Ashton C. Cuckler

Effect of Thiabendazole Upon Experimental Trichinosis in Swine

Summary Pigs fed a diet containing 0.1% thiabendazole and exposed to larvae of T. spiralis developed either no infection or an infection of negligible severity. A concentration of 0.01% thiabendazole in the diet did not prevent pigs from acquiring trichinosis, but no mortality occurred when the pigs were exposed to huge numbers of Trichinella larvae during the period of medication. A moderate experimental infection of trichinosis was not eradicated by feeding 0.15% thiabendazole for 7 days, beginning on 5th day of infection. Pigs fed 0.3% thiabendazole for 7 days, beginning 2 or 4 weeks after exposure to massive infections, suffered no mortality, while 4 of 6 untreated pigs died. The data further indicate that the majority of the Trichinella larvae in the muscles of the treated pigs were killed by the medication employed.

Effect of certain antihistamine and antiserotonin agents upon experimental trichinosis in mice.

Abstract Diets containing an antihistamine drug, 2-[ P -chloro-α-(2-dimethylamino-ethyl)benzyl] pyridine maleate (chlorpheniramine maleate), or an antiserotonin drug, 1-benzyl-2-methyl-5-methoxytryptamine (B.A.S.), or a drug possessing both properties, 1-methyl-4-(5-dibenzo-[α,e]-cycloheptatrienylidine)-piperidine hydrochloride monohydrate (cyproheptadine), were fed to mice during the acute intestinal phase of experimental trichinosis. In each instance the number of worms remaining in the small intestine on days 17 and 21 of infection was greater in the treated than in the untreated mice. It is suggested that the cellular reaction responsible for the expulsion of Trichinella from the gut may be mediated, to some extent, by histamine.

Induction of Immunity to Trichinosis in Mice by means of Chemically Abbreviated Infections.

Abstract In two experiments mice were exposed to four heavy infections of Trichinella spiralis within a period of 11 days. Each infection was terminated by 2-[4′-thiazolyl]-benzimid-azole (thiabendazole) therapy within 1 day after exposure. In both experiments the mice were subjected to a challenge infection approximately 1 month after the last immunizing exposure. On day 7 after challenge the number of adult worms in the immunized mice was 63–72% less than that in the control mice. In a third experiment thiabendazole therapy was applied from days 14 to 21 after exposure of mice to a severe Trichinella infection. The mice were exposed to a severe challenge infection 1 month after the initial exposure. On day 7 after challenge, the number of adult worms in the previously infected mice was 63% less than that in the control mice. In one experiment, in which multiple infections were used for immunization, the number of larvae in the muscles of the immunized mice was 50% less than that in the control mice. In the other two experiments, however, no reduction in the number of larvae in the muscles of the immunized mice was demonstrated. These experiments have demonstrated that (1) protective immunity against reinfection with Trichinella can be stimulated by repeated intestinal infections of only 1 day duration, and (2) a similar degree of protection can be elicited by a single infection of 14 days duration; (the effect of a single 1-day-old infection was not studied).

ANTIPARASITIC DRUGS. V. ANTICOCCIDIAL ACTIVITY OF 4-AMINO-2-ETHOXY-BENZOIC ACID AND RELATED COMPOUNDS.

Summary 1. Preparations of the 4-amino, 4-acetamido and 4-benzamido derivatives of methyl-2-ethoxybenzoate and of 4-amino-2-ethylaminobenzoic acid are reported. 2. Anti-coccidial activity is demonstrated for 2-substituted PABAs, especially those containing 2-alkoxy, alkythio and alkylamino groups. 3. The most potent compounds are 4-amino-2-ethoxybenzoic acid and its ester and N-acyl derivatives. The authors gratefully acknowledge the help of Mr. J. L. Ciminera in designing the statistical procedure used in the bio assay.

Antiparasitic Drugs. II. Anticoccidial Activity of 4,5 imidazoledicarboxamide and Related Compounds

Summary 1. Preparation of 7 substituted imidazoles has been described. 2. Anticoccidial activity was demonstrated for imidazole-4-carboxamide and certain related compounds. 3. The most potent compound was 4,5-imidazoledicarboxamide (glycarbylamide). 4. Replacement of one or both carboxamides in the 4.5 positions on the imidazole ring reduced or completely eliminated the anticoccidial activity of glycarbylamide. Substitutions at the 1 or 2 positions on the imidazole ring produced compounds of less activity than glycarbylamide.

Nithiazide I. Chemical and Biological Studies on l-ethyl-3-(5-nitro-2-thiazolyl) urea and Related Compounds

Summary 1. The preparation of 1-mono-substituted and 1,1-disubstituted nitrothia-zolylureas has been described. 2. Antihisto-monad activity was demonstrated for mono-substituted thiazolylureas with not more than 4 carbon atoms. The 1-methyl compound was more toxic and less effective than the 1-ethyl derivative. The dimethyl compound was less toxic and also less effective than the mono-methyl compound. 3. In addition to therapeutic activity in enterohepatitis, nithi-azide [l-ethyl-3-(5-nitro-2-thiazolyl) urea] was found to have antitrichomonal activity but antimalarial, antitrypanosomal or anticoc-cidial activity was not demonstrable.

