| Abstract [eng] |
SUMMARY The aim of present study was to assess the importance of two main reservoir hosts A. flavicollis and M. gareolus, and their ectoparasites I. ricinus immature ticks in Lyme disease agent B. burgdorferi s.l. circulation in natural foci. The following research tasks were formulated: 1. To establish the infectivity level of questing immature I. ricinus ticks with B. burgdorferi s.l. and to determine it’s genotypes composition. 2. To investigate the infectivity level of two main Lithuania rodent species A. flavicollis and M. glareolus with B. burgdorferi s.l. and to determine it’s genotypes composition. 3. To estimate prevalence and abundant of infestation with immature I. ricinus ticks in A. flavicollis and M. glareolus species rodents. To calculate any differences between rodents in species, age and sex level. 4. To evaluate transmition efficient of B. burgdorferi s.l. from rodent to feeding I. ricinus larvae. The infectivity level in questing I. ricinus nymphs in fragmented mixed forests of Lithuania was relatively high, and varied in different districts from 14% to 24%. The most prevalent genotype was B. afzelii, and only in one district B. garinii was found. In case of I. ricinus larvae the overall infectivity level with Lyme disease spirochete was 3,5%. In order to establish the infectivity level with B. burgdorferi s.l. in total 302 rodents comprising 3 species - A. flavicollis, M. glareolus and A. agrarius were investigated. The results have showed that in all rodent species the infectivity level with B. burgdorferi s.l. was extremely high. It was higher than in previous studies made in Lithuania. Comparing difference of infection of two main species A. flavicollis and M. glareolus only in one district –Joniškis – infectivity level was significantly higher in A. flavicollis than in M. glareolus. There were differences in age categories of both species. It was established, that adult individuals were more infested with B. burgdorferi s.l. than juveniles. In case of M. glareolus, in three districts of five males were more infested with B. burgdorferi s.l. than females. But there were no such differences between A. flavicollis. B. afzelii was absolutely dominant genotype among rodents. Only in three individuals mixed infection with two genotypes was found: in A. flavicollis – B. afzelii + B. burgdorferi s.s. and B. afzelii + B. garinii, in M. glareolus - B. afzelii + B. garinii. In 2009 the prevalence and abundance of infestation with immature I. ricinus ticks on rodents was extremely higher than in 2005-2006 period. In three districts the prevalence of infestation with I. ricinus nymphs was significantly higher in A. flavicollis than in M. glareolus. In both species no straight tendency of infestation between sex was observed. There is no doubt, that both A. flavicollis and M. glareolus species play significant role in B. burgdorferi s.l. circulation in endemic foci, because infectivity level from fully engorged I. ricinus larvae was higher than in questing ones. The efficiency of B. burgdorferi s.l. transmission was significantly higher in M. glareolus than in A. flavicollis. But in case of infestation with I. ricinus larvae, in four of five districts A. flavicollis was more infested than M. glareolus. So it is hard to predict which species is more important in B. burgdorferi s.l. circulation in natural foci. |
