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Conventional chemoprophylaxis of canine toxocariasis is based upon the treatment of young puppies. It is proposed that physiological considerations and the complexity of the host-parasite relationship in the case of Toxocara canis demand that anthelmintic evaluation should properly be conducted in such animals rather than in adolescent or adult dogs. A screening model using the critical trial technique in early weaned pups gave variable results even with compounds known to be of high efficacy in older dogs. Circumstantial evidence suggested that this inconsistency may be related to the rate of passage of ingesta through such young animals. More satisfactory results were obtained by pairing unweaned naturally infected puppies by weight and sex and treating one of each pair with the test compound. Natural in utero and transmammary infection was found to give fairly consistent worm-burdens within each litter and a good indication of efficacy could therefore be estimated by comparing post mortem worm-counts. On this basis, the apparent efficacies of pyrantel pamoate (5 mg kg-1) and piperazine (100 mg kg-1) were found to be 83.5 and 82.5%, respectively. This method was extended to evaluate a prophylactic programme in which anthelmintic therapy was given to pups when aged 10, 20 and 30 days. Intestinal T. canis populations were reduced, at 35 days of age, by between 94.2% and 98.0%. This programme increased overall weight gains between 10 and 30 days of age by 18% (P less than 0.05) although there was great variation between litters. The biggest response was observed in male pups between 20 and 30 days old.

When the anthelmintic Banminth 'Katze' was administered twice to ninety-two cats, the owners were questioned on the method by which the animals took this paste. Minor, if any, problems were observed in 94.5 per cent of the cats. Major problems occurred in 5.5 per cent of the animals. Significantly more adult than young cats had difficulties in taking the paste.

In a trial involving 185 school children, pyrantel pamoate (Combantrin) at a dose of 20 mg/kg body weight for 1-3 days was found to be very effective against the Ascaris and moderately effective against the hookworm, with mean cure rates ranging from 93.3-96.7% and 53.3-73.3% respectively. No apparent action against the Trichuris was detected, a mean cure rate of between 34.2 and 46.1% being only slightly, but not significantly, better than the 33.8% cure for a placebo-treated control group. Single and multiple doses of the suspension and tablet formulations of the drug were well tolerated. From the series of randomized and controlled trials conducted, we recommend that, in this area, the appropriate dose of the drug to use for treating ascariasis is 10 mg/kg per day for 1 day, and for infections which include hookworm, 20 mg/kg per day for 3 days.

A new method for the determination of pyrantel tartrate in swine feed an supplements has been developed because the current official AOAC method is not applicable to feeds co-medicated with tylosin. The new method involves: (a) leaching of drug from feed with methanolic NaCl solution, (b) removal of interfering substances by ion pair liquid-liquid extraction and high performance liquid chromatography, and (c) quantitation of pyrantel tartrate by monitoring the ultraviolet absorption of the effluent stream at 313nm. The method of standard addition is used to compensate for the effect of the feed matrix on drug recovery. No interference is encountered from tylosin, carbadox, lincomycin, non-drug components of feeds and supplements, or potential degradation products of pyrantel tartrate, i.e., cis isomer of pyrantel tartrate and (E)-N-(3-methylaminopropyl)-2-thiopheneacrylamide. Results for the assay of 3 lots each of feeds and supplements containing 0.0106 and 0.106% pyrantel tartrate, respectively, were within +/-4% of label claim. Coefficients of variation ranged from 1.6 to 1.8% for feeds and from 1.9 to 3.9% for supplements.

A mixture of 150 mg mebendazole and 30mg pyrantel pamoate was given on 3 consecutive or near-consecutive days to 70 children infected with one or more of Necator americanus, Ascaris lumbricoides, Strongyloides stercoralis, S. fuelleborni-like and Trichuris trichiura. This treatment had an efficacy of 95 per cent for N. americanus infections, 100 per cent for A. lumbricoides, 57 per cent for Strongyloides spp., and 75 per cent for T. trichiura. The results indicate that the treatment given is effective against the infections of N. americanus and A. lumbricoides but is only partially effective for Strongyloides and T. trichiura infections.

