Robert K. Ridley

Effect of 0.29% w/w fipronil spray on adult flea mortality and egg production of three different cat flea, Ctenocephalides felis (Bouché), strains infesting cats

To evaluate the effect of fipronil spray on adult flea mortality and flea egg production of three different cat flea, Ctenocephalides felis (Bouché) strains, 30 domestic short hair cats were randomly allocated into six groups of five cats each. On day 0, cats in groups 2, 4 and 6 were treated with fipronil at 5-6ml/kg. Cats in groups 1, 3 and 5 served as untreated controls. On days -2, 7, 14, 21, and 28 each cat was infested with 50 adult cat fleas. Groups 1 and 2 were infested with fleas from the Kansas1 Colony (KS1) strain. Groups 3 and 4 were infested with a recently colonized cat flea strain from Florida (R6). Groups 5 and 6 were infested with fleas from the ARC strain. The adulticidal activity of fipronil was determined by flea comb counts 48h after treatment and then 48h after each reinfestation. Any flea eggs produced during the infestations were collected and counted prior to the 48h comb counts. Fipronil spray was > or = 99.5% effective against adults of all three cat flea strains when applied during an active infestation. Fipronil spray provided > or = 98.2 and > or = 99.5% control of adult fleas and egg production, respectively, for all strains through week 2. On days 23 and 30 control of R6 adults and egg production was significantly lower than either the ARC or the KS1 strain. On day 30, control of R6 adults and egg production was 77.3 and 87.3%, respectively. Control of KS1 adults and egg production on day 30 was significantly lower than the ARC strain. Fipronil provided > or = 99.5 and > or = 99.9% control of ARC fleas and egg production, respectively, throughout the entire study. The susceptibility to fipronil for the three strains was also evaluated on filter paper pesticide bioassays. The R6 strain was found to be less susceptible than the KS1 and ARC strains. The LC(95) estimates for the strains were 10.13, 4.77 and 2.62mg/m(2) for the R6, ARC and KS1 strains, respectively.

Helminth parasites of lesser prairie-chicken Tympanuchus pallidicinctus in southwestern Kansas: incidence, burdens and effects

We conducted a 3-year study of helminth parasites to assess their effect on the lesser prairie-chicken Tympanuchus pallidicinctus. Helminth parasites were found in most of the examined wild prairie chicken carcasses: 95% had eye worm Oxyspirura petrowi, 92% had stomach worm Tetrameres sp., and 59% had caecal worm Subulura sp. Few parasite burdens or incidences of infection were related to prairie chicken body mass, gender, age or season of collection. Droppings from transmitter-equipped prairie chickens were examined for parasite eggs and the data were used to determine which free-ranging prairie chickens harboured parasites. Telemetry data from 46 heavily parasitized and 52 lightly parasitized or parasite-free prairie chickens indicated no difference between mean daily movements, monthly home ranges, clutch sizes, nest success or survival. No adverse impacts were evident in the lesser prairie-chicken population from the incidences or burdens of the helminth parasites found in our study.

Electron Microscopic Studies on Dicyemid Mesozoa. II. Infusorigen and Infusoriform Stages

