A blind test of the serological response of dogs to infection with Taenia ovis

Fifty six dogs of mixed age and sex were acquired from farms in the Otago/Southland region, and maintained at the Hydatid Research Unit, Taieri, where 43 were each fed two Taenia ovis cysts. All were bled fortnightly for six or 12 weeks. Coded sera were sent to Wallaceville Animal Research Centre for testing using ELISA, with antigen from T. ovis scoleces. Dog treatments were identified after all tests were complete. A discriminant level was derived from the mean absorbance value plus three standard deviations of 56 sera taken at time zero and 78 sera from serially bled uninfected dogs. None of these 134 sera registered as a false positive using this discriminant level. The data showed no significant deviation from normality, and the expected frequency of the occurrence of false positives is therefore less than 0.14%. Four weeks after infection 63% of dogs proved to be infected were serologically positive, rising to 78% after 6 weeks. When worms were removed by anthelmintic treatment, ELISA absorbance levels decreased. Four weeks after removal 70% of previously infected dogs remained positive, decreasing to 30% after 6 weeks.

Six weeks after infection the sensitivity of the test was 78%, and the specificity 63%. However, if dogs with positive ELISA absorbance levels, but which did not purge worms, were regarded as having had worms, the respective figures would be 82% and 100%. The latter figures are similar to our previously published laboratory results. The test is of comparable efficiency to arecoline purgation for surveillance, and has the additional advantage of detecting infection in the majority of those dogs that have been infected for three weeks or more but fail to pass worms on purgation, and a substantial proportion of those infected dogs that were treated by their owners prior to presenting them for purgation in order to avoid detection of infection.     

A blind test of the serological response of dogs to infection with Taenia ovis

Fifty six dogs of mixed age and sex were acquired from farms in the Otago/Southland region, and maintained at the Hydatid Research Unit, Taieri, where 43 were each fed two Tueniu ovis cysts. All were bled fortnightly for six or 12 weeks. Coded sera were sent to Wallaceville Animal Research Centre for testing using ELISA, with antigen from T. ovis scoleces. Dog treatments were identified after all tests were complete. A discriminant level was derived from the mean absorbance value plus three standard deviations of 56 sera taken at time zero and 78 sera from serially bled uninfected dogs. None of these 134 sera registered as a false positive using this discriminant level. The data showed no significant deviation from normality, and the expected frequency of the occurrence of false positives is therefore less than 0.14%. Four weeks after infection 63% of dogs proved to be infected were serologically positive, rising to 78% after 6 weeks. When worms were removed by anthelmintic treatment, ELISA absorbance levels decreased. Four weeks after removal 70% of previously infected dogs remained positive, decreasing to 30% after 6 weeks. Six weeks after infection the sensitivity of the test was 78%, and the specificity 63%. However, if dogs with positive ELISA absorbance levels, but which did not purge worms, were regarded as having had worms, the respective figures would be 82% and 100%. The latter figures are similar to our previously published laboratory results. The test is of comparable efficiency to arecoline purgation for surveillance, and has the additional advantage of detecting infection in the majority of those dogs that have been infected for three weeks or more but fail to pass worms on purgation, and a substantial proportion of those infected dogs that were treated by their owners prior to presenting them for purgation in order to avoid detection of infection.     

Duration of immunity and absorption of cysticerci in calves after treatment of Taenia saginata cysticercosis with praziquantel

Calves were first infected with 5000 Taenia saginata eggs at six to 10 weeks old and treated with praziquantel 12 weeks later. Complete immunity against challenge lasted for at least 12 weeks following anthelmintic treatment. Six months after drug treatment over 90 per cent of the cysticerci had been completely absorbed but some were still detectable especially in the heart. An increase was observed in the ELISA values of sera from infected calves following treatment with praziquantel, but no such rise was detected in sera from resistant calves after challenge infection.     

The serological response of dogs to Taenia ovis

The effect of 4-weekly anthelmintic dosing and other treatment regimes on the serological response of dogs to Taenia ovis was examined. Most dogs which were frequently fed infected meat and dosed with a cestocidal anthelmintic at 4-week intervals eventually showed a positive ELISA absorbance. The absence of dosing, or intermittent dosing, of repeatedly infected dogs raised ELISA absorbances to very high levels in most dogs and these absorbances took an increasingly longer time to fall after each new infection. The feeding of large numbers of frozen, dead cysts to sensitised dogs raised absorbance levels. The serological test for T. ovis infections in dogs does not detect false postives. Positive tests result from the dog being exposed to T. ovis scolex secretory antigen.     

