been resident in the area for at least five years, with n o previously noticed major illness, a n d was presented for treatment because of swelling of the sheath. Salient clinical features were depression, emaciation, oedematous swelling of the sheath extending along the ventral abdomen a n d thorax to the pectoral area, a loud systolic heart m u r m u r , pale mucous membranes, penile protrusion a n d pollakiuria. T h e urine contained small amounts of blood pigment a n d protein detectable by dipstick analysis. Haematological examination revealed severe anaemia with mild leucopaenia. The horse was killed by the owner the following day, there having been no improvement after antibiotic a n d diuretic therapy, and was not available for post-mortem examination. Differential diagnostic possibilities include congestive heart failure, chronic parasitism and malnutrition, a n d urinary tract disease. However, as the clinical findings a n d haematology were consistent with a n acute haemolytic episode, plasma was submitted to Attwood Veterinary Research Laboratory for testing for EIA by the a g a r gel immunodiffusion test ( A C I D ) . The plasma reacted positively in this test. This indicated that
the horse was infected with EIA virus, a n unusual finding in Victoria, where, of almost 1000 horses tested, only this animal has reacted positively (Harrison 1978). Samples tested from 15 other horses in the immediate area had n o antibodies detected by A G I D . G . J . MclNTYRE, 509 Greensborough Road, Greenshorough, Victoria 3088 25 Ocrober, 1978 References Albiston, H. E. (1966) - Ser-v. Publs. Depr. Hlth. AIJsr. vel. Hyg. 8: 127. Harrison, M . I . (1978) - Afisf. ver. .I. 54: 597 Lepherd, E . €3. (1978) - Ausr. vef. ./. 54: 42. Oxer, D.T. ( 1962) - A i i s r . vei. J . 38: 190. Oxer, D. T. (1965) - Ausr. ver. .I. 41: 1. Thomas, R . I . a n d Elder, Jean K . (1978) - AUSC.ver. J . 54: 456.
PRE-NATAL INFECTIONS WITH LARVAL TAPEWORMS There have been several reports of the occurrence of prenatal infection with larval tapeworms. Taenia saginara cysticerci which, o n the basis of morphological development, were considered to have been acquired pre-natally, have been observed in very young calves (McManus 1960; Slais a n d Mann 1976). They have also been found in calf foetuses (McManus 1963). Similarly a hydatid cyst has been observed in a new born lamb (Oparin 1958). Taeriia ovis has a distribuiion i n the muscles of sheep similar to that of T . saginara in cattle. Experimental infections either with eggs o r injected embryos in sheep at various times during pregnancy, failed to induce prenatal infections (Gemmell 1973). These ewes, however, were strongly imniune to T. o v i s d u e to repeated natural exposure to eggs. T h e possibility exists that these superimposed infections failed to survive long enough to reach the foetus in ewes with a naturally acquired immunity. T h e question arises as to whethei o r not pre-natal infections can occur in lanibs carried by ewes that have lost their immunity. Such a situation might occur from a breakdonn during a control program. In the experiment here, 5-year-old ewes. which had not recently been exposed to the eggs of T . ovis were obtained from a farm in an experimental control area in the S o u t h Island of New Zealand. About o n e month before lambing, 6000 activated embryos of 7'.ovi.swere injected into the jugular vein of 3 of the ewes and the other 3 received 6000 unhatched eggs of
T. ovis given orally i n a gelatine capsule. T h e ewes and their lambs were autopsied a n d examined for T.ovis cysts when the lambs were about o n e month old. T h e number of T . 0vi.s cysticerci found in the injcctcd ewes a n d the orally infected ewes were I , 9, 13 a n d 236, 316, 398 respectively a n d in o n e of them 3 I5 cysticerci were viable. Despitc the large numbers of cysticerci found throughout the muscles of the ewes, n o organisms developed in any of their 8 lambs. Hence, i t would seem unlikely that pre-natal infections coninionlv occur during late nreenancv . - . even when the ewe is fully susceptible to infection. R. J . SUTTON, M . A. G E M M E L L , Hydatid Research Unit. University of O t a g o Medical School, P.O. Box 913, Dunedin, New Zealand 19 Ocrober 1978
References Gemniell. M . A . (1973) - Ausr. vet. ./. 49: 344. Mchlanus, D. (1960) - Ver. Kec. 72: 847. McManus, D. (1963) - Ver. Kec. 75: 697. Oparin, P . C;. (1958) - Vererinarija 35: 82. Slais, J . and M a n n , I . (1976) - Folia Parasirologica23: 321
FAILURE OF C L o s m i m u M CHAUVOEIVACCINES TO PROTECT AGAINST BLACKLEG
In the J u n e issue of the Australian Veterinary Journal, Woolcock a n d Frost (1978) raised a iiumbei- of questions regarding C1. chauvoei vaccines a n d the reported vaccine breakdowns. T h e letter raises many questions for which there arc few answers. However, the ensuing coninients may be of interest to readers of the Journal. The potency test for CI. chauvoeivaccines i n the current edition of the Bririsli V e t e r i n a r ~Codex is not considered to be en598
tirely adequate because neither (lie challenge strain nor the size of the challenge dose a r e specified l o r thc potency test. These points were discussed last year at a meeting of interested groups in Melbourne. I t was agreed that the challenge strain should be o n e which is capable of breaking thi-ough low levels of protection afforded by p o o r vaccines. Work carried out a i the C'ornmonwealth Serum Laboratories by Chandler and co-workers (1970. 1974, 1975 a, b) was discussed. On the
Aiisrralinn Vercriri;iry
./oirriia/,Vol.
