Local Community Composition Drives Avian Borrelia burgdorferi Infection and Tick Infestation

Area of Science:

• Ecology
• Epidemiology
• Veterinary Science

Background:

• Zoonotic vector-borne diseases, including Lyme disease, are increasing globally.
• Lyme disease is transmitted by *Ixodes* ticks carrying *Borrelia burgdorferi* sensu lato (s.l.) to vertebrate hosts.
• While small mammals are primary reservoirs, the role of birds in Lyme disease transmission is understudied.

Purpose of the Study:

• To investigate the role of avian hosts in the transmission cycles of *Borrelia burgdorferi* s.l. in the western United States.
• To assess *B. burgdorferi* s.l. infection prevalence in birds and ticks.
• To examine the relationship between avian infection, tick burden, and host community composition.

Main Methods:

• Field surveys were conducted at nine sites in northern California.
• Birds, mammals, and ticks were sampled to detect *B. burgdorferi* s.l. infection.
• Data on host community composition (abundance/diversity of birds, mammals, lizards, predators) and tick infestation were collected.

Main Results:

• *Borrelia burgdorferi* s.l. was detected in 22.8% of surveyed birds.
• Avian infection likelihood correlated significantly with local host community composition and pathogen prevalence.
• An average of 0.22 ticks per bird was found, with predator and lizard abundance predicting tick infestation.

Conclusions:

• Birds are significant hosts in the *Borrelia burgdorferi* s.l. transmission cycle in the western U.S.
• Avian hosts may contribute to the maintenance and spread of Lyme disease.
• Further research is required to fully quantify the role of birds in Lyme disease dynamics.