Transmission of feline calicivirus via the cat flea (Ctenocephalides felis).

In this study, a possible role of the cat flea (Ctenocephalides felis) in transmitting feline calicivirus (FCV) was examined. Fleas were fed via artificial membranes with FCV-spiked bovine blood, free of anti-FCV antibodies. Flea feces were collected daily for 10 days and incubated at room temperature. Infectivity of the feces was tested in vitro using Crandell-Reese Feline Kidney (CRFK) cells. FCV remained infectious for 8 days. These flea feces were also used to oronasally inoculate four specific pathogen-free (SPF) kittens. All kittens were successfully infected as demonstrated by virus isolation from pharyngeal swabs and seroconversion. Two of the cats showed, in addition, clinical signs. Besides the infection of cats with flea feces containing FCV, four SPF kittens were exposed to fleas that were fed with FCV-spiked bovine blood. One of the kittens was successfully infected via this route as demonstrated by virus isolation from pharyngeal swabs and virus isolation. The results of this study show that fleas can spread infectious virus through their feces or by stitch and must be considered a source of infection for uninfected cats.

Experimental quantification of the feline leukaemia virus in the cat flea (Ctenocephalides felis) and its faeces.

Cat fleas (Ctenocephalides felis) were fed via artificial membranes and infected with the feline leukaemia virus (FeLV) from cell cultures. After removing the fleas from the blood source, the quantity of virus in the flea and its faeces was measured over a defined period of time. The virus was detectable in the fleas for up to 30 h at room temperature and up to 115 h at 4 degrees C. In the faeces, the amount of virus decreased much more slowly--after 2 weeks half of the initial amount of virus could still be detected. Thus the faeces might be a source of further infections, e.g. for the flea larvae or the cat itself.

Molecular biological investigations of Brazilian Tunga sp. isolates from man, dogs, cats, pigs and rats.

Twenty-four isolates of Tunga were collected from afflicted humans, dogs, cats, pigs and rats in Brazil. To investigate genetic diversity, a hypervariable section of mitochondrial 16S rDNA was amplified using PCR and subsequently sequenced. In order to compare results with another species of the genus Tunga, three isolates of the recently described Tunga trimamillata were also checked. Whereas eleven isolates (five from cats, three from dogs and three from humans) were of identical sequence, thirteen isolates collected from dogs, humans, pigs and rats showed differences in sequence up to 49%, so that the existence of one or more new species of Tunga may be presumed.

Molecular phylogeny of isolates of Ctenocephalides felis and related species based on analysis of ITS1, ITS2 and mitochondrial 16S rDNA sequences and random binding primers.

The phylogenetic relationships among 31 different flea isolates representing seven different species were studied by nucleotide sequence comparison of the internal transcribed spacer 1 (ITS1), internal transcribed spacer 2 (ITS2) and/or mitochondrial 16S ribosomal RNA gene (mt16S-rDNA) to examine the patterns of variation. Results show that all regions are useful in discriminating among flea species. In Ctenocephalides felis and Tunga penetrans, some differences in these gene regions occurred among different isolates within the same species. In the latter case, the differences are in the mt16S-rDNA region, with one isolate showing 48% divergence in nucleotide sequence. The taxonomic implications of this result are unclear at present. The gene regions revealed differences between C. felis isolates only after DNA sequencing the PCR products. Further differentiation among C. felis isolates was obtained using four different random binding primers (decamers) and primers for mammalian aldolase to amplify narrow differences in the genome. Using these primers we were able to discriminate between different C. felis isolates and determine that some of the genetic variation coincided with minor differences in response to the control agent imidacloprid. However, overall findings do not support the existence of subspecies of C. felis.

Evidence of horizontal transmission of feline leukemia virus by the cat flea ( Ctenocephalides felis).

The feline leukemia virus (FeLV) is a naturally occurring and widespread retrovirus among domestic cats. The virus is mainly transmitted horizontally through saliva, blood and other body fluids by close contact between cats. Vectors other than cats, e.g. blood-sucking parasites, have not been reported. This study tested the vector potential of the cat flea ( Ctenocephalides felis) for FeLV. In a first feeding, fleas were fed for 24 h with blood from a FeLV-infected cat with persistent viremia. FeLV could be detected in the fleas, as well as in their feces. Fleas were then divided in two populations and fed in a second feeding for 5 h or 24 h with non-infected non-viremic blood. FeLV was again detected in the fleas and their feces. In addition, the two resulting blood samples of the second feeding were subsequently tested for FeLV and both samples were positive for FeLV RNA. The cat flea transmitted the FeLV from one blood sample to another. In a third feeding, the same populations of fleas were fed again with non-infected blood for 5 h or 24 h. This time FeLV was not detected in the fleas, or in the feces or blood samples. Results show that cat fleas are potential vectors for FeLV RNA in vitro and probably also in vivo.