54, D e c e m b e r , 1978
basis of this work it was agreed that the CSI. Strain C6207 would be accepted as the challenge strain for potency testing as i t appears to satisfy the above criteria. The National Biological Standards Laboratory is at present preparing a spore suspension of C6207 in a form suitable for routine use by vaccine manufxturers. The suspension will be freeze dried 10preclude variation in the challenge slrain. Woolcock and Frost (1978) questioned the use of more than one strain of organism in a vaccine. The reason for this objection is not clear and it is not unusual for the manufacturer to include 2 or more strains of CI. chauvoei i n a vaccine. The National Biological Standards Laboratory (NBSL) was consulted by ICI-TVL before inclusion of the Yeerongpilly isolate i n the vaccine. The demonstration that vaccine prepared from this isolate produced good immunity against challenge with the homologous organism was considered by the N I3SL to justify inclusion of this strain i n the ICI-TVL vaccine if the company wished. The approach adopted agrees in principle w i r h the recommendalion of Woolcock and Frost (1978) thai any vaccine qtrain can only be evaluated by animal inoculation and subsequent challenge. There is a dearth of information on field strains of CI. chauvoei. There is, for example, no information to indicate whether the recent outbreak of blackleg was due to changes iii the antigenic characteristics of the field strains, t o unusually heavy challenge or was due to some other reason.
An additional problem is the lack of a systematic reporting system which would give early warning and information on outbreaks such as that recently experienced. Indeed it is not even clear how many of the available vaccine brands were implicated in the recent breakdown in vaccine protection. I would agree that there is a need for investigation and discussion. L . F. DODSON,
Director, National Biological Standards Laboratory, Department of Health, 9 Morrissett St. Queanbeyan, New South Wales 2620 16 October 1978 References Woolcock, J . B. and Frost, A . I . (1978) - Ausr. vet. J . 54: 319. Chandler, H. M. and Gulasekharem, J . (1970) - Ailsf. ./. expt. Biol. med. Sc. 48: 187. Chandler, H. M. and Gulasekharem, .I. (1974) - J . gen. Microbiol. 84: 128. Chandler, H . M. and Hamilton, R . C. (1975a) - J . gen. Microbiol. 88: 27. Chandler, H . M . and Hamilton, R . C. (1975b) - J . gen. Microbiol. 88: 179.
