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.

Factors influencing the outcome of primary immunization against rabies in young dogs.

There is currently limited information on the factors influencing the outcome of rabies vaccination in dogs based on the primary immunization schedule. The objective of this study was to investigate whether selected variables (signalment, number of vaccinations, vaccine brand and multivalence, and time interval between the most recent vaccination and blood sampling) were associated with the achievement of an acceptable titer threshold (based on international standards) and with absolute antibody titers in young dogs vaccinated with commercially available vaccines. Serologic data from 662 dogs tested prior to their first annual booster for rabies were retrospectively reviewed. Neutralizing antibody titers were determined using a fluorescent antibody neutralization test. An acceptable titer threshold (≥0.5IU/ml) was achieved in 86.5% of the dogs. Dogs that had been vaccinated twice had significantly (P<0.001) higher antibody titers compared with dogs vaccinated once. The odds of achieving seropositivity and the median absolute antibody titer tended to decrease with increasing time between vaccination and blood sampling. Dogs vaccinated with monovalent vaccines were more likely to achieve an acceptable titer than dogs vaccinated with polyvalent vaccines. Dogs that were vaccinated after 3-6 months of age were more likely to develop higher antibody titers. These results indicate that the administration of two vaccines rather than one vaccine in the primary immunization schedule for rabies, result in a superior vaccination response and may be a more beneficial policy for ensuring pre-exposure prophylaxis and for travel certification of young dogs.

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.

Evaluation of the first oral rabies vaccination campaign of the red foxes in Greece.

Following the late 2012 recurrence of rabies in wild foxes (Vulpes vulpes) in central and north-western Greece, the first oral fox vaccination campaign co-financed by the European Union (EU) and the Greek state budget, was implemented. Initially, it involved 24 regional units of the Greek territory during the period October-December 2013. Vaccine-baits were aerially distributed by fixed-wing aircrafts. Vaccines were scattered along parallel flight paths 500m apart in order to optimize aerial missions and achieve homogeneous distribution. A geographical information system was used to objectively evaluate bait distribution. This system identified areas of inadequate bait density that would require additional flights. A total number of 1,504,821 baits were distributed covering an area of 54,584.29km(2). To assess the effectiveness of oral vaccination campaign a monitoring program was introduced, which entailed examination of serum samples and canine teeth derived from red foxes collected in the field. The laboratory analysis revealed 60% seropositivity and detection of tetracycline biomarker in 70% of the foxes tested.

Rabies in Greece; historical perspectives in view of the current re-emergence in wild and domestic animals.

Greece has been rabies free since 1987 while no human cases have been seen since 1970. The re-emergence of rabies in Northern Greece during 2012-2013 in wild and domestic animals prompted a systematic review of historical evidence of the presence of the disease in the country from ancient years till the present. Historical data is presented along with efforts to prevent disease in animals and humans especially during the high prevalent periods in the country in the mid-20th century. These efforts serve as a guide to current extensive efforts to prevent spread especially in the wild and domestic animal populations.