The field efficiency of oral rabies vaccination in the Lithuanian red fox population from 2006 to 2013

Abstract

The objective of the present study was to assess the efficacy of an oral rabies vaccination (ORV) program in the period from 2006 to 2013 based on epidemiological data (Incidence of confirmed rabies in red foxes), biological marker evaluation (presence of tetracycline [TTC] indicating bait uptake), and the assessment of seroconversion (based on ELISA for rabies antibodies) in red foxes in Lithuania. Results were compared between juvenile and adult red foxes, and between the spring (March to May) and autumn (October to December) campaigns. On average, 20 baits/km2 were distributed over the entire territory of Lithuania. During the entire period of 2006-2013 1179 red foxes (10% of 11 829) were rabies-positive. While in 2006, 23.8% of tested foxes were rabies-positive, the incidence decreased to 2.4% in 2009, and 0.7% in 2011. Based on jaw bone investigation 78.1% of the foxes had ingested TTC from baits, 52.2% had seroconverted. The percentage of ELISA-positive red fox sera samples remained stable at 44.7-53.2% during both most recent ORV periods. The majority were adults (83%), 81.1 ± 8.54% of which were TCC-positive, and 73.8 ± 6.33% were TTC-positive juveniles. 52.5 ± 5.81% of adult red foxes had seroconversed, while 48.2 ± 4.51% of the young animals had a positive ELISA test in the years 2006 to 2013. This is in contrast to 2006 where only 29.5% of the young foxes were ELISA-positive. There were no significant differences between TTC- and ELISA-positive populations in different geographical regions of Lithuania.

Keywords

• baltic states
• prevention
• rabies
• wildlife
• ttc marker
• elisa seroconversion