The serological response of dogs to Taenia ovis

The effect of 4-weekly anthelmintic dosing and other treatment regimes on the serological response of dogs to Taenia ovis was examined. Most dogs which were frequently fed infected meat and dosed with a cestocidal anthelmintic at 4-week intervals eventually showed a positive ELISA absorbance. The absence of dosing, or intermittent dosing, of repeatedly infected dogs raised ELISA absorbances to very high levels in most dogs and these absorbances took an increasingly longer time to fall after each new infection. The feeding of large numbers of frozen, dead cysts to sensitised dogs raised absorbance levels. The serological test for T. ovis infections in dogs does not detect false positives. Positive tests result from the dog being exposed to T. ovis scolex secretory antigen.     

Attempted immunisation of calves against infection with the cysticercus stage ofTaenia saginata

Summary Calves were inoculated with activated oncospheres ofTaenia hydatigena orT. ovis, dosed orally with eggs ofT. hydatigena or inoculated with living or lyophilised cysticerci ofT. crassiceps. There was no visible survival or development of any of these species in calves and none of these procedures stimulated an effective immunity against challenge withT. saginata eggs. Nevertheless, infections ofT. hydatigena andT. ovis developed in control lambs demonstrating the viability of the eggs used.

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Ensayos De Inmunizacion De Terneros Contra Infecciones Con El Cisticerco De LaTaenia Saginata

Resumen Se inocularon terneros con oncosferas activadas deTaenia hydatigena oTaenia ovis, se dosificaron oralmente con huevos deT. hydatigena o se inoculanon con cisticercos vivos o liofilizados deT. crassiceps. No se observó desarrollo alguno de estas especies en terneros inoculados y ninguno de los procedimientos estimuló una inmunidad efectiva contra la descarga con huevos deT. saginata. Sinembargo, los animales controles (ovejas) desarrollaron infecciones conT. hydatigena y T. ovis, demostrando así la viabilidad de los huevos usados en el experimento.

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Essai D'Immunisation De Veaux Contre L'Infection ATaenia Saginata Au Stade De Cysticerque

Résumé Des veaux ont été inoculés avec des oncosphères activées deTaenia hydatigena ouT. ovis. Ils ont reçu des doses orales d'oeufs deT. hydatigena, ou bien ont été inoculés avec des cysticerques vivants ou lyophilisés deT. crassiceps. Il n'y a pas eu de survie visible ou de developpement d'aucune de ces espèces chez les veaux et aucune de ces inoculations n'a a stimulé une immunité effective contre l'infection d'épreuve avec des oeufs deT. saginata, alors que des infections deT. hydatigena etT. ovis se sont développées chez des agneaux témoins démontrant la viabilité des oeufs utilisés.

     

Attempted reactivation of latent bovine herpesvirus 1 infection in calves by infection with ruminant pestiviruses

Three calves, latently infected with bovine herpesvirus 1 (BHV 1), were each inoculated intranasally with 9 strains of ruminant pestivirus (BVDV). All three calves developed a biphasic pyrexia and a lymphopenia followed by a neutrophilia. They did not shed BHV 1 in their nasal secretions in the 14 days following BVDV inoculation, and their BHV 1 antibody levels remained static, as did those of 2 control calves not given BVDV. All five calves were subsequently shown to be latently infected with BHV 1 by the production of recrudescent infections following the administration of dexamethasone. BHV 1 was recovered from nasal secretions and there was a marked rise in BHV 1 antibody titres in the second week after dexamethasone administration.     

The serological response of three month old calves to infection withTaenia saginata (Cysticercus bovis) and their resistance to reinfection

Summary Three calves, to which had been given100,000 eggs ofTaenia saginata at3 months of age, were significantly more resistant to a challenge infection10 months later than two previously uninfected control calves, although their resistance to reinfection was not complete. Following their initial infection the three calves developed a strong serum antibody response involving both haemagglutinating and precipitating antibodies. There was an increase in the serum globulin concentration during the first11 weeks after initial infection. There appeared to be no direct relationship between the globulin concentrations and the antibody response.

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Sumario Resistencia a la reinfección. Tres terneros, a los cuales se les suministró una dósis individual de 100.000 huevos deTaenia saginata a los tres meses de edad, fueron significativamente más resistentes a una descarga infecciosa 10 meses después, que dos terneros controles, aunque la resistencia no fue total. Después de la infección inicial, los tres animales desarrollaron un buen nivel de anticuerpos hemaglutinantes y precipitantes. Se notó un aumento en la concentración de seroglobulinas durante las primeras 11 semanas después de la infección inicial. No parece existir relación directa entre las concentracions de globulina y desarrollo de anticuerpos.