Nithiazide II. Effect on Enterohepatitis in Turkeys

Summary 1. The data presented show that nithiazide [1-ethyl-3-(5-nitro-2-thi-azolyl) urea | was more potent and less toxic than 2-amino-5-nitrothiazole when fed to turkeys with enterohepatitis. 2. Nithiazide was most effective when administered prior to infection or beginning 3 to 7 days after infection. It prevented mortality from enterohepatitis produced either by oral exposure to cecal worm eggs or by rectal inoculation of Histomonas meleagridis cultures. Nithiazide may be administered in the feed or water and is equally effective in either form. 3. The therapeutic feeding of rations containing 0.05% nithiazide, starting 3 days after infection, prevented mortality from infectious enterohepatitis which was lethal for 73% to 83% of the untreated control turkeys.

Use of thiabendazole-medicated feed for prophylaxis of four common roundworm infections in dogs.

Thiabendazole, mixed into commercial dog food at concentrations of 0.005, 0.01, and 0.025%, was fed three times daily to young dogs which were exposed to infection with Toxocara canis, Ancylostoma braziliense, Ancylostoma caninum, Strongyloides stercoralis, and Trichuris vulpis. All three levels of thiabendazole were effective in preventing patent infections of Ancylostoma and Toxocara. Hookworm eggs were never observed in the feces of dogs receiving any level of thiabendazole, nor were hookworm larvae ever recovered from cultures made from the feces of these dogs. Necropsy revealed that adult hookworms had developed only in the dogs receiving the lowest concentration of drug (0.005%); but supplementary studies indicated that infertile hookworms may develop in some dogs treated with 0.01 or 0.05% thiabendazole. The number of Strongyloides larvae recovered from the feces of dogs fed thiabendazole was much less than in the case of the untreated, exposed controls; at 0.025% recovery was virtually nil. At necropsy, adult Strongyloides were found in all but one of the treated dogs, but their number was appreciably smaller than in the controls. In dogs fed 0.025% thiabendazole, prophylaxis of Trichuris was essentially complete. Thiabendazole at 0.01% had no effect on the number of whipworms becoming established although the mean number of eggs produced was appreciably lower than in the controls. The feeding of 0.005% thiabendazole had no effect on the number of Trichuris eggs produced or the number of whipworms present at necropsy. The life cycles of four common intestinal parasites of the dog can thus be broken by the regular administration of thiabendazole in dog food. Since three of these helminths are pathogenic for man, these findings may have considerable public health importance. Continuous prophylactic administration of an anthelmintic in dog food is a potentially useful approach to the effective control of helminths in dogs. In addition, the transmission of these parasites to humans, especially children, might be abated by such a measure. The present report is a summary of studies on the effectiveness of thiabendazole in the feed for prophylactic control of the common intestinal nematodes of dogs. MATERIALS AND METHODS Twenty-eight young beagle pups (about 5 to 6 weeks old) were distributed into 7 groups of 4 dogs each. The dogs were housed individually in metal cages. Fecal samples were collected from each animal prior to the start of the experiment to ascertain existing parasitic infections. Toxocara eggs were observed in the feces of seven dogs; each group of dogs was then adjusted to contain a single dog with a patent peri-natal Toxocara infection. During the experiment fecal samples were collected once weekly until the 11th week, and twice weekly thereafter. The fecal samples were examined quantitatively for parasite eggs using a modified Stoll dilution technique and centrifugal flotation in magnesium sulfate (1.250 sp gr). The mean egg-count for each group was derived from a logarithmic transformation of the values obtained for the individual counts. From the 11th week onward a pair of 3-g charcoal Received for publication 11 October 1967. 359 cultures was prepared from each fecal sample and was subsequently examined for larvae by the Baermann technique. All pups were treated with a sulfonamide for 3 days to control subclinical coccidiosis and all were vaccinated for canine distemper, hepatitis, and leptospirosis (Triod Plus Vaccine, Fromm Laboratories). Three times daily, prior to the experiment, the young dogs were each fed 20 g of finely ground commercial dog food (Purina Dog Chow) mixed with 25 ml of reconstituted milk. When the test commenced, the ration consisted of 30 g of canned dog food (Ken-L-Ration) mixed with 10 g of the ground dog food and 25 ml of milk. A suspension of thiabendazole in 2% methylcellulose was added to individually weighed portions of the dog food in amounts sufficient to give final concentrations of 0.005, 0.01, or 0.025%. Nitrodan (3Methyl-5-[(p-nitrophenyl)azo], Rhodanine; Cooper, Tinsley Laboratories, Harrison, New Jersey) was given as a reference compound at a concentration of 0.025%-the use level recommended in a commercial announcement by the manufacturer. The medicated ration was mixed by hand and presented to each dog. As the test progressed the food allowance was increased and the dry food was replaced with additional canned dog food. From the 9th week to termination, each dog received 200 g of canned dog food 3 times daily. In the 3rd week of the experiment, the milk was omitted from the ration, and only the canned food mixed with the proper medication was presented. The control dogs received 2% methylcellulose suspension in volumes equal to what the medicated dogs received. A daily food consumption record was kept, and the mean daily drug consumption was calculated on This content downloaded from 157.55.39.138 on Mon, 27 Jun 2016 06:21:59 UTC All use subject to http://about.jstor.org/terms 360 THE JOURNAL OF PARASITOLOGY, VOL. 54, NO. 2, APRIL 1968 TABLE I. Summary of parasite exposures of dogs on thiabendazole prophylaxis. Inoculum, Week of Parasite no. eggs or Route exposure* larvae/dog 1st Toxocara canis 500 eggs oral 2nd Trichuris vulpis 200 eggs oral 3rd Toxocara canis 50 larvae** oral 7th Ancylostoma caninum 60 larvae oral Ancylostoma braziliense 120 larvae oral 12th Strongyloides stercoralis 800 larvae oral * From commencement of medication. ** Larvae in carcasses of mice previously administered eggs of Toxocara and recovered from brain and lung digesta. the basis of the average weekly body-weight and daily food consumption of each dog. At five intervals during the experiment, the dogs were exposed to infection with common parasitic helminths, as shown in Table I. The dogs were killed at the end of the 16th week of medication by an intravenous injection of sodium phenobarbital. The small and large intestines, and cecum, were removed separately, slit open and soaked for 1 hr at 37 C in 0.85% saline; the contents were washed and the mucosa scraped to remove embedded worms. Fifteen grams of the following tissues were removed, ground and digested separately in artificial gastric fluid: small intestine, lung, liver, skeletal muscle and combined diaphragm and rib muscle. The digested material was washed and collected on a sieve having an aperture of 0.074 mm (200 mesh per inch). The larvae from the digested tissues were collected by sedimentation, identified and counted. The data pertaining to worm counts at necropsy and the number of larvae recovered from fecal cultures were examined by linear regression methods. The nitrodan data were not examined statistically, as only a single dosage had been employed.

