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PubMed1996

Iscoms in parasitological research.

During the history of vaccine development, a number of adjuvants and adjuvant formulations have been tested and evaluated for their ability to increase the immunogenicity of different antigens. In this review, Anna Lundén, Karin Lövgren Bengtsson, Anders Sjölander and Arvid Uggla focus on iscoms (immune stimulating complexes), their characteristics and applications to different types of parasitic antigens.

Journal Article↗
PubMed1991

Immuno-parasitological parameters in schistosomiasis--a perspective view of a vaccine-oriented immunochemist.

It has been almost 10 years since we became involved in research on schistosomiasis. With a background of many years of research on structure-function relationships in protein antigens and a wide experience in the development of peptide-based synthetic vaccines, I was intrigued by the complexity of the immunological aspects of host-parasite relation and the unique capacity of parasites to evade the immune response of their hosts. Being of very ancient lineage, schistosomes, which evolved from blood flukes during the Permian era, had two hundred million years of evolution to their advantage, to perfect their survival strategies. As a result, they are capable of circumventing the immunological machinery of the mammalian host and may consequently survive in it for decades. It seemed to us that an understanding, at least in part, of these processes, was a prerequisite for any attempt to enhance the capacity of the host to mount effective immunity, the long-range goal of such studies being the development of an efficient vaccine. In this review I have attempted to summarize the various approaches pursued in our laboratory towards this goal. This is definitely not a comprehensive review, and I had no intention of covering the vast literature in this field, except for that closely relevant to the discussed topics. This is rather a perspective review summarizing our own findings concerning different aspects of the biological, biochemical and immunological properties of Schistosoma mansoni, and their contribution toward the global effort of the research on schistosomiasis.

Acetylcholinesterase↗
PubMed1993

Vitamin D overload and experimental Trypanosoma cruzi infection: parasitological and histopathological aspects.

1. Six groups of 45-day-old, 23.0 +/- 1.7 g, female Balb/c mice were inoculated intraperitoneally with 63, 252, 440, 630, 2520 or 6300 I.U. of vitamin D for 6 days. A seventh group was inoculated with saline. Each group consisted of 30 animals. 2. All animals inoculated with the doses of 2520 and 6300 and 70% of mice which received 630 I.U. of vitamin D died 21 days after the first administration of the vitamin. The LD50 was 630 I.U. 3. The survivors were divided into two groups inoculated intraperitoneally with 5000 trypomastigotes of either Y or CL strain of Trypanosoma cruzi. 4. Based on the survival index on day 73 after infection, Vitamin D gave statistically significant protection (P < 0.01) for mice inoculated with doses of 63 or 430 I.U. of Y or CL strains, respectively. 5. On histopathological examination, inflammatory reaction and cellular and tissue parasitism were less intense in animals which received higher doses of vitamin D. 6. It is concluded that an overload of vitamin D had a protective effect against CL and Y strains of Trypanosoma cruzi infection in Balb/c mice.

Animals↗
PubMed1987

Evaluation of the parasitological and production responses of a cow/calf operation to an anthelmintic program with ivermectin.

The efficacy of a treatment schedule using ivermectin, given subcutaneously at the rate of 200 micrograms kg-1, to control gastrointestinal parasitism and its effect on liveweight gains was assessed. Two herds with a total of 466 Hereford X Brangus cow/calf pairs were used. Each herd was on six pasture plots of comparable size, stocking rate, and quality and quantity of forage. Pasture groups were paired across the two herds. Pasture groups from one herd were randomly assigned to nonmedicated control and the other three to ivermectin treatment. Treatment assignments per pasture group were reversed in the other herd. The control group contained 118 cows and 112 calves and the medicated group 121 cows and 115 calves. Cows were treated in early July and the calves in late July or early August. Cattle from one herd were weighed on Days -28, 0 (day of cow treatment), 30 (day of calf treatment), 58, and 86, while the other herd was weighed on Days -29, 0 (day of cow treatment), 27 (day of calf treatment), 61, and 89. Day 0 was not the same calendar day for the two herds. Fecal samples for parasite egg counts were obtained from the rectum on weight days from five cows and six calves from each pasture; in most cases the same cattle were sampled each time. Calves treated with ivermectin gained (P less than 0.05) more weight than control calves between day of treatment for cows and the end of the trial.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Prospects for molecular vaccines in veterinary parasitology.

