Bovis ISSN 2398-2993

Neospora caninum

Contributor(s): Wendela Wapenaar , Andrew Forbes

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Introduction

Classification

Taxonomy

  • Phylum: Apicomplexa.
  • Family: Sarcocystidae.
  • Genus: Neospora.

Etymology

  • Neospora caninum is a coccidian parasite that was identified as a species in 1988.

Active Forms

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Clinical Effects

Epidemiology

  • Cattle get infected by ingesting sporulated oocysts or by vertical transmission via the placenta.
  • Although conflicting results are presented in studies, semen and milk appear to be unlikely sources of infection.
  • Oocysts are only found in fecal material from definitive hosts. Thus far only the dingo, coyote and domestic dog have been confirmed to be definitive hosts.
  • Cows that have aborted once due to N. caninum are more likely to have either subsequent abortions or infected fetuses in future pregnancies.

Pathological effects

  • In the cow the parasite appears to localize to neuromuscular tissue in its slow growing stage (bradyzoite), but in its initial fast growing stage (tachyzoite) it can pass the placenta and infect the fetus.
  • N. caninum does not always cross the placenta. Uninfected calves can therefore be born, but the majority of fetuses in seropositive dams will be infected via the placenta.
  • The majority of these infected fetuses will develop without any clinical signs but are persistently infected.

Other Host Effects

  • In some studies seropositive heifers and multiparous cows have been found to have lower milk production compared to seronegative animals.
  • A UK study demonstrated that seropositive heifers were more likely to suffer gestational loss (late embryonic, early fetal loss and abortion) than seronegative heifers during their first and second pregnancy.
  • Offspring of seropositive heifers were also four times more likely to experience perinatal mortality (calf born dead or dying within 24 hours of parturition) at first and second calving. However, current studies fail to show a significant association between seropositivity and fertility parameters (age at first breeding and calving, days from calving to first service and conception, services per conception and calving interval) or conception failure; this lack of association may have been due to an insufficient sample size.

Control

Control via chemotherapies

  • None available, except for supportive therapy where required after abortion.

Control via environment

Prevent vertical transmission
  • In low prevalence herds: consider culling of all seropositive animals.
  • In high prevalence dairy herds: breed seropositive animals to beef, do not keep offspring.
  • Only seronegative females should be introduced into the herd. However, a seropositive cow is unlikely to be a risk on the farm until she calves/aborts.
  • Embryo transfer Embryo transfer: overview: harvest embryos from a seropositive dam, implant embryos in seronegative recipients.
  • Avoid any condition that may lower the immunity of pregnant animals; for example, implement control measures for other diseases such as BVDv Bovine viral diarrhea virus and leptospirosis Leptospirosis.
  • Dairy herds: lower abortion rates have been reported when using beef bull semen for AI, possibly due to the improved placental function in cross bred pregnancies.
Prevent horizontal transmission
  • Prevent access of dogs, especially puppies, to silage pits, hay sheds, feeding areas and concentrate food stores.
  • Soiling of pasture by canine faeces should be avoided.
  • Access of birds, rodents and other wildlife to on farm food should be prevented.
  • Dogs should not have access to calving areas or recently calved animals.
  • Dead fetuses, dead animals, uterine discharges and placentae should be disposed of so that dogs and wildlife cannot get access to them.
  • The safest practice would be not to feed any form of raw meat to dogs.
  • It is advisable to calve known neospora-positive animals in isolation from seronegative animals, even though horizontal transmission between cattle has not (yet) been shown to occur.
  • There is no reason to remove the farm dog; once infected the dog will remain infected but is unlikely to shed oocysts again. There is even an argument of keeping the dog, as it may have a protective effect by keeping rodents and other possible intermediate hosts of the property.

Vaccination

  • No effective vaccine available (vertical transmission has often occurred before vaccination can take place).

Other countermeasures

  • See control measures above.

