An In Vitro Assay of Disinfectants on the Viability of Heterakis gallinarum Eggs.

Nematodes are widespread and common in poultry. Disinfectants are used to reduce infection rates in poultry houses, but there is little documentation of their effectiveness. An in vitro assay was developed to test the efficacy of products to damage Heterakis gallinarum eggs, and nine disinfectants and chemicals commonly used in the poultry industry were tested. Embryonated eggs of H. gallinarum were pipetted into wells of plastic cell culture plates (250-300 eggs/well in water). Measured amounts of test articles were added to the suspensions for 2, 4, 6, or 24 hr. After exposure, eggs were washed with water and treated with trypan blue (1 ml of 0.4% solution, added to each well) at room temperature for 2 min. Eggshell integrity was determined microscopically by counting the number of eggs that were clear (intact) or that contained blue dye (compromised). As a test of embryo viability, five eggs per well from treatments containing compromised eggs were transferred to a Petri dish and hatched manually, using forceps to open the eggshell. Released larvae were then observed for signs of controlled movement. In a test of Clorox bleach (NaOCl), Green Klean, Decon7, Kem San, PLT, Virkon S, NaCl, dry limestone (CaCO3), and diesel fuel, only NaOCl (bleach) and Green Klean damaged the eggshell, and only 20,625 ppm of NaOCl rendered the larvae nonviable.

Nota de Investigación- Un ensayo in vitro de desinfectantes sobre la viabilidad de los huevos de Heterakis gallinarum. Los nematodos son comunes y están generalizados en la avicultura. Los desinfectantes se usan para reducir las tasas de infección en las granjas avícolas, pero existe poca documentación de su efectividad. Se desarrolló un ensayo in vitro para probar la eficacia de los productos para afectar los huevos de Heterakis gallinarum, y se probaron nueve desinfectantes y productos químicos comúnmente utilizados en la industria avícola. Los huevos embrionados de H. gallinarum se pipetearon en pozos de placas plásticas de cultivo celular (250­300 huevos/pozo en agua). Se agregaron cantidades medidas de los compuestos a probar a las suspensiones durante dos, cuatro, seis o 24 horas. Después de la exposición, los huevos se lavaron con agua y se trataron con azul tripán (1 ml de solución al 0.4%, se agregaron a cada pozo) a temperatura ambiente durante dos minutos. La integridad de la cáscara del huevo se determinó microscópicamente al contar el número de huevos que estaban claros (intactos) o los que contenían colorante azul (afectado). Como prueba de la viabilidad de los embriones, se transfirieron cinco huevos por pozo de los tratamientos que contenían huevos afectados a una placa de Petri y se eclosionaron manualmente utilizando fórceps para abrir la cáscara del huevo. Las larvas liberadas fueron observadas para detectar signos de movimiento controlado. En una prueba con blanqueador Clorox (NaOCl), Green Klean, Decon7, Kem San, PLT, Virkon S, NaCl, caliza seca (CaCO3) y combustible diesel, solo NaOCl (lejía) y Green Klean dañaron la cáscara del huevo, y solo 625 ppm de NaOCl provocaron que las larvas no fueran viables.

EVALUATION OF THE THERAPEUTIC EFFICACY OF LEVAMISOLE HYDROCHLORIDE ON THIRD-STAGE LARVAE OF Lagochilascaris minor IN EXPERIMENTALLY INFECTED MICE.

Lagochilascariosis, a disease caused by Lagochilascaris minor, affects the neck, sinuses, tonsils, lungs, the sacral region, dental alveoli, eyeballs and the central nervous system of humans. A cycle of autoinfection may occur in human host tissues characterized by the presence of eggs, larvae and adult worms. This peculiarity of the cycle hinders therapy, since there are no drugs that exhibit ovicidal, larvicidal and vermicidal activity. Given these facts, we studied the action of levamisole hydrochloride on third-stage larvae in the migration phase (G1) and on encysted larvae (G3) of L. minor. To this end, 87 inbred mice of the C57BL/6 strain were divided into test groups comprising 67 animals (G1-37; G3-30) and a control group (G2-10; G4-10) with 20 animals. Each animal was inoculated orally with 2,000 infective eggs of the parasite. The animals of the test groups were treated individually with a single oral dose of levamisole hydrochloride at a concentration of 0.075 mg. The drug was administered either 30 minutes prior to the parasite inoculation (G1 animals) or 120 days after the inoculation (G3 animals). The mice in the control groups were not treated with the drug. After the time required for the migration and the encysting of L. minor larvae, all the animals were euthanized and their tissues examined. The data were analyzed using the Student's unpaired t-test and the Levene test. The groups showed no statistically significant difference. Levamisole hydrochloride was ineffective on third-stage larvae of L. minor. These findings explain the massive expulsion of live adult worms, as well as the use of long treatment schemes, owing to the persistence of larvae and eggs in human parasitic lesions.

