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M. W. Dryden

The cat flea: applied biology

Cats and their environment are freąuently infested with fleas, and eradication of these fleas can be a long and onerous task. Fleas are a major nuisance because they cause or transmit various illnesses to man and his pet animals. The species most freąuently incriminated is Ctenocephalides felis felis, the cat flea. Numerous advances relating to the biology and control of cat fleas have been madę over the last ten years.

Medical and yeterinary importance

Ctenocephalides felis is responsible for the transmission of murine typhus. This illness is transmitted via contamination of a wound, by faeces or crushed particles of parasites infected by a rickettsia, Rickettsia typhi. It is not transmitted by bites. It is characterised clinically by headaches, shivering and skin eruptions, and, less freąuently, by effects on the kidneys or the central nervous system Murine typhus affects humans and many smali mammal species, particularly rats and mice. It is endemic throughout the world, but seems morę freąuent in South America (Argentina, Brazil, Chile, Columbia) which has a third of the cases reported world-wide. Traditionally, the causative vector is the oriental rat flea, Xenopsylla cheopis. However, Ctenocephalides felis seems to be eąually implicated. Typhus is observed in the United States along the coasts of the south-east, the south-west and the Gulf of Mexico. In southem Califomia, it seems that transmission occurs via opossums and cat fleas².

Ctenocephalides felis has recently been cited as the cause of transmission between cats of Bartonella henselae, the bacterium responsible for cat scratch disease in humans³. Immunocompetent patients with cat scratch disease have painful lymph nodes and a fever that resolve with appropriate antibiotics. Immunosuppressed patients can present with serious complications (e.g. bacillary angiomatosis), which can be fatal.

Over and above its role in the transmission of viral and bacterial disease, Ctenocephalides felis is the cause of severe nuisance and dermatitis in humans and in animals. Flea allergy dermatitis (FAD) is an immunological disease in which hypersensitivity States are produced, following injection of antigens present in flea salivary glands. This ubiąuitous disease is the most common dermatosis in cats and one of the major causes of self-induced symmetrical alopecia and miliary dermatitis⁴. A similar dermatosis, papular urticaria, is freąuently seen in humans.

Fleas are haematophagous insects responsible for anaemia in major infestations, especially in young animals. This has been reported in dogs, cattle, goats and sheep, but also in cats⁵. Sometimes severe blood loss can lead to death. Cat fleas can also transmit some intestinal parasites. Dipylidium caninum is one of the most common intestinal helminths of dogs, cats, and rarely children. It develops as an immature form (cysticercoid) in the fleas of cats, dogs and humans. The flea larvae ingest the eggs which develop into cysticercoids in the body of the flea. When grooming, dogs and cats can swallow the infested fleas and the cysticercoids are then released.

Species of flea encountered

Although many species of flea have been reported in cats, only Ctenocephalides felis felis (Fig. 8:1), Ctenocephalides canis, Pulex irńtans and Echidnophaga gallinacea ⁶⁹ are seen in sufficient numbers to be

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