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PubMed2003

Efficacy and longevity of nitenpyram against adult cat fleas (Siphonaptera: Pulicidae).

Nitenpyram (Capstar) is a fast acting, orally administered flea treatment that is absorbed into the blood of the host animal and is readily available for uptake by feeding fleas. We examined the efficacy of a single dose of nitenpyram against adult cat fleas, Ctenocephalides felis (Bouché), over several days. We recorded adult flea mortality and flea egg production on treated and untreated cats. Nitenpyram provided 100% kill of all fleas on the host at the time of treatment and for up to 24 h after treatment. Between 24 and 48 h after treatment, there was a 98.6% reduction in adult flea numbers. From 48 to 72 h, there was a 5% reduction in adult fleas. There was a 97% reduction and 95.2% reduction in the number of flea eggs collected from treated versus untreated animals during the first 48 h and from 48 to 72 h, respectively. In addition, we quantified three distinct behavioral responses of infested adult cats treated with nitenpyram to determine the extent of any immediate, overt behavioral responses in treated animals. A significant increase in scratching, biting, licking, and twitching occurred for 5 h. The biting and licking continued for 7 h after treatment. Administration of nitenpyram provides an effective mechanism to eliminate adult fleas from hosts for up to 48 h after treatment.

Animals↗
PubMed2006

Mammal and flea relationships in the Great Basin Desert: from H. J. Egoscue's collections.

Host-parasite association among 58 flea species parasitizing 40 mammal species in the Great Basin Desert of the western United States was investigated. Increased flea species richness was correlated with larger geographic ranges and stable locomotion of hosts. Hosts from habitats of moderately low productivity (sage and grass) and of Peromyscus maniculatus size, 10-33 g, had the highest flea species richness. Larger hosts had fewer flea species, but fleas were more prevalent. Increased host species richness correlated with flea species eye size. Mammals clustered into 3 major and 1 minor ecological groups, and fleas clustered into 2 major groups among rodents, and 6 minor groups, forming 12 host-parasite biocenoses. Factors producing biocenoses were shared burrows of mice and rats; food chains of hares, rabbits, squirrels, and their predators; keystone mammals: Lagurus curtatus, Neotoma lepida, Ochotona princeps, and Spermophilus townsendii; keystone fleas: Megabothris abantis, and Meringis hubbardi; or host isolation, Neotoma cinerea with Oropsylla montana, Sorex vagrans with Corrodopsylla curvata, and Tadarida brasiliensis with Sternopsylla distincta. Although host relatedness accounted for flea prevalence, host sociality explained the presence or absence of mammal-flea relationships.

Animals↗
PubMed1998

Estimation of vector infectivity rates for plague by means of a standard curve-based competitive polymerase chain reaction method to quantify Yersinia pestis in fleas.

The prevalence of infectivity within a vector population is a critical factor in arthropod-borne disease epidemiology but it is difficult to estimate. In the case of bubonic plague, infective flea vectors contain large numbers of Yersinia pestis within a bacterial mass that blocks the flea's foregut, and only such blocked fleas are important for biologic transmission. A bacterial quantitation method could therefore be used to assess the prevalence of plague-infective (blocked) fleas in a population. We developed a standard, curve-based, competitive polymerase chain reaction (PCR) procedure to quantitate Y. pestis in individual fleas. The quantitative PCR (Q-PCR) method equaled a colony count reference method in accuracy and precision when evaluated using mock samples and laboratory-infected fleas. The Q-PCR was more reliable than colony count, however, for field-collected fleas and for blocked fleas collected after their death. In a sample of fleas collected from a prairie dog colony in the aftermath of a plague epizootic, 48% were infected but less than 2% contained numbers of Y. pestis indicative of blockage. The method provides a means to monitor plague epizootics and associated risks of flea-borne transmission to humans, and is applicable to the study of other vector-borne diseases.

Animals↗
PubMed2000

Quantitative competitive PCR as a technique for exploring flea-Yersina pestis dynamics.

