Disease Risk & Landscape Attributes of Tick-Borne Borrelia Pathogens in the San Francisco Bay Area, California.
Habitat heterogeneity influences pathogen ecology by affecting vector abundance and the reservoir host communities. We investigated spatial patterns of disease risk for two human pathogens in the Borrelia genus-B. burgdorferi and B. miyamotoi-that are transmitted by the western black-legged tick, Ixodes pacificus. We collected ticks (349 nymphs, 273 adults) at 20 sites in the San Francisco Bay Area, California, USA. Tick abundance, pathogen prevalence and density of infected nymphs varied widely across sites and habitat type, though nymphal western black-legged ticks were more frequently found, and were more abundant in coast live oak forest and desert/semi-desert scrub (dominated by California sagebrush) habitats. We observed Borrelia infections in ticks at all sites where we able to collect >10 ticks. The recently recognized human pathogen, B. miyamotoi, was observed at a higher prevalence (13/349 nymphs = 3.7%, 95% CI = 2.0-6.3; 5/273 adults = 1.8%, 95% CI = 0.6-4.2) than recent studies from nearby locations (Alameda County, east of the San Francisco Bay), demonstrating that tick-borne disease risk and ecology can vary substantially at small geographic scales, with consequences for public health and disease diagnosis.
Department of Biology, Colorado State University, Fort Collins, Colorado, United States of America; Woods Institute for the Environment, Stanford University, Stanford, California, United States of America.
Daniel J
DJ
Salkeld
Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, United States of America.
Nathan C
NC
Nieto
Center of Excellence for Next Generation Computing, Clemson University, Clemson, South Carolina, United States of America.
Patricia
P
Carbajales-Dale
College of Engineering & Science, Clemson University, Clemson, South Carolina, United States of America.
Michael
M
Carbajales-Dale
Woods Institute for the Environment, Stanford University, Stanford, California, United States of America.
Stephanie S
SS
Cinkovich
Woods Institute for the Environment, Stanford University, Stanford, California, United States of America; School of Earth, Energy and the Environment, Stanford University, Stanford, California, United States of America.
Eric F
EF
Lambin
D000818:Animals; D001096:Arachnid Vectors / Q000382:microbiology; D061006:Bays / Q000382:microbiology / Q000469:parasitology; D025065:Borrelia burgdorferi / Q000472:pathogenicity; D017753:Ecosystem; D006801:Humans; D008193:Lyme Disease / Q000453:epidemiology* / Q000382:microbiology* / Q000635:transmission; D008969:Molecular Sequence Data; D009758:Nymph / Q000382:microbiology; D012306:Risk; D012495:San Francisco / Q000453:epidemiology; D017282:Tick-Borne Diseases / Q000453:epidemiology* / Q000382:microbiology* / Q000635:transmission; D013987:Ticks / Q000382:microbiology*