"Worms" is a very broad term for a range of parasites that can infect an animal (or humans in some cases). Although when talking about worms we are mainly talking about intestinal parasites (roundworms and tapeworms), there are also species that can exist in the lungs and airways (Lungworm) and (although not yet a problem in the UK), there are even parasites that infect the heart and bloodstream (Heartworm).
Often animals can have a worm infection without it causing a problem. However in very young or very old animals, those animals that are ill or those that have a particularly heavy infection, a variety of signs and problems can be caused.
Certain worms (such as the roundworm Toxocara) can infect people or farm animals who come into contact with contaminated faeces!
The method of infection varies not only between families of worms, but also individual species. Broadly speaking, the lifecycle of worms usually consists of adult worms laying eggs, which then hatch into young larvae which then go on to grow into adult worms - thus completing the cycle. Adults tend to live in the animal's intestines where they will lay eggs which are inevitably passed in the faeces. Once out in the open either the eggs or the larvae can be ingested back into a new animal. However before the larvae develop into adults they often migrate around the animal.
Therefore transmission can be one of several ways:
FAECO-ORAL -the animal becomes infected by ingesting eggs or larvae that have originated from an infected animals faeces. This doesn't necessarily mean the animal has to "eat poo"! Eggs can be picked up on the skin and later ingested by grooming.
ORAL - can occur if an animals eats another animal that may be infected or contain encysted larva. For example if a cat eats a mouse that has larval cysts inside it, or if a dog scavenges offal from an infected sheep. This route of infection is called "Paratenic" transmission.
MATERNAL - some species of worm can be transmitted to young offspring. This can either occur directly from the mother in the womb, or can also occur through the milk.
OTHER - the common household flea can transmit a tapeworm (called Dipylidium) to dogs and cats when its bites.
It is very difficult to completely stop your animal getting worms, and so for this reason it is important to get your animal treated for worm on a regular basis to ensure that there is not a serious build up of parasites which can then go on to cause problems. Unlike a lot of medicines, the drugs used for worming don't tend to have a residual action - in other words a couple of days after an animal has been wormed, the drug will have gone and potentially the level of parasites can begin to build up again.
As a result of this, it is recommended that all animals are wormed every 3-4 months against both roundworms and tapeworms.
It must be stressed that human problems associated with worms are rare, but this does not mean that we should ignore them. Certain practices should be undertaken to help reduce the chance of any problems:
There are a lot of worming drugs to choose from ranging from "over-the-counter" treatments to prescription only drugs. A lot of the non-prescription drugs are quite old, and therefore there is some resistance around. Also wormers may not treat all worms - i.e. you may be treating tapeworms without treating for roundworms. If in doubt you should always talk to a vet or veterinary nurse who will be able to advise you.
The prescription drugs are very effective and also come in a variety of forms that should help with the administration of the drug - often a big complaint with pet owners! These days wormers can be given as:
Prescription drugs can only be obtained via your veterinary surgeon, and we are happy to supply them to you without the need for a specific consultation. Please contact our repeat prescription service to obtain your wormers.
For Registered Clients