SARCOCYSTIS INFECTION IN FIJI As a consequence of the lack of indigenous inainnials in Fiji, a high proportion of the domestic livestock is descended from imported Australian stock. The importation of these aninials also introduced a number of parasites. I t i q possible that Sarcocy9ti.s may have arrived in this manner. Sarcocysris has an obligate 2 host life cycle. In general. herbivores and omnivores act as intermediate hosts and carnivores as definitive hosts. The domesticated food aninials are comrnonly infected and dogs, cats and man can become infected by the ingestion of the sarcocysls i n undercooked meat. The importance 0 1 Sarcoc 9ri.s is largely unkno\cn. In the intermediate host, certain spc es (S. crirziin cattle: S. ovicani.~ in sheep; S. porcifrlis in pigs) are capable of causing serious disease (Johnston er a / 1975; I h b e y 1976). Several species may cause mild disease whilst others are of unknown pathogenicity. Although Dubey (1976) states that Sarcocystis is nonpathogenic to the definitive host, the presence of Sarcocyctis in meat for human consuniption must be considered a potential health hazard (Seniveratna 1977). As no information was available on the extent of sarcosporidiosis in Fiji, a survey was conducted on animals slaughtered at the niain abattoir. Over the 6-month period, July-December, 1977, 88 cattle (> 2 years) and 99 pigs (83one year) were examined using the peptic digestion technique (Jacob an(' Melton 1957). The mean infection rate in cattle was 76.1% and 82.8V0 i n pigs. The incidence of infection in cattle falls w i t h i n the range of figures quoted for oilier couiitries. However, the use of different methods (histological, digestion and serological) renders comparisons o f doubtful value. In pigs, the relationship of age to infection rate differs widely from the findings i n the USA (Seniveratna 1975) and Tasmania (Munday 1975). I3y histological examination of diaphragni and myocardium. Munday (1975) found Snrcocystis in I .4"h of pip\ Icss than I 2
Australian V e t e r i ~ ~ a r y . / o u r i ~VaoI ,l . 54, Dcceinlier, 1978
months of age and 16.7"lo of those over 12 months. Seniveratna (1975) used a digestion technique on oesophagus but failed to detect infection in pigs under one year although 12.7% of pigs over 12 months harboured the parasite. The present survey presents a different picture with infection rates being 85.50h in pigs less tliaii one year old and 68.8% in those over one year. I t has been suggested by these 2 authors that access, by boars and sows, to contaminated pastures accounted for the greater frequency of infection i n adults when compared to younger stock which were usually housed. Such an explanation does not explain the findings i n Fiji where neither adults nor young stock have access to pasture and where there appears to be a greater prevalence of sarcosporidiosis in the younger pigs. As yet the reasons underlying the liighcr infection rates and their relationship to different age groups in Fiji's pigs have not been elucidated. N. R . RAJU, R . MUNRO, Veterinary Pathology Laboratory, Koronivia, Fiji 22Augusr 1978
References Dubey, J. P. (1976) - J . Am. vet. med. Ass. 169: 1061. Jacob, L., Melton, M. L. (1957) - .I. Parasit. 43: (Suppl.) 38. Johnston, A . J.; Hildebrandt, P. K . ; Fayer, R . (1975) - Ani. J . vet. Rrs. 36: 995. Munday, B. L. (1975) - A~rsr.vet. J . 51: 478. Seniveratna, P. (I977) - Meat Inspection Guides, N o . 4. Australian Bureau of Animal Health. Seniveratna, P., Edward, A. G . and DeGiusti, D. L. (1975) Am. J . vet. Res. 36: 337.
599
the horse was infected with EIA virus, a n unusual finding in Victoria, where, of almost 1000 horses tested, only this animal has reacted positively (Harrison 1978). Samples tested from 15 other horses in the immediate area had n o antibodies detected by A G I D . G . J . MclNTYRE, 509 Greensborough Road, Greenshorough, Victoria 3088 25 Ocrober, 1978 References Albiston, H. E. (1966) - Ser-v. Publs. Depr. Hlth. AIJsr. vel. Hyg. 8: 127. Harrison, M . I . (1978) - Afisf. ver. .I. 54: 597 Lepherd, E . €3. (1978) - Ausr. vef. ./. 54: 42. Oxer, D.T. ( 1962) - A i i s r . vei. J . 38: 190. Oxer, D. T. (1965) - Ausr. ver. .I. 41: 1. Thomas, R . I . a n d Elder, Jean K . (1978) - AUSC.ver. J . 54: 456.
