Immunization of pigs against experimental Ascaris suum infection by feeding ultraviolet-attenuated eggs

Pigs fed Ascaris suum eggs attenuated by short-wave ultraviolet radiation developed a resistance to challenge infections that varied according to the protocols used. Two doses of eggs irradiated at total exposures (ET) of 150 muW-min/cm2 resulted in a reduction of adult worm burden in 3 groups challenged with 50, 100, or 500 eggs by 45, 35, and 49%, respectively. However, these results were not statistically significant (P greater than 0.05). Three other groups were fed eggs as follows: Group 1, 3 doses irridated at ET's of 150, 150 and 150; Group 2, 3 doses irradiated at ET's of 150, 150, 100; and Group 3, 3 doses irradiated at ET's of 150, 100, and 75. All of these regimens provided significant protection: Group 1 (P less than 0.02), Group 2 (P less than 0.05), Group 3 (P less than 0.001). An analysis of the lengths of worms recovered showed that in controls fed varying doses of eggs, worm sizes were inversely related to the number of eggs in the challenge dose. Measurements of worms from vaccinated animals showed that 23 of 116 adult worms recovered were probably survivors of one or more of the vaccinating doses. A ratio of 18 female to 5 male worms indicated that males are more susceptible to ultraviolet radiation than females.

[Comparison of the sensitivity of the passive, indirect hemagglutination reaction and the latex fixation test in the demonstration of the migratory phase of experimental ascariasis (Ascaris suum) in swine]

The authoresses verified diagnostic sensitivity of two serological tests -passive indirect hemagglutination [IHA] reaction modified by the authoresses and latex-fixation test [LFT] when proving the post-invasion migratory phase of ascariasis [Ascaris suum] in experimentally infected swine. The IHA reaction was found to be more sensitive than the LFT in most cases [62.2%] by two to three values of the geometric series. The invasion can be detected by the IHA reaction from 7th to 120th day and by the LFT from 7th to 49th day after invasion.

Visceral larva migrans and alveolar hydatid disease. Dangers real or imagined

For both visceral larva migrans and alveolar hydatid diseases, it is the feces of companion animals that are the primary source of human infection. Clearly, whatever is done to reduce this form of environmental contamination and the prevalence of the parasites' infective stages will help to protect the health of the human population in the United States and Canada, particularly the children. Very important are appropriate anthelmintic treatment programs, especially for T. canis, and proper control of close associations between pets and people. Probably the known incidence of visceral larva migrans in humans and the range of its known pathogenicity will increase as better diagnostic methods become available. In addition, other animal helminths, for instance Toxocara cati and Toxascaris leonina, may become more substantially documented as causes of human visceral larva migrans. Until more is known of the geographical distribution and prevalence of Echinococcus multilocularis among animals in North America, it will be difficult to assess accurately the future significance of alveolar hydatid disease in the continent's human population. Another important advance would be the development of anthelmintics that are effective for somatic second stage larvae of T. canis, and others effective for adult or larval Echinococcus species. Meanwhile it is a most important responsibility of the veterinary profession to educate its clients thoroughly concerning these dangerous helminths.

[Effectiveness of antigens from various developmental stages of Ascaris suum in the deomonstration of the migratory phase of experimental ascariasis in pigs]

Tests of the efficiency of antigens prepared from different developmental stages of Ascaris suum in indirect haemagglutination test in the course of proving the migration phase of experimental ascariasis in pigs show that the antigens prepared by ultrasound from the invasive larval stage of A. suum in comparison with antigens of sexually mature stages have higher serological activity. By using this antigen it is possible to prove specific antibodies in experimentally invaded pigs from 6 to 120 days after invasion as opposed to the other tested antigens (the detectability of antibodies from the 7th-8th day to the 64th day after invasion).

Esophagogastric ulcers associated with Ascaris suum infestation in swine

When a group of 3-month-old pigs was moved to another location, several died from internal bleeding. Two pigs that were necropsied had large esophagogastric ulcers, hepatic fibrosis with "milk spots" and swollen edematous lungs. The ulcers involved the full thickness of the gastric mucosa with pronounced eosinophilic infiltration and perivascular cuffing of the submucosal vessels. There was an acute interstitial and granulomatous pneumonia with an inflammatory exudate composed mainly of eosinophils. Ascarid larvae were recovered from the lungs. Gastric ulceration could have resulted from a second exposure to Ascaris suum infestation because pigs not removed from their original location did not develop ulcers.

