Humans and dogs, however, may stand to suffer more from their itchy bites than cats, which tolerate them better.
Recent weather, particularly in the South-east, may be accelerating their life cycle to a brief three weeks and flea numbers are expected to peak over the next few weeks as late summer is the usual time for cat fleas to emerge from their pupae.
The cat flea is about 2mm long and can jump six inches (15cm). Nick Wilson, assistant secretary of the Institution of Environmental Health Officers, said that human fleas were very rare and usually only found where there was poor hygiene.
Households which do not own pets are not immune from cat fleas.
Dr John Maunder, director of the Medical Entomology Centre at Cambridge University, a research and education unit partly funded by local authorities, said that 'flea complaints' so far suggested it was going to be a bad year for everyone except fleas. 'Once again we are seeing greater flea problems, they keep rising year after year. Fleas like very high humidity and heat and conditions have been very good,' he said.
Veterinary surgeons are also seeing a large number of infested cats and dogs. John Bower, a former president of the British Veterinary Association said that between a third and a quarter of all cases he and his partners were treating were for cats and dogs with itchy skins.
'We do see more in the summer but this year it is happening earlier. Dogs seem to be reacting worse than cats. Just a few bites a week can cause a permanent itchy rash,' he said.
He recommended treating pets and their bedding with an effective spray or powder once week until October. 'There is not much point doing it only once,' he said.
But Dr Maunder said there was little point spraying the animals since the adult flea only lived in the coat of a cat for three days. 'People need to understand the life cycle of the flea. They will lay about 10 eggs a day which drop off onto the floor and take three days to a week to hatch.
'The maggots burrow into the carpets or cracks and can take 14 days to several months, depending on the conditions, to develop,' he said. They feed on tiny spots of mould, any food crumbs but mostly flakes of human skin and animal dander. But they must have moisture. The larvae pupate and the flea emerges.
'The fleas then lie in wait for a cat to walk past and they jump on. They then begin a frenzy of biting, mating and egg laying and die in about three days.'
He recommended a house spray containing methoprene which gives flea larvae 'eternal youth', preventing them from developing any further.