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

Ultraviolet Irradiation Suppresses Adhesion on TiO2

Environmental concerns have recently spurred a quest for materials that stay clean, such as TiO2, when subjected to the combined action of sunlight irradiation and exposure to rain. However, the fundamental mechanism that governs the self-cleaning properties of TiO2 still needs to be elucidated. TiO2 is known to be photocatalytic as well as to decompose organic adsorbents, but these properties do not explain its capacity to eliminate mineral contaminants. In the present paper, we report that hydrophilic UV-irradiated TiO2 layers are nonadhesive in the presence of water, thus preventing adhesion of mineral particles. Surface force measurements done using atomic force microscopy reveal the presence of an additional short-range repulsive force, which screens the van der Waals attractive forces, while long-range interactions are preserved. This additional short-range force does not originate from UV-induced trapping of surface charges or OH group creation, as we demonstrate by second harmonic generation and ambient pressure X-ray photoelectron spectroscopy investigations. This short-range repulsive force, which appears to be intrinsic to the TiO2 surface, is certainly a key phenomenon for a strong self-cleaning capacity