Activity of disaccharidases in the intestinal contents of piglets infected with gastrointestinal nematodes and activity in these nematodes

The activity of maltase, saccharase, cellobiase, trehalase and lactase was estimated in the intestinal contents of non-infected pigs and pigs infected with several gastrointestinal nematodes and in the nematodes themselves.

Enzyme activities in the intestinal contents of pigs infected withHyostrongylus rubiduswere similar to those in uninfected control pigs. However the enzyme activity of the contents of the whole intestine was increased inStrongyloides ransomiinfections and moderately increased inAscaris suuminfection. InTrichurisandOesophagostomuminfections activity was only increased in the large intestine contents.

Ascaris suumcontained high activity of maltase and saccharase in its intestine and lower levels in other organs, while levels were much lower in other pig nematodes.Hyostrongylus rubidusand its third-stage larva did not contain any disaccharidases activity.

The disaccharidases in the pig nematodes, especially inStrongyloides, were more sensitive to high temperatures (70°C) than those in the contents of the pig intestine.

Some disaccharidases were demonstrable in embryonatedAscarisandTrichuriseggs and in third-stage larvae ofStrongyloidesandOesophagostomum.

Anthelmintic efficacy of thenium closylate-piperazine phosphate combination tablets against Toxocara canis in pups and young dogs

Thenium closylate-piperazine phosphate combination tablets, tablets containing either thenium or piperazine, and control tablets (excipients only) were administered in 2 doses 5 to 7.5 hours apart to weaned pups and young dogs, in critical controlled trials to test efficacy against naturally acquired infections of Toxocara canis. In the 1st trial, the combination tablets produced a mean clearance of 94% from 18 pups. Tablets containing thenium alone showed a mean clearance of 9% from 25 pups, and tablets containing piperazine alone caused a mean clearance of 56% from 16 pups. Clearances, corrected for spontaneous worm losses observed in pups treated with the control tablets, were 90% (combination), 5% (thenium alone), and 52% (piperazine alone). In the 2nd and 3rd trials, efficacy of the combination tablet in 15 pups was 78% when corrected for worm losses in pups which had received placebo (excipient) tablets. Each component in the combination tablet contributed its full single-entity efficacy and, if in combination, synergistic effect between the components.

Prevalence of Toxocara spp. and other parasites in dogs and cats in Halifax, Nova Scotia

Several cases of visceral larva migrans syndrome in children led to an investigation of the ova of Toxocara spp. and other species in stool specimens from stray dogs and cats in Halifax, Nova Scotia. Fecal samples from 474 stray dogs and 299 stray cats were examined. Ova of Toxocara canis or cati were present in stools from 26.6% of the dogs and 25.1% of the cats. In dogs the prevalence of Toxocara canis was noticeably greater in puppies (56.1%) than in mature animals (11.9%).

[Toxocariasis in calves. Recent diagnosis and treatment (author's transl)]

Toxocara vitulorum, a parasite of suckling calves, was again diagnosed in Belgium in imported cattle of French origin. The infectious larvae are present in the milk and colostrum; they do not undergo further migration in the tissues of calves. This form of transmammary migration is not specific of T. vitulorum, but was also reported in S. ransomi in pigs. Treatment with levamisole at a dosage of 5 mg/kg results in complete disappearance of the worms. In addition to the cycles, the elements of a specific parasitological diagnosis are also described.

[Influence of Ascaridia-galli invasion on amino acid, protein and aminotransferase (GOP, GTP) levels and activities in chickens]

A negative influence of the helminths Ascaridia galli on the level of free plasma amino acids and aspartate and alanine aminotransferase activities was demonstrated in the host chick serum. Despite the above negative influence single experimental Ascaridia galli invasion failed to influence the serum protein level or weight increments in chicks. At low invasion intensity the experimental chicks were able to compensate for the pathogenic effect of the helminth Ascaridia galli, manifested by decreased amino acid and aminotransferase activity levels, provided that they were given a full-value and the chicks were kept under suitable zoohygienical conditions.

