Efficacy of oral rabies vaccination in individual age groups of juvenile red foxes.

Although juvenile red foxes (Vulpes vulpes) are considered a single age group, essential for monitoring the effectiveness of the oral rabies vaccination (ORV), there appear to be significant differences among age subgroups. Herein, a subset of 335 foxes aged 0-1 year that had not consumed bait in previous campaign were collected for monitoring the effectiveness of the first seven ORV campaigns in Greece, carried out from 2013 to 2017. These juveniles were additionally assigned to three individual 4-month age groups, according to the exact date on which they were killed. The aim was to identify differences in seroconversion rate and bait uptake level and determine whether reconsideration is needed in the way that ORV monitoring is being implemented and evaluated. Statistically significant differences were observed following the analysis of mandible bone, teeth and blood samples obtained from 1-4 and 5-8-month old foxes as compared to the respective samples derived from 9-12-month old animals, whereas no differences were revealed in samples between foxes aged 1-4 and 5-8 months. Hunting juveniles during the whole period of spring ORV campaigns monitoring should be reevaluated and even discouraged. On the contrary, juvenile foxes hunted for the evaluation of autumn campaigns, aged > 8 months, had similar assessment rates to adult individuals and are equally helpful for assessing the efficacy of an ORV campaign. Taking the above into consideration and by distinguishing recent and old tetracycline uptake, ORV monitoring and evaluation could be performed in an alternative, more comprehensive way.

First four Oral Rabies Vaccination campaigns of the red foxes in Greece: Evaluating factors and assessment.

Following the last animal rabies outbreak in Greece in 2012, Oral Rabies Vaccination (ORV) campaigns of red foxes (Vulpes vulpes) were conducted in order to halt the spread of the disease, as widely and effectively have also been implemented in other countries. The present study aims to report the main outcomes following the first Greek ORV campaigns during autumn 2013, 2014, 2015 and spring 2016, to assess their effectiveness and to investigate factors potentially related to their success. Blood samples, mandible bones and teeth, derived by 452 foxes, were tested for rabies antibody titration, animal age determination and tetracycline (TTC) detection. The laboratory results obtained were statistically analyzed. High seroprevalence and TTC detection rates were obtained following the autumn campaigns studied, while these rates were significantly reduced following the spring campaign. The year or the season of the vaccination campaign, the estimated age group of the animal and the geographical Regional Unit (RU), where the animal was hunted, were identified as important factors. On the contrary, no significance could be ascertained for TTC detection based on exclusively previous uptake, use of filter paper, blood sample type and quality, as well as sex of animal. Based on the monitoring results achieved, the first ORV campaigns conducted in the country can be generally considered to be satisfactory. No positives cases were detected since May 2014. Seasonal, geographical parameters and factors related to fox ecology may interfere with monitoring results and should be always considered when planning future ORV programs.

Lumpy skin disease outbreaks in Greece during 2015-16, implementation of emergency immunization and genetic differentiation between field isolates and vaccine virus strains.

The objective of this study is to present epizootiological data from the lumpy skin disease (LSD) outbreaks in Greece during 2015-16, following the implementation of emergency vaccination and total stamping-out, along with laboratory data regarding the genetic differentiation between field isolates and live attenuated vaccine virus strains. Descriptive geographical chronology analysis was conducted to present the progressive shift of the outbreaks westwards, and at the same time, the absence of further outbreaks in previously affected regional units where high vaccination coverage was achieved. Isolation and molecular characterization of LSDV from the first recorded case in Greece (Evros/GR/15 isolate) was performed. The two live attenuated LSD vaccine viruses, currently used for emergency immunization in Greece, were sequenced and compared to the Evros/GR/15 isolate, in 3 genomic regions (GPCR gene, RPO30 gene, and partial LSDV126/LSDV127 genes). Sequence comparisons revealed prominent differences between the Evros/GR/15 isolate and the vaccine strains. Phylogenetic analysis resulted in the classification of the Evros/GR/15 isolate in the same clade with all field LSDV isolates, whereas vaccine strains were grouped in a distinct cluster within the LSDV clade. Additional samples from animals presenting skin nodules (N=13) were characterized by sequencing in the 3 aforementioned genomic regions. Among them, in 5 animals that were vaccinated, the attenuated vaccine virus was identified. A PCR-RFLP method targeting the LSDV127 gene was developed and proved to be able to discriminate between the characterized field and vaccine strains. The findings of the present study substantiate the importance of timely and intensive vaccinations for the control of LSDV epizootic and the genetic differences between the Evros/GR/15 isolate and the vaccine strains. This provides the basis for the development of PCR-based DIVA assays, which would be of major importance for effective disease surveillance and stamping-out during LSD vaccination campaigns.