Part Two: What are the risks?
The purpose of this part of our article is to provide you with some information regarding the parasites we routinely treat in veterinary medicine and consideration of any potential risks when not treating for them. As mentioned in Part One, parasite treatment is an area of veterinary medicine currently under heavy debate, with many people raising concerns regarding what impact the drugs we use to prevent parasite infestation may or may not be having on the wider environment.
We have aimed to provide you information about most common parasites we tend to treat for in the UK, along with a summary of the risks involved. We haven’t written this as a “quick read” but have tried to provide a fuller explanation into the challenges we need to consider when treating our pets. (However, a shorter summary can be found here or at the end of the article).
Fleas
The most common flea seen in cats and dogs is the “cat flea”. These fleas can be picked up outdoors and brought inside. Here they will merrily breed all year long, occasionally nibbling their human housemates while doing so (they often tend to have a favourite target!). Once established on our pets, a female flea can lay up to 50 eggs a day. These eggs can then hatch in the environment as larvae which like to find somewhere dark to hide. Here they form a pupae (like caterpillars). This pupal stage can last in the environment for up to a year before hatching out as an adult flea and starting the cycle all over again. When treating a pet for fleas, it is always important to remember to treat the household with a good quality house spray. It is also worth bearing in mind that even the best household treatments cannot kill the pupal stages and so once a flea problem has become established in a household it can take some time to resolve!
What is the risk to your pet?
The main problem fleas pose to your pets is that they can be incredibly irritating, particularly if your pet is allergic to the flea’s saliva. Fleas are also part of the tapeworm lifecycle and some pets with fleas subsequently go on to develop tapeworm infestations. Additionally, over time a large flea burden can also cause an anaemia to develop in your pet. Finally, fleas have been shown to carry bartonella, a species of bacteria that can cause “Cat Scratch Fever”.
Are they a risk to human health?
The most common concern clients have with flea infestation (other than seeing the fleas themselves!) is that family members have been receiving flea bites. However, there is also a disease seen in people, referred to as “Cat Scratch Fever”, which is caused by the infection of a bartonella species of bacteria. The bartonella bacteria can be transmitted via flea dirt in a variety of ways but the most common is via cat scratches. The symptoms of this disease in people are usually mild, but it can cause more serious complications in immunocompromised people. Due to the non-specific and often mild symptoms shown in people, it is hard to really know how commonly the disease is spread or its incidence within the UK.
What are the risks of not treating?
It is important not to ignore the risk of Cat Scratch Fever in households with immunocompromised people, however, the major concern with fleas to most of us is the annoyance factor of bites coupled with the length of time it could take to clear a household of infestation.
Who should consider treatment?
As mentioned, the cat flea is the most common culprit in UK households and so UK households with cats that go outside are more likely to encounter fleas. Many of us believe that dogs that live in cat free households are at lower risk of picking up fleas and so owners may consider not using preventative treatment. While this is probably true, there are no studies to confirm that this is the case. As such pet owners who chose not to treat should be aware that cat fleas can live quite happily on dogs and owners need to be aware of the challenges to treatment should their pet pick up fleas.
Roundworms
Dogs and cats tend to pick up roundworms by ingesting eggs from the environment including direct contact with other dogs; eating undercooked meat; or by eating other infected animals such as rodents, earthworms and birds. Once our pets are infected, the roundworm will complete its lifecycle, develop into adults, and start laying eggs of their own
What is the risk to your pet?
Roundworms rarely cause significant disease in adult dogs and cats, but infection can pass through the placenta and high worm burdens can cause significant disease in puppies and kittens.
Are they a risk to human health?
Yes, but the incidence of infection is hard to know. The roundworm eggs can be picked up via contact with contaminated soil and sand; eating unwashed fruit and vegetables; or by placing contaminated objects in our mouths. Classic examples of environmental infection could be contact with contaminated fur and bedding, or children playing in gardens or parks where infected dogs or cats have defecated.
Ingested eggs won’t develop to the adult stage in people but can cause disease. Again, symptoms of the disease in people are normally mild but worm eggs once ingested may develop to the larval stage and migrate to eyes, brain or liver causing serious problems. Children seem to be at more risk of this disease. Again, with the wide range of clinical symptoms and lack of routine surveillance, it is hard to know the exact incidence of this disease in the UK. It is thought that there are 1.4 billion people affected worldwide, and some studies have shown around 10.5 percent of people tested in European regions have been exposed at some stage. In addition, studies carried out in the UK have shown contamination in public parks all over the UK.
Who should consider treatment?
