Further characterization of the biology of Hammondia heydorni

Blagburn, Byron L.; Lindsay, David S.; Swango, L J; Pidgeon, Guy L.; Braund, K. G.

doi:10.1016/0304-4017(88)90033-7

Cited by 30 publications

(25 citation statements)

References 6 publications

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“…aborted bovine fetuses, dogs with neuromuscular disorders), tachyzoite and bradyzoite stages could often be detected readily (Dubey and Lindsay 1996). In contrast to N. caninum, H. heydorni is regarded as non-pathogenic for its hosts (Heydorn 1973;Matsui et al 1986;Blagburn et al 1988).…”

Section: Introductionmentioning

confidence: 99%

Hammondia heydorni -like oocysts shed by a naturally infected dog and Neospora caninum NC-1 cannot be distinguished

Schares¹,

Heydorn

Cüppers

et al. 2001

Parasitology Research

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This study describes transmission experiments using Hammondia heydorni-like oocysts isolated in 1996 from a naturally infected dog. The isolate was designated as H. heydorni-Berlin-1996. Examination of sera from infected intermediate hosts showed immunoblot reactions that resembled patterns observed after Neospora caninum NC-1 infection. Furthermore, N. caninum DNA could be demonstrated in tissue samples (e.g. heart, brain) of experimentally infected intermediate hosts and in oocyst preparations from H. heydorni-Berlin-1996. The isolated oocysts did not induce any detectable disease in any of the inoculated adult intermediate hosts (goats, sheep, gerbils, guinea pigs, multimammate rats, BALB/c mice, SCID mice), even upon immunosuppression. Furthermore, neither histological lesions nor parasite stages could be identified in the tissues of all fetuses recovered from two multimammate rats that had been infected prior to pregnancy. An experiment with one dog fed a second time on infected intermediate host tissue indicated that immunity may prevent repeated oocyst shedding in N. caninum-infected dogs. In addition, the study clearly demonstrates that N. caninum can be readily transmitted by dogs that have ingested exclusively skeletal muscles of infected intermediate hosts. Therefore, the study has consequences for the recommendations for farmers to prevent postnatal transmission of N. caninum to cattle. It indicates that feeding of any tissues of potential intermediate hosts (including sheep, goats, rodents) to final hosts may induce the shedding of oocysts in these hosts and thus pose a risk for post-natal infection of cattle. With respect to oocyst morphology and the infectivity of muscle tissues for final hosts, no differences were seen in comparison with observations made in the past on Isospora bigemina/I. heydorni/H. heydorni. Therefore, earlier studies made on I. bigemina/I. heydorni/H. heydorni have to be re-evaluated critically to determine whether they may have included N. caninum or other protozoan parasites that use dogs as final hosts and have an oocyst morphology resembling that of I. bigemina/I. heydorni/H. heydorni.

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Section: Introductionmentioning

confidence: 99%

Hammondia heydorni -like oocysts shed by a naturally infected dog and Neospora caninum NC-1 cannot be distinguished

Schares¹,

Heydorn

Cüppers

et al. 2001

Parasitology Research

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“…In fact, this was never the case (Speer et al 1988;Speer and Dubey 1989b;Ellis et al 1999;Dubey et al 2002aDubey et al , 2002b. Blagburn et al (1988) already had doubts about the identity of their isolate with previously described isolates because it differed from them in some biological characteristics. It produced rather high numbers of oocysts of which the smallest measured 11.3·10.8 lm.…”

Section: Introductionmentioning

confidence: 81%

“…The differences again claimed by Dubey et al (2002aDubey et al ( , 2002b between the NC-1 strain of N. caninum and H. heydorni are based on the error of considering the oocysts isolated by Blagburn et al (1988) as H. heydorni. It is further asserted by Dubey et al (2002a) that: ''based on oocyst size alone it is not possible to determine the identity of Isospora bigemina-like parasites because calculation techniques may cause varying amounts of error in the case of these small objects''.…”

