Mycoplasma bovis infection in respiratory disease of dairy calves less than one month old

Mycoplasma bovis is an important cause of bovine respiratory disease, especially in young calves where it can also cause arthritis, tenosynovitis and otitis. During 2009 and 2010 a survey was carried out on carcasses of calves less than one month old sent to the Diagnostic Laboratory of the Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna in Brescia, regardless of the presence of lung lesions, to detect this pathogen. PCR tests for Mycoplasma spp. and M. bovis were applied. 83 out of 224 (37%) lung tissue samples examined were positive at PCR test for Mycoplasma spp.; in 64 cases of these we observed typical respiratory lesions (P<0.001). M. bovis was identified in 26 out of 83 (31%) lung tissue samples positive at PCR test for Mycoplasma spp.; in 24 cases of these we observed typical respiratory lesions (P=0.039). Our data demonstrate that presence of Mycoplasma spp. and M. bovis positively correlates with pneumonic lung lesions in young dairy calves.

Epidemiological investigation of Streptococcus equi subspecies zooepidemicus involved in clinical mastitis in dairy goats

An outbreak of clinical mastitis was observed in dairy goats due to the zoonotic pathogen Streptococcus equi ssp. zooepidemicus. Affected goats were culled to prevent transmission of infection to other animals or humans. The objective of the study was to determine whether horses on the same farm were the source of the pathogen. Streptococcus equi ssp. zooepidemicus was obtained from milk of 10% of goats in the herd and from feces of 3 of 7 healthy horses that shared pasture and housing with the goats. Isolates of caprine and equine origin had identical biochemical profiles, including the ability to ferment sorbitol and lactose, which distinguishes S. equi ssp. zooepidemicus from S. equi ssp. equi. Sequencing of the 16S-23S intergenic spacer region and results from sodA-seeI multiplex PCR supported identification of isolates as S. equi ssp. zooepidemicus. Based on random amplified polymorphic DNA typing and rpoB and sodA sequencing, caprine isolates were indistinguishable from each other, but distinct from equine isolates. Further analysis of equine fecal samples showed that multiple strains of S. equi ssp. zooepidemicus can be present in a single sample or in sequential samples obtained from a single horse. Failure to detect the mastitis-causing strain in equine feces may indicate that horses were not the source of the mastitis outbreak in goats. Alternatively, the outbreak may be due to presence of multiple S. equi ssp. zooepidemicus strains in equine feces and a failure to detect all strains when analyzing a limited number of isolates per sample.

Milk hygiene and udder health in the periurban area of Hamdallaye, Niger

The prevalence of intra-mammary infections in dairy herds was studied in Hamdallaye, Niger. A total of 956 milk samples were collected in 2007 from 239 lactating cows of four local breeds in eight traditional herds; the first sampling was undertaken in the dry season at morning milking, and the second in the rainy season at evening milking. Staphylococcus aureus, Coagulase-Negative Staphylococci (CNS) and environmental microorganisms were detected in significantly (p < 0.05) more samples in the rainy season, 55.2%, than in the dry season, 27.1%. Statistically significant (P < 0.05) differences in prevalence were observed among herds and according to lactation number. Infections were assigned to four classes, according to the major pathogen, and the respective mean somatic cell counts during the dry season were: S. aureus, 775 x 10(3) cells/ml; CNS, 447 x 10(3) cells/ml; environmental microorganisms, 407 x 10(3) cells/ml; and non-infected, 262 x 10(3) cells/ml. Most of the tested strains were sensitive to antibiotics, and selected strains of S. aureus (n = 15) were negative to the multiplex PCR tests for production of enterotoxins.