PRE-NATAL INFECTIONS WITH LARVAL TAPEWORMS There have been several reports of the occurrence of prenatal infection with larval tapeworms. Taenia saginara cysticerci which, o n the basis of morphological development, were considered to have been acquired pre-natally, have been observed in very young calves (McManus 1960; Slais a n d Mann 1976). They have also been found in calf foetuses (McManus 1963). Similarly a hydatid cyst has been observed in a new born lamb (Oparin 1958). Taeriia ovis has a distribuiion i n the muscles of sheep similar to that of T . saginara in cattle. Experimental infections either with eggs o r injected embryos in sheep at various times during pregnancy, failed to induce prenatal infections (Gemmell 1973). These ewes, however, were strongly imniune to T. o v i s d u e to repeated natural exposure to eggs. T h e possibility exists that these superimposed infections failed to survive long enough to reach the foetus in ewes with a naturally acquired immunity. T h e question arises as to whethei o r not pre-natal infections can occur in lanibs carried by ewes that have lost their immunity. Such a situation might occur from a breakdonn during a control program. In the experiment here, 5-year-old ewes. which had not recently been exposed to the eggs of T . ovis were obtained from a farm in an experimental control area in the S o u t h Island of New Zealand. About o n e month before lambing, 6000 activated embryos of 7'.ovi.swere injected into the jugular vein of 3 of the ewes and the other 3 received 6000 unhatched eggs of
T. ovis given orally i n a gelatine capsule. T h e ewes and their lambs were autopsied a n d examined for T.ovis cysts when the lambs were about o n e month old. T h e number of T . 0vi.s cysticerci found in the injcctcd ewes a n d the orally infected ewes were I , 9, 13 a n d 236, 316, 398 respectively a n d in o n e of them 3 I5 cysticerci were viable. Despitc the large numbers of cysticerci found throughout the muscles of the ewes, n o organisms developed in any of their 8 lambs. Hence, i t would seem unlikely that pre-natal infections coninionlv occur during late nreenancv . - . even when the ewe is fully susceptible to infection. R. J . SUTTON, M . A. G E M M E L L , Hydatid Research Unit. University of O t a g o Medical School, P.O. Box 913, Dunedin, New Zealand 19 Ocrober 1978
References Gemniell. M . A . (1973) - Ausr. vet. ./. 49: 344. Mchlanus, D. (1960) - Ver. Kec. 72: 847. McManus, D. (1963) - Ver. Kec. 75: 697. Oparin, P . C;. (1958) - Vererinarija 35: 82. Slais, J . and M a n n , I . (1976) - Folia Parasirologica23: 321
FAILURE OF C L o s m i m u M CHAUVOEIVACCINES TO PROTECT AGAINST BLACKLEG
In the J u n e issue of the Australian Veterinary Journal, Woolcock a n d Frost (1978) raised a iiumbei- of questions regarding C1. chauvoei vaccines a n d the reported vaccine breakdowns. T h e letter raises many questions for which there arc few answers. However, the ensuing coninients may be of interest to readers of the Journal. The potency test for CI. chauvoeivaccines i n the current edition of the Bririsli V e t e r i n a r ~Codex is not considered to be en598
tirely adequate because neither (lie challenge strain nor the size of the challenge dose a r e specified l o r thc potency test. These points were discussed last year at a meeting of interested groups in Melbourne. I t was agreed that the challenge strain should be o n e which is capable of breaking thi-ough low levels of protection afforded by p o o r vaccines. Work carried out a i the C'ornmonwealth Serum Laboratories by Chandler and co-workers (1970. 1974, 1975 a, b) was discussed. On the
Aiisrralinn Vercriri;iry
./oirriia/,Vol.
54, D e c e m b e r , 1978
basis of this work it was agreed that the CSI. Strain C6207 would be accepted as the challenge strain for potency testing as i t appears to satisfy the above criteria. The National Biological Standards Laboratory is at present preparing a spore suspension of C6207 in a form suitable for routine use by vaccine manufxturers. The suspension will be freeze dried 10preclude variation in the challenge slrain. Woolcock and Frost (1978) questioned the use of more than one strain of organism in a vaccine. The reason for this objection is not clear and it is not unusual for the manufacturer to include 2 or more strains of CI. chauvoei i n a vaccine. The National Biological Standards Laboratory (NBSL) was consulted by ICI-TVL before inclusion of the Yeerongpilly isolate i n the vaccine. The demonstration that vaccine prepared from this isolate produced good immunity against challenge with the homologous organism was considered by the N I3SL to justify inclusion of this strain i n the ICI-TVL vaccine if the company wished. The approach adopted agrees in principle w i r h the recommendalion of Woolcock and Frost (1978) thai any vaccine qtrain can only be evaluated by animal inoculation and subsequent challenge. There is a dearth of information on field strains of CI. chauvoei. There is, for example, no information to indicate whether the recent outbreak of blackleg was due to changes iii the antigenic characteristics of the field strains, t o unusually heavy challenge or was due to some other reason.