Anthelmintic resistance in non-strongylid parasites of horses.

Since 2002, selected populations of Parascaris equorum in several countries have been reported to survive treatment with macrocyclic lactone (M/L) anthelmintics. Clinical treatment failures are characterized by negligible fecal egg count reduction, but M/L resistance has been confirmed in ascarids by controlled efficacy testing. Resistance was selected by current parasite control practices for foals, which often include exclusive and excessively frequent use of M/L dewormers, thereby minimizing refugia within the host and in the environment. Chemical control of M/L-resistant isolates can be accomplished with pyrimidine and/or benzimidazole anthelmintics, but a few M/L-resistant populations have recently exhibited resistance to pyrantel pamoate as well. Some specimens of Oxyuris equi regularly survive treatment with macrocyclic lactones, but it is uncertain whether this constitutes resistance or merely confirms the incomplete oxyuricidal efficacy of virtually all broad spectrum equine anthelmintics. Variations in other biological parameters of Oxyuris and Parascaris, specifically atypical infection of older hosts and shorter prepatent periods, have been reported anecdotally. These changes may represent genetic modifications that have evolved in parallel with resistance as a result of anthelmintic selection pressure.

[Development of a new hydrocarbon extract from the medicinal raw material of Circassian walnut (Juglans regia) and study of its antiparasitic activity].

The authors developed a technology for preparing a hydrocarbon extract from the medicinal raw material of Circassian walnut (Juglans regia), including its green fruits, green leaves, and fresh roots. To prepare the preparation, they obtained for the first time a new extragent called petroleum Russia that was found to contain more than hundred chemical compounds by chromatography mass spectrometry. The new agent was named irillen. Experiments on albino mice and albino rats established that the new agent was low toxic. The lethal doses of irillen were calculated: LD50 was 16377 +/- 457.5 mg/kg; LD16 = 12986.4 mg/kg; LD84 was 18976.6 mg/kg for albino mice; LD50 was 16998.0 +/- 535.4 mg/kg; LD16 = 12875.3 mg/ kg; LD84 = 18583.4 mg/kg for albino rats. The irillen prepared by the authors should be referred to as a low toxic and practically nontoxic agent (Toxicity Class IV and V). Irillen has a broad spectrum of antiparasitic activity. It is effective in treating toxocariasis in dogs, larval alveolar echinococcosis, ascaridiasis, and eimeriasis in chickens, and siphachiasis.

Synergistic action of a cyclic depsipeptide and piperazine on nematodes.

The present study describes the synergistic effects of the cyclic depsipeptide BAY 44-4400 and piperazine in the treatment against the nematodes Trichinella spiralis, Heligmosomoides polygyrus, and Heterakis spumosa. The in vitro anthelmintic activity of a combination of the two compounds (1.7 motility units) against T. spiralis larvae was significantly higher than the sum of the individual drug effects (1.3 motility units). With regard to the rate of expulsion of H. polygyrus worms from the intestine of infected mice, an additive effect was observed; piperazine alone exerted an efficacy of 54.4% and BAY 44-4400 alone, one of 44.4%, whereas the combination of these compounds had an efficacy of 97.5%. With regard to the expulsion of H. spumosa worms, the effect of the combination was more than 5 orders of magnitude greater than the sum of the effects of the single compounds, i.e., there was a considerable potentiation of the actions of BAY 44-4400 and piperazine. Moreover, the combination exerted a significantly higher degree of degenerative effects on the intestine and on the nerve chords of H. spumosa as compared with the single compounds.

