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Biomedical subjects

J Vercruysse

Publications and source records attributed to J Vercruysse.

At least 145 records · Page 8Linked to original sources
PubMed1997

Immunity development against Ostertagia ostertagi and other gastrointestinal nematodes in cattle.

The immunological response to gastrointestinal nematodes is complex and it will take time and financial support to dissect the different components of protective immunity in ruminants. The present review briefly summarises different aspects and manifestations of protective immunity in cattle against gastrointestinal nematodes, especially Ostertagia ostertagi, and the factors that may interact with the development of this immunity.

Animals↗
PubMed1997

Potential of a recombinant Schistosoma bovis-derived glutathione S-transferase to protect cattle against experimental and natural S. mattheei infection.

The potential of a recombinant Schistosoma bovis-derived glutathione S-transferase (rSb28GST) to protect cattle against S. mattheei infection was tested in Zambia. All animals were challenged 2 weeks after the second inoculation with either 0.250 mg rSb28GST in adjuvants (vaccinated calves, n = 14) or adjuvants alone (controls, n = 14). In a first experiment, 7 vaccinated and 7 control animals were exposed to 10000 S. mattheei cercariae percutaneously. All animals developed clinical schistosomiasis 7-8 weeks after challenge. At perfusion, 12 weeks after challenge, vaccinated and control groups had averages of 887 and 541 eggs per gramme (epg) faeces, 6515 and 5990 worms, and 4.2 and 3.4 million tissue eggs, respectively. These results indicate that the immunization protocol used did not protect these calves against the massive single experimental challenge. In a second experiment, another 2 groups (n = 7) of vaccinated and control animals were challenged naturally over a period of 9 months on a farm known to be endemic for S. mattheei. The natural infections were much lighter in intensity, as indicated by the mean faecal egg count (13 epg), worm count (139) and tissue egg count (294000) in non-vaccinated controls. In vaccinated calves, significant reductions in female worm burdens (50%), faecal egg count (89%) and miracidial counts (93%) were recorded. Total tissue egg counts were also reduced by 42% in vaccinated animals. It therefore appears that the rSb28GST can provide significant protection in cattle against S. mattheei under conditions of low to moderate natural infection.

Animals↗
PubMed1997

Circulating anodic and cathodic antigen in serum and urine of mixed Schistosoma haematobium and S. mansoni infections in Office du Niger, Mali.

In Office du Niger, an area endemic for both Schistosoma haematobium and S. mansoni in Mali, circulating anodic (CAA) and cathodic (CCA) antigen detection assays were performed on pretreatment serum and urine samples from two villages, Rigandé and Siguivoucé, and compared with egg counting methods. The highest prevalence was obtained with the urine-CCA assay which also had the highest sensitivity to S. haematobium, S. mansoni or mixed infection. A single urine-CCA assay was as sensitive as repeated egg counts (one stool+two urine examinations per individual). When the different assays were tested in parallel, several combinations including assays on serum were found to be highly sensitive. As urine sampling is widely accepted, urine assays will be used for further monitoring these villages one and two years after chemotherapy.

Animals↗
PubMed1997

Observations on compatibility between Bulinus truncatus and Schistosoma haematobium in the Senegal River Basin.

In experiments to determine the compatibility between isolates of Schistosoma haematobium and Bulinus truncatus from Mali and Senegal, the parasite isolates were shown to differ in their intermediate host specificity. Bulinus truncatus from the Lower and Middle Valleys (Senegal) and the Upper Valley (Mali) of the Senegal River Basin (SRB) were all susceptible to S. haematobium isolated from the urines of children living in Tenegue, Office du Niger, Mali. However, none of the B. truncatus tested was susceptible to a parasite isolated from children living in Mbodiene, a village in the Lower Valley of the SRB, where natural transmission is normally associated with B. globosus. As B. truncatus is widely distributed in the SRB, the possible appearance of a Bulinus-truncatus-borne parasite in the Middle and Lower Valleys should be carefully monitored.

Animals↗
PubMed1997

Failure of mebendazole in treatment of human hookworm infections in the southern region of Mali.

