ABSTRACT
Leptospires excreted by urine are able to survive for long periods in surface water and soil depending on the pH, humidity and organic matter presence. This paper reported the influence of environment conditions on the transmission of leptospirosis in two sheep-only farms (A and C) and two cattle-sheep farms (F and H) from December 2007 to September 2008. Serum samples were examined by microscopic agglutination test; urine, surface water and soil samples were cultured for leptospires, and ovine urine pools were analyzed by PCR. Regional edaphoclimatic conditions, pH of surface water and soil, granulometry and permeability of soil were analyzed. All herds presented at least one reactor to Leptospira spp. Only the PCR of an ovine urine pool of herd H was positive and Leptospira spp. was isolated from the F lake. The pH of water samples ranged from 6.0 to 7.0; while in soil it was around from 4.5 to 6.8. Soil organic matter were 24 to 35 g/dm3 in A, C e H, and 63 g/dm3 in F. Soil samples of A and F showed loamy-clay texture; C had clay soil, and H loamy-silt soil; as mixed compositions are able to maintain the humidity, mainly where clay is present. As the presence of reactors in all herds indicated the contact with Leptospira spp., it was concluded that the cycle of transmission is dependent on the synergistic and antagonistic interaction of many variables; but the close contact of animals grazing in a high humidity habitat seems to be limiting.
KEY WORDS
Ovine leptospirosis; ovine - bovine grazing together; edaphoclimatic conditions