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Résumé Trois veaux ont re?u chacun, à l'age de trois mois, 100,000 oeufs deT. saginata. Ils se sont montrés plus résistants, de fa?on significative, à un essai de réinfestation opéré dix mois plus tard que deux autres veaux témoins reconnus comme non parasités au préalable. A noter que cette résistance à une réinfestation n'a pas été totale. A la suite de leur infestation initiale, les trois veaux ont réagi de fa?on marquée aussi bien en ce qui concerne les anticorps hémoagglutinants que précipitants. Durant les onze mois qui ont suivi la première infestation, un accroissement de la teneur en hémoglobine du plasma a été observé sans qu'une relation entre la concentration en globuline et en anticorps ait pu être observée.

     

Cross-reactivity of anti-Taenia crassiceps cysticerci immune antibodies with Taenia solium antigens

A comparative study of antibody production was carried out using BALB/c mice immunized with 20 or 50microg vesicular fluid (VF)-Tcra (Taenia crassiceps) antigens, and gel of <30kD or eluate from <30kD peptides. Good IgM, IgA and IgG levels were detected by ELISA-Tcra and the antibodies presented reactivity with the <20kD peptides when tested by immunoblotting-Tcra. The antibodies from animals immunized with 20 and 50microg presented high anti-Tso cross-reactivity in ELISA (IgG>IgM and IgA). All groups presented IgG antibodies identifying the 12kD Tso-peptide.     

Oncospheres of Taenia solium develop into cysticerci in normal mice

In vitro-hatched oncospheres of Taenia solium, prepared by the sodium hypochlorite method and adjusted to approximately 5 x 10(2)/2ml phosphate buffer saline, were injected intramuscularly or intravenously into normal Balb/c mice. When these mice were sacrificed 2 months later, all cysticerci were exclusively recovered in the lungs from the mice with intravenous inoculation, but not with intramuscular injection. A high infection rate of 76% was obtained and a total of 45 cysticerci were collected from 50 mice. Thirty-five cysticerci were mature and with normal appearance but the rest were either with abnormal appearance (4) or degenerated (6). These findings give strong evidence that T. solium oncospheres may migrate to the normal mouse lung through venous circulation and develop in this organ.     

The serological response of pigs experimentally infected with a species of Taenia from Taiwan

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibody in pigs infected with a possibly new species of Taenia isolated in Taiwan is described. The test antigen ThFAS was fractionated from the cyst fluod of a heterologous cestode Taenia hydatigena. In lightly infected pigs ( 4 recovered cysts at necropsy 17 weeks post-inoculation), antibody was detected as early as 3 weeks post-inoculation. In more heavily infected pigs (6–72 recovered cysts at necropsy 32 weeks post-inoculation), antibody was still detectable at the time of necropsy. Cysterci were found only in the livers of the infected pigs. This ELISA should be highly useful for detecting infection of pigs with this larval cestode in regions where the presence of Taenia solium is unlikely.     

Performance of the ELISA test for swine cysticercosis using antigens of Taenia solium and Taenia crassiceps cysticerci

Studies were conducted to evaluate antigens of Taenia solium (Tso) and Taenia crassiceps (Tcra) cysticerci in the ELISA test for the diagnosis of swine cysticercosis. The samples analyzed were cysticercosis positive and negative control sera and heterologous sera. Four antigens were assayed: vesicular fluid (VF) and crude (T) Tcra and scolex (S) and crude (T) Tso. All antigens showed good performance, but VF-Tcra was the best followed by T-Tcra. Sensitivity rates of ELISA were respectively, in 2nd and 3rd standard deviation cut-offs, 96.0 and 80.0% for the VF antigen and specificity of 97.5 and 100.0%. Cross-reactivity was verified only for hidatidosis and ascaridiosis. Due to the high performance observed, the ELISA test using Tcra antigens should be recommended for the diagnosis of swine cysticercosis.     

Metabolic traits affecting growth rates of pre-pubertal calves and their relationship with subsequent survival

This study related growth and metabolic traits in Holstein-Friesian calves (n=45) to subsequent performance and longevity. Animals were measured at birth, 3, 6 and 9 months (weight, crown rump length (CRL), heart girth and height). Endocrine and metabolic traits were assessed at 6 months of age. These traits were not influenced by sire (n=5). Milk production and mortality records were obtained through 3 lactations. Seven heifers failed to achieve a lactation, 6 were culled after one, 17 after two and 15 (33%) survived >/=3 lactations. Birth weight and girth but not skeletal measures were highly positively correlated with the repeated size measurements at 3-9 months. Calves with higher cortisol at 6 months were smaller in weight and girth at 3 months, with reduced 3-6 months skeletal growth. GH secretion was related to height, weight and growth, whereas urea was most strongly related to CRL. Calves not achieving a single lactation had lower IGF-I. Calves with higher glucose or BHB were more likely to be culled after 2 lactations, an effect which was independent of yield. Size and metabolic measurements of growing calves may therefore prove useful in predicting longevity.     