A study was made of 48 patients from the different departments of the Hospital del Niño, DIF, in which hookworm eggs were demonstrated by qualitative coproparasitoscopic study (CPS). During the study, quantitative CPS was practiced on them by Stoll's dilution and the Harada-Mori technique, for the identification of the hookworm larvae. They were divided into three groups: A, B and C (16 patients in each group); the study was single-blind. The effectiveness of the evaluated drugs was based on the disappearance or diminution of hookworms eggs in the CPS (Stoll) practiced 2 weeks after the drug treatment had finished. The work was done with patients parasitized by Necator americanus (verified by the Harada-Mori technique). The A group was given pyrantel pamoate; the B group, thiabendazole and the C group, mebendazole. The results obtained were statistically processed by means of X2 proportions. There was no significant difference between the three groups when a light to moderate necatoriasis was treated; when a massive infection was involved, there was a significant difference and it was found that the best drug was pyrantel pamoate administered at the dose of 20 mg/kg/day/3 days. There were few side effects in the three groups, but they were not sufficient to cause suspension of the treatment. The cheapest drug was thiabendazole.

Clinical trials on the three broad spectrum anthelmintics against trichuriasis, ascariasis and hookworm infection were carried out in a rural community in Irosin, Sorsogon. Flubendazole (Fluvermal) appears to be a promising drug against trichuriasis particularly when periodic mass treatment of a community is carried out. Mebendazole (Antiox) also appears to be promising given as single dose during mass treatment of soil-transmitted helminthiasis. As shown in previous studies, oxantel-pyrantel (Quantrel) should be given at 15 mg/kg body weight at 12-hour intervals or 20 mg/kg body weight single dose rather than 10 mg/kg body weight in a single dose when treating trichuriasis.

An experiment was conducted with 96 weanling pigs (avg initial wt 18.5 kg) divided into six treatment with two replicates of eight pigs each. Pigs in Treatments 1, 2 and 3 were penned in outside pens with dirt lots that previously were contaminated with A. suum ova to induce a natural ascaris infection. Pigs in Treatments 4, 5 and 6 were penned in an open-front building with solid concrete floors and were experimentally infected with 2,000 embryonated A. suum. ova on d 1, 15 and 29 of the experiment. Pigs in Treatments 1 and 4 were medicated with fenbendazole (FBZ, 3 mg/[kg BW.d]) for three consecutive days during three consecutive time periods. Pigs in Treatments 2 and 5 were medicated with pyrantel tartrate (PT, 106 mg/kg feed) for 28 d. Pigs in Treatments 3 and 6 served as infected, unmedicated controls. All pigs were challenged with 100 A. suum eggs 7 d after termination of the final FBZ treatment. All pigs were killed 66 d after challenge and worms were recovered. Fenbendazole treatment resulted in greater (P less than .07) average daily gain than PT treatment in pigs penned outside. Among inside pigs, FBZ treatment resulted in better (P less than .02) feed utilization than in controls. The FBZ and PT treatments reduced (P less than .03) the total number of A. suum, the length and weight of female ascarids and the length of male ascarids compared with controls. A natural continual infection with A. suum was less effective than experimental infection in inducing protective immunity in pigs.

Eleven dogs dosed at approximately the recommended rate of 1.029 mg of pyrantel pamoate/kg of body weight were used. The efficacy against Ancylostoma in the 11 dogs was 99% (av; min-max, 94-99%). In 4 dogs with both Toxocara and Ancylostoma, average efficacy against Toxocara was 96%, and in 5 dogs with both Toxoscaris and Ancylostoma, efficacy against Toxascaris was 93%. Only 2 dogs of the 11 were infected with the 3 species; the average efficacy was 90%. There appeared to be no activity against the Trichuris found in one dog and the Dipylidium found in another. Treated dogs did not vomit or have other noticeable ill effects.

The anthelminthic efficacy of pyrantel pamoate (Combantrin) in a single dose of 10 mg/kg body weight was compared with that of thiabendazole (Mintezol) in two doses each of 25 mg/kg body weight in a controlled trial. Follow-up examination, 6 weeks after treatment with Combantrin gave cure rates of 93.8%, and 29.1% for infection with Ascaris and the Hookworm respectively, and 44.3% and 27.3% in those treated with Mintezol. The reduction in hookworm egg counts was higher in patients treated with Combantrin than with Mintezol, and Combantrin was better tolerated. Neither drug was effective against the Trichuris. The results are compared with those from other parts of the world.

