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Streptococcus suis is a zoonotic pathogen that causes a major health problem in the pig production industry worldwide. Spain is one of the largest pig producers in the world. This work aimed to investigate the genetic and phenotypic features of invasive S. suis isolates recovered in Spain. A panel of 156 clinical isolates recovered from 13 Autonomous Communities, representing the major pig producers, were analysed. MLST and serotyping analysis revealed that most isolates (61.6%) were assigned to ST1 (26.3%), ST123 (18.6%), ST29 (9.6%), and ST3 (7.1%). Interestingly, 34 new STs were identified, indicating the emergence of novel genetic lineages. Serotypes 9 (27.6%) and 1 (21.8%) prevailed, followed by serotypes 7 (12.8%) and 2 (12.2%). Analysis of 13 virulence-associated genes showed significant associations between ST, serotype, virulence patterns, and clinical features, evidencing particular virulence traits associated with genetic clusters. The pangenome was generated, and the core genome was distributed in 7 Bayesian groups where each group included a variable set of over- and under-represented genes of different categories. The study provides comprehensive data and knowledge to improve the design of new vaccines, antimicrobial treatments, and bacterial typing approaches., (© 2024. The Author(s).)

Studies on the microbiota of ticks have promoted hypotheses about the combined effects of the bacterial community, its functional contributions to the tick's physiology or probable competition effects with some tick-borne pathogens. However, knowledge on the origin of the microbiota of newly hatched larvae is missing. This study aimed to elucidate the source(s) of the microbiota in unfed tick larvae, addressing the composition of the "core microbiota" and the best ways to decontaminate eggs for microbiota studies. We applied laboratory degree bleach washes and/or ultraviolet light treatments on engorged Rhipicephalus australis females and/or their eggs. No significant effects of these treatments on the reproductive parameters of females and the hatching rates of eggs were observed. However, the different treatments did show striking effects on the composition of the microbiota. The results indicated that bleach washes disrupted the internal tick microbiota in females, implying that bleach may have entered the tick and subsequently affected the microbiota. Furthermore, the analyses of results demonstrated that the ovary is a main source of tick microbiota, while the contribution of Gené's organ (a part of the female reproductive system that secretes a protective wax coat onto tick eggs) or the male's spermatophore requires further investigation. Further studies are needed to identify best practice protocols for the decontamination of ticks for microbiota studies., (© 2023. The Author(s).)

Background: Hepatitis E virus (HEV) infection is a serious health problem in developing countries and is also increasingly reported in industrialized regions. HEV is considered a zoonotic agent and strains isolated from swine and human sources are genetically similar. Thus, HEV is of increasing importance to both public and animal health. The aim of the present study was to evaluate the distribution of HEV in a large population of pigs from herds located in different autonomous regions throughout Spain., Results: The presence of anti-HEV IgG antibodies was analyzed in 1141 swine serum samples (corresponding to 381 pigs younger than 6 months and 760 pigs older than 6 months) collected from 85 herds. Herds were located in 6 provinces in 4 autonomous regions throughout Spain. At least one pig tested positive for anti-HEV IgG in over 80% of herds. Of individual pigs, 20.4% (233/1141) were positive for anti-HEV IgG, with the prevalence being higher in adult pigs than in those under 6 months (30.2% vs. 15.5%). A subset of serum samples taken at 2- to 5-week intervals showed that seroprevalence dropped between 3 and 11 weeks of age, and then rose significantly by the 15th week. Pigs were also examined for the presence of HEV-RNA by RT-PCR. Of pigs tested for the presence of HEV-RNA 18.8% (64/341) were positive, with at least one pig in almost half of the herds testing positive. HEV-RNA amplicons from several positive pigs were sequenced and all were of genotype 3., Conclusions: HEV was found to be widely distributed among swine farms across Spain, with the prevalence being highest among animals older than 6 months. These results indicate that HEV infection either is or is likely to become endemic in the Spanish swine population.

This study investigates the role of water quality parameters as possible risk or protection factors in Aeromonas spp-affected rainbow trout hatcheries in northeastern Spain. The results revealed an association between oxygen concentration, ammonia concentration and total dissolved solids (TDS) with the prevalence of Aeromonas spp cases on the affected fish farms. The oxygen and ammonia concentrations acted as risk factors when their values were lower than 7.06 mg/L or higher than 0.05 mg/L, respectively, generating odds ratio (OR) values of 2.0 and 2.3. TDS levels, however, acted as a protective factor (OR = 0.39), from an epidemiological point of view but not statistically, when the values were outside the normal range, 199-261 mg/L. On a multivariate level, fish farms exposed to all the associated factors at the same time, had a risk of being affected by Aeromonas spp that was 1.74 times higher than farms with normal quality parameters; the risk increased when TDS had a normal value and it decreased when oxygen and/or ammonia concentrations had normal values.

The effect of Baypamun, a non-specific immune system stimulant, on the treatment and control of furunculosis was studied in experimentally infected rainbow trout. A statistically significant association between the Baypamun treatment and a reduction in cumulative incidence of the clinical symptoms of Furunculosis and the infection level, despite the presence of the bacteria in blood and organs was observed. A reduction in the mortality rate in Baypamun-treated fish was also observed but this was not statistically significant. The results suggest that the treatment of fish diseases with non-specific immune stimulants could be, in the future, a good defense strategy leading to a reduction in disease symptoms and a greater control of the asymptomatic carriers after an outbreak.