In the absence of regular worm egg counting, we would advise treating pets for roundworms at least 4 times a year. Households that are at greater risk, such as those with children or whose pets are regular hunters, should consider treating more regularly. It is also very important to help reduce environmental contamination by picking up faeces and disposing them promptly, both in the garden and in public areas. For those who do not wish to treat regularly, it is advisable to perform worm counts on your pets at least four times a year. Faecal egg counts can be performed either via your vet, or via a reliable commercial laboratory in which there is growing availability. But owners who chose this option need to be aware there is a chance their pet could become infected and shed eggs between tests.
Tapeworms
Both cats and dogs can pick up tapeworm in the UK. Cats tend to pick up tapeworm from hunting or ingesting fleas and lice; dogs can also pick up tapeworm from eating infected carcasses (sheep, cattle, pigs and other livestock) or raw food diets that have been inadequately frozen. Cats and dogs are considered the “definitive host” for these tapeworm species and as such the tapeworms will develop to full maturity and release eggs. However, other mammalian species are involved in the transmission. When the tapeworm eggs are picked up by these “intermediate” hosts (birds/sheep/cattle/pigs) they won’t develop into mature worms. Instead, the immature stage of the tapeworm moves to organs such as the liver and lungs of these species and form cystic disease.
What is the risk to your pet?
Tapeworms are rarely associated with significant clinical signs of disease in pets. Tapeworm segments leaving the anus may cause anal irritation. However, it should be noted that tapeworm does cause more significant disease in the “intermediate hosts” including wild birds in the case of cats, and livestock in the case of dogs. This can have significant welfare impacts to these animals as well as an economic impacts in farming areas.
Are they a risk to human health?
The dog tapeworm present in the UK, Echinococcus granulosus, can cause significant health concerns in people but this rarely occurs in the UK. Like the “intermediate hosts”, this tapeworm infection can cause cystic disease in multiple organs in infected people. This disease is seen more commonly in more tropical climates, but there is thought to be 10-20 new cases in the UK every year.
Who should consider treatment?
Owners of pets that regularly hunt, have access to carcasses or are on raw food diets that have been inadequately prepared should consider treating for tapeworm monthly. Owners of pets that have had a significant flea infestation should consider treating for tapeworm as well as fleas. Pets that receive regular flea treatment and have limited access to hunting or raw food diets are at much lower risk and require less regular treatment.
Travel Considerations
In addition to concerns about tapeworms currently present in the UK, it should be noted that there are also tapeworm species currently in mainland Europe that pose more significant risk of ill health to owners. There are concerns in the veterinary industry that the current legislation regarding pet travel to mainland Europe is not be adequate to prevent the importation of these tapeworm species. As such, in addition to your legal requirement to treat your pet prior to returning to the UK, we would also recommend repeating this treatment after you’ve returned to the UK. This will cover for any potential exposure to tapeworm between the day of treatment while away and your return to the UK.
Ticks
There are several species of tick widespread throughout the UK. These ticks are most often found in wooded areas or areas with long grass, especially in the spring, summer and autumn months. Ticks are multi-host parasites, they attach themselves to one host to feed, then drop off to go through a development stage before attaching to another host. Most ticks in the UK attach to 3 different hosts in their lifecycle. Whilst ticks can cause some discomfort and localised infection, especially if not removed correctly, the main health concern with ticks is the potential of spread of disease
What is the risk to your pet?
In the UK we have several diseases that can be spread to our pets and ourselves via tick bites. The most well-known one of these is Lyme disease. Lyme disease can infect dogs, humans, and (more rarely) cats, causing various problems including fever, lameness and kidney disease. The symptoms of the disease can be significant and prompt identification and treatment is vital. However, other diseases include anaplasmosis in cats, babesia infection and tick-borne encephalitis.
Are they a risk to human health?
While people can pick-up tick-borne diseases, this would be due to a bite from a contaminated tick picked up in the same area as your pet found one, rather than transmission of disease from your pet. Lyme disease has been established in the UK for a long time and can cause a range of symptoms from mild fever through to paralysis if untreated. However, tick borne encephalitis is a relatively new arrival, having spread from mainland Europe, with only a few human cases being confirmed in the UK. It is a viral condition spread via tick bites that can cause a range of symptoms from mild flu-like symptoms up to meningitis. As of October 2024 the disease has been confirmed in ticks in Thetford Forest, Hampshire/Dorset Border, the New Forest and North Yorkshire Moors, but that list is likely to grow.
Who should consider treatment?
