Risks of suffering tick-borne diseases in sheep translocated to a tick infested area: a laboratory approach for the investigation of an outbreak.

This study was designed to investigate an outbreak of high mortality that occurred in naïve Assaf sheep introduced into a Latxa sheep flock in the Basque Country, a region where piroplasmosis is endemic. To identify the causes of this outbreak, a panel of different methods, including traditional pathological, biopathological and parasitological analyses combined with recently developed molecular methods, was used. These novel molecular methods included a multiplex real-time PCR assay to screen for the presence of the most important tick-borne pathogens (piroplasms and anaplasmas), followed by a second species-specific multiplex real-time PCR assay for the identification of Anaplasma-positive samples. The identification of piroplasm-positive samples was carried out by a multiplexed microsphere-based suspension array using a Luminex(®) xMAP technology-based procedure. Anaplasmas and/or piroplasms were detected in 7/10 lambs and 11/13 ewes, with Babesia ovis being detected in 12 of the 23 animals, Theileria ovis in 6 and Anaplasma ovis in 4, both as single and mixed infections. Most of the animals infected with B. ovis had a marked decrease in the values of the red blood cell parameters. Ticks collected from the animals were identified as Riphicephalus bursa, recognised vector of B. ovis. Other haemolytic pathologies (clostridial disease, copper poisoning and leptospirosis) were ruled out and, considering all clinical, laboratory and epidemiological data, babesiosis by B. ovis was diagnosed. A detailed description of the clinical outcome, with ca. 60% of mortality, laboratory results and epidemiological findings are provided. The implications of the introduction of naïve animals into a piroplasmosis endemic area are discussed.

Four-year evaluation of the effect of vaccination against Coxiella burnetii on reduction of animal infection and environmental contamination in a naturally infected dairy sheep flock.

Vaccination is considered one of the best options for controlling Coxiella burnetii infection in livestock. The efficacy of a phase I vaccine was investigated over 4 years in a sheep flock with confirmed C. burnetii infection. Shedding was not detected in ewes and yearlings in the last 2 years, but C. burnetii still persisted in the environment.

Detection of Border disease virus in fetuses, stillbirths, and newborn lambs from natural and experimental infections.

The purpose of the present study was to evaluate the use of enzyme-linked immunosorbent assay (ELISA) antigen detection in blood or fetal fluids and reverse transcription polymerase chain reaction (RT-PCR) amplification in tissues for routine laboratory diagnosis of Border disease virus (BDV) infection. Samples from 67 fetuses, 6 stillbirths, and 11 lambs from 25 commercial flocks with suspicion of BDV abortion and 3 fetuses, 7 stillbirths, and 15 lambs obtained from an experimental infection with a local isolate (BDV genotype 4) were investigated. Presence of BDV was detected by RT-PCR in 7.9% of fetuses, 50% of stillbirths, and 50% of lambs from the commercial flocks analyzed, corresponding to 8 of the 25 farms (32%). A similar percentage of the lambs and stillbirths from the experimental infection were positive by RT-PCR of tissue samples (54.5%), and the highest positivity was detected in lymph node, thyroid gland, and kidney. The current study revealed that RT-PCR analysis of stillbirths and lambs with clinical symptoms is more suitable than the analysis of fetuses to confirm the presence of BDV in a flock. Pestiviral antigen was detected by antigen ELISA in a high proportion of fetuses (24/58) and stillbirths (3/4) from commercial flocks, but in lambs, the presence of colostral antibodies masked the detection of the antigen by ELISA. Nevertheless, in lambs from the experimental infection that were not fed colostrum, antigen ELISA was less efficient than RT-PCR in detecting viral presence in stillbirths and lambs. Antigen ELISA is therefore recommended for fetuses with advanced autolysis that can adversely affect RNA integrity.