Feline Tickborne Pathogen Prevalence in the United Kingdom

Ticks serve as important arthropod vectors for a variety of bacteria, viruses, and protozoa. The available literature estimates that tick infestation and tickborne pathogen transmission in the United Kingdom are higher in dogs than in cats (30% vs 6.6%), although relatively few studies have focused specifically on cats.

UK researchers recently performed a nationwide survey to determine the prevalence of several tickborne pathogens (Anaplasma phagocytophilum, Bartonella spp., Hepatozoon spp., and 3 hemoplasma species) in ticks collected from client-owned domestic cats.

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Study Design

Ticks were collected from cats during examination at participating veterinary hospitals throughout the United Kingdom. Before processing, each tick was spiked with an internal amplification control to monitor successful DNA extraction and rule out polymerase chain reaction (PCR) inhibition, which commonly occurs in blood samples. The researchers also used primers for feline 28S rDNA to serve as an endogenous positive control. Several conventional and quantitative PCR assays for tickborne pathogens were performed.

Specific qualitative PCR assays targeted:

• Anaplasma phagocytophilum
• Bartonella spp (positive samples were also screened for B henselae)
• 3 hemoplasma species (Mycoplasma hemofelis, “Candidatus Mycoplasma hemominutum,” and “Candidatus Mycoplasma turicensis”)

Hepatozoon spp were detected using conventional PCR. DNA sequencing was performed to identify pathogens in positive samples to the species level.

Results

A total of 540 ticks were collected from 540 cats at 278 practices between May and October 2016. Most ticks were removed from cats in England, and most were adult females. Feeding status of the ticks, based on level of engorgement, was categorized as follows: 122 fully fed, 372 partially fed, and 46 unfed.

The internal amplification control successfully amplified in all 540 samples, while 475 (88%) samples detected feline 28S rDNA, suggesting that most ticks had a blood meal prior to collection. Nineteen tick samples (3.5%) were positive for a single pathogen, and no co-detections of multiple pathogens were noted.

• 5 ticks (0.9%) with A phagocytophilum
• 7 ticks (1.3%) with Bartonella spp
• 5 ticks (0.9%) with hemoplasma DNA
• 2 ticks (0.4%) with Hepatozoon spp

All pathogens were distributed widely throughout the United Kingdom except for Hepatozoon spp, which were detected only in Wales and southeastern England. In a previous study with the same 540 tick samples, investigators determined that 6 (1.1%) samples contained Babesia spp and 10 (1.9%) contained Borrelia burgdorferi.

Comparing the UK study to similar surveys conducted throughout Europe, the investigators found the prevalence of M hemofelis, “Candidatus M turicensis,” A phagocytophilum, and H felis was higher in the United Kingdom than in Italy and Switzerland. Meanwhile, Bartonella spp, B clarridgeiae, and “Candidatus M hemominutum” were detected less frequently.

The Bottom Line

While most (93.5%) of the ticks collected from cats in the UK study were pathogen-free, several tickborne pathogens were widely distributed throughout the country.

Dr. Stilwell received her DVM from Auburn University, followed by an MS in Fisheries and Aquatic Sciences and a PhD in Veterinary Medical Sciences from the University of Florida. She provides freelance medical writing and aquatic veterinary consulting services through her business, Seastar Communications and Consulting.