A study was carried out to find out the incidence of helminthic infections in hospitalized patients at Sher-e-Bangla Medical College, Barisal and to determine the comparative efficacy of pyrantel pamoate, levamisole, and mebendazole. It was observed that 76.2 per cent of total hospitalized patients were infected with intestinal helminths. Polyparasitism (52.6 per cent) was more frequent than single infection (21.8 per cent). Amongst these, 47.5 per cent was suffering from Asearis lumbricoides (AL), 42.5 per cent from Hookworm (H.W) and 65.8 per cent from trichuris trichura (TT). Out of 255 cases examined separately, 40 per cent was suffering from Enterobious vermicularis (EV) infection. The comparative study showed that mebendazole produced egg negative stool in 90.9 per cent of AL, 95.6 per cent of HW and 86.8 per cent of TT after eight days of treatment. On the other hand, pyrantel pamoate cured AL in 93.3 per cent, HW in 78.5 per cent and TT in 34.2 per cent eases. Levamisole cured 75 per cent AL, 4.1 per cent H.W. and 22.2 per cent TT within the same period.

Carbadox (CBX), an antibacterial agent, and pyrantel tartrate (PT), an anthelmintic, are formulated either separately or together in swine feeds. The official Association of Official Analytical Chemists (AOAC) spectrophotometric methods for both drugs are long, nonspecific, and require standard addition techniques. Results by this technique are positively biased. A simple, direct, specific, high-pressure liquid chromatographic (HPLC) method to determine either one or both drugs simultaneously with apparent accuracy and precision is developed. Drugs are released from feed matrices by water, extracted with dimethylformamide (DMF), cleaned up on alumina, and quantitated by direct comparison to standards using a Whatman Partisil 10 ODS-3 column and a mobile solvent containing 23.5 +/- 1.5% DMF in phosphate buffer (pH 2.0). Fourteen laboratories participated in a collaborative study of this method for determination of CBX and PT in animal feeds.

Single doses of oxantel given to 24 children and 37 adults with light to moderate infections of Trichuris trichiura effected cures in 20 of 26 (77%) trials with 10 mg/kg body weight, in 23 of 25 (92%) with 15 mg/kg, and in 10 of 10 trials with 20 mg/kg. In cases not cured, the egg-counts were reduced 50% to 91%. Side effects were not observed, and no drug-associated changes were detected by biochemical, hematologic, and urine examinations before and after treatment.

Oral administration of solutions of pyrantel tartrate at 50, 75, 100 and 125 mg/kg body weight gave 43.9, 82.1, 92.8 and 99.1 per cent efficacy respecively. None of the chicks given 100 and 125 mg/kg body weight showed any sign of toxicity.

Pyrantel tartrate caused spastic paralysis through stimulating nicotinic cholinoceptors in Angiostrongylus cantonensis.

The study design of a project to investigate the epidemiology, population dynamics and control of intestinal nematode infections in fishing village communities in Southern India is described. The paper focuses on Ascaris lumbricoides infection and describes changes in prevalence and intensity (worm burdens) with host age, the aggregated frequency distributions of parasite numbers per person, a density-dependent relationship between parasite fecundity and worm burden and rates of reinfection following chemotherapeutic treatment. The age-intensity of infection profile is convex in form, where maximum worm burdens are attained in children in the age range five to nine years. On the basis of juvenile to adult worm ratioos, the life expectancy of Ascaris in man is estimated to be of the order of one year. Rates of reacquisition of worms after chemotherapy are shown to be dependent on host age. Wormy individuals with heavy infections are shown to be predisposed to this state such that they reacquire heavier than average worm burdens following treatment.

Analysis of egg and worm counts of Ascaris recorded at various intervals following a mass anthelmintic treatment programme in a South Indian fishing community is presented. Three indices of infection in the community are compared, namely the prevalence and intensity of egg output (at 2, 6 and 11 months following treatment) and the number of worms expelled following an 11 month period of reinfection. Detailed examination of these measurements revealed significant associations with patient sex and age. The age-prevalence profile of Ascaris infection changed little over time (except immediately following treatment) with the peak prevalence found in the 5-9 year age group. Although 85% of both males and females harboured Ascaris initially, the prevalence following 11 months reinfection was decreased, due to a significantly lower proportion of males being reinfected. By the 11th month of reinfection, the age-intensity profiles of egg output were similar to those observed at initial treatment in the older age groups (10 years and above) and in male children (less than 10 years). However, a dramatic increase in the egg output of female children, greatly exceeding the initial mean, was observed within a 6 month period of reinfection. The intensity of egg output did not accurately reflect the abundance of Ascaris recovered via drug-induced expulsion following an 11 month period of reinfection. Although the egg output attained preintervention levels, the average worm intensity reached only half the initial value. The trends in the sex- and age-intensity profiles were consistent at the two sampling dates and showed similar patterns to the egg output curves. The relevance of the results to helminth control and the monitoring of reinfection is discussed.

