 56/500 (11.2%; IC95% 8.7-14.2% ) sheep. The most frequent serovars in the 1000 animals studied were Hardjobovis (14.6%) and Autumnalis (13.4%). In the PCR of the renal tissues three animals were positive, whilst in the urine was not detected any positive animal. The cultivation was negative for all the samples. It is concluded that sheep and goats of the semi-arid region of the Northeast may have become adapted to the sorovars Harjobovis and Autumnalis, as well as wild rodents may be involved in the transmission of the disease. It is suggested the hypothesis that the rusticity of the small ruminants in the studied region contributed to the low sero-reactivity verified, and these may be resistant to infection. The PCR revealed to be an important tool in the detection of animals carriers of leptospires, demonstrating to be a highly sensitive technique even in negative animals.