Vaccination of calves against Taenia saginata infection using a “parasite-free” vaccine

Calves were vaccinated with antigens collected during in vitro cultivation of the larval stages of Taenia ovis, T. hydatigena or T. saginata, and challenged 4 weeks later with 4 000 T. saginata eggs. Calves vaccinated with T. saginata antigen were highly resistant to the challenge infection and those groups vaccinated with T. ovis and T. hydatigena were also significantly resistant.     

Passive immunity and serological immune response in dairy calves associated with natural Giardia duodenalis infections

In a previous study, Giardia infection patterns were studied in newborn dairy calves over a 4-month period. Chronic Giardia infections were observed in all calves with initial cyst excretion occurring at approximately 1 month of age. In the work presented here, the passive immunity and serological immune response associated with these Giardia infections were examined. Colostrum and milk samples were collected from the dams of these calves, and monthly serum samples were collected from each calf. The colostrum, milk and sera samples were analyzed by ELISA and Western blot for the presence of anti-Giardia IgG antibodies. In addition, the in vitro anti-Giardia activity of milk and colostrum was examined using a miniculture adherence assay. When examined by ELISA, mean anti-Giardia antibody titres were found to be significantly higher in colostrum compared to milk. The monthly mean serum antibody titres in the calves were not found to differ significantly at any time point during the study. Western blot analysis revealed that colostrum from the dams reacted strongly with many different Giardia antigens between 205 and 7.5kDa, while milk reacted with few antigens in the same size range. Sera collected from the calves when 30 and 60 days of age reacted with few Giardia antigens, but as the calves aged, IgG antibodies in their sera began to react with antigens of 21, 50, 65, 73 and 79kDa. The miniculture adherence assay demonstrated that colostrum had significantly more anti-Giardia activity in vitro compared to milk. These results suggest that the calves in this dairy did not mount a significant humoral immune response against Giardia following infection. However, colostrum contained a high level of anti-Giardia antibodies and exhibited anti-Giardia activity in vitro. Therefore, colostrum may have the potential to provide initial protection against Giardia infections in calves, but the lack of a strong, specific humoral immune response by these calves could account for the high prevalence and chronic duration of the infections.     

The effect of corticosteroids on the cysticerci of Taenia ovis in sheep.

The effect of two synthetic corticosteroids on the cysticerci of Taenia ovis in sheep has been investigated. Dexamethasone given from four days before infection had no effect on the number of cysticerci recovered but did enhance their survival. When betamethasone was used there was an increase in the number of cysts compared with controls. Corticosteroids given for 12 days after infection did not increase the number of viable cysticerci recovered at autopsy three months later but when treatment was continued until the time of autopsy, a very high proportion of cysticerci were viable.     

Larval viability and serological response in horses with long-term Trichinella spiralis infection

The horse is considered an aberrant host for the nematode parasite Trichinella spiralis, and many aspects of the biology and epidemiology of Trichinella infection in the horse are poorly understood. It has been reported that experimentally-infected horses produce a transient serological response to infection and that muscle larvae are cleared more rapidly than in parasite-adapted hosts such as the pig and humans. However, limited numbers of animals have been studied, and both the longevity of larvae in horse musculature and the immune response to Trichinella larvae remain unclear. In this study, we infected 35 horses with 1000, 5000, or 10,000 T. spiralis muscle larvae and followed the course of infection for 1 year, assessing larval burdens in selected muscles, the condition and infectivity of recovered larvae, and the serological response of infected horses. The results demonstrated that T. spiralis establishes infection in horses in a dose dependent manner. Anti-Trichinella IgG antibodies peaked between weeks 6-10 post-inoculation. Viable, infective larvae persisted in horse musculature for the duration of the study (12 months), and exhibited no apparent reduction in muscle burdens over this period. Encapsulated larvae showed no obvious signs of degeneration in histological sections. Larval capsules were surrounded by infiltrates consisting of mature plasma cells and eosinophils. Macrophages were notably absent. Given the lack of a detectable serological response by 26 weeks p.i. and the persistence of infective muscle larvae for at least 1 year, parasite recovery methods are currently the only suitable detection assays for both meat inspection and epidemiological studies of Trichinella infection in the horse.