We used a quantitative competitive polymerase chain reaction assay to quantify Yersinia pestis loads in fleas and bacteremia levels in mice that were used as sources of infectious blood meals for feeding the fleas. Xenopsylla cheopis, the Oriental rat flea, achieved higher infection rates, developed greater bacterial loads, and became infectious more rapidly than Oropsylla montana, a ground squirrel flea. Both flea species required about 10(6) Y. pestis cells per flea to be able to transmit to mice. Most fleas that achieved these levels, however, were incapable of transmitting. Our results suggest that at the time of flea feeding, host blood must contain > or = 10(6) bacteria/ml to result in detectable Y. pestis infections in these fleas, and > or = 10(7) bacteria/mL to cause infection levels sufficient for both species to eventually become capable of transmitting Y. pestis to uninfected mice. Yersinia pestis colonies primarily developed in the midguts of O. montana, whereas infections in X. cheopis often developed simultaneously in the proventriculus and the midgut. These findings were visually confirmed by infecting fleas with a strain of Y. pestis that had been transformed with the green fluorescent protein gene.

Animals↗
PubMed1999

Control of fleas on pets and in homes by use of imidacloprid or lufenuron and a pyrethrin spray.

OBJECTIVE: To evaluate imidacloprid and the combination of lufenuron and pyrethrin to control flea infestations in households with pets. ANIMALS: 37 dogs and 19 cats in 34 flea-infested households. PROCEDURE: Households were assigned randomly to 1 of 2 groups. Pets in group 1 were treated topically with imidacloprid on day 0, then once a month for 90 days. Pets in group 2 were given lufenuron orally on day 0 and at monthly intervals for 90 days and also were treated topically with a pyrethrin spray every 1 to 2 weeks throughout the study. Flea numbers in homes were assessed by use of intermittent light traps, and flea burdens on pets were assessed using visual area counts done once a week during the first month, then every other week. RESULTS: One application of imidacloprid reduced flea burdens on pets by 96 and 93.5% on days 7 and 28, respectively, compared with day-0 burdens. Following 3 applications, flea burdens on pets and in homes were reduced by 98.8 and 99.9%, respectively. Lufenuron and pyrethrin spray reduced flea numbers on pets by 48.9 and 91.1% on days 7 and 28, respectively. By the end of the study, this combination reduced flea burdens on pets and in homes by 99.2 and 99.7%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Imidacloprid applied topically or lufenuron administered orally along with a topically applied pyrethrin spray were effective in eliminating fleas on pets and in homes. Flea control can be achieved with topical application of adulticides or oral administration of insect growth regulators without concomitant treatment of the surroundings.

Administration, Oral↗
PubMedDate not supplied

[The longevity of Leptopsylla segnis fleas (Siphonaptera: Leptopsyllidae)].

In experiments, the mean life duration of fleas Leptopsylla segnis on white mice (abundance of fleas within natural limits, up to 10 fleas per mouse) was 22.7 days in females and 18.8 day in males. Maximum life duration was 51 and 37 days respectively. In cases, when the initial numbers of fleas were 20 and 28-34 fleas, the duration of life was decreased. The maximum limit decreased greater than the mean duration of life. A survival dynamics of fleas depended upon the flea number. It was found out, that in cases of high abundance of fleas in the beginning of experiments, the mortality rate of males was lower than in females. During the stay on a host the fleas lost gradually an ability to endure a starvation. Possible mechanisms of the regulation of flea abundance are discussed.

Animals↗
PubMed1991

Fleas as an allergen in Egyptian asthmatic patients.

Fleas are widely distributed and partially host specific ectoparasites of man and animal. The aim of this work was to study the role of fleas as one of the causative allergens of bronchial asthma in Egyptian patients. Two flea extract antigens were locally prepared. The first from the head and the salivary glands and the second from the abdomen. The sensitivity of the first antigen (head and salivary glands) was evaluated among a known group of flea bite allergic individuals and normal control group using two dilutions 1/50 and 1/100, and proved to be sensitive. Regarding bronchial asthma and fleas, two groups of individuals were examined, asthmatic patients and control ones, using flea extract antigen and common inhalant antigens as skin test as well as precipitin test using flea extract antigen. This test was done by prick method using the routine allergens (house dust, cotton dust, mixed mould, mixed pollens, cat hair, dog hair, wool, feather) and also with locally prepared two flea extracts: one was prepared from the head and salivary glands, the second was prepared from the abdomen. Out of these sixty asthmatic patients, only six (10%) gave positive skin reactions to the antigens of fleas extract. All the control gave negative skin reaction. The precipitin test using the double immuno diffusion method gave positive results with one case who showed reaction to flea extract skin antigen.

