Zoonosis in the bedroom

Setting aside the animals at risk of anaemia and those with flea allergic dermatitis (FAD), fleas can often be perceived as little more than an itchy nuisance, but the risks fleas present go beyond the parasite itself. Disease transmission is an often-forgotten aspect of flea infestation but is a common occurrence.

One study investigating pathogen carriage of fleas discovered 50% of flea samples were PCR positive for at least one pathogen and 20% were infected with more than one pathogen species.¹ These pathogens present a risk to our pets but increasingly, emerging zoonotic diseases are being recognised as a direct result of the fleas our pets are bringing into the home.²

A study conducted by Prof R Bond et al showed 7% of dogs and 21% of cats in the UK have a flea infestation.³ It also revealed almost half of the owners of these animals have no idea their pet is harbouring these parasites.

Closer to our pets than ever

A recent survey revealed 44% of dog and cat owners frequently share their own bed with their pet.⁴

While this practice may enhance the “wellness” benefits of pet ownership, increased exposure to pets will inevitably lead to increased exposure to their parasites, plus any diseases they may be carrying.

There are case studies demonstrating this increased zoonotic risk as a result of sharing personal space with pets from across the globe:³

• a systemic case of cat scratch disease (CSD) with hepatic, splenic, and renal involvement caused by Bartonella henselae was diagnosed in a 9-year-old patient who had been sleeping with a cat at night
• a 50-year-old man from Japan, who had left cervical lymphadenopathy as a result of B henselae owned a dog that often licked his face
• a 2008 US matched case-control study surveyed 9 plague survivors, 12 household members of these survivors, and 30 age and neighbourhood matched controls and showed sleeping in the same bed with a pet dog remained significantly associated with infection

A domestic problem

Whereas sylvatic plague remains endemic in the western USA and is a public health concern for humans and their pets – especially cats – there have been no reported cases in humans and their pets since 1918 in the UK.

However, a very real and prevalent domestic flea borne zoonotic disease threat is CSD caused by B henselae. Multiple studies have shown that incidence of B henselae infection in UK pet cats is over 40%^5,6 and in another study looking at flea pathogen carriage, 17% of those fleas studied were found to be carrying B henselae.²

Pet cats are recognised as the principal reservoir of infection for B henselae. This reservoir is allowed to perpetuate because of fleas, namely Ctenocephalides felis, as transmission between cats relies on these vectors. More than 4.5 million UK cats live in multi-cat households and it has been shown the risk of infection increases as the population of cats does (including within a single household).⁷

In humans, despite the common name of cat scratch disease (a cat scratch is usually reported in the large majority of the human cases), aggressive feline behaviour does not necessarily preclude infection if an existing wound or abrasion exists that comes into contact with infected flea faeces. CSD is more frequently observed in people under 20 years of age and those who own a cat under a year of age, especially if this cat is infested with fleas.

Stopping the spread with Seresto

Control of many flea-borne diseases should focus on vector control, as this is often the only effective way to prevent further increase of the infection reservoir and ultimate transmission risk to people. This is particularly true for B henselae, as antibiotic treatment has been shown to have limited value in infected cats and non-immunocompromised people.

All animals in a household should receive constant and effective protection from fleas, particularly individuals in multi-cat households that are at a greater risk of infection but also other species, including dogs, as they can become infected too. This is very important; constant and multi-species protection is something a continuous release product, such as a Seresto collar, provides really effectively.

Releasing controlled doses of active ingredients Imidacloprid and Flumethrin, Seresto provides effective protection against fleas and other parasites for up to eight months with a single application.⁸ By killing fleas quickly, the infected individuals are removed from the population, helping to reduce the reservoir of infection.

^{Use Medicines Responsibly (www.noah.co.uk/responsible). An attachment of single ticks after treatment cannot be excluded. Seresto® contains imidacloprid & flumethrin POM-V (UK) POM (IRL). Advice should be sought from the medicine prescriber. Further information from the datasheet at noahcompendium.co.uk or on request. ®Registered Trade Mark of Bayer AG. Bayer plc, 400 South Oak Way, Green Park, Reading, Berkshire, RG2 6AD. Tel: 0118 206 3000. Bayer Ltd., The Atrium, Blackthorn Road, Dublin 18. Tel: (01) 299 9313. L.GB.MKT.09.2017.17756.}

^{*SPC tick repellency & Mehlhorn et al. Parasitol Res (2001) 87:198-207, information is regarding mode of action and is not intended to imply parasites can be completely stopped from biting. An attachment of single ticks after treatment cannot be excluded.}