Takala, Anni Maria

The aim of this study was to examine the prevalence and abundance of Echinococcus multilocularis in red foxes (Vulpes vulpes) in Lithuania. Furthermore we evaluated an improved enumeration method for E. multilocularis with the sedimentation and counting technique (SCT). Red foxes (n=70) were hunted in 25 districts of Central/Eastern Lithuania between November 2018 and May 2020. The prevalence of E. multilocularis in red foxes was 31.4 % (95% CI 20.5-42.3) and the abundance varied between 1-2266 worms per infected fox. The juvenile foxes harbored higher (P>0.05) numbers of worms (401 (3-2266); 95% CI -366.31-1168.88) than those of adults (263 (1-1255); 95% CI 31.06-494.54). This was especially true in case of male juveniles which had the highest (P>0.05) average worm burdens of 921 worms per fox (228-2266; 95% CI -1971.95-3814.62), whereas the male adults had a mean abundance of 195 (2-930; 95% CI -58.92-448.25). However, in case of females, adults had higher average worm burdens (365 (1-1255); 95% CI -205.30-935.30) than the juveniles (14 (7-20); 95% CI -2.29-30.29). The differences in worm burden between adult and juvenile foxes and different genders most probably should be related to habits of different predation on rodents and differences in diet. An improved calculation based on the number of scolices and excess of gravid proglottids found in the samples improved the detection level for the abundance by 19.61% (95% CI: 11.9-27.3) in low abundance (1-20), 53.39% (95% CI: 49.9-56.9) in moderate abundance (21-130) and 6.73% (95% CI: 6.1-7.4) in high abundance (above 130) group as compared to those of calculation based on the scolices of E. multilocularis only (p<0.05).