We should consider regular treatment for pets that access areas that are more prone to ticks such as long grass or wooded areas. Ticks are more prevalent in the spring, summer and autumn months. Regardless of whether you treat your pet or not, all owners should regularly check their pets for ticks and seek veterinary advice for the correct method of removing ticks using recommended tools to assist. Cats seem to be less susceptible to tick disease than their canine counterparts. It is not clear if this may be because they are less prone to picking up ticks, or if they are better at removing them before we find them; but cats are certainly capable of picking them up, especially if they like to visit animal burrows
Travel Considerations
There are many more disease risks associated with tick bites in pets that have travelled to mainland Europe than we have in the UK, and we would strongly advise discussing any travel plans with your vet. There are no compulsory steps in the travel legislation that will protect your pet against tick borne disease while travelling and some of the tick species in Europe can be brought back to the UK to live quite happily in your household.
One of the European ticks that can carry a disease called babesia has been established in the UK for many years but has not previously been known to carry the babesia infection. However, in 2015 and 2016 there were confirmed cases of Babesia in the UK in dogs that had not travelled to Europe prompting concerns that the disease could be established here if given the opportunity. Prompt identification and management of the affected area seems to have helped reduce its transmission, but it is still an area for concern.
Lungworm in Dogs
Lungworm is spread to dogs via the ingestion of infected slugs or snails or via toys or bowls that have come into contact with contaminated slugs and snails. Once infected, the larvae develop into worms which reside in the heart and major blood vessel of the lungs.
What is the risk to your pet?
Symptoms of lungworm are variable but can include breathing problems and pneumonia as well as bleeding and neurological disorders. Symptoms can be mild initially but can progress to fatal disease if not identified and treated.
Is there any risk to human health
No
Who should consider treatment?
We know that lungworm presence in the UK can be very patchy, with the disease being much more prevalent in some local areas compared to others. Dogs that like to eat slugs and snails are at more risk and should receive regular treatment, but we should be conscious of the risk to all dogs if they have toys or bowls that are left outdoors. It is an area where more information on local exposure would massively help our understanding of risks to individual households. However, the only route to discovering that information is by regularly testing the pets that have not been treated for disease.
What are the next steps?
Thank you for investing so much time in reading this article, we know this hasn’t been a quick read! The next step is to consider what risks your pet is exposed to on a day-to-day basis and discuss any concerns with our team at the clinic. As it is clear, there is no “one solution fits all” and we are always happy to individualise the treatment plan for your pet and your household depending on what you are concerned about. To help with the costs we have a well-established Pet Health Club. Our Pet Health Club can provide you with an individualised vaccination and parasite treatment plan as well as unlimited vet and nurse consults among other benefits to help provide the care your pet needs.
For more information on this or anything else discussed in either of these articles, please feel free to contact us (will add a link) at the clinic. Otherwise, we hope they have been helpful and thank you very much for your time.
Best wishes,
The Team at Mayne Vets
More information can be found on the European Scientific Counsel Companion Animal Parasites (ESCCAP) website (https://www.esccap.org/)
(Summary table containing bite sized information on the article above)
| Source | Risk To Pets | Risk to people | |
| Fleas (Cat Flea) | Picked up outdoors or eggs brought into house after visiting infected households. Once established in a household, fleas can breed all year round and can take over a year to clear once discovered. | Irritation, Flea Allergy, Anaemia, Tapeworm infection. | Irritation, Cat Scratch Fever, the symptoms of which can vary from mild flu like symptoms to serious disease in immunocompromised individuals. |
| Roundworms | Contact with contaminated soil, Eating undercooked meat Ingestion of other infected animals including rodents, birds and earthworms. | Rarely cause significant disease unless high worm counts in puppies and kittens. | Yes, but incidence is hard to know. Normally signs of infection in people are mild but larval forms of worms can travel to organs including eyes and liver. |
| Tapeworms | Fleas and Live Hunting, Eating infected carcass (livestock), Raw food diets that have been inadequately frozen. | Minimal risk to dogs and cats but can cause significant disease to other animals in lifecycle. | The dog tapeworm present in UK can cause significant disease in people but this is rare in UK. |
| Ticks | Picked up in long grass and wooded areas. | Tick borne disease would be greatest risk, including Lyme disease, anaplasmosis and babesia. | Tick borne diseases are also a risk to people including Lyme disease and tick – borne encephalitis. |
| Lungworm | Picked up from eating slugs or snails or contact with bowls or toys that been in contact with infected slugs and snails. | Yes, symptoms can vary from breathing problems and pneumonia through to bleeding and neurological disorders | No |
Image 1: https://unsplash.com/photos/a-sheep-standing-on-a-lush-green-field-PvWLieySGsM
Image 2: https://unsplash.com/photos/brown-snail-in-rule-of-thirds-photography-SHpbGW-sSYE