Adolescent↗
PubMed1989

[The determination of toxicity of four insecticides on ground squirrel flea].

This paper reports the results of toxicological effect of four insecticides on Citellophilus tesquorum sungaris. The toxicity of Deltamethrin was the strongest in four insecticides, DDVP & DDT were stronger than 1-(3,4-dichlorophenyl)-2,2,2-trichloroethyl acetate. For the LD50 of four insecticides on suckling blood female flea of two-day-age, were 1.17 x 10(-6) micrograms per flea 1.20 x 10(-3) micrograms per flea 1.25 x 10(-3) micrograms per flea & 3.46 per flea respectively. The data showed that there were marked differences in the susceptibility to the same insecticide between unsuckling blood fleas and suckling blood fleas. Male fleas were more susceptible than female fleas in suckling blood fleas.

Animals↗
PubMed2003

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.

Animals↗
PubMed2005

What are the factors determining the probability of discovering a flea species (Siphonaptera)?

Our aim was to determine which of four variables (number of host species exploited by the parasite, taxonomic distinctness of these hosts, geographic range of the principal host, and year of description of this host) was the best predictor of description date of fleas. The study used previously published data on 297 flea species parasitic on 197 species of small mammals from 34 different regions of the Holarctic and one region from the Neotropics. We used both simple linear and multiple regressions to evaluate the relationships between the four predictor variables and the year of flea description, on species values as well as on phylogenetically independent contrasts. Whether or not the analyses controlled for flea phylogeny, all predictor variables correlated significantly with year of flea description when tested separately. In multiple regressions, however, the number of exploited host species was the best predictor of the date of flea description, with the geographic range of the principal host species as well as the date of its description having a lesser, though significant, influence. Overall, our results indicate that a flea species is more likely to be discovered and described early if its biological characteristics (exploitation of many host species) and those of its hosts (long-known to science, broad geographic distributions) increase its chances of being included in a collection. Because the variables we investigated only explained about 10-11% of the variation in year of description among flea species, other factors must be important, such as temporal variability in the activity of flea taxonomists.

Animals↗
PubMed1999

Effects of imidacloprid on adult and larval stages of the flea Ctenocephalides felis after in vivo and in vitro application: a light- and electron-microscopy study.

The effects of imidacloprid (Advantage) on the larval and adult stages of cat fleas (Ctenocephalides felis) were studied in vivo and in vitro by means of light and electron microscopy. It was found that: 1. The compound acted rapidly on both larval and adult fleas, killing both stages within 20 min of contact. 2. When applied as a spot-on to the skin of dogs, the compound localized in the water-resistant lipid layer of the skin surface and in the hairs but not in the blood. 3. Thus, the compound was not taken up during sucking of the flea but was absorbed via the thin intersegmental membranes, since larval and adult fleas that had only external contact with imidacloprid-impregnated paper or with shaved hairs from imidacloprid-treated dogs showed reactions similar to those shown by fleas sitting on treated skin. 4. The compound led to a continuous blockage of insect-specific nicotinic-acetylcholine receptors (nAChR), causing tetanic muscle cotractions within minutes of exposure. This manifested as intense trembling of the legs and pumping movements of the body. The affected flea stages remained motionless while the nerves and muscles were constantly and irreversibly destroyed due to hyperactivity. The ganglia of the head and thorax and the striated muscles of the flea body and legs were damaged first, whereas the intestinal movements (e.g., visible in larvae) took longer to exhibit damage. In summary, these studies show that imidacloprid kills larval and adult flea stages rapidly via the same mode of action and thus prevents the development of flea populations in human or animal dwellings.

Animals↗
PubMedDate not supplied

High infection rate of Wolbachia endobacteria in the sand flea Tunga penetrans from Brazil.

