febantel and Trichostrongyloidiasis

Haemonchus contortus- and Trichostrongylus colubriformis-infected jirds (Meriones unguiculatus) are useful for anthelmintic studies. With concurrent infections of these parasites established in the jird, questions of not only anthelmintic activity, but to some extent spectrum, could be assessed in a single model system. This report outlines a model using immunosuppressed (0.02% hydrocortisone in feed) jirds concurrently infected with H. contortus and T. colubriformis. Immunosuppressed jirds were inoculated with approximately 1,000 exsheathed infective larvae of each species, treated per os on day 10 postinoculation (PI), and killed on day 13 PI. Stomachs and small intestines were removed, opened longitudinally, incubated in distilled water at 37 C for 5 hr, fixed in formaldehyde solution, and stored for subsequent examination. Contents of both organs were examined using a stereomicroscope (15-45 x). Various standard anthelmintics were evaluated in the model; modern broad-spectrum ruminant anthelmintics (benzimidazoles, febantel, ivermectin, levamisole hydrochloride, and milbemycin D) are active uniformly and in most cases at doses comparable to those required for efficacy against these parasites in ruminants. This model, using worms of 2 genera living in distinct sites, allows preliminary evaluation of anthelmintic activity and spectrum for experimental compounds in a single cost- and resource-efficient experiment.

Topics: Animals; Anthelmintics; Anti-Bacterial Agents; Benzimidazoles; Bithionol; Diethylcarbamazine; Gerbillinae; Guanidines; Haemonchiasis; Macrolides; Piperazine; Piperazines; Pyrantel Tartrate; Rodent Diseases; Trichostrongyloidiasis

The efficacy of febantel at a dosage of 5 mg/kg (45.5% paste formulation) against inhibited early 4th-stage larvae (EL4) of Ostertagia ostertagi, other nematodes of the abomasum, and Dictyocaulus viviparus was investigated in 4- to 6-month-old Holstein calves that grazed on pasture heavily contaminated with parasites from February 24 to April 1, 1986 (36 days). In Louisiana, this is the first month of a 3-month period in which increasing numbers of inhibition-prone O ostertagi larvae are acquired, and infection risk with D viviparus may remain high. Three of 4 calves that died of lungworm infection during the pasture-exposure period were necropsied. Large numbers of abomasal nematodes, including inhibited O ostertagi larvae, and large numbers of D viviparus were recovered. Twenty-five calves were randomly allotted by equal distribution of body weight to 2 groups and treated on April 4: placebo-treated calves (n = 13) and febantel-treated calves (n = 12). Equal numbers of treated and control calves were killed at 6 and 7 days, respectively, after treatment. Mean numbers of O ostertagi in control cattle were: adults, 4,931; developing 4th-stage larvae (DL4), 1,119; and inhibited EL4, 3,410. Ostertagia lyrata, Trichostrongylus axei, Haemonchus sp, and D viviparus were well distributed in nearly all control calves. Percentage reduction of O ostertagi in treated calves, when compared with controls, was: adults, 83.6%; DL4, 57.8%; and inhibited EL4, 34.8%. Percentage reductions of other species were: O lyrata, 92.6%; T axei adults, 99.3% and 4th-stage larvae (L4), 100%; Haemonchus sp adults, 66.7%, and L4, 64%; D viviparus adults 90.6%, and immature forms, 97.1%.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Abomasum; Animals; Cattle; Cattle Diseases; Dictyocaulus Infections; Drug Evaluation; Feces; Guanidines; Ostertagiasis; Parasite Egg Count; Trichostrongyloidiasis

Anilides bearing a guanidino, thioallophanato, isothioallophanato or amidino group in the ortho position were synthesised (6) for investigations of their anthelmintic effects, and tested against sheep trichostrongylides. The most active anilides are those containing a 5-alkylthio, 5-alkylsulphinyl (alkyl = C3H7, C4H9), 5-phenylthio, 5-phenylsulphinyl or 4-phenylsulphonyloxy group, and a guanidino group substituted at both nitrogen atoms by a methoxycarbonyl group. The most active anthelmintic anilides are the form-, propion-, butyr- and methoxy-acetanilides (e.g. 60, 61, 66, 95, 100, 110). Of the guanidines unsubstituted at N' and N", the 2-guanidino-5-phenylthio-2-methoxyacetanilide (123) and the 2-guanidino-5-phenylsulphinyl-2-methoxyacetanilide (152) were more active than parbendazole. From the class of bismethoxycarbonylguanidines (6 alpha), which are also the most interesting products in terms of stability, febantel (110, Rintal) has been introduced into veterinary practice for the treatment of nematode infections in horses, cattle, sheep and swine.

Topics: Aniline Compounds; Animals; Anthelmintics; Chemical Phenomena; Chemistry; Female; Guanidines; Haemonchiasis; Hookworm Infections; Nippostrongylus; Rats; Rats, Inbred Strains; Sheep; Strongyloidiasis; Trichostrongyloidiasis