Despite the profound developments in recombinant DNA technology there is only one marketed recombinant vaccine (for human viral hepatitis B). The development of others proceeds with great difficulty. Molecular vaccines against veterinary parasites are at the utmost pole of complexity in the spectrum of potential vaccines since these parasites are complex eukaryotic organisms, often dwelling at mucosal surfaces where anamnestic responses are problematic, where the immunogenicity of the parasite components is poorly understood and where the effector mechanisms of immunity are unresolved. Cloning a "protective" gene is only the first step, and perhaps the easiest, in a long process which will be necessary to develop vaccines against parasites. Additional steps will involve comprehensive analyses of the immunological responses to ensure that vaccine antigens contain the correct epitopes to induce appropriate immune effector mechanisms for parasite elimination and immunological memory and that these responses are not genetically restricted. The great expectations for recombinant vaccinia-based vaccines must be modified substantially in the light of recent evidence indicating immunological and other constraints on this approach. The use of anti-idiotype vaccines is an underexplored opportunity for practical parasite vaccines since they have several potentially important advantages. The need to include T cell antigenic peptides in peptide vaccines to extend the range of genetic responsiveness and to induce anamnestic responses is now clear. New algorithms for the prediction of such sites exist and these can be tested experimentally with synthetic peptides. There are no major technical obstacles to the development of vaccines for parasites which cannot be overcome. However substantial long term basic research is needed over a range of disciplines to achieve this worthwhile objective.

Animals↗
PubMed1989

Experimental trichinellosis in horses: biological and parasitological evaluation.

Three groups of three horses each were, respectively, infected with 5000, 20,000 and 50,000 larvae of Trichinella spiralis. The strain used was isolated from a human biopsy during horsemeat-related outbreaks of trichinellosis in France. Transient muscular disorders were only observed in two of the horses infected with 50,000 larvae but none of the horses had fever. A significant increase in blood eosinophils was noticed in 5 horses. Serum LDH, aldolase and CPK peaked at the fifth week post-infection. Specific IgG assayed by indirect immunofluorescence and ELISA, appeared 2-5 weeks post-infection and disappeared between 16 and 40 weeks. The distribution of T. spiralis larvae was maximal in the tongue, masseters and diaphragm, but a large decrease in the number of larvae recovered from the muscles was noticed among the horses slaughtered at the beginning and end of the experiment. In muscular histological sections, larvae were observed in an intramyofibrillar position and were surrounded by a mild to severe inflammatory reaction.

Animals↗
PubMed1990

Comparison between six parasitological methods for diagnosis of Trypanosoma evansi in the subtropical area of Argentina.

In a total of 165 blood samples from horses in the Province of Formosa (Argentina), the diagnosis for equine trypanosomiasis (T. evansi) was made using Giemsa-stained smears (GSS), wet blood films (WBF), Strout's concentration method (SCM), haematocrit centrifuge technique (HCT), buffy coat method (BCM) and mouse inoculation of blood (MBI). Trypanosoma evansi was demonstrated in 52 samples. Mouse inoculation gave a sensitivity of 88.2%; HCT 71.1%; BCM 63.4%; WBF 53.8%; SCM 46.1% and GSS 45.6%. No single method alone was totally effective. The haematocrit centrifuge technique, mouse inoculation of blood and Giemsa-stained smears were proposed as the most effective diagnostic combination.

Animals↗
PubMed1992

Sudden death of calves by experimental infection with Strongyloides papillosus. I. Parasitological observations.

Recently, an unknown disease, 'sudden death', in calves has been found in Japanese beef production farms. A previous study conducted by Taira and Ura indicated that sudden death can be effected in calves by hyperinfection of Strongyloides papillosus (SPL) and that the disease is possibly caused by SPL infection. In the present work, an experimental infection of SPL in calves was conducted to confirm the field occurrence. Fifteen Holstein Friesian calves, ranging from 45.5 to 85.6 kg in body weight, were divided into six groups. Calves of Groups A, B, C, D, E and F were infected once at the rate of 100,000, 320,000, 1,000,000, 3,200,000, 10,000,000 and 32,000,000 SPL larvae per 100 kg of body weight, respectively. Five calves were assigned to Group B, while two calves were assigned to the other groups. After showing no premonitory signs, sudden death of ten calves took place. The survival time of these calves was 27.4 and 16.8 days (Group B), 14.8 and 14.8 days (Group C), 13.3 and 14.2 days (Group D), 11.0 and 11.1 days (Group E) and 11.6 and 10.8 days (Group F). Three calves of Group B did not exhibit sudden death. The results of this study demonstrate that strongyloidiasis was the cause of sudden death.

Animals↗
PubMed1992

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) methods for the detection of anthelmintic resistance in nematodes of veterinary importance.

