Background: Fasciola hepatica (F. hepatica) infection reduces antibody avidity to foot-and-mouth disease virus (FMDV) vaccination in cattle despite preserved total antibody levels. However, its effect on vaccine-induced immunity in water buffaloes (Bubalus bubalis), which contribute to FMDV maintenance in endemic settings, has not been investigated. Objectives: To evaluate the effect of natural F. hepatica infection on the magnitude and functional quality of the FMDV–specific antibody response in buffaloes under field conditions. Methods: Two buffalo herds (n = 50 each) were classified by infection status using coproparasitological analysis and serology. All animals were vaccinated within the national foot-and-mouth disease control programme, with the last dose administered 264 days before sampling. Serum neutralising titres, total antibodies by liquid-phase blocking ELISA, IgG levels, and IgG avidity to the A24/Cruzeiro vaccine strain were determined. Results: F. hepatica-infected buffaloes exhibited consistent decreases across all vaccine-induced antibody parameters. Neutralising titres were reduced approximately two-fold, IgG avidity by about 38 percent, IgG levels by about 36 percent, and liquid-phase blocking ELISA titres by about 1.6-fold compared with non-infected animals. Conclusions: This study provides the first field evidence that fasciolosis is associated with changes in the magnitude and quality of vaccine-induced humoral responses following FMDV vaccination in water buffaloes, indicating that F. hepatica infection may influence the interpretation of post-vaccination serological monitoring in this species under endemic field conditions.

Bluetongue virus diagnosis in Argentina, primarily via RT-qPCR, faces challenges due to the limited number of laboratories, many of which are located in regions where BTV is exotic and far from primary sample collection areas. Consequently, blood samples must be transported over considerable distances for analysis, posing significant logistical challenges due to the specific transport conditions needed. Therefore, the development of methodologies that optimize sample collection, preservation, and safe transport is of vital importance. The objective of this work was to standardize a sampling protocol for BTV using filter paper cards, to achieve adequate preservation and transport of blood samples for subsequent diagnosis. Hydration with TE at 37°C yielded the lowest Cq among tested conditions, with a detection limit of 2.75 10² gc/µL. We evaluated the stability of the sample on the cards by storing them at 25°C, 4°C, -20°C, and -80°C for 1, 7, 30, 60, 120, and 360 days. Stability was verified up to 360 days at all temperatures. Additionally, we confirmed the absence of infectious material in the card eluate. Finally, we conducted a preliminary field evaluation by collecting blood samples from cattle and sheep in tubes and on cards. According to the Cohen´s Kappa index, the agreement between both methods was almost perfect. The standardized methodology represents a significant advance in BTV diagnosis, as it will allow samples to be transported without refrigeration and with adequate biosafety conditions without losing diagnostic capacity.

Bovine botulism is a lethal disease caused by Clostridium botulinum neurotoxins (BoNT). In cattle, the most frequent form of this disease in several South American countries and elsewhere is caused by BoNT type D, which has been associated with phosphorus deficiency, leading to pica and osteophagy. An outbreak of botulism occurred in a fully vaccinated 600-steer herd of cattle. The cattle were grazing on native pasture in a paddock in which several decomposing animal carcasses were found; the animals had performed osteophagy. The first 2 deaths were recorded in November 2016, and the number of fatalities increased to 84 through April of 2017. All the cases had similar clinical signs, which were consistent with botulism. The affected animals had hypophosphatemia and rear-leg weakness, ataxia, progressive flaccid paralysis of several muscles, recumbency, and death. Autopsies were performed on 3 animals; gross findings included hydropericardium, congestion of the cerebellum, and bone fragments and stones in the rumen and reticulum. Botulism was confirmed in the 3 animals by detecting BoNT type D by mouse bioassay. A large outbreak of botulism in vaccinated cattle associated with phosphorus deficiency and osteophagy has not been reported previously in Argentina, to our knowledge. Our case demonstrates that, even in vaccinated herds, rigorous carcass management is essential to reduce the risk of environmental contamination and to prevent fatal botulism outbreaks, especially in phosphorus-deficient areas. Improved reporting of similar cases is vital to refine prevention strategies and reduce the economic impact of the disease.

El objetivo del presente estudio fue determinar la asociación entre el estado serológico y las causas de abortos relacionadas a infecciones bacterianas y protozoarias en tres establecimientos ganaderos con bajo desempeño reproductivo en la provincia de Corrientes, Argentina. Durante 2020-2021, se realizó raspado prepucial de toros, diagnóstico de gestación por ecografía transrectal en vacas y recolección de fetos. Se tomaron muestras de sangre de vacas gestantes, no gestantes y abortadas para el diagnóstico serológico de Leptospira spp., Neospora caninum y Brucella abortus. Además, se tomó una muestra de moco cervicovaginal (CVM) para cultivo en vacas abortadas. En el 5% de los toros fueron positivos para Tritrichomonas foetus y en el 7% para Campylobacter fetus (localidad 1). En el 1,8% (10/546; IC95% 1-3) de 546 sueros analizados fueron positivos para Leptospira spp., observándose una asociación positiva entre la alta seroprevalencia y las hembras no gestantes (p = 0,0174). Además, para N. caninum, la seroprevalencia fue del 49,1% (268/546 IC95% 45-54), mostrando una asociación estadísticamente significativa entre la serología positiva a N. caninum y las hembras preñadas (p = 0,0151). De 14 hembras abortadas en el seguimiento, el 42,8% se volvió seropositiva a N. caninum, lo que podría indicar una infección por transmisión horizontal, siendo este hallazgo de gran importancia. Todos los animales fueron seronegativos para B. abortus. Además, T. foetus (3/61) y C. fetus (3/61) se aislaron en el 9,8% (6/61) del CVM. Solo en el 42,9% (3/7) de los fetos, como agentes infecciosos se identificaron como causa del aborto. El presente estudio muestra información sobre la causa infecciosa de pérdidas reproductivas en rebaños extensivos de la Mesopotamia argentina, confirmando además la importancia de la enfermedad venérea en toros y el muestreo de vacas y fetos abortados para identificar la causa de la pérdida.

The diagnosis of Bluetongue Virus (BTV) in Argentina is primarily conducted via RT-qPCR and faces challenges due to the limited number of diagnostic laboratories, many of which are located in regions where BTV is exotic and far from primary sample collection areas. As a result, blood samples must be transported over considerable distances for analysis. This poses significant logistical challenges due to the specific transport conditions that are required. Consequently, the development of methodologies that optimize sample collection, preservation, and safe transport is of vital importance. The objective of this study was to standardize a sampling protocol for the detection of BTV using filter paper cards. This protocol was developed to ensure adequate preservation and transport of blood samples for diagnosis. Hydration with TE at 37 °C resulted in the lowest Cq among the tested treatments, with ~10 TCID₅₀/mL representing the lowest viral concentration that was consistently detected under the experimental conditions. The stability of the sample on the cards was evaluated through a series of storage trials at temperatures of 25 °C, 4 °C, −20 °C, and −80 °C for 1, 7, 30, 60, 120, and 360 days. Stability was verified up to 120 days at all temperatures. Furthermore, the absence of infectious material in the card eluate was confirmed. A preliminary field evaluation was conducted, in which blood samples from cattle and sheep were collected in tubes and on cards. According to the Cohen’s Kappa index, the agreement between both methods was nearly perfect. The standardized methodology signifies a substantial advancement in BTV diagnosis, as it facilitates the transportation of samples without the necessity of refrigeration and with adequate biosafety conditions without losing diagnostic capacity.