Prevalence of Mycoplasma bovis udder infection in dairy cattle: preliminary field investigation in southeast France.

AIMS: To update epidemiological data on Mycoplasma bovis infection in dairy herds from six departments in the southeast of France, in order to obtain a first estimate of the prevalence of M. bovis infection through bacteriological investigations on bulk tank milk, and estimate the prevalence of M. bovis in clinical mastitis in this population of cattle. METHODS: To estimate a prevalence of M. bovis of 2%, with 95% confidence, a sample of >270 herds was required. Bulk tank milk samples were collected from herds between January and February 2005 and milk samples from cows with clinical mastitis were collected between January 2007 and March 2008. Bulk tank milk and composite mastitic samples were analysed for M. bovis using culture and/or PCR. RESULTS: Mycoplasma bovis was not detected by either technique in any of the 345 bulk tank milk samples. The prevalence of M. bovis infection in this population of dairy herds was <1%, with 95% confidence. Mycoplasma bovis was not isolated from any of the 166 composite samples obtained from 828 samples of mastitic milk. The prevalence of M. bovis in clinical mastitis was <0.44%, with 95% confidence. CONCLUSIONS: These preliminary results suggest that the prevalence of udder infections with M. bovis is very low in dairy herds in the southeast of France. These two studies provide preliminary data, that can be used to derive working hypotheses for future statistically representative investigations at the national level.

Serological prevalence of Mycoplasma bovis infection in suckling beef cattle in France.

The prevalence of Mycoplasma bovis infection in France was assessed by means of a serological survey of suckling beef cattle, using an ELISA. The survey included 824 randomly selected herds in eight French counties and a total of 32,197 animals more than one year old. In each county, the number of herds tested was determined statistically on the basis of the hypothesis that about 40 per cent of herds are infected. The proportion of herds containing at least one infected animal ranged from 28 to 90 per cent depending on the county. Among the 32,197 sera tested, the animal infection rate ranged between 2 per cent and 13 per cent. In infected herds, the average number of positive animals per herd was between 10 and 20 per cent, and the infection was unevenly distributed among the areas tested.

Development of a recombinant antigen for antibody-based diagnosis of Mycoplasma bovis infection in cattle.

Mycoplasma bovis induces various clinical manifestations in cattle, such as mastitis, arthritis, and pneumonia. We have evaluated the immunoreactivity of three variable surface proteins (Vsps) of M. bovis, namely VspA, VspB, and VspC, with sera collected from herds with mycoplasmosis or from cattle experimentally infected with M. bovis. Western blot analysis revealed that the Vsps are the predominant antigens recognized by the host humoral response during M. bovis infection. The immunoreactivity of VspA, VspB, and VspC with host antibodies was independent of the clinical manifestations, the geographical origin of the M. bovis isolates, the mode of infection, and the animal's history. Moreover, the results showed that Vsp-specific host antibodies can be detected about 10 days after experimental infection and for up to several months. The full-length or truncated versions of the VspA product were overexpressed in Escherichia coli as fusion proteins (FP-VspA). Recombinant products showed strong immunoreactivity with the Vsp-specific monoclonal antibodies 1A1 and 1E5, with the corresponding epitopes localized at the VspA N-terminal and C-terminal ends, respectively. Anti-M. bovis sera of cattle naturally or experimentally infected also strongly recognized the full-length FP-VspA. The seroreactivity of sera collected from cattle between 6 and 10 days after experimental infection was weaker with truncated versions of VspA lacking the 1E5 epitope than with the full-length VspA or the truncated versions lacking the 1A1 epitope. Overall, the results indicate that the Vsps, despite their inter- and intraclonal variability, may be applied as target antigens in serodiagnostic assays for epidemiological studies.

Observation on bovine congenital erythrocytic protoporphyria in the blonde d'Aquitaine breed.

Three blonde d'Aquitaine calves (one male and two females) about four months old, exhibited skin lesions just after birth, the site and nature of which suggested photosensitisation. Their porphyrin metabolism indicated a marked decrease in the activity of lymphocytic ferrochelatase, leading to a diagnosis of congenital erythrocytic protoporphyria. The associated nervous disorders of the 'recurrent epileptiform seizure' type are discussed in the light of complementary histological and biochemical tests.