Diagnosis

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Goodswen S J, Kennedy P J & Ellis J T (2013) A review of the infection, genetics, and evolution of Neospora caninum: from the past to the present. Infect Genet Evol 13, 133-50 PubMed.
  • Reichel M P, Ayanegui-Alcérreca M, Gondim L F P & Elllis J T (2013) What is the global economic impact of Neospora caninum in cattle – The billion dollar question. Int j parasit 43, 133-142 PubMed.
  • Bartley P M, Wright S E, Zimmer I A, Roy S, Kitchener A C et al (2013) Detection of Neospora caninum in wild carnivorans in Great Britain. Vet parasitol 192 (1-3), 279-83 PubMed.
  • (2013) Northern Ireland disease surveillance report: Northern Ireland disease surveillance, January to March 2013. Vet Rec 172, 657-658.
  • Dubey J P & Schares G (2011) Neosporosis in animals--the last five years. Vet parasitol 180, 90-108 PubMed.
  • Rosbottom A, Gibney H, Kaiser P, Hartley C, Smith R F et al (2011) Up regulation of the maternal immune response in the placenta of cattle naturally infected with Neospora caninum. PLoS one 6 (1) PubMed.
  • Brickell J S, McGowan M M & Wathes D C (2010) Association between Neospora caninum seropositivity and perinatal mortality in dairy heifers at first calving. Vet rec 167 (3), 82-85 PubMed.
  • Lyon C (2010) Update on the diagnosis and management of Neospora caninum infections in dogs. Topics in companion animal medicine 25, 170-175 PubMed.
  • Almería S, López-Gatius F, García-Ispierto I, Nogareda C, Bech-Sàbat G et al (2009) Effects of crossbreed pregnancies on the abortion risk of Neospora caninum-infected dairy cows. Vet parasitol 163 (4), 323-329 PubMed.
  • Hughes J M, Thomasson D, Craig P S, Georgin S, Pickles A & Hide G (2008) Neospora caninum: detection in wild rabbits and investigation of co-infection with Toxoplasma gondii by PCR analysis. Exp parasitol 120 (3), 255-60 PubMed.
  • McCann C M, Vyse A J, Salmon R L, Thomas D, Williams D J et al (2008) Lack of serologic evidence of Neospora caninum in humans, England. Emerg infect dis 14 (6), 978-80 PubMed.
  • Woodbine K A, Medley G F, Moore S J, Ramirez-Villaescusa A, Mason S & Green L E (2008) A four year longitudinal sero-epidemiology study of Neospora caninum in adult cattle from 114 cattle herds in south west England: associations with age, herd and dam-offspring pairs. BMC Vet Res 4 (35) PubMed.
  • Gibney E H A, Kipar A, Rosbottom C S, Guy R F, Smith U et al (2008) The extent of parasite-associated necrosis in the placenta and foetal tissues of cattle following Neospora caninum infection in early and late gestation correlates with foetal death. Int j para 38 (5), 579-588 PubMed.
  • Tiwari A, Vanleeuwen J A, Dohoo I R, Keefe G P, Haddad J P et al (2007) Production effects of pathogens causing bovine leukosis, bovine viral diarrhea, paratuberculosis, and neosporosis. J dairy sci 90 (2), 659-69 PubMed.
  • Wapenaar W, Barkema H W, O'Handley R M & Bartels C J (2007) Use of an enzyme-linked immunosorbent assay in bulk milk to estimate the prevalence of Neospora caninum on dairy farms in Prince Edward Island, Canada. Can vet j 48 (5), 493-9 PubMed.
  • Bartels C J, van Schaik G, Veldhuisen J P, van den Borne B H, Wouda W & Dijkstra T (2006) Effect of Neospora caninum-serostatus on culling, reproductive performance and milk production in Dutch dairy herds with and without a history of Neospora caninum-associated abortion epidemics. Prev vet med 77 (3-4), 186-98 PubMed.
  • Milne E, Crawshaw M, Brocklehurst S, Wright S, Maley S & Innes E (2006) Associations between Neospora caninum specific antibodies in serum and milk in two dairy herds in Scotland. Prev vet med 77 (1-2), 31-47 PubMed.
  • Lobato J, Silva D A, Mineo T W, Amaral J D, Segundo G R et al (2006) Detection of immunoglobulin G antibodies to Neospora caninum in humans: high seropositivity rates in patients who are infected by human immunodeficiency virus or have neurological disorders. Clin vaccine immunol 13 (1), 84-9.
  • Hughes J M, Williams R H, Morley E K, Cook D A N, Terry R S et al (2006) The prevalence of Neospora caninum and co-infection with Toxoplasma gondii by PCR analysis in naturally occurring mammal populations. Parasitology 132 (1), 29-36 PubMed.
  • Hamilton C M, Gray R, Wright S E, Gangadharan B, Laurenson K et al (2005) Prevalence of antibodies to Toxoplasma gondii and Neospora caninum in red foxes (Vulpes vulpes) from around the UK. Vet parasitol 130, 169-173 PubMed.
  • Boyd S P, Barr P A, Brooks H W & Orr J P (2005) Neosporosis in a young dog presenting with dermatitis and neuromuscular signs. JSAP 46 (2), 85-8 PubMed.
  • Podell M (2002) Inflammatory myopathies. The Veterinary clinics of North America. Small animal practice 32, 147-167 PubMed.
  • Schock A, Buxton D, Spence J A, Low J C & Baird A (2000) Histopathological survey of aborted bovine fetuses in Scotland with special reference to Neospora caninum. Vet rec 147 (24), 687-8 PubMed.
  • Davison H C, French N P & Trees A J (1999) Herd-specific and age-specific seroprevalence of Neospora caninum in 14 British dairy herds. Vet rec 144 (20), 547-50 PubMed.
  • Moen A R, Wouda W, Mul M F, Graat E A M & van Werven T (1998) Increased risk of abortion following Neospora caninum abortion outbreaks: a retrospective and prospective cohort study in four dairy herds. Theriogenology 49, 1301-1309 PubMed.
  • Barber J S, Gasser R B, Ellis J, Reichel M P, McMillan D et al (1997) Prevalence of antibodies to Neospora caninum in different canid populations. J Parasitol 83 (6), 1056-8 VetMedResource.
  • Buxton D, Caldow G L, Maley S W, Marks J & Innes E A (1997) Neosporosis and bovine abortion in Scotland. Vet rec 141 (25), 649-51 PubMed.
  • Simpson V R, Monies R J, Riley P & Cromey D S (1997) Foxes and neosporosis. Vet rec 141 (19), 503.
  • Lathe C L (1994) Neospora caninum in British dogs. Vet rec 134 (20), 532 PubMed.
  • Trees A J, Guy F, Tennant B J, Balfour A H & Dubey J P (1993) Prevalence of antibodies to Neospora caninum in a population of urban dogs in England. Vet rec 132 (6), 125-6 PubMed.

Other sources of information

Organisation(s)

  • School of Veterinary Medicine and Science, University of Nottingham, UK.

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