Coccidiosis: Summary of evaluation and selection of coccidiostats

The purpose of this paper is to summarize the many excellent reports which have been presented and to assess the various alternative methods used in the comparative evaluation of coccidiostatic drugs. There are many ways of doing this in battery, pen trial and field trial, or commercial operations. I will briefly consider each of these procedures. Battery trials. It is evident that once an investigator is interested in evaluating and developing a new or improved coccidiostatic drug he will need to design carefully his experiments to consider the many variables which have been enumerated by Shumard and Callender (1970) and Waletzky ( 1970). It is axiomatic that the test design should be as simple as possible and amenable to statistical evaluation of the data. The data should provide statistically significant responses for the various criteria being evaluated. The most important consideration is for the investigator to establish his “standard” conditions with the physical facilities available: the number of birds and their breed, sex, and age; the ration used; the lighting and temperature conditions; and duration of the test. He will then need to consider whether he wants information on the prophylactic (before inoculation) or therapeutic (after inoculation) efficacy of the drug. He must then choose between the use of pure populations of a single species or strain of coccidia or the combination of several species for inoculating his birds. Since it is well known, and reemphasized here by Long ( 1970) and Hymas ( 1970), that the pathogenicity of strains of the same species varies widely, it will behoove the investigator to utilize several strains and as many species as he considers pertinent to the investigation. The number of oocysts used for the inoculum should be based upon previous estimates or titrations of the infectivity and pathogenicity of the particular strains or species being used. The lethal dose 50 ( LDno) of coccidia can be estimated with the “killer” species, and Waletzky (1970) pointed out that the use of “over-kill” numbers of coccidia can and should be avoided. Reid (1970) has emphasized the need for a more realistic level of mortality and has suggested that 2030% mortality is probably adequate. With the inclusion of appropriate control groups for comparative purposes, the criteria used to evaluate the anticoccidial efficacy of the compounds can be estimated by several parameters (Reid et al. 1969) including mortality, weight gain, feed conversion, fecal or dropings scores ( Morehouse and Baron 1970), oocyst production, and lesion scores of samples of birds or all birds at termination of trial (Reid, Taylor, and Johnson 1969). Although the lesion scores are highly subjective, it is possible to acquire skill and uniformity in grading the lesions and assigning standardized quantitative values for the degree of intestinal damage produced by the parasites (Johnson and Reid 1970). The use of developing chick embryo or tissue culture techniques, and physiological

Antagonistic Effect of Thiocarbanilide on 4,4′-Dinitrocarbanilide, A Component of Nicarbazin

Summary 1) Thiocarbanilide, in a 1 to 1 ratio or less, effectively inhibited the anticoccidial activity of nicarbazin when given parenterally as well as orally. 2) Thiocarbanilide also antagonized the effect of nicarbazin on the depigmentation of egg shell color. 3) In both instances, the antagonistic effect of thiocarbanilide was correlated with decreased plasma concentrations of dinitrocarbanilide. 4) It is suggested that thiocarbanilide may interfere with the activity of nicarbazin through competition in absorption.