Infusorigens of Dicyema typoides, and infusoriforms of D. typoides, D. aegira, and an undescribed Dicyema sp. were studied with the electron microscope. The infusorigen axial cell has a hyaline appearance and contains autophagic vacuoles. Spermatogenic cells are also hyaline, although they are more electron-dense than the axial cell. Spermatozoa are small and tailless. Mitochondria in infusorigen cells have few, short, tubular cristae. In infusoriforms, the tubular cristae are longer and more numerous, especially in the urn cells. Annulate lamellae are present in oocytes. Glycogen occurs in the infusorigen cells, but does not accumulate. Ciliated peripheral cells of mature infusoriform larvae are hyaline and start to degenerate while the infusoriform is within the hosts renal sacs. Glycogen is abundant in peripheral cells of immature infusoriform larvae, but is less abundant in mature ones. Microvilluslike structures are present on the ciliated external cells. Apical cells contain little cytoplasm in mature larvae; in immature stages these cells contain small amounts of glycogen, and the ground substance is denser than when mature. Anterior medial bands, composed of deeply staining, granular material, appear to be formed within the enveloping cells of D. aegira. Typical cilia and ruffles (reported earlier on vermiform stages, Ridley, 1968), extend from the ventral internal cells into the urn cavity. Dorsal internal cells contain an abundant endoplasmic reticulum. Glycogen, which is especially abundant in dorsal internal cells of immature forms, is in the form of alpha rosettes which are smaller than those in external cells. Eosinophilic granules within the capsule cells contain an inner matrix in infusoriforms of mature Dicyema sp. No inner matrix was observed in eosinophilic granules of immature D. typoides. Urn cells contain many secretion granules and dictyosomes. Endoplasmic reticulum is more conspicuous in urn cells of immature infusoriforms than in those of mature stages. It is suggested that eosinophilic granules within the capsule cells might perform some sort of lytic function, possibly serving in the release of the urn cells from the infusoriform. The secretory granules within the urn cells may liquefy and form a cyst, with the eosinophilic granules of the capsule cells functioning in the liquefaction process. In the dicyemid mesozoans, infusorigens develop from infusorigen mother cells found within the axial cells of rhombogens. The infusorigen usually is considered to be an hermaphroditic individual which produces male and female gametes, the union of which results in the infusoriform embryo. The infusoriform apparently is the dissemination stage; it leaves the cephalopod host via the urine and its fate is unknown. References pertinent to the development and morphology of the infusorigen and infusoriform stages can be found in Lameere (1918), Nouvel (1947), McConnaughey (1951), and Short and Damian (1966). Bresciani and Fenchel (1967) have described certain aspects of the fine structure of the infusoriforms of Dicyema clausianum (from Octopus vulgaris) collected from Naples, and D. truncatum (from Rossia macrosoma) collected from the west

Distribution of fasciolosis in Kansas, with results of experimental snail susceptibility studies

A total of 278 veterinarians throughout Kansas were sent mail-in survey forms asking specific questions relating to their experience with fasciolosis in their practice area. Replies were received from 178 (64%) veterinarians representing six practice types; one-third reported having seen cases of fasciolosis in their practice. The results of our survey indicate that the majority of the cattle diagnosed with liver fluke disease in Kansas are imported from other areas of the USA. However, in both central and southeastern regions of Kansas, some cattle that had never been out of the state were infected with Fasciola hepatica. Thus, these areas of Kansas should be considered endemic for liver fluke disease. Methods of diagnosis, types of operations, and improvements seen after treatment were also discussed. In order to ascertain the existence of one or more possible snail intermediate hosts within Kansas, five species of lymnaeid snails were collected from central and southeastern parts of the state and tested for their susceptibility to infection by Fasciola hepatica. The snails collected included Pseudosuccinea columella, Fossaria obrussa, Fossaria bulimoides, Fossaria parva and Fossaria dalli. Of these, Pseudosuccinea columella and Fossaria bulimoides proved susceptible to experimental infection by Fasciola hepatica. Metacercariae obtained from experimentally infected snails were used to infect both a weanling calf thereby completing the life cycle of the parasite. This report is the first to identify the existence of suitable snail intermediate hosts for Fasciola hepatica in Kansas.

Production and characterization of monoclonal antibodies against excretory-secretory products of Fasciola hepatica

Four monoclonal antibodies (mAbs) (9.49, 24.27, 46.71 and 179.57) were produced against Fasciola hepatica excretory-secretory products. Isotype analysis revealed the antibodies to be IgM, IgG3, IgG1, and IgM. In immunoblot assays, the mAbs recognized different antigenic polypeptides migrating between 29 and 180 kDa. Specificity of the mAbs was evaluated by ELISA against antigens of Fascioloides magna, Anoplocephala magna, Stichorchis subtriquetrus, Haemonchus contortus, sheep liver extract (SLE), bovine liver extract (BLE), bovine serum albumin (BSA), bovine viral diarrhea virus (BVDV), and Madin-Darby bovine kidney (MDBK) cells. Monoclonals 9.49 and 24.27 were specific, and reacted only with Fasciola hepatica antigens. However, mAb 46.71 cross-reacted with antigens of Fascioloides magna, A. magna, Stichorchis subtriquetrus, and H. contortus but not with SLE, BLE, BSA, BVDV or MDBK cells. Monoclonal antibody 179.57 cross-reacted with Fascioloides magna, A. magna, S. subtriquetrus, H. contortus, SLE, and BLE, but not with BSA, BVDV, or MDBK cells.