Nonsteroidal anti-inflammatory drugs: a review. New applications in hypersensitivity reactions of cattle and horses

Nonsteroidal anti-inflammatory drugs inhibit the biosynthesis of kinins and prostaglandins and stabilize leukocyte lysosomal membranes. Nonsteroidal anti-inflammatory drugs also weakly block the biosynthesis of histamine and serotonin, and pharmacologically antagonize kinins, prostaglandins and slow-reacting substance of anaphylaxis. Nonsteroidal anti-inflammatory drugs effectively control both cardiovascular and respiratory manifestations of hypersensitivity in cattle and horses. This, coupled with the contrasting lack of effectiveness of "antiamine" drugs, suggests that bio-amines such as histamine and serotonin (5-hydroxytryptamine) may be less important than kinins, postaglandins and slow-reacting substance in the mediation of the hypersensitivity/inflammatory reaction, at least in cardiopulmonary systems of these species. Nonsteroidal anti-inflammatory drugs justify more prominence in the clinical control of acute respiratory disease in domestic herbivores.

Toxocara infection in pigs. The use of indirect fluorescent antibody tests and an in vitro larval precipitate test for detecting specific antibodies

An in vitro larval precipitate test using second-stage Toxocara canis larvae and an indirect fluorescent antibody (IFA) test employing cuticles of T. canis larvae as antigen were evaluated using antisera produced in pigs experimentally infected with T. canis, T. cati, Ascaris suum, Toxascaris leonina and Parascaris equorum. The former test was both specific and sensitive and is suggested as a reliable and simple method of detecting Toxocara antibodies in pigs. The latter test was considered unsuitable because of cross-reactions that occurred when sera from pigs infected with other ascarids were tested. An IFA test for Ascaris antibodies, employing cuticles of A. suum larvae as antigen, is described. The degree of specificity of this test suggests that it may be of value in the detection of antibodies to Ascaris in pigs under natural conditions.

Ascariasis: the development of eggs of Ascaris suum under the conditions prevailing in a pig house

Eggs were collected from gravid female Ascaris suum in the abattoir. Cultures were prepared with the eggs in 2 to 3 mm depth of 1 per cent sulphuric acid or on the surface of 2% aqueous agar. They were allowed to develop in a piggery, fresh cultures being started at intervals from January to September. Eggs on the surface of agar developed failry uniformly and a high proportion eventually reached L2. In contrast those under 1% sulphuric acid were less uniform, slower in development and generally less successful. Cultures started on agar between January and May, or from September became infective at approximately the same time in July while those started during June and July contained infective eggs in August and September respectively. No recognisable development occurred between October and April. The significance of these findings for the epidemiology of ascariasis is discussed.

Effect of age and sex on the prevalence of intestinal parasitism in dogs

The effects of age, sex, and neutering on the prevalence of canine intestinal parasitism were evaluated by fecal examination of 1,468 pet dogs admitted to the University of Missouri Veterinary Teaching Hospital during 1975. Evidence of hookworm infection was encountered in 35.8% of the dogs examined, whipworms in 18.5%, ascarids in 17.9%, tapeworms in 5.2%, and coccidia in 4.5%. Evidence of intestinal parasitism was not detected in 653 (44.4%) dogs. Whipworm infections were detected less often in young dogs than in older ones, whereas ascarid and coccidial infections were more prevalent in pups that in mature dogs. In dogs more than 6 months old, hookworm infections were the most common parasitism. Tapeworm infections were diagnosed sporadically in all age groups. For most of these parasites, castrated males and spayed females had decreased prevalence of infection, compared with their respective intact counterparts. There were significant (P less than 0.05) differences in the prevalence of both ascarid and hookworm infections between intact and spayed female dogs. Also, there were significant (P less than 0.001) differences between age categories for all parasites observed. Overall, parasitism tended to decrease with age.

Critical evaluation of oxfendazole as a swine anthelmintic

Sixty feeder pigs with mixed naturally acquired nematode infections were medicated with oxfendazole, a new benzimidazolecarbamate compound, at dose levels of 0, 3, 9, and 18 mg/kg of body weight. The dosage of 3.0 mg/kg administered once in the feed proved as efficacious as larger dosages and the same dosage administered 2 or 3 times in the removal of adult Ascaris suum, Oesophagostomum dentatum, and Metastrongylus pudendotectus. Trichuris suis adults were less susceptible. Anthelmintic efficacy was based upon comparative nematode egg counts, appearance of eggs, and recovered nematode burdens at necropsy. Signs of toxicosis were not seen in pigs given any one of the medicated feed schedules.