Dogs are definitive hosts of Neospora caninum.

Neospora caninum is a protozoan parasite of animals. Until 1988, it was misidentified as Toxoplasma gondii. Since its first recognition in dogs in 1984 and the description of the new genus and species Neospora caninum in 1988, neosporosis has emerged as a serious disease of cattle and dogs worldwide. Abortions and neonatal mortality are a major problem in livestock operations, and neosporosis is a major cause of abortion in cattle. Although antibodies to N. caninum have been reported, the parasite has not been detected in human tissues. Thus, the zoonotic potential is uncertain. This review is focused mainly on the epidemiology and control of neosporosis in cattle, but worldwide seroprevalences of N. caninum in animals and humans are tabulated. The role of wildlife in the life cycle of N. caninum and strategies for the control of neosporosis in cattle are discussed.

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Epidemiology and Control of Neosporosis and Neospora caninum

Neospora caninum is a coccidian parasite of animals. It is a major pathogen for cattle and dogs and it occasionally causes clinical infections in horses, goats, sheep, and deer. Domestic dogs are the only known definitive hosts for N. caninum. It is one of the most efficiently transmitted parasite of cattle and up to 90% of cattle in some herds are infected. Transplacental transmission is considered the major route of transmission of N. caninum in cattle. Neospora caninum is a major cause of abortion in cattle in many countries. To elicit protective immunity against abortion in cows that already harbor a latent infection is a major problem. This paper reviews information on biology, diagnosis, epidemiology and control of neosporosis in animals.

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Review of Neospora caninum and neosporosis in animals.

Rodents are the most abundant and diversified order of living mammals in the world. Already since the Middle Ages we know that they can contribute to human disease, as black rats were associated with distribution of plague. However, also in modern times rodents form a threat for public health. In this review article a large number of pathogens that are directly or indirectly transmitted by rodents are described. Moreover, a simplified rodent disease model is discussed.

Rodent-borne diseases and their risks for public health

Neosporosis in animals--the last five years.

Repetitive abortion in Neospora-infected ewes.

Experimental inoculation of domestic pigeons (Columbia livia) and zebra finches (Poephila guttata) with Neospora caninum tachyzoites

OBJECTIVE To test the hypothesis that cats are definitive hosts of Neospora caninum. ANIMALS 6 weaned male kittens obtained from 2 sources, and several dozen outbred mice. PROCEDURE Cats were fed large numbers of 3 strains of N caninum: tissue cysts in buffered saline solution, mouse brain homogenates, and whole carcass homogenates from seropositive mice. Fecal specimens were examined for 4 weeks by use of flotation tests, and bioassays were performed in mice. One cat was inoculated parenterally with tachyzoites, to determine whether cats could respond serologically to N caninum. Tissue cysts from portions of oral inocula were cultured to verify viability. Indirect fluorescent antibody serologic testing, histologic and immunohistologic examinations, cell culture, and polymerase chain reaction procedures were performed 4 to 8 weeks after oral exposure, to seek evidence of infection of cats and mice. RESULTS None of the cats or mice seroconverted to N caninum, with the exception of the single cat inoculated parenterally. Fecal shedding of oocysts was not observed, except for Isospora felis oocysts that were shed by 2 cats beginning prior to oral challenge exposure. Evidence of infection was not detected in tissues of cats or mice, with the exception of the parenterally inoculated cat. CONCLUSIONS The hypothesis that cats are definitive hosts of N caninum is not supported. CLINICAL RELEVANCE Extermination of cats in efforts to control bovine neosporosis is not warranted.

Rebecca A Wills

Papers

Dogs are definitive hosts of Neospora caninum.

Repetitive abortion in Neospora-infected ewes.

Experimental inoculation of domestic pigeons (Columbia livia) and zebra finches (Poephila guttata) with Neospora caninum tachyzoites

Oral inoculation of cats with tissue cysts of Neospora caninum.

Ingestion of Neospora caninum tissue cysts by Mustela species.