Preliminary studies indicated that single-dose (500 mg) mebendazole gave disappointing results in the treatment of hookworm infections (Necator americanus) in Mali. A placebo-controlled, randomized trial conducted with the participation of 103 infected subjects (background hookworm prevalence > 50%) confirmed that mebendazole (Vermox) did not reduce parasite burdens significantly, as assessed through fecal egg counts. In contrast, a group of subjects treated with pyrantel (Combantrin) experienced a significant reduction in fecal worm egg counts (overall, both sexes combined showed a 75% reduction). Male subjects carried significantly more intense infections compared with females, but there was no gender difference in response to treatment. A standard egg hatch assay showed that N. americanus from our subjects in Mali was more resistant to benzimidazoles compared with a laboratory-maintained strain that had not been exposed to anthelmintics in more than 100 generations (50% effective dose = 0.12 and 0.07 microg/ml of thiabendazole, respectively), suggesting that, among other possibilities, the development of resistance to the benzimidazoles by N. americanus may have contributed to the drug failure. Whatever the underlying explanation, our results indicate that single-dose treatment with mebendazole is an ineffective treatment for hookworm infections and despite its relatively cheap cost and wide availability, mebendazole should not be considered a drug of choice in the mass treatment of hookworm infections in this region of Mali.

Adolescent↗
PubMed1996

The effect of truncated infections with Ostertagia ostertagi on the development of acquired resistance in calves.

The relative contribution of the third (L3), fourth (L4) and adult stages of Ostertagia ostertagi to the development of immunity was assessed in calves which were either continuously infected during 21 weeks or subjected to infections truncated by anthelmintic treatment at the L3 or L4 stage. A fourth group remained uninfected (control group). Faecal samples and blood samples were collected weekly for faecal egg counts and determination of pepsinogen and antibody levels. Only the continuously infected animals showed positive egg counts, which fell towards the end of the primary infection period. Pepsinogen and antibody levels remained high in the continuously infected group until the end of the primary infection period. At that time, they were significantly higher compared to the control calves, with intermediate values in the truncated infection groups. After the 21 weeks primary infection period all animals were dewormed. To evaluate the protection provided by the different immunisation protocols, all animals were challenged 1 week later with 156000 Ostertagia L3, spread over 12 consecutive days. The marked reduction in egg counts following challenge infection indicated a certain degree of immunity in the continuously infected calves, which was confirmed at necropsy by the reduced worm burdens, the high percentage of inhibited early L4 larvae, the reduced size of the adult worms and the higher numbers of mucosal mast cells in this group. Numbers of globule leucocytes and eosinophils were not significantly different from the control group. Infections truncated by anthelmintic treatment elicited poor development of immunity as shown by the egg output after the challenge infection and the percentages of arrested larvae and the lengths of adult worms which were intermediate to those of the continuously infected calves and control animals.

Animals↗
PubMed1996

Thelazia rhodesii (Desmarest, 1828) infections in cattle in Mindanao, Philippines.

Thelazia rhodesii was found in the eyes of 149 of 643 bovine heads (23%) that were examined at the abattoir of Cagayan de Oro City, Philippines, during the period February 1994 to February 1995. In nearly half of the animals both eyes were infected and an average of 4.1 worms per infected animal was recovered. Of the 1286 eyes examined, 17% were infected; worm burdens ranged from one to 36 (average 2.9) worms per infected eye. Monthly prevalence of infection ranged from 13% to 36%. T. rhodesii infection was significantly more common in cattle of more than 3 years of age (25%) than in younger animals (15%). Ocular lesions were observed in 73 (11%) cattle; 22% of these were infected with T. rhodesii. There was no relationship between presence of T. rhodesii and ocular lesions.

Abattoirs↗
PubMed1996

Mammomonogamus laryngeus (Railliet, 1899) infections in cattle in Mindanao, Philippines.

