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.     

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.     

Echinococcus granulosus,Taenia hydatigena,T. ovis: Evaluation of cyst fluids as antigen for serodiagnosis of larval cestodes in sheep

In order to monitor the progress of New Zealand's hydatids eradication campaign, a specific, serological, diagnostic test is required to identify infected sheep. An indirect haemagglutination test, using pyruvic aldehyde-stabilized sheep erythrocytes as the antigen carrier, was developed for the serodiagnosis of larval cestode infections of sheep. Using cyst fluid from Echinococcus granulosus, Taenia hydatigena and T. ovis as the antigens in this test, it was shown that the larval cestode species, responsible for an infection in sheep harbouring a single specific infection, could be identified by the higher titre given with the homologous antigen, in comparison to that given with the heterologous antigens. Sera of sheep infected with two or more species were also tested by this method, and the only specific infections to be diagnosed by differential titres were those due to the presence of live E. granulosus cysts. These antigens cannot be used for the diagnosis of specific larval cestode infections in the field because of the cross-reactivity between cyst fluids. However, the test did show that infection with larval cestodes could be diagnosed on a non-specific basis.     

Specific antibody responses to Taenia hydatigena, Taenia pisiformis and Echinococcus granulosus infection in dogs

Groups of dogs reared free of both nematodes and cestodes were infected with Taenia hydatigena, Taenia pisiformis or Echinococcus granulosus. After infections with the Taenia spp became patent, dogs were purged to remove the worms. They were later reinfected and the second infections again removed by purging after patency. A group of 3 uninfected worm free dogs was kept as age-matched controls. The dogs were bled at intervals of 5 days and their serums tested for antibodies using the enzyme-linked immunosorbent assay (ELISA) with excretory/secretory (ES) antigens collected during in vitro incubation of evaginated scoleces (scolex ES antigen) and oncosphere antigens. Antibodies to scolex ES antigen were detected by 3 weeks after infection with each cestode species whereas antibodies to oncosphere antigen were not detected until about one week after eggs were found in the faeces of the infected dogs. Antibody responses to both oncosphere and scolex ES antigens decreased rapidly following removal of the worms by purging. Uninfected control dogs were invariably negative to both oncospheral and scolex ES antigens. There were cross-reactions between the serums from dogs infected with T. pisiformis and T. hydatigena when tested with scolex ES antigens, but oncospheral antigens showed a high degree of species specificity. Scolex ES antigens from E. granulosus were compared with those prepared from T. hydatigena and T. pisiformis for their ability to discriminate between antibodies in serums collected from dogs 31 and 32 days after infection with 100,000 protoscoleces of E. granulosus or dogs infected with Taenia spp.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of nitroscanate on Echinococcus granulosus and Taenia hydatigena infections in dogs.

Trials with nitroscanate carried out on 186 dogs infected with either Echinococcus granulosus or Taenia hydatigena indicated that a single treatment at a dose rate of 1000 mg/kg or two treatments at 250 mg/kg eliminated the former, but a single treatment at 64 mg/kg was sufficient to eliminate the latter. At this dosing schedule, vomiting and diarrhoea occurred, as well as a transient 'tranquillising' effect on some dogs.     

The lethal effect of some benzimidazoles on Taenia hydatigena in dogs

The lethal effect of some benzimidazoles on Taenia hydatigena infections in dogs have been compared. Fenbendazole, parbendazole and oxibendazole were more effective than cambendazole and thiabendazole, while coarsely ground mebendazole did not differ significantly from any of them.     

The effect of fospirate on Echinococcus granulosus and Taenia hydatigena infections in dogs.

Trials with fospirate carried out with 170 dogs infected with either Echinococcus granulosus or Taenia hydatigena indicated that a dose rate of 40 mg/kg given on three occasions and 10 mg/kg given on one occasion eliminated each species, respectively. Increasing the dose rat substantially above 40 mg/kg did not reduce the number of treatments required to eliminate all hydatid organisms. Vomiting was observed in some dogs.     

Detection of Taenia hydatigena copro-antigens by ELISA in dogs

A sandwich-ELISA was developed for the detection of soluble Taenia hydatigena antigens in fecal samples of dogs. Affinity-purified polyclonal catching antibodies and alkaline phosphatase-conjugated detecting antibodies were employed, which had been obtained from rabbits hyperimmunized with excretory/secretory antigens derived from in vitro maintained adult Taenia hydatigena. The assay allowed the detection of 800 ng T. hydatigena antigen g-1 of feces as a lower limit. Six helminth-free dogs were each infected with 10 T. hydatigena cysticerci isolated from Swiss sheep. After prepatent periods ranging from 57 to 71 days, the dogs started to excrete Taenia eggs and/or proglottids. The ELISA detected Taenia antigens in all six dogs during the prepatent period starting individually between Day 18 and 45 post-infection (p.i.). Anthelmintic treatment of three dogs at Day 95 p.i. resulted in elimination of the cestodes and within the 5 following days in the disappearance of Taenia antigens from feces. The specificity of the assay was evaluated by testing crude antigens derived from helminths or bacteria. Four Taenia species showed cross-reactivity at concentrations of 5 micrograms protein ml-1. Conversely, no cross-reactions occurred with various antigen batches derived from Echinococcus granulosus, E. multilocularis, Dipylidium caninum, Mesocestoides corti, Diphyllobothrium sp., Toxocara canis and bacterial antigens (Salmonella and Escherichia). Moreover, fecal samples from dogs naturally infected with T. canis (n: 13), hookworms (n: 2), Trichuris vulpis (n: 13) and of 10 dogs with mixed infections with these three nematode groups were tested, and results confirmed the high degree of specificity. The Taenia antigens detectable by this ELISA remained immunologically stable in native feces stored at +25 degrees, +4 degrees or at -20 degrees C for at least 5 days.     

