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PubMed1993

Isolation and in vitro translation of messenger RNA encoding allergens of the cat flea, Ctenocephalides felis.

Polyadenylated [poly(A)+] mRNA was isolated from the cat flea, Ctenocephalides felis by oligothymidylic acid-cellulose spin column chromatography and translated in vitro using a cell-free rabbit reticulocyte system. The relative incorporation of 35S-methionine into trichloroacetic acid-precipitable translation products obtained using poly (A+) mRNA was 48.5-fold over control translations performed without added mRNA. SDS-PAGE analysis of the translation products in combination with autoradiography showed that many proteins with apparent molecular weights in the range 14-90 K were synthesized. Immunoprecipitation studies performed using flea-allergic dog sera showed that several of the synthesized proteins corresponded with flea allergens. The allergenicity of the lysates was also confirmed by skin testing.

Allergens↗
PubMed1994

The cat flea: biology, ecology and control.

Control failures and recurrences of infestation of dogs, cats and their home environment with the cat flea, Ctenocephalides felis felis are common. Attempts to control these infestations are often impaired by an inadequate understanding of the interaction of the cat flea with its hosts and environment. This review presents information on the medical and veterinary importance of the cat flea and discusses recent information on the environmental and host factors that affect its development and survival. Additionally, information is presented on the use and effectiveness of various insecticides and insect growth regulators against the four life stages.

Animals↗
PubMed1985

The effects of cadmium on ALA-D activity, growth and haemoglobin content in the water flea, Daphnia magna.

The ALA-D activity, haemoglobin content and growth was studied in the water flea, Daphnia magna, exposed to 0, 0.1, 0.2, 0.4, 0.8 and 1.6 micrograms Cd/l. The ALA-D activity in water fleas exposed to 0.2-1.6 micrograms Cd/l fluctuated around the control value. The activity in animals exposed to 0.1 micrograms Cd/l decreased during the entire experiment. After 16 days exposure to cadmium the haemoglobin content in water fleas ranged between 80 and 31% of control value. In animals exposed to 0.8 and 1.6 micrograms Cd/l the haemoglobin content decreased progressively during the experiment. Growth was not affected by cadmium at these concentrations.

Animals↗
PubMed2004

Insect allantoinase: cDNA cloning, purification, and characterization of the native protein from the cat flea, Ctenocephalides felis.

Allantoinase catalyses the hydrolysis of allantoin to allantoic acid. This reaction is a step in the purine degradation pathway, which produces nitrogenous waste for excretion. A cDNA encoding full-length allantoinase was cloned from a Ctenocephalides felis hindgut and Malpighian tubule (HMT) cDNA library. The cDNA encoded a 483 amino acid protein that had 43% identity with the bullfrog Rana catesbeiana allantoinase and contained the conserved histidine and aspartic acid residues required for zinc-binding and catalytic activity. Unlike the bullfrog allantoinase, the C. felis allantoinase sequence was predicted to contain a 22 amino acid signal sequence, which targets the protein to the secretory pathway. Expression of the mRNA was detected by Northern blot in the first, third, and wandering larval stages as well as in fed and unfed adults, but was not seen in eggs or pupae. In adults, mRNA encoding allantoinase was detected only in the HMT tissues. Immunohistochemistry performed using affinity-purified rabbit immune serum generated against purified recombinant flea allantoinase showed that the native protein localized to the HMT tissues in adult fleas. The anti-allantoinase serum recognized two proteins in an adult flea soluble protein extract, one migrating at 56 kDa and the other at 53 kDa. The two proteins were separated by gel filtration chromatography and were both associated with allantoinase activity. The difference in size appeared to be due to a difference in glycosylation of the proteins. The 53 kDa protein was further purified to near homogeneity by affinity chromatography and retained allantoinase activity. A comparison of the sizes of the native and recombinant C. felis proteins indicated that the 53 kDa native protein may be the product of a post-translational cleavage event, possibly at the putative 22 amino acid signal sequence at the N-terminus of the protein.