During one year, 597 cattle were examined for Mammomonogamus laryngeus infections in the abattoir of Cagayan de Oro, Philippines. The overall prevalence was 23% with no obvious seasonal variations. The infection rate was 19% in animals up to 4 years old and 24% in animals 4-12 years old. In infected animals up to 8 years old an average of eight parasite pairs was found; infected animals of 8-12 years old had 5.2 parasite pairs on average. All worms were located on the posterior side of the epiglottis. Field observations on cattle in Mindanao revealed that adult M. laryngeus had developed on the epiglottis of a tracer calf that had been on pasture for 30 days and then kept away from possible nematode infection for 28 days.

Abattoirs↗
PubMed1996

Variations in Schistosoma mattheei egg morphology and viability according to age of infection in cattle.

Comparison of the numbers of Schistosoma mattheei eggs and miracidia per gram faeces in groups of naturally infected calves, heifers and adult cows showed that the reduction in faecal egg excretion recorded as infection progresses is associated with a decline in the ability of eggs to hatch. While 50% of the eggs from calves produced a miracidium, only 15% of those excreted from adult cows did the same. The decline in egg viability is at least partly associated with morphological changes of the eggs. About twice as many smaller and vacuolated eggs were found in the faeces of heifers and adult cows (33.8%) as compared to animals in early infection (16.1%).

Age Factors↗
PubMed1996

Isolation, characterization and immunolocalization of a globin-like antigen from Ostertagia ostertagi adults.

Western blot analysis using an anti-globin rabbit serum Rb94 revealed a major band of 17 kDa in extracts of Ostertagia ostertagi adults and 4th-stage larvae. The adult stage globin-like antigen (OoAdGlb) was purified from total worm extracts by liquid chromatography. The protein has an estimated molecular mass of 36 kDa under non-reducing conditions, suggesting a dimeric structure containing 2 non-covalently linked 17 kDa monomers. Tryptic peptides were sequenced and showed strong similarities with the globins of free-living and parasitic nematodes. Immunolocalization revealed the presence of this globin-like antigen in the body wall musculature and/or the cuticle of O. ostertagi adults. An enzyme-linked immunosorbent assay based on the purified OoAdGlb showed no differences in response between calves infected by O. ostertagi and/or Cooperia oncophora and the negative controls.

Amino Acid Sequence↗
PubMed1996

Circulating antigen levels in serum of cattle naturally infected with Schistosoma mattheei.

Levels of 2 Schistosoma circulating antigens, the circulating anodic antigen (CAA) and the circulating cathodic antigen (CCA), were determined in serum samples collected, on a monthly basis over a period of 1.5 years, from 32 farm animals of different ages and from 12 tracer calves exposed to Schistosoma mattheei infection on a Zambian farm. Faecal egg counts were monitored in all animals and worm burdens in tracers determined after perfusion. Antigen determination tests in serum, with sensitivities between 95 and 100% in heifers and adult cows, proved to be excellent tools for the diagnosis of cattle schistosomiasis. Also in young calves, some infections could be demonstrated earlier by CCA determination than by faecal egg examination. A poor correlation was seen between the data for faecal egg counts and for CAA and CCA levels. It therefore appears that circulating antigen measurements in serum are of limited value as indicators of the pathogenesis of infection in cattle. Although all tracer calves were found infected at perfusion, large variations were recorded in antigen levels. An unexpected finding was the observation in farm animals of a clear seasonal pattern in CAA levels, with significant increase between August and October during the second half of the dry season, when animals are subjected to heavy physical and nutritional stress. It therefore appears that, although circulating antigen determination may provide an indication of the worm burden in ageing infections, possible variations of antigen clearance rate with the physiological condition of the host may complicate the interpretation of the results.

Age Factors↗
PubMed1996

Pharmacokinetics and anti-trichomonal efficacy of a dimetridazole tablet and water-soluble powder in homing pigeons (Columba livia).

The anti-trichomonal efficacy and pharmacokinetics of dimetridazole were investigated in the homing pigeon (Columba livia). Dimetridazole was formulated for drinking water medication and as a prolonged-release tablet. To suppress a Trichomonas gallinae infection successfully, medicated drinking water containing dimetridazole (400 mg/L) had to be administered for at least 3 days. A two-day treatment with a dimetridazole tablet (20 mg/tablet) in fasted, as well as in fed, pigeons was shown to be ineffective. After intravenous administration of 20 mg dimetridazole, the drug plasma concentration-time profile fitted a one-compartment open model with a mean half-life of 3.9 h. The absolute bioavailability of the tablet in fasted pigeons was 83.8%. The bioavailability of the tablet administered with food was reduced by 20%. Dimetridazole was rapidly metabolised to (1-methyl-5-nitroimidazol-2-yl) methanol.

