Longitudinal study regarding Borrelia burgdorferi sensu lato populations in defined habitats in Latvia

Okeyo, Mercy Akinyi (2020): Longitudinal study regarding Borrelia burgdorferi sensu lato populations in defined habitats in Latvia. Dissertation, LMU München: Tierärztliche Fakultät

Abstract

Borrelia burgdorferi sensu lato (B. burgdorferi s.l.) is a species complex that currently comprise 22 named or proposed genospecies. In Europe five species are known to be the agents of the human disease - Lyme borreliosis (LB). With approximately 650,000-850,000 assumed new LB cases in Europe annually, LB is the most common human tick-borne disease in Europe (Lit EU). For control measures and eventual prevention of this tick-borne disease, it will be beneficial to study and interpret the B. burgdorferi s.l. population dynamics and structure. The bacteria are maintained in a natural transmission cycle between reservoir hosts and ticks of the genus Ixodes. Keeping in mind that the tick vectors` life cycle may be up to more than five years, long term studies are required for a better understanding of such correlations. Hence this study is designed to cover the tick sampling periods between 1999 and 2010 in defined habitats in Latvia. As preliminary study the most economical and efficient method for DNA extraction was determined. Subsequently polymerase chain reaction (PCR) and Multilocus Sequence Typing (MLST) was used to obtain information about population structure, fluctuations and stability regarding B. burgdorferi s.l.. The average prevalence over all years was 18.9 %. From initial high infection prevalences of 25.5 %, 33.1 % and 31.8 %, from 2002 onwards the infection rates steadily decreased to 7.3 % in 2010. Borrelia afzelii and B. garinii were the most commonly found genospecies but striking local differences were obvious. In one habitat, a significant shift from rodent-associated to birdassociated Borrelia species was noted whilst in the other habitats, Borrelia species composition was relatively stable over time. Sequence types (STs) showed a random spatial and temporal distribution. These results demonstrated that there are temporal regional changes and extrapolations from one habitat to the next are not possible.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Keywords: B. burgdorferi sensu lato, PCR, MLST, NGS
• Themengebiete: 500 Naturwissenschaften und Mathematik ; 500 Naturwissenschaften und Mathematik > 590 Tiere (Zoologie)
• Fakultäten: Tierärztliche Fakultät
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 25. Juli 2020
• 1. Bericht­erstatter:in: Straubinger, Reinhard