Cat fleas home in on dogs as numbers rise

Twice the number of dogs are infected with fleas compared with a decade ago, because of an increase in the number of cat fleas in homes.

A survey of dogs in the London area found that 46 per cent were infested, mostly with the cat flea, compared with less than half this number in a similar survey in 1981. Cat fleas on cats had increased from 56 per cent to 63 per cent over the same period.

Susan Shaw, an immunologist at Bristol University, said the increase is highly significant because it shows both a trend for cat fleas to live on dogs and a general increase in the flea population as the blood-sucking parasite is able to survive all year round in centrally heated homes.

Ms Shaw said that fleas can cause a range of allergies and skin problems in humans when animal infestations get out of control, resulting in hungry fleas biting pet owners. Fleas also carry tapeworms which can pass from one pet to another, she said.

A major factor in the rise of the cat flea is fitted carpets, where their larvae live, and the rise in the temperature of British homes. Ms Shaw said that average room temperatures have increased from 16C to 21C over the past 15 years.

Humidity within homes has also increased with draught-proof windows and poorer ventilation. John Maunder, director of the Medical Entomology Centre in Cambridge, said the increase in humidity has also helped fleas to survive better because "a house is similar to a desert in that it never rains indoors and flea larvae are usually on the verge of water stress".

The success of the cat flea appears, though, to be leading to a decline in the dog flea.