Animals↗
PubMed1996

Effect of chemoprophylaxis on immunity to gastrointestinal nematodes in cattle.

Control of gastrointestinal nematodes in calves is largely based on either strategic anthelmintic treatment or the use of anthelmintic-release devices. Control is evolving towards more efficacious anthelmintics and delivery systems, almost annihilating host-parasite contact. Recent studies have demonstrated the inverse relationship between the intensive use of modern anthelmintics and the build-up of immunity to gastrointestinal nematodes. A study performed by the Department of Parasitology, Faculty of Veterinary Medicine, Merelbeke, Belgium did provide further support for the finding that the development of immunity can be impaired by the implementation of preventive control measures.

Animals↗
PubMed1995

Mating behaviour in mixed infections of Schistosoma haematobium and S. mattheei.

In mixed infections of Schistosoma haematobium and S. mattheei, homospecific and heterospecific pairs are formed, with a preponderance of homospecific pairs indicating the existence of a mate preference system. S. haematobium apparently exhibits a greater specific mate recognition system than does S. mattheei. In sequential infections when mice are exposed to S. mattheei 4 weeks after infection with S. haematobium, S. haematobium males are better at pairing with S. mattheei females than are S. mattheei males. Hence, genetic exchanges between S. haematobium and S. mattheei giving rise to viable hybrids poses the problem of the genetic identity of these species of schistosomes. The most important reproductive isolating mechanisms are definitive host specificity, S. haematobium being primarily a parasite of man, whereas S. mattheei is a parasite of domestic stock and wild ungulates, and the preference for homospecific pairings in simultaneous infections. In contrast, when S. haematobium is the older infection, S. haematobium males are better than S. mattheei males at pairing with females of either species. Hybridisation is the likely outcome of such interactions. The lack of viability of S. mattheei male X S. haematobium female indicates genetic differences between the two species. Occurrences of natural hybridisation between S. haematobium and S. mattheei may lead to a change in the response of the parasite to chemotherapeutic treatment.

Animals↗
PubMed1995

Immunisation of calves with Ostertagia ostertagi fourth stage larval antigens failed to protect calves from infection.

Excretory-secretory and somatic antigens of Ostertagia ostertagi fourth stage larvae, emulsified with complete Freund's adjuvant, were intraperitoneally administered to calves on three occasions. Two weeks after the last immunisation all calves were infected with a single dose of 130,000 O. ostertagi third stage larvae. All animals were necropsied 25 days after infection. The immunisation procedure resulted in IgG1 and IgG2 antibodies, however no protective immunity was induced as O. ostertagi worm burdens and worm length were similar in all groups.

Animals↗
PubMed1995

Interactions between Ostertagia ostertagi and Cooperia oncophora in calves.

Development of immunity to Ostertagia ostertagi and Cooperia oncophora and interactions between both species in primed calves were investigated after homologous, heterologous and concurrent challenge infections. Worm counts, faecal egg output, IgG1 and IgG2 antibodies and the presence of globule leucocytes were used to evaluate the possible interactions. Results show that immunity build-up against O. ostertagi is slow in comparison with C. oncophora. The presence of early fourth-stage larvae and globule leukocytes in the O. ostertagi primed groups was significantly different to that of a previously uninfected control group. Ostertagia ostertagi and C. oncophora IgG1 antibodies were high in the previously exposed groups compared with uninfected controls and C. oncophora antibodies cross-reacted strongly with O. ostertagi antigens. There was no conclusive evidence for an interaction between C. oncophora and O. ostertagi. Globule leukocytes, IgG1 antibodies and early fourth-stage larvae seem to be related to development of immunity to O. ostertagi.

Animals↗