Fleas and their Control

Fleas are probably the most common parasite of our cats and dogs. A recent survey estimated that over 20% of cats and 10% of dogs suffered from fleas. There are different species of flea, but it is the “cat flea” (Ctenocephalides felis), which is the most ubiquitous, affecting both cats and dogs.  To understand how to control fleas effectively, it is very important to understand their life-cycle as shown here.



On your pet, adult fleas take a blood meal (bite) and mate. Within 24 to 48 hours, the female starts laying her eggs. These eggs fall off the animal, wherever it goes in your house. A typical female flea may lay 200 eggs over a period of five days.  These are now in your carpets and they'll hatch in a further 4-12 days, depending on the temperature and humidity.

Flea eggs hatch into worm-like larvae that move away from light and downwards. This means that they are usually found deep in the carpet pile. They tend to accumulate in areas where the pet rests, but have been observed to crawl as far as 20 feet while in this stage of the life cycle.

After 7-18 days, flea larvae pupate. Inside the cocoon, fleas are almost impervious to insecticides. It takes between 5-14 days for fleas to develop inside the cocoon, after which they are triggered to hatch in response to vibration (being stepped on), or the carbon dioxide exhaled by a passing host. But in the absence of a trigger, they can survive inside the cocoon for up to nine months.

So, important facts here are:

• For every flea you can see on your cat or dog, there may be another 200 eggs around the house.
  
• The most effective flea control involves using 2 types of treatment: one to kill adult fleas on the pet, and the other to prevent fleas reproducing in your house.
  
• Flea prevention is better than cure. It is far better to make sure that you do not get a flea infestation in your house in the first place, as trying to eliminate it later can be far more difficult, less successful and more expensive!
  
• There are no chemical sprays on the market today that will penetrate the pupal cocoon. So, if you already have pupal fleas in the house, you will need to start your flea control programme and accept that it may be weeks before they hatch and can be completely eliminated from the house.
  
• There is no such thing as an effective flea repellent; they are not repelled or killed by things such as garlic, brewer’s yeast or citronella.
  
• Adult fleas are permanent ectoparasites. In other words, once they are living on a pet, they'll stay there until they're removed by grooming or die.
  
• Adult fleas usually live for a matter of days on a cat or dog, unless swallowed by the pet, or killed by an insecticide. They account for only 5% of a typical flea infestation at any one time (the rest existing in the egg, larval and pupal life stages).
  

Health Problems caused by Fleas

• Pruritis (Itching)
  

As the flea bites your pet, it releases saliva to stop blood from coagulating. This saliva contains chemicals that cause an irritant reaction and this causes pruritus (itching) .The animal will start to scratch or groom/bite at itself excessively, eating many of the fleas in the process.

• Flea Allergic Dermatitis (FAD)
  

This is a severe allergic skin reaction in animals that have become allergic (sensitised) to flea saliva. In these animals, even one flea bite can trigger a severe skin reaction resulting in extreme itching, hair loss, infected and inflamed skin. Animals become sensitised by being exposed to being repeatedly bitten by fleas over a long period of time.
The itching that occurs in dogs and cats with FAD is intense, and can result in self-mutilation. Generally, clinical signs are distributed over the inner thigh and abdomen and along the spine and hindquarters. Medications are sometimes needed to relieve the clinical signs temporarily.

• Tapeworms
  

One common species of tapeworm (Dipylidium caninum) uses the flea as an intermediate host in its own life cycle. Eggs deposited by the adult tapeworm are shed into the environment where they are consumed by the flea larvae. If a pet then ingests an adult flea that consumed tapeworm eggs as a larva, the tapeworm parasite is passed on. Tapeworms can cause some animals to vomit or lose weight. Tapeworm segments can sometimes be seen wriggling near the hind end of the animal near the base of the tail. People can also become infected with tapeworm if they accidentally ingest an infected flea.

• Anaemia
  

Because fleas are blood sucking insects, a heavy infestation can produce parasitic anaemia, particularly in young animals. Fleas have been reported to produce anaemia in dogs, cats, goats, cattle and sheep. Severe flea infestations in young pups and kittens can cause anaemia to the point of death.

• Transmission of Infectious Diseases
  

Fleas have been shown to transmit a number of infectious organisms, including Feline Leukaemia Virus(FeLV) , Bartonella henselae (the cause of “Cat-Scratch Fever” in man), Mycoplasma haemofelis (an infectious anaemia of cats) and, of course, Bubonic Plague (Yersinia pestis) which ravaged Europe as the “Black Death” in the XIVth century. Happily, usually the most unpleasant problem that fleas cause humans are nasty itchy bites around the ankles and midriff.

Control of Flea Infestations

An effective flea treatment regime should include treatment to kill adult fleas on your pet and also treatment of the environment (ie. your house) to kill the infestation there. Once fleas have been eliminated, there are products that can effectively prevent re-infestation of your house.

• Spot-On Treatments
  

Veterinary products such as Activyl, Effipro, Prac-tic or Stronghold are applied to your pet at regular (usually monthly) intervals where the insecticide either distributes itself in the grease layer on the skin, or gets absorbed systemically. Fleas are killed either by direct contact of the insecticide, or by ingesting it with their next blood meal.

• Household Sprays
  

These are sprayed around the house, usually in areas where dust accumulates such as edges of carpets and under furniture, and will help to kill fleas as they hatch from the pupal cocoon. Most remain active, once applied, for up to 12 months.

• Program Tablets/Injections
  

Program is given as a monthly tablet to dogs and a 6-monthly injection to cats. If an adult flea bites an animal that is being treated with Program, it can only lay eggs that are unable to develop or hatch. The flea’s life cycle is therefore completely broken. Program treatment is ideal for prevention of a flea infestation and will avoid the need to continually put insecticidal products on your pet. 

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