An additional problem is the lack of a systematic reporting system which would give early warning and information on outbreaks such as that recently experienced. Indeed it is not even clear how many of the available vaccine brands were implicated in the recent breakdown in vaccine protection. I would agree that there is a need for investigation and discussion. L . F. DODSON,
Director, National Biological Standards Laboratory, Department of Health, 9 Morrissett St. Queanbeyan, New South Wales 2620 16 October 1978 References Woolcock, J . B. and Frost, A . I . (1978) - Ausr. vet. J . 54: 319. Chandler, H. M. and Gulasekharem, J . (1970) - Ailsf. ./. expt. Biol. med. Sc. 48: 187. Chandler, H. M. and Gulasekharem, .I. (1974) - J . gen. Microbiol. 84: 128. Chandler, H . M. and Hamilton, R . C. (1975a) - J . gen. Microbiol. 88: 27. Chandler, H . M . and Hamilton, R . C. (1975b) - J . gen. Microbiol. 88: 179.
SARCOCYSTIS INFECTION IN FIJI As a consequence of the lack of indigenous inainnials in Fiji, a high proportion of the domestic livestock is descended from imported Australian stock. The importation of these aninials also introduced a number of parasites. I t i q possible that Sarcocy9ti.s may have arrived in this manner. Sarcocysris has an obligate 2 host life cycle. In general. herbivores and omnivores act as intermediate hosts and carnivores as definitive hosts. The domesticated food aninials are comrnonly infected and dogs, cats and man can become infected by the ingestion of the sarcocysls i n undercooked meat. The importance 0 1 Sarcoc 9ri.s is largely unkno\cn. In the intermediate host, certain spc es (S. crirziin cattle: S. ovicani.~ in sheep; S. porcifrlis in pigs) are capable of causing serious disease (Johnston er a / 1975; I h b e y 1976). Several species may cause mild disease whilst others are of unknown pathogenicity. Although Dubey (1976) states that Sarcocystis is nonpathogenic to the definitive host, the presence of Sarcocyctis in meat for human consuniption must be considered a potential health hazard (Seniveratna 1977). As no information was available on the extent of sarcosporidiosis in Fiji, a survey was conducted on animals slaughtered at the niain abattoir. Over the 6-month period, July-December, 1977, 88 cattle (> 2 years) and 99 pigs (83one year) were examined using the peptic digestion technique (Jacob an(' Melton 1957). The mean infection rate in cattle was 76.1% and 82.8V0 i n pigs. The incidence of infection in cattle falls w i t h i n the range of figures quoted for oilier couiitries. However, the use of different methods (histological, digestion and serological) renders comparisons o f doubtful value. In pigs, the relationship of age to infection rate differs widely from the findings i n the USA (Seniveratna 1975) and Tasmania (Munday 1975). I3y histological examination of diaphragni and myocardium. Munday (1975) found Snrcocystis in I .4"h of pip\ Icss than I 2
Australian V e t e r i ~ ~ a r y . / o u r i ~VaoI ,l . 54, Dcceinlier, 1978
months of age and 16.7"lo of those over 12 months. Seniveratna (1975) used a digestion technique on oesophagus but failed to detect infection in pigs under one year although 12.7% of pigs over 12 months harboured the parasite. The present survey presents a different picture with infection rates being 85.50h in pigs less tliaii one year old and 68.8% in those over one year. I t has been suggested by these 2 authors that access, by boars and sows, to contaminated pastures accounted for the greater frequency of infection i n adults when compared to younger stock which were usually housed. Such an explanation does not explain the findings i n Fiji where neither adults nor young stock have access to pasture and where there appears to be a greater prevalence of sarcosporidiosis in the younger pigs. As yet the reasons underlying the liighcr infection rates and their relationship to different age groups in Fiji's pigs have not been elucidated. N. R . RAJU, R . MUNRO, Veterinary Pathology Laboratory, Koronivia, Fiji 22Augusr 1978
References Dubey, J. P. (1976) - J . Am. vet. med. Ass. 169: 1061. Jacob, L., Melton, M. L. (1957) - .I. Parasit. 43: (Suppl.) 38. Johnston, A . J.; Hildebrandt, P. K . ; Fayer, R . (1975) - Ani. J . vet. Rrs. 36: 995. Munday, B. L. (1975) - A~rsr.vet. J . 51: 478. Seniveratna, P. (I977) - Meat Inspection Guides, N o . 4. Australian Bureau of Animal Health. Seniveratna, P., Edward, A. G . and DeGiusti, D. L. (1975) Am. J . vet. Res. 36: 337.
599
