Contents lists available at ScienceDirect Veterinary Microbiology journal homepage: www.elsevier.com/locate/vetmic Short communication Efficacy of oral rabies vaccination in individual age groups of juvenile red foxes Dimos P. Papatheodorou a, ⁎ , Konstantia E. Tasioudi a , Laskarina-Maria Korou b , Vasileios L. Georgiou c , Gerasimos Markantonatos a , Peristera Iliadou a , Aikaterini Kirtzalidou a , Aggeliki Katsifa a , Spyridon Ztrivas d , Georgia Bechtsi e , Myrsini Tzani b , Eleni Chondrokouki a , Olga Mangana-Vougiouka a a Virology Laboratory – National Reference Laboratory for Rabies in Animals, Department of Molecular Diagnostics, FMD, Virological, Rickettsial & Exotic Diseases, Directorate of Veterinary Center of Athens, Directorate General of Veterinary Services, Ministry of Rural Development and Food, Athens, Greece b Department of Zoonoses, Animal Health Directorate, Directorate General of Veterinary Services, Ministry of Rural Development and Food, Athens, Greece c School of Science & Technology, Hellenic Open University, Patra, Greece d Veterinary Department, Regional Unit of Trikala, Greece e Veterinary Department, Regional Unit of Serres, Greece ARTICLE INFO Key words: Oral rabies vaccination Red fox Efficacy Juvenile Tetracycline Serological test ABSTRACT Although juvenile red foxes (Vulpes vulpes) are considered a single age group, essential for monitoring the ef- fectiveness 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. 1. Introduction The last animal rabies epizootic outbreak in Greece started in October 2012 (Tasioudi et al., 2014). Greece is among many countries that implement oral rabies vaccination (ORV): five autumn and two spring campaigns were carried out from 2013 to 2017 (Papatheodorou et al., 2018), aerially distributing SAG2 vaccine baits (Korou et al., 2016) followed by a programme for monitoring the effectiveness of the red foxes vaccination. The results are interpreted in terms of the per- centages of seropositive and tetracycline (TTC) positive animals / total tested and also by animal age (EFSA, 2015); sampling juvenile foxes (< 1 year old) is needed, so as to assess the most recent campaign (European Commission, 2017). ORVs are usually conducted on a biannual basis, but mainly the autumn campaigns target both adults and juveniles (Cliquet et al., 2012). Several studies have previously affirmed that juveniles have comparatively low seroconversion rate and bait uptake level (Robertson et al., 2000; Bugnon et al., 2004) and are not good indicators for campaign assessment (Zienius et al., 2014). It has been suggested that shooting young foxes during summer in Greece has to be discouraged https://doi.org/10.1016/j.vetmic.2018.10.006 Received 13 July 2018; Received in revised form 9 October 2018; Accepted 10 October 2018 Abbreviations: ORV, oral rabies vaccination; TTC, tetracycline ⁎ Corresponding author at: Virology Laboratory – National Reference Laboratory for Rabies in Animals, Directorate of Veterinary Center of Athens, 25 Neapoleos St, Agia Paraskevi, PC 15341, Athens, Greece. E-mail addresses: dppapatheodorou@minagric.gr, dppapatheodorou@gmail.com (D.P. Papatheodorou). Veterinary Microbiology 226 (2018) 59–63 0378-1135/ © 2018 Elsevier B.V. All rights reserved. T