It’s summer! That means longer days, weekends at the beach, long hikes, and, unfortunately, checking for ticks. Even with precautions, I’ve already spotted them on myself and my dog after a long walk. But dogs aren’t the only pets you should be checking for these pests. Cats, especially ones that spend a lot of their of time outside, also need to be checked, and considered when researching tick-borne diseases.
Currently, “domestic cats are often overlooked in epidemiological investigations of tick-borne infections compared with their canine counterparts.” Seeking to explore this niche, Smith et al. published a new research paper in Parasites & Vectors entitled Detection of pathogens within Ixodid ticks collected from domestic cats across the USA, “the largest survey for tick-borne pathogens within Ixodid ticks collected from domestic cats in the USA.”
For this study, the authors selected Ixodid ticks (also known as hard ticks) from those sent to Show Us Your Ticks, an initiative that works with veterinary clinics across the country to collect tick specimens. Participating clinics can send in ticks they collect from animals, with the goal of identifying tick species in the US and characterizing “the tick-borne disease agents carried by ticks in different geographic regions”. In order to qualify for the study, specimens had to have been taken from a feline; be adult hard ticks; have been collected between the beginning of 2019 and end of 2023; and not have been used before for detecting pathogens or extracting DNA. In total, the authors studied 802 Ixodid ticks collected from 512 cats.
Once they had made their selection, the researchers morphologically identified the species and tested for pathogens using nested conventional polymerase chain reaction (PCR). In total, Smith et al. found that they had 431 Ixodes scapularis, 218 Amblyomma americanum, and 53 Dermacentor variabilis. In 19.5% of I. scapularis they detected Borrelia burgdorferi, a cause of Lyme disease, but that’s not all they found. “Ehrlichia ewingii was detected in 3.2% of A. americanum. Anaplasma phagocytophilum was detected in 0.7% of I. scapularis. Cytauxzoon felis was detected in 0.5% of A. americanum. Borrelia miyamotoi was detected in 0.2% of I. scapularis.” (Cytauxzoon felis can prove especially serious, with infection proving fatal in many pet cats.) About one in seven of the cats had a tick infected with a significant pathogen.
However, Smith et al. were unable to draw conclusions regarding the effect of many of these pathogens on cats. As they state: “An inherent limitation of this style of study is that detection of a pathogen within a tick does not imply pathogen transmission from the tick to the host nor subsequent development of disease if transmission did occur,” pointing a potential way forward for further studies.
So, what are cat owners to do? Prevent their kitties from getting out and about no matter how much they complain? Apparently, even that might not be enough, especially if other pets still venture outside. Smith et al. found that while apparently the majority of ticks collected from cats were from those that spent more than half of their time outside, 4.5% reportedly had no outdoor access – but still had ticks. And these ticks can pose a threat not only to cats, but, if they can hitch a ride on an unsuspecting feline, also one to humans and other pets in their home.
It is therefore very important to ensure proper compliance with feline ectoparasite control and check your Felix’s and Garfield’s for ticks, so that you can rest easy when they go off adventuring.
(Cover image from Smith et al.)