Amidohydrolases↗
PubMed2005

Evolution of host specificity in fleas: is it directional and irreversible?

Evolutionary trends in the evolution of host specificity have been the focus of much discussion but little rigorous empirical testing. On the one hand, specialization is often presumed to lead irreversibly into evolutionary dead ends and little diversification; this would mean that generalists might evolve into specialists, but not vice versa. On the other hand, low host specificity may limit the risk of extinction and provide more immediate fitness benefits to parasites, such that selection may favour evolution toward a generalist strategy. Here, we test for directionality in the evolution of host specificity using a large data set and phylogenetic information on 297 species of fleas parasitic on small mammals. The analyses determined whether host specificity, measured both as the number of host species exploited and their taxonomic diversity, was related to clade rank of the flea species, or the number of branching events between an extant species and the root of the phylogenetic tree (i.e., the total path length from the root of the tree to the species). Based on regression analyses, we found positive relationships between the number of host species used and clade rank across all 297 species, as well as within one (Hystrichopsyllidae) of four large families and one of seven large genera investigated separately; in addition, we found a positive relationship between the taxonomic diversity of host species used and clade rank in another of the seven genera. These results suggest a slight evolutionary trend of decreasing host specificity. Using a much more conservative likelihood ratio test, however, a random walk, or null model, of evolution could not be discarded in favour of the directional trends in all cases mentioned above. Still, these results suggest that host specificity may have tended to decrease in many flea lineages, a process that could have been driven by the benefits of exploiting a wide range of host species.

Adaptation, Biological↗
PubMed2005

Prevalence of Bartonella species, haemoplasma species, Ehrlichia species, Anaplasma phagocytophilum, and Neorickettsia risticii DNA in the blood of cats and their fleas in the United States.

Ctenocephalides felis were killed and collected from 92 cats in Alabama, Maryland, and Texas. The fleas and blood from the corresponding cat were digested and assessed in polymerase chain reaction assays that amplify DNA of Ehrlichia species, Anaplasma phagocytophilum, Neorickettsia risticii, Mycoplasma haemofelis, 'Candidatus M haemominutum' and Bartonella species. DNA consistent with B henselae, B clarridgeiae, M haemofelis, or 'Candidatus M haemominutum' was commonly amplified from cats (60.9%) and their fleas (65.2%). Results of this study support the recommendation to maintain flea control on cats in endemic areas.

Alabama↗
PubMed2005

Advances in the control of Ctenocephalides felis (cat flea) on cats and dogs.

Cat fleas are the most important ectoparasite of cats and dogs worldwide. During the past ten years, topical and oral applications of insecticides such as fipronil, imidacloprid, lufenuron and, most recently, selamectin have revolutionized cat-flea control. Recent studies show that these therapies eliminate the need to treat indoor and outdoor environments, and their use markedly reduces the severity and prevalence of flea allergic dermatitis. Surveys have yet to reveal the development of insecticide resistance to these chemical compounds. Extending the longevity of these effective host-targeted therapies should be a major goal of the veterinary community.

Animals↗
PubMed2004

Pathogen carriage by the cat flea Ctenocephalides felis (Bouché) in the United Kingdom.

The carriage of Bartonella, Rickettsia felis and haemoplasma species was investigated in cat fleas (Ctenocephalides felis) collected from 121 cats and dogs in the United Kingdom. DNA extracted from fleas was analysed using genus and species-specific PCR and amplicons were characterised using DNA sequencing. Fifty percent of flea samples were PCR positive for at least one pathogen. Twenty one percent were positive for R. felis, 17% for Bartonella henselae, 40% for haemoplasma species and 20% were infected with more than one of the pathogen species studied. It is clear from the results in this study that companion cats and dogs are commonly infested with Ct. felis carrying bacterial pathogens of significance to human and animal health. These findings raise the possibility that Ct. felis found on dogs and cats are a potential source of infection with such pathogens for humans.