Tunga penetrans is an ectoparasite causing considerable morbidity in endemic communities. Recently, endobacteria of the genus Wolbachia were identified also in T. penetrans. Since Wolbachia were suggested as targets for intervention of insect pests and human filariasis, sand fleas were collected from infested humans, dogs and rats in a hyperendemic area in northeastern Brazil, and screened for Wolbachia infections. Twenty-one adult fleas and four batches of flea eggs were examined by PCR using primers targeting the 16S rDNA, the DNA coding for FtsZ cell-cycle protein or a Wolbachia surface protein (WSP-1). Wolbachia were detected in all examined samples from eggs, free-living male and female fleas and from neosomic female fleas. No Wolbachia DNA was detected in two samples containing flea faeces. In addition, Wolbachia were labelled by immunohistology in the ovaries of 37 female fleas using antisera raised against WSP-1 of Wolbachia the filarial parasite Dirofilaria immitis. In the vicinity of the embedded fleas containing the Wolbachia, infiltrations of neutrophils and macrophages were observed. This study showed that Wolbachia endobacteria are abundant in T. penetrans and that all examined fleas were infected by these endobacteria. Our findings may have important implications for the future development of control strategies for human tungiasis.

Animals↗
PubMed1999

Advances in flea control.

With an increase in our knowledge of flea life cycle and biology, flea control has improved tremendously over the past 10 years. Treatment programs should be tailored to each case. The goal of effective flea control is to eliminate adults and to prevent reinfestation and the development of new generations of fleas. New products are of great benefit to flea-infested and flea-allergic animals and allow a safe and effective way to control fleas. Even if the consistent use of a topical adulticide alone is tempting, rotation and a combination of products should still be used to delay resistance. In addition, environmental flea control is a wise approach, especially in cases of severe infestation or in situations where there is a flea-allergic animal. Finally, in order to avoid failures and resistance, it is important to treat all pets in the household.

Animals↗
PubMed1997

Host-habitat relations as an important determinant of spatial distribution of flea assemblages (Siphonaptera) on rodents in the Negev Desert.

We studied flea assemblages on rodents in different habitats of the Ramon erosion cirque in the Negev Desert to examine whether host-habitat relations influence flea spatial distribution. Eleven flea species parasitizing 12 rodent species were recorded. There was significant positive relationship between flea species richness and body mass of the host species; no relationships were found between relative richness of flea assemblage and either the number of habitats occupied by the host species or the size of host geographical range. The differences in pattern of flea parasitism among habitat types within host species were determined by both environmental features of a habitat and the specific pattern of habitat use by rodents. There was replacement of Xenopsylla conformis by Xenopsylla ramesis on Meriones crassus and Gerbillus dasyurus among different habitats. The results of ordination of the flea collections from each individual host demonstrated that the flea assemblages were segregated mainly along 4 axes, which explained 86% of total variance. Each of the ordination axes corresponded with a change in flea species composition. The directions of these changes were (1) among-hosts within a habitat and (2) among-habitats within a host.

Animals↗
PubMed2001

Control of flea populations in a simulated home environment model using lufenuron, imidacloprid or fipronil.

Control strategies were evaluated over a 6-month period in a home simulation model comprising a series of similar carpeted pens, housing matched groups of six cats, in which the life-cycle of the flea Ctenocephalides felis felis Bouche (Siphonaptera: Pulicidae) had been established. Additional adult fleas were placed on the cats at intervals to mimic acquisition of extraneous fleas from outside the home. Treatment strategies included a single subcutaneous deposition of injectable lufenuron supported by initial treatments with a short-acting insecticidal spray, or monthly topical applications of imidacloprid or fipronil. An untreated control group indicated that conditions were suitable for flea replication and development. Controls had to be combed on 18 occasions to remove excessive flea burdens and two developed allergic reactions. Lufenuron cats were combed once and required two insecticidal treatments in the first month to achieve control. Even so, small flea burdens were constantly present thereafter. Imidacloprid and fipronil treatments appeared to give virtually complete control throughout. Single fleas were found on imidacloprid cats on two occasions, whereas none were recovered from fipronil cats at any time after the first treatment. Tracer cats were used to monitor re-infestation rates at the end of the trial period. Small numbers of host-seeking fleas were demonstrated in all treatment pens, indicating that total eradication had not been accomplished. It is concluded that the home environment simulation model incorporating tracer animals could provide a powerful tool for studying flea population dynamics under controlled conditions but improved techniques are needed for quantifying other off-host life-cycle stages.