Ecotoxinogenesis of Pithomyces chartarum.

Facial eczema is a hepatogenous photosensitivity mycotoxicosis resulting from sporidesmin ingestion. The morphological characters of toxigenic strains of P. chartarum are reported and the effect of temperature on growth and mycotoxin production are studied. The temperature range for which there is an actual risk of toxin accumulation (20-25 degrees C) is much narrower than for an appreciable growth (5-30 degrees C).

Clinical biochemistry of sporidesmin natural intoxication (facial eczema) of sheep.

The effects of facial eczema, i.e. intoxication by the mycotoxin sporidesmin, were investigated by extensive biochemical screening of serum in 100 controls (A), 31 clinically ill (B) and 219 apparently healthy (C) Manech ewes under field conditions. Dramatic increases of gamma-glutamyltransferase1), alkaline phosphatases, bilirubin, cholesterol, aspartate and alanine aminotransferases, and lactate dehydrogenase confirmed the severity of liver damage in group B, but they were also observed in slightly more than 50% of group C animals. This demonstrated the true extent of the disease, which could be best assessed by the measurement of serum gamma-glutamyltransferase; but since this enzyme was still elevated one year later, it cannot be used as a reliable prognostic parameter.

[Distribution of alanine and aspartate aminotransferases, gamma-glutamyltransferase, lactate dehydrogenase, alkaline phosphatases and creatine kinase in the main organs of adult goats and kids]. / Distribution de l'alanine et de l'aspartate aminotransférases, de la gamma-glutamyl transférase, de la lactate deshydrogénase, des phosphatases alcalines et de la créatine kinase dans les principaux organes de chèvres adultes et de chevreaux.

In adult ewes, the distribution of enzymes in the liver, kidney, spleen, pancreas, muscle, lung and myocardium was very similar to that in cows or sheep: aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), lactate dehydrogenase (LDH) and creatine kinase (CK) were mainly in skeletal muscles and the myocardium, while gamma-glutamyl transferase (GGT) and alkaline phosphatases (PAL) predominated in the kidneys. Age-related changes of tissue enzyme patterns were dominated by a dramatic decrease of liver ALAT in adults whereas this enzyme was liver-specific in one month old animals; a decrease of muscle LDH and CK, and an increase of kidney GGT and ALP were also observed in adults.

[Biochemical semiology of the liver in ruminants]. / Sémiologie biochimique du foie chez les ruminants.

Many different serum biochemical tests can help in the diagnosis of liver disturbances in ruminants. The best tests for hepato-cellular damage are the measurement of enzymes such as glutamate dehydrogenase, sorbitol dehydrogenase and, if available, arginase or ornithine carbamoyl transferase. Disturbances of biliary function can be investigated through the measurement of so-called "cholestasis enzyme markers" such as gammaglutamyl transferase or alkaline phosphatases; bilirubin and bile salts can also be helpful. Liver insufficiency can be approached through the measurement of serum albumin, fibrinogen and coagulation tests whereas inflammative and inductive processes are difficult to investigate. Moreover, liver clearances (bromosulfonephtalein or indocyanine green) can provide useful data about whole liver function.

Transfer of gamma-glutamyltransferase from mother colostrum to newborn goat and foal.

In goat and mare colostrum, gamma-glutamyltransferase (GGT) activity is relatively low (mean values are, respectively, 900 and 350 U/l). In the serum of newborns before suckling, GGT is also low (less than or equal to 28 U/l in goats and less than or equal to U/l in foals); then in goats GGT is much increased on the 1st day (mean = 127 U/l), and it decreases during the following days. In foals, serum GGT slowly but regularly increases for the first 5 days, then decreases. Such differences can be attributed to intestinal protein absorption capabilities which are selective in newborn foals and unselective in goats. Therefore, serum GGT measurement can be a good test of colostrum intake in newborn goats, but not in foals.