Molecular prevalence of Chlamydia and Chlamydia-like bacteria in Tunisian domestic ruminant farms and their influencing risk factors

Chlamydia and Chlamydia-like bacteria are well known to infect several organisms and may cause a wide range of diseases, particularly in ruminants. To gain insight into the prevalence and diversity of these intracellular bacteria, we applied a pan-Chlamydiales real-time PCR to 1,134 veterinary samples taken from 130 Tunisian ruminant herds. The true adjusted animal population-level prevalence was 12.9% in cattle, against 8.7% in sheep. In addition, the true adjusted herd-level prevalence of Chlamydiae was 80% in cattle and 25.5% in sheep. Chlamydiales from three familylevel lineages were detected indicating a high biodiversity of Chlamydiales in ruminant herds. Our results showed that Parachlamydia acanthamoebae could be responsiblefor bovine and ovine chlamydiosis in central-eastern Tunisia. Multivariable logistic regression analysis at the animal population level indicated that strata and digestive disorders variables were the important risk factors of bovine and ovine chlamydiosis. However, origin and age variables were found to be associated withbovine and ovine chlamydiosis, respectively. At the herd level, risk factors for Chlamydia positivity were as follows: abortion and herd size for cattle against breeding system, cleaning frequency, quarantine, use of disinfectant and floor type for sheep. Paying attention to these risk factors will help improvement of control programs against this harmful zoonotic disease

Effects of in vitro contamination by Brucella Abortus on mice and cows embryos

On a cultivé in vitro des embryons de souris et de vache, à zone pellucide intacte, dans des milieux contenant 101 à 105 brucella par mi pour tester la viabilité et les risques de contamination de ces embryons après contact prolongé de 24 h et 48 h. Il en ressort que : — pour de faibles concentrations en brucella (101 à 102 b/ml), la viabilité des embryons est peu modifiée par rapport aux témoins ; — dans nos conditions expérimentales, aucun embryon n’a été conta miné après 48 heures de contact quelle que soit la concentration en brucella et en particulier celles-ci ne sont pas adsorbées sur la zone pellucide ; — dix lavages successifs des embryons contaminés, même à des concentrations elevées sont suffisants pour éliminer les brucella du milieu de transfert (effet dilution) à condition de respecter le protocole proposé. En conclusion, il paraît possible d'utiliser des vaches brucelliques de haute valeur génétique comme donneuses d’embryons, sans risque de transmission de cette maladie aux receveuses et aux futurs produits.In vitro cultures of mice (as a model) and cows embryos with intact zona pellucida have been performed in media containing 101 to 105 brucella per ml. This was aimed at evaluating both viability and risks of contamination of these embryos after 24 or 48 h of such cultures. It was found : (1) with low concentrations of brucella (101 - 10- b./ml, embryo viability was not affected when compared to that of controls ; (2) in our experimental conditions, no embryo was found to be contaminated after 48 h whatever was the brucella concentration in the culture medium ; in particular, brucella were not adsorbed on the zona pellucida ; (3) ten consecutive washings of the embryos initially inserted in a brucella-infected medium (at any of the concentrations studied) are definitely sufficient to eliminate all brucella from the transfer medium under strict conditions defined in the present paper. In conclusion, embryos from cows with high breeding values but unfortunately affected with brucellosis may be transferred with no risk of contamination neither to the embryo nor to the recipient

Reassessment of pre-industrial fire emissions strongly affects anthropogenic aerosol forcing

Uncertainty in pre-industrial natural aerosol emissions is a major component of the overall uncertainty in the radiative forcing of climate. Improved characterisation of natural emissions and their radiative effects can therefore increase the accuracy of global climate model projections. Here we show that revised assumptions about pre-industrial fire activity result in significantly increased aerosol concentrations in the pre-industrial atmosphere. Revised global model simulations predict a 35% reduction in the calculated global mean cloud albedo forcing over the Industrial Era (1750–2000 CE) compared to estimates using emissions data from the Sixth Coupled Model Intercomparison Project. An estimated upper limit to pre-industrial fire emissions results in a much greater (91%) reduction in forcing. When compared to 26 other uncertain parameters or inputs in our model, pre-industrial fire emissions are by far the single largest source of uncertainty in pre-industrial aerosol concentrations, and hence in our understanding of the magnitude of the historical radiative forcing due to anthropogenic aerosol emissions

Sanitary control in bovine embryo transfer - How far should we go? A review

Embryo transfer is a globally executed technique which, when properly done, has both economic and sanitary advantages. International guidelines are available to prevent infection of the embryo with pathogens, both originating from the donor animals as from the environment. This manuscript describes the bacteria, viruses, protozoa, fungi and prions that are of major concern in the context of embryo transfer in cattle. In addition, the actual scientific knowledge on these pathogens is evaluated in terms of the current international and national guidelines and legislation