Methods have been described to assist in the detection of anthelmintic resistance in strongylid nematodes of ruminants, horses and pigs. Two tests are recommended, an in vivo test, the faecal egg count reduction test for use in infected animals, and an in vitro test, the egg hatch test for detection of benzimidazole resistance in nematodes that hatch shortly after embryonation. Anaerobic storage for submission of faecal samples from the field for use in the in vitro test is of value and the procedure is described. The tests should enable comparable data to be obtained in surveys in all parts of the world.

Animals↗
PubMed1994

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines for evaluating the efficacy of anthelmintics for dogs and cats.

Guidelines have been designed to assist in the planning, operation and interpretation of studies for the assessment of the efficacy of drugs against helminth parasites of dogs and cats. The advantages, disadvantages and application of critical and controlled tests are presented. Information is also provided on the selection of animals, housing, feeding, dose-titration, confirmatory and clinical trials, record keeping and necropsy procedures. These guidelines should assist both investigators and registration authorities involved in the evaluation of anthelmintics to employ comparable and standard procedures and will have the added benefit of minimising the numbers of animals needed for such tests.

Animal Husbandry↗
PubMed1994

The efficacy of moxidectin 0.5% pour-on against Hypoderma bovis in naturally infested cattle: parasitological and serological data.

The field efficacy of moxidectin 0.5% pour-on formulation was assessed in heifers naturally infested with Hypoderma bovis. After their first grazing season in an infested area 34 heifers were selected on the basis of results of an ELISA test performed in January 1992. Twenty-five animals were treated with moxidectin 0.5% pour-on at a dose of 0.5 mg kg-1 bodyweight and nine heifers were left untreated. No local or general side-effects associated with the treatment were noticed. In April, seven of the nine untreated heifers were affected by warble fly, and in May all were infested; none of the treated animals harboured warble fly at any time during the trial. All the extracted larvae were identified as Hypoderma bovis. On the basis of the warble counts, efficacy was 100%. The antibody kinetics, studied on blood samples collected on Days 0 (14 January), 6, 27, 48, 90, 119 and 150, showed that in the untreated animals, the antibody titres increased until May (Day 119) and then declined sharply, whereas in the treated animals there was a drop from Day 30 onwards. The mean ELISA titres of the control and treated groups became significantly different from Day 48 onwards (P < 0.05). In conclusion, moxidectin 0.5% pour-on formulation at a dose of 0.5 mg kg-1 bodyweight can effectively treat cattle naturally infested with Hypoderma bovis first instar larvae.

Administration, Topical↗
PubMed1994

Application of a composite faecal egg count procedure in diagnostic parasitology.

Egg counts from a simple composite faecal counting procedure using equal amounts of sample from ten sheep were compared statistically against the arithmetic means of the same ten samples prepared by a conventional egg counting method. Forty separate data sets were analysed in an untransformed bivariate plot and after natural logarithmic transformation. A sign test analysis indicated a high degree of similarity between the two data sets. A confidence interval for the composite count (n = 10) was calculated to give a result between five eggs more and 15 eggs less than the arithmetic mean count of the ten samples. When multiple faecal samples are to be examined, the composite method has significant advantages in time saving and increased throughput whilst still providing an accurate result. This technique has been used to monitor gastrointestinal helminthosis and for faecal egg count reduction testing to assess anthelmintic efficacy.

Animals↗
PubMed1996

Marine parasitology with special reference to Japanese fisheries and mariculture.

Marine parasites with special relation to Japanese fisheries and mariculture include various types of pathogens: those causing mortality, deformity, weight loss, etc.; those giving unesthetic appearances to the hosts; those which are zoonotic. Japanese mariculture typically utilizes net cage culture systems in coastal areas. Parasite invasion in such systems is more difficult to control practically than in freshwater facilities. The limited use of chemicals and drugs for treatment makes the situation even more difficult to handle. About five species of parasites from marine organisms are known to be zoonotic. This is closely associated with the Japanese tradition of eating raw fishes and invertebrates. Infection of maricultured species with zoonotic trematodes, cestodes and nematodes has not been confirmed. On a more positive side, attempts have been made to utilize parasites as biological tags to obtain information on host biology, ecology, etc. Recent trends in Japanese mariculture include technical improvement in seed production and importation of large quantities of various species of culture seedlings. Drastic increase in the supply of seedlings of selected fish species has resulted in changes in culture methods and created parasite problems on a much larger scale. International trade of live fishes and shellfishes has introduced parasites hitherto unknown to Japan. An efficient quarantine system to prevent and control introduction and spread of marine parasites urgently needs to be established.

Animals↗