440 children aged between 3 and 5 were examined for Oxyuriasis in three schools of Milan during three different days. 31% of the children resulted parasited by Enterobius vermicularis: a clear correlation between parasitosis and socio-economic condition has been demonstrated. Treatment with "pirantel pamoate" has been proved effective in 88% of the cases.

A modified spectrophotometric method for determining pyrantel tartrate in swine feeds was subjected to a preliminary collaborative study. Two small-scale commercial pyrantel-medicated feed samples (0.0881 and 0.0106%) were assayed in replicate by 4 collaborators. The mean results of all laboratories were 0.0862 and 0.0112%. The mean coefficients of variation were 10.57 and 6.48%, repectively. Suggestions for improving recovery include the following: complete dissolution of standard, use of analytical grade KI, careful phase separation, thorough mixing, and minimum exposure of compound to light.

Pyrantel tartrate caused spastic paralysis in various parasitic nematodes, but not in cestodes and trematodes.

The spectrophotometric method for pyrantel tartrate in swine feeds was collaboratively studied. Twenty-seven laboratories assayed feeds containing 0.0103, 0.0965, and 0.7902% pyrantel tartrate. Repeatability (sigmao) and reproducibility (sigmax) standard deviations were: sigmao = 0.00068%, sigmax = 0.00105% (10% of grand mean) for 0.0103% pyrantel tartrate level; sigmao - 0.0065%, sigmax = 0.0090% (10% of grand mean) for 0.0965% pyrantel tartrate level; and sigmao = 0.0415%, sigmax = 0.0743% (10% of grand mean) for 0.7902% pyrantel tartrate level. The mean theoretical recovery values for feeds containing 0.0103, 0.0965, and 0.7902% were 100, 97, and 96%, respectively. The method was adopted as official first action for feeds or concentrates containing 0.0106-0.8811% pyrantel tartrate.

Two experiments were carried out to define the effect of repeated anthelmintic treatments with or without repeated infections by H. polygyrus on the receptivity of the mouse to subsequent infections by the same parasite. The aim of the first experiment was to show the effect of these interventions on the future development of host resistance. This experiment did not reveal a marked difference in behaviour between treated or non-treated animals. During the second experiment a modification of the acquisition of resistance during the period of infections and multiple treatments was looked for. It was shown that multiple treatments of the host during the period of immunity markedly improved the mechanisms of defense against a new infection. Any direct action of anthelmintics was ruled out in explaining this mechanism. Two drugs were compared: pyrantel tartrate and levamisole. No difference has been shown between these two drugs. It is possible, however, that the multiple treatments act by enabling a more intense renewal of the parasitic population and therefore by increasing the stimulus initiating protection.

In order to confirm benzimidazole resistance as recommended at a workshop of the Commission of the European Communities the isolate 'E' of cyathostome strongyles originating from a stud where benzimidazole resistance had been demonstrated by egg hatch tests and by egg count reduction tests was investigated in two series of critical tests. Each of 11 foals reared strongyle-free was infected with 130,000 third stage cyathostome larvae. One animal remained untreated, two pairs of foals were treated with paste formulations of the (pro)benzimidazoles cambendazole (20 mg/kg bodyweight) or febantel (6 mg/kg bodyweight) and two groups of three foals were given pastes containing the non-benzimidazole drugs pyrantel pamoate (19 mg/kg bodyweight) or ivermectin (0.2 mg/kg bodyweight) either at 101 days (trial 1) or at 59 to 62 days (trial 2) after infection. Strongyles were counted in faecal samples collected daily between treatment and post mortem examination five or seven days later and worm burdens were counted in the intestinal contents and mucosal digests. Nine species of the cyathostome subfamily were found in the infected foals. The numbers of luminal stages were reduced by only 3.1 and 20.2 (mean 7.9) per cent by cambendazole and by 13.6 and 32.8 (mean 21.3) per cent by febantel in the individual animals. However, pyrantel pamoate (93.6 to 98.2, mean 96.3 per cent reduction) and ivermectin (100 per cent reduction) were highly effective. These trials provide the first report of benzimidazole resistant Cylicostephanus poculatus anywhere in the world and demonstrate (pro)benzimidazole resistance in seven other species for the first time in Europe.