Strategic use of ivermectin during pregnancy to control toxocara canis in greyhound puppies.

Twenty-one greyhound bitches were bred (Day 0) and housed throughout their pregnancies on three greyhound breeding farms in Kansas. These dogs were assigned randomly to one of four treatment groups. Group A dogs (6) were given ivermectin subcutaneously (300 microg/kg) on Day 0 (the first day the dogs were bred), and Days 30 and 60 of gestation. Group B dogs (6) were given ivermectin (300 microg/kg SQ) on Day 42. Group C dogs (3) were given ivermectin (300 microg/kg SQ) on Days 0, 30, and 60 plus 10 days after whelping. Group D dogs (6) served as controls and received no anthelmintic. Bitches and puppies were moved to the university on the day after birth and were maintained inside for 28 days. Weekly quantitative fecal exams were done on the bitches during this time. The puppies were euthanized humanely at 28 days of age. Intestinal parasites were recovered, identified, counted, sexed, and preserved in either 10% formalin or frozen at -70 degrees C. The geometric mean numbers of adult Toxocara canis in the small intestines for Group A puppies (n = 40) were 2.8, 8.5 for Group B puppies (n = 39), and 29.7 for Group D puppies (n = 28). No adults were found in the Group C puppies (n = 15). The geometric mean eggs per gram of feces from the pups in group A, B, and D were 1.3, 704, and 27, 134, respectively. No eggs were recovered from the Group C pups. The strategic use of ivermectin at 300 microg/kg in greyhound bitches on Days 0, 30, and 60 of gestation reduced the worm burden carried by the puppies by 90% and the actual number of eggs passed into the environment by 99.8%. The same dose on day 42 reduced the worm burden by 71.4% and the number of eggs passed into the environment by 97.4%. This dose given on days 0, 30, and 60 plus 10 days postwhelping, reduced the worm burden by 100%, and no eggs were passed into the environment.

Rapid Diagnosis of Bovine Cryptosporidiosis with a Modified Commercial Acid-Fast Staining Procedure

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The hispid cotton rat (Sigmodon hispidus) as an experimental host for the bovine liver fluke (Fasciola hepatica)

The results of a study testing the susceptibility of the hispid cotton rat, Sigmodon hispidus, to infection with Fasciola hepatica are described. Ten cotton rats were placed into one of four test groups, one uninfected control or three animals each receiving two, five, or 10 F. hepatica metacercariae. Three of nine (33%) became infected, and two of these animals carried the infection to patency. At necropsy one animal had two mature F. hepatica within the common bile duct, and the other harbored a single fluke. Gross and microscopic changes, primarily of the liver, associated with infection are described, as are fecal egg counts throughout the duration of infection.

Efficacy of fenbendazole granules and pyrantel pamoate suspension against Toxocara canis in greyhounds housed in contaminated runs.

The efficacy of fenbendazole granules against Toxocara canis in naturally infected greyhounds housed in contaminated environments was evaluated. Eight pens, each containing three to seven greyhounds, 3-12 months of age, were randomly allotted into two treatment groups. Greyhounds in Group 1 were treated with fenbendazole granules mixed in their feed at 50 mg/kg/day for 3 consecutive days once a month for 4 months. Greyhounds in Group 2 were treated with pyrantel pamoate suspension at 5.0 mg/kg per os once a month for 4 months. Quantitative fecal examinations were performed on days 0, 10 and then on the first day of each monthly treatment. Greyhounds administered fenbendazole had fecal egg count reductions (FECRs) of 95.8 and 99.8% at 10 and 31 days following initial treatment, respectively. Greyhounds administered pyrantel pamoate had FECRs of 85.8 and 88.3% at 10 and 31 days after the first treatment, respectively. T. canis fecal egg counts conducted from Day 31 through Day 128 were significant lower in those greyhounds administered fenbendazole as compared to greyhounds administered pyrantel pamoate. Fenbendazole produced FECRs in greyhounds from Day 31 through Day 128 by 96.8-99.8%. Pyrantel pamoate reduced fecal egg counts during the same time period 71.4-98.3%.

Immunofluorescent Localization of Sarcocystis Cruzi Antigens, IgG and IgE, in Lesions of Eosinophilic Myositis in Cattle

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