Animals↗
PubMed2003

Glucosinolates, flea beetle resistance, and leaf pubescence as taxonomic characters in the genus Barbarea (Brassicaceae).

Glucosinolate content of leaves and roots, diversity in leaf pubescence, and resistance to two near-isogenic lines of the flea beetle Phyllotreta nemorum with or without an R-gene, were determined for 27 accessions of 7 Barbarea taxa, i.e. B. stricta, B. orthoceras, B. intermedia, B. verna, B. vulgaris var. vulgaris, the G-type of B. vulgaris var. arcuata and the P-type of B. vulgaris var. arcuata. Four variable glucosinolate biosynthetic characters were deduced. For (formally) homophenylalanine-derived glucosinolates: (1). Presence or absence of 2-hydroxylation, and if present, R- or S-configuration of 2-hydroxylation; (2). presence or absence of p-hydroxylation; and for tryptophan-derived glucosinolates: (3). presence or absence of N-methoxyglucobrassicin; and (4). presence or absence of 1,4-dimethoxyglucobrassicin. Three phenotypes of leaf-pubescence were observed; (1). glabrous to glabrate leaves; (2). glabrous to glabrate leaves with hairs along the edge; (3). pubescent leaves. The hairs were characterized as simple by scanning electron microscopy. Full resistance to a flea beetle line (ST) was found in B. vulgaris var. vulgaris and in the G-type of var. arcuata; partial resistance was found in B. verna and B. intermedia, while the remaining taxa were fully susceptible to the ST line. All investigated Barbarea taxa were susceptible to larvae from another line containing an R-gene, indicating a similar flea beetle resistance mechanism in the three resistant species. Most Barbarea taxa could be characterized by a particular combination of the investigated characters. The most aberrant was the P-type of B. vulgaris var. arcuata, and the taxonomic status of this type should be reconsidered.

Animals↗
PubMed1988

Flea allergy dermatitis.

Flea allergy dermatitis is one of the most common causes of pruritus in dogs and cats. The degree of pruritus observed in the allergic animal varies widely and is dependent on numerous factors. Management of the flea-allergic patient is extremely frustrating for the owner and the veterinarian. Establishing an organized flea control program for use on the patient and in the environment will help to avoid frustration when dealing with this common ectoparasite of cats and dogs.

Animals↗
PubMed2003

Comparison of the activity of selamectin, fipronil, and imidacloprid against flea larvae (Ctenocephalides felis felis) in vitro.

The activity of selamectin, fipronil and imidacloprid against larval cat fleas (Ctenocephalides felis felis) was evaluated in an in vitro potency assay system. One hundred microliters of each compound at various concentrations in acetone were added to glass vials (1.5 by 3 cm) to which had been previously added 20 mg of sand and 10 mg of flea feces. Vials were then ball milled to allow the acetone to evaporate. Selamectin and fipronil were tested at 0.001, 0.003, 0.005, 0.01, 0.03, 0.05, 0.11, 0.3, and 0.5 microg of active compound per tube. Imidacloprid was tested at 0.01, 0.03, 0.05, 0.1, 0.3, 0.5, 1.0, 3.0, and 5.0 microg of active compound per tube. Thirty first instar C. felis larvae were added to each vial. The number of larvae remaining alive in each vial was determined once daily for 72 h. With selamectin, reductions of >/=93.5% were achieved at 24 h after exposure at doses of >/=0.3 microg. In contrast, at 24 h neither fipronil nor imidacloprid reached 90% reduction, even at the highest doses tested (0.5 microg for fipronil and 5.0 microg for imidacloprid). Selamectin was significantly (P</=0.05) more potent than imidacloprid and fipronil at levels >/=0.03 microg. A similar pattern of activity was observed at both 48 and 72 h, but higher percentages of larvae were killed for each of the compounds as the incubation time increased. At 72 h selamectin was significantly (P</=0.05) more potent than imidacloprid at levels of 0.01-0.1 microg and significantly (P</=0.05) more potent than fipronil at levels of 0.003-0.01 microg. Therefore, selamectin was more potent than either fipronil or imidacloprid in killing flea larvae in this in vitro assay system.