Effects of the synergistic action of febantel and pyrantel on the nematode Heterakis spumosa: a light and transmission electron microscopy study.

The present study proved that combined administration of pyrantel and febantel to Heterakis spumosa-infected mice yielded clear synergistic effects (seen in a quicker expulsion of the worms and a significant higher degree of worm degeneration), whereas the different doses of both drugs never reached the same efficacy, when given alone. It is concluded that the synergistic action of pyrantel and febantel on the functions of different organs of the parasites (muscle, nerve, inertine etc.) seen in the rodent model - also holds for the gut dwelling nematodes of the dog.

In vitro anthelmintic activity of root-tuber extract of Flemingia vestita, an indigenous plant in Shillong, India.

The in vitro activity of root-tuber-peel extract of Flemingia vestita, an indigenous plant consumed by the natives in Northeast India, was tested against helminth parasites. Live parasites (nematode: Ascaris suum from pigs, A. lumbricoides from humans, Ascaridia galli and Heterakis gallinarum from domestic fowl; cestode: Raillietina echinobothrida from domestic fowl; trematode: Paramphistomum sp. from cattle) were collected in 0.9 % physiological buffered saline (PBS) and maintained at 37 +/- 1 degrees C. In vitro treatment of the parasites with the crude extract (50 mg/ml) in PBS revealed complete immobilization of the trematode and cestode in about 43 and 20 min, respectively. However, the cuticle-covered nematodes did not show any change in physical activity and remained viable even after a long period of exposure to the extract. Exposure of R. echinobothrida to genistein (0.5 mg/ml), an active principle isolated from the root-tuber peel, caused spontaneous loss of movement (paralysis) in 4.5 h, which was slower than the time required for praziquantel, the reference flukicide and cestodicide. The treated parasites showed structural alteration in their tegumental architecture. This study suggests the vermifugal activity of this plant extract against trematodes and cestodes.

[Structural disorders in the tissues of nematodes of the suborder Ascaridata after exposure to anthelmintics]. / Strukturnye narusheniia tkanei nematod podotriada Ascaridata posle vozdeistviia antigel'mintikov.

The paper analyzes the authors' original findings and the data available in the literature concerning the structural changes in the tissue of Ascaridae after exposure to anthelmintics. The subject of the study of structural changes occurring in the digestive and genital systems represented As. canis lumbricoides, Toxocara mystax, Ascaridia galli. All the anthelmintics under study were found to greatly affect their hypodermis, the wall of the middle intestine and the epithelium of various parts of the genital tubes. All the agent differently caused vacuolization and impaired the integrity of cellular organoids. The middle intestine displayed a local or complete destruction of the brush border, as well as the swelling or pyknosis of epithelial nuclei. Each anthelminthic affected the same tissue of different helminths in a different manner. The nature and magnitude of structural derangements in the digestive and genital systems of Ascaridae depended on the properties of an agent and species-specific responses of nematodes. The used anthelmintics caused only insignificant structural changes in the excretory system.

Effects of testosterone on Heterakis spumosa infections in mice.

This study describes the effects of testosterone (Te) on the intestinal nematode Heterakis spumosa in mice. The course of Heterakis infections is apparently under Te-control. At high circulating Te-levels as occurring in intact males, Te-treated females, and Te-treated castrated males, the period of release of Heterakis eggs in mouse faeces is greatly extended and the number of eggs released per unit time is markedly elevated in comparison to low Te-levels, as found in untreated females and castrated male mice. Also, the onset of the patent period occurs earlier in Te-treated mice. Testosterone also accelerates development and growth of both female and male worms of Heterakis in mice. Thus, young adult male worms can be observed in the upper colon of Te-treated castrated male mice on day 21 post-infection (p.i.), whereas, at that time, only L4 larvae are present in Te-untreated male castrates. Testosterone also favours the survival of nematodes in hosts. In untreated male castrates, the number of worms present on day 7 p.i. (L2 larvae) is approximately two thirds higher than that found on day 21 p.i. However, such a reduction in the number of worms does not occur in Te-treated castrated mice during the same period of time. The early phases of the life-cycle of Heterakis, i.e. hatching in the small intestine and final settling of L2 larvae in the upper colon are independent of Te. Also, Te does not affect motility and even slightly reduces the fecundity of adult female worms in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)