Abstract
Rickettsia felis, the agent of flea-borne spotted fever, has a cosmopolitan distribution. Its pathogenic role in humans has been demonstrated through molecular and serologic tests in several cases. The cat flea (Ctenocephalides felis) is considered the main reservoir and the biological vector. The aim of this study was to assess the presence and occurrence of R. felis in fleas collected from dogs and cats in various sites of Palermo (Sicily). Between August and October 2012, 134 fleas were collected from 42 animals: 37 fleas from 13 dogs and 97 fleas from 29 cats. Two species of fleas were identified: 132 Ctenocephalides felis (98.51%) collected on all animals and only two C. canis (1.49%) on one dog. Out of 132 C. felis, 34 (25.76%), 12 from dogs (32.43%) and 22 (22.68%) from cats, were positive for R. felis DNA by a polymerase chain reaction (PCR), confirmed by sequencing. The only two C. canis fleas were negative. About half of examined animals (47.62%, 20/42) were infested with at least one infected flea; in particular 46.15% of dogs (6/13) and 48.28% of cats (14/29). It seems that in the Palermo district there is a peri-domestic cycle, with a relatively high prevalence of R. felis infection in the cat flea, an insect widely diffused in home environments and which can frequently bite humans. The results also suggest that R. felis should be considered in the human differential diagnosis of any spotted-like fever or febrile illness without a clear source of infection in Sicily, especially if the patient is known to have been exposed to flea bites.
Highlights
Rickettsioses are vector-borne zoonotic infections caused by obligate intracellular bacteria of the genus Rickettsia.Rickettsia felis was probably first detected in Ctenocephalides felis in 1918, and named ‘‘Rickettsia ctenocephali’’ [1]
C. felis fleas were collected on all the animals and were 29 males and 103 females, while C. canis fleas, one male and one female, were collected on one dog
The results of our research show that almost all fleas collected both on cats and dogs (132/134) were Ctenocephalides felis
Summary
Rickettsioses are vector-borne zoonotic infections caused by obligate intracellular bacteria of the genus Rickettsia. Rickettsia felis was probably first detected in Ctenocephalides felis in 1918, and named ‘‘Rickettsia ctenocephali’’ [1]. This record was neglected until 1990, when a Rickettsia-like organism was found in C. felis fleas by electron microscopy [2]. It was referred to as the ‘‘ELB agent’’, for the original source of the fleas at Elward Laboratory (Soquel, CA, USA). The species R. felis was formally validated by molecular criteria in. 2001, and the reference strain was isolated and definitely characterized in 2002 [3]. R. felis has recently been included in the rickettsial transitional group [4]
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