Section: Discussionmentioning

confidence: 99%

“…But if we consider the smallest size of sporulated oocysts, then we can distinguish two groups, isolates forming oocysts of which the smallest diameter definitely measures less than 10 lm and isolates with the smallest diameter of oocysts measuring ‡10 lm (e.g. Levine and Ivens 1965;Heydorn 1973;Blagburn et al 1988;Schares et al 2001aSchares et al , 2002Dubey et al 2002a). As we have no knowledge on the existence of more than two species, we must consider these two groups to represent two separate species.…”

Section: Discussionmentioning

confidence: 99%

“…This led to the doubtful application of the name Hammondia heydorni to all small coccidian oocysts which were isolated from the faeces of dogs worldwide, without any true comparison of the different isolates until the description of oocysts of the incorrectly named Neospora caninum (Dubey 1993;Dubey et al 2002a;Heydorn and Mehlhorn 2002). The most important error leading to the recent confusion in naming the two distinct small coccidian species of dogs (Dubey et al 2002b) was made by Dubey, who as author or co-author of several papers arbitrarily considered and still considers an oocyst isolate of Blagburn et al (1988) as the ''type or reference material'' for H. heydorni. In fact, this was never the case (Speer et al 1988;Speer and Dubey 1989b;Ellis et al 1999;Dubey et al 2002aDubey et al , 2002b.…”

Section: Introductionmentioning

confidence: 95%

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Electron microscopic study of in vitro cultures of Hammondia heydorni (Berlin 1996) tachyzoites after passages through dogs, mice, rats, guinea pigs and jirds

Mehlhorn

Heydorn²

2003

Parasitology Research

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This study describes the fine structure and reproduction of tachyzoites of Hammondia heydorni (isolate Berlin 1996) after in vitro cultivation of stages isolated from serial passages between dogs and various intermediate hosts such as mice, rats, guinea pigs, jirds, knock-out mice, goats and sheep. The tachyzoites are identical with respect to their ultrastructural features to the corresponding stages of the NC-1-strain of Neospora caninum. This fact conforms with other already published data and underlines our opinion that the recently redescribed N. caninum Dubey et al. 2002 is a synonym of the previously described H. heydorni (Tadros and Laarman 1976) Dubey 1977.

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Neospora caninum is an invalid species name: an evaluation of facts and statements

Heydorn

Mehlhorn

2002

Parasitol Res

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An evaluation of both the formal requirements of the International Rules of Zoological Nomenclature and the scientific reasons for the description of new genera and species shows that the name Neospora caninum is a nomen nudum. The only characteristic criteria for discriminating between the previously described species Hammondia heydorni and the proposed new species N. caninum (i.e. the lack of a parasitophorous vacuole) has been shown to be wrong in many publications. Furthermore, absolutely no criteria were presented as to why a new genus (i.e. Neospora) should be established besides the already existing genera Hammondia, Toxoplasma and Isospora. In addition, recent transmission experiments show that an oocyst isolate (from the faeces of dogs) is morphologically indistinguishable from H. heydorni [synonymous with Isospora bigemina - small form, Isospora heydorni (Tadros and Laarman 1976) and H. heydorni (Tadros and Laarman 1976) Dubey 1977] and is almost identical with respect to molecular biological features with the NC-1 strain of N. caninum.

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Further characterization of the biology of Hammondia heydorni

Cited by 30 publications

References 6 publications

Hammondia heydorni -like oocysts shed by a naturally infected dog and Neospora caninum NC-1 cannot be distinguished

Hammondia heydorni -like oocysts shed by a naturally infected dog and Neospora caninum NC-1 cannot be distinguished

Electron microscopic study of in vitro cultures of Hammondia heydorni (Berlin 1996) tachyzoites after passages through dogs, mice, rats, guinea pigs and jirds

Neospora caninum is an invalid species name: an evaluation of facts and statements

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