2020 Jan 15. pii: tjz253. doi: 10.1093/jme/tjz253. [Epub ahead of print]

Circulation of Tick-Borne Spirochetes in Tick and Small Mammal Communities in Santa Barbara County, California, USA.


A diversity of Borrelia burgdorferi sensu lato (Johnson, Schmid, Hyde, Steigerwalt & Brenner) (Spirochaetales: Spirochaetaceae) genomospecies, including the Lyme disease agent, Borrelia burgdorferi sensu stricto (s.s.), have been identified in the western United States. However, enzootic transmission of B. burgdorferi s.l. in small mammals and ticks is poorly characterized throughout much of the region. Here we report prevalence of B. burgdorferi s.l. in small mammal and tick communities in the understudied region of southern California.

We found B. burgdorferi s.l. in 1.5% of Ixodes species ticks and 3.6% of small mammals. Infection was uncommon (~0.3%) in Ixodes pacificus Cooley and Kohls (Acari: Ixodidae), the primary vector of the Lyme disease agent to humans in western North America, but a diversity of spirochetes-including Borrelia bissettiae, Borrelia californiensis, Borrelia americana, and B. burgdorferi s.s.-were identified circulating in Ixodes species ticks and their small mammal hosts.

Infection with B. burgdorferi s.l. is more common in coastal habitats, where a greater diversity of Ixodes species ticks are found feeding on small mammal hosts (four species when compared with only I. pacificus in other sampled habitats). This provides some preliminary evidence that in southern California, wetter coastal areas might be more favorable for enzootic transmission than hotter and drier climates. Infection patterns confirm that human transmission risk of B. burgdorferi s.s. is low in this region.

However, given evidence for local maintenance of B. burgdorferi s.l., more studies of enzootic transmission may be warranted, particularly in understudied regions where the tick vector of B. burgdorferi s.s. occurs.



Remember – they find ticks on beaches – it doesn’t get much hotter and drier than there.  I know dogs are picking up ticks in the sand dunes of Padre Island, TX – another inferno.


Rosenkranz explained, “Think about it, right now there’s a lot of seagulls and other birds flying and they can carry ticks. People who are walking their dogs they are still allowed to do that they can get a tick that falls off of a dog, it’s pretty common in that sense.”

When it comes to Assateague, ticks can actually fall off the ponies and latch on to you.

Kelly Taylor, an Assistant Public Information Officer at Assateague National Seashore said, “You know you come out, ticks can be on horses so you want to keep your distance from the horses. We always recommend school bus length is the safe length for you, the safe length for the horses.”

And remember, just because ticks are found anywhere in low numbers doesn’t mean they aren’t there and can’t infect you or your pets.