The effect of mebendazole on Echinococcus granulosus and Taenia hydatigena infections in dogs.

The effect of micronised mebendazole on Echinococcus granulosus and Taenia hydratigena has been investigated in a trial involving 175 dogs. The hydatid organism was eliminated from the dogs at dose rates of either 160 mg/kg given on one occasion or 20 mg/kg given on two occasions. A single dose of 20 mg/kg eliminated T hydratigena. The drug was readily accepted when given in food and there were no untoward sequelae.     

The importance of the New Zealand campaign against Echinococcus granulosus and Taenia hydatigena on the prevalence of Taenia ovis

Extract

An important aspect of the campaign in New Zealand directed against Echinococcus granulosus and Taenia hydatigena is its possible effect on the prevalence of Taenia ovis. The burying of offal to eliminate E. granulosus and T. hydatigena is recommended as being preferable to cooking it and feeding it to dogs. The drastic reduction in the number of European rabbits (Oryctolagus cuniculus) in many districts has also virtually eliminated an important dog-food. Consequently, in addition to commercial products, many farmers are relying on more sheep carcass-meat than previously as a source of dog-food. Other things being equal, conditions would seem ideal for an increase in the prevalence of. T. ovis. This is particularly significant to New Zealand which depends so much on a meat export trade. Damage to this on account of T. ovis could in turn pre- judice a campaign directed against E. granulosus and T. hydatigena.     

The effect of oxfendazole on Echinococcus granulosus and Taenia hydatigena infections in dogs

Trials with oxfendazole carried out on 120 dogs infected with either Echinococcus granulosus or Taenia hydatigena indicated that a single treatment significantly reduced the proportion of dogs infected with tapeworms. Diarrhoea occurred occasionally when the dose rate exceeded 20 mg/kg.     

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.     

The effect of nitroscanate tablets of Echinococcus granulosus and Taenia hydatigena infections in dogs

Tablets of micronised nitroscanate (nominal particle size 2--3 microns) were given to a total of 190 dogs that had been experimentally infected with either Echinococcus granulosus or Taenia hydatigena. The efficiency of the drug in tablet form in freeing dogs from tapeworms, was investigated. The dose rate at which 50 per cent of normally fed dogs can be expected to be freed from E granulosus was found to be 89 mg/kg (95 per cent confidence limits 55 mg/kg to 140 mg/kg). The 90 per cent effective dose rate was not determined within the range 32 mg/kg to 250 mg/kg. The dose rate at which 90 per cent of normally fed dogs can be expected to be freed from T hydatigena was 37 mg/kg (95 per cent confidence limits 23 mg/kg to 60 mg/kg).     

Treatment of Taenia hydatigena infections in dogs with-bunamidine hydroxynaphthoate incorporated in food

Abstract

Extract

Theoretically, the life-cycle of the sheep metacestodes with their strobilate phase in dogs permits combinations of at least three methods of control. These are the prevention of dogs gaining access to larval cestodes, the chemical elimination of the strobilate and or the larval stage in the appropiate hosts, and the immunization of either the definitive or intermediate hosts or both. The first approach using arecoline hydrobromide primarilv as a diagnostic agent has reduced the prevalence of Echinococcus granulosus (Gemmell, 1968 Gemmell, M. A. 1968. The Styx field-trial. A study on the application of control measures against hydatid disease caused by Echinococcus granulosus. Bull. Wld Hlth Org., 39: 73–100.  [Google Scholar]). However, it did not markedly reduce the prevalence rate of Taenia hydatigena and may have been indirectly associated with an increase in that of Taenia ovis.     

The effect of Taenia hydatigena infection on existing and concurrent infections of Fasciola hepatica in sheep

Sheep given a primary infection of Fasciola hepatica were challenged 18 weeks later with Taenia hydatigena or F hepatica, or both parasites together, or were not challenged. At the same time, control sheep were infected with T hydatigena and/or F hepatica separately or concurrently. All sheep were killed seven weeks after challenge and the number of cysts and flukes counted. Challenge infection with T hydatigena did not affect the numbers of flukes recovered from either primary or challenge F hepatica infections. On the other hand, the numbers of cysticerci were reduced in sheep previously infected with F hepatica but not in those given T hydatigena and F hepatica concurrently.