Animals↗
PubMed1997

Salivary antigens of the cat flea, Ctenocephalides felis felis.

The cat flea, Ctenocephalides felis felis, is the major cause of flea bite hypersensitivity (FBH) in dogs and cats, yet little progress has been reported on identifying the antigens responsible. We obtained flea salivary antigens by washing secretions from containers probed by the mouthparts of fleas, and by extracting whole flea salivary glands. Mice were exposed to feeding fleas to generate antibodies to salivary antigens injected in vivo. The sera were tested for antibodies against the salivary antigens described and against a whole flea extract; in indirect ELISA, antibodies to salivary secretions were detected in 60% of the sera from mice exposed to feeding fleas. These sera identified four protein bands at apparent MW 56, 54, 42 and 40 K which corresponded to prominent protein bands in whole salivary gland extracts identified by protein staining after SDS-PAGE. Fixed sections of whole fleas exposed to the antisera showed that only structures within the salivary glands were identified. The salivary secretions and gland extracts are now being used to study immune responses of dogs suffering from FBH.

Animals↗
PubMed1993

Sex ratio and phoretic mites of fleas (Siphonaptera: Pulicidae and Hystrichopsyllidae) on the Nile grass rat (Arvicanthis niloticus) in Kenya.

The sex ratio of fleas and their phoretic mites associated with the Nile grass rat, Arvicanthis niloticus (Desmarest), were studied during 14 mo in a grassland community of Lake Nakuru National Park, Kenya. Females of the fleas Dinopsyllus lypusus Jordan & Rothschild, Ctenophthalmus calceatus cabirus Jordan & Rothschild, and Xenopsylla cheopis bantorum Jordan infested more grass rats and in greater numbers than did males. Phoretic hypopi (hetermorphic deutonymphs) of two species of mites, Psylloglyphus uilenbergi Fain and Paraceroglyphus xenopsylla Fain & Schwan, varied seasonally in their abundance on fleas and utilized female fleas over male fleas for their major source of transport. Additionally, the mites were very host specific with nearly 100% of those identified on D. lypusus and C. calceatus cabirus being P. uilenbergi and 89% of the mites identified on X. cheopis bantorum being P. xenopsylla. This level of specificity suggests that these mite-flea associations are highly evolved. The importance of female fleas as hosts for transporting mites also suggests that female-biased sex ratios of fleas on their hosts may be caused, in part, by females being more important as dispersers within flea populations.

Animals↗
PubMed1993

Mutation in the pla gene of Yersinia pestis alters the course of the plague bacillus-flea (Siphonaptera: Ceratophyllidae) interaction.

Yersinia pestis possesses a unique gene (pla) encoding coagulase and fibrinolysin which is implicated in the transmission of plague by fleas. This gene is encoded on the highly conserved but poorly characterized 'pesticin' plasmid pKYP1. The role of the pKYP1-encoded gene, pla, in plague transmission was addressed by feeding fleas on blood containing avirulent Y. pestis strain EV76-6 and three derivatives of this strain (K10-2, K10-3, and K10-5) carrying Tn801 insertions in pKYP1. One of these mutant strains, K10-5, contains an insertion within the pla gene that eliminates both coagulase and fibrinolysin activities, whereas strains K10-3 and K10-2 retain both pla-associated phenotypes. After feeding, it was found that flea mortality at 4 d after infection associated with strain K10-5 (26%) was significantly lower than the mortality observed with other strains (53-64%). These results suggest that expression of the pla gene product may contribute to the deleterious effects of plague bacilli on fleas that have been associated with flea blockage and plague transmission. This increased mortality is not caused simply by an increased bacterial load in fleas containing pla+ bacteria because fleas ingesting pla+ strains contained no more bacteria by flea blot hybridization analysis than did those that ingested the pla- strain K10-5. It is anticipated that further work in this area will clarify the mechanism by which pla acts and will reveal additional genetic loci in the plague bacillus which are required for transmission by fleas.

Animals↗