Animals↗
PubMed2000

Avermectins and flea control: structure-activity relationships and the selection of selamectin for development as an endectocide for companion animals.

Evaluation of a wide range of avermectin derivatives for flea activity in an in vitro feeding screen using the cat flea, Ctenocephalides felis, revealed a narrow structure-activity relationship (SAR) with activity surprisingly associated with monosaccharides and especially their C-5-oximes. We discovered commercially exploitable flea activity in a single compound, selamectin 33, which also possessed the necessary antiparasitic spectrum and margin of safety for development as a broad-spectrum companion animal endectocide.

Animals↗
PubMed1971

Myxomatosis: the introduction of the European rabbit flea Spilopsyllus cuniculi (Dale) into wild rabbit populations in Australia.

1. The European rabbit flea Spilopsyllus cuniculi (Dale) bred successfully in wild rabbits on three properties in New South Wales and, within two breeding seasons, almost every rabbit shot within a quarter of a mile of a release site was infested.2. It was demonstrated that the flea transmitted myxoma virus in the field.3. In areas where more than 75% of the rabbits shot at the beginning of the breeding season were flea-infested and myxoma virus was present, populations failed to show the expected summer build-up.

Agriculture↗
PubMed1979

Myxomatosis: the release and spread of the European rabbit flea Spilopsyllus cuniculi (Dale) in the Central District of Victoria.

The European rabbit flea was first released in Victoria in August 1969 at Werribee. Releases were made on five different land forms. At one site the first flea was recovered 2 weeks after release. Fleas were recovered between 4 and 6 weeks after release at the other sites. Differences in establishment and spread on the different land forms were due to physically restricted movement of some rabbit populations. By June 1971 80% of rabbits were infested but an occasional young uninfested rabbit was still found in August 1978. Infestation numbers were higher than in the Mallee region especially on pregnant does.

Age Factors↗
PubMed1977

Myxomatosis: the transmission of a highly virulent strain of myxoma virus by the European rabbit flea Sphilopsyllus cuniculi (Dale) in the Mallee region of Victoria.

The European rabbit flea Spilopsyllus cuniculi (Daley was introduced into Australia to act as a vector of myxoma virus. It was first released in the semi-arid Mallee region of Victoria in 1970 where epizootics cuased by field strains of myxoma virus occur each summer. Introductions of the readily identified Lausanne strain were made annually following the release of the flea. The introductions were successful and the strain persisted for up to 16 weeks despite competition from field strains. The Lausanne strain is more readily spread by fleas than the Glenfield strain which has been widely used in rabbit control. The ability of the Lausanne strain to persist and its effective transmission compared with the Glenfield strain may be due in part to the more florid symptoms of the disease.

Animals↗
PubMed2006

Resource predictability and host specificity in fleas: the effect of host body mass.

Ecological specialization is hypothesized to result from the exploitation of predictable resource bases. For parasitic organisms, one prediction is that parasites of large-bodied host species, which tend to be long-lived, should specialize on these hosts, whereas parasites of small host species, which represent more ephemeral and less predictable resources, should become generalists. We tested this prediction by quantifying the association between the level of host specificity of fleas and the mean body mass of their mammalian hosts, using published data from 2 large, distinct geographical regions (South Africa and northern North America). In general, we found supporting evidence that flea host specificity, measured either as the number of host species exploited or their taxonomic distinctness, became more pronounced with increasing host body mass. There were, however, some discrepancies among the results depending on the different measures of host specificity, the geographical region studied, or whether we used the raw values or phylogenetically independent contrasts. These are discussed with respect to other forces acting on the evolution of host specificity in parasites, as well as in the context of the regions' contrasting evolutionary histories. Overall, though, our findings indicate that the exploitation of large-bodied, and therefore long-lived, host species has promoted specialization in fleas, most likely because these hosts represent predictable resources.

Animals↗