Neosporosis is a parasitic disease caused by the protozoan Neospora caninum, which primarily affects cattle but can also infect other animals, including dogs. This disease is of particular concern to the cattle industry due to its association with reproductive issues, including abortion, which can lead to substantial economic losses.
Neospora caninum is an intracellular protozoan parasite. Dogs and other canids (such as foxes) are the definitive hosts, shedding the parasite's oocysts in their faeces. Cattle become infected primarily through ingesting these oocysts from contaminated feed, water, or environment. Once inside the cattle, the parasite can cross the placenta, leading to congenital infection of the foetus.
The disease can have a profound economic impact on cattle farms due to increased abortion rates, subsequent metritis, and reduced yield or loss of the lactation.
The most significant clinical sign of neosporosis in cattle is abortion, which can occur at any stage of gestation but is most common between 5 to 7 months. Other manifestations include:
Reproductive Failure: Infected cows may experience reduced fertility, stillbirths, and the birth of weak calves.
Neurological Signs: While rare, some infected calves may show neurological symptoms such as ataxia, hind limb paralysis, and muscle stiffness.
Seemingly normal calves. Calves from infected cows which are born alive and survive are highly likely to have been infected in the uterus. As such, they will carry the disease with them, and, while they cannot directly transmit it to other cattle, they are highly likely to go on to abort their own calves.
Diagnosing neosporosis involves a combination of clinical evaluation and serological testing:
Serology: Blood tests can detect antibodies against N. caninum, indicating exposure to the parasite. The sensitivity of this test declines rapidly after the abortion has taken place, so cattle must be tested as soon as possible after aborting. If serology is being used as a screening test, late pregnancy is the best time to do it.
Polymerase Chain Reaction: PCR tests (just like BVD Tag&Test kits) can identify the parasite's DNA in tissues, confirming infection.
Histopathology: Examination of aborted foetuses and placental tissues can reveal characteristic lesions and the presence of the parasite.
Managing the disease is challenging, as no vaccine exists, and farms often face a constant risk of infection, especially in fields with footpaths which are popular with dog walkers. Control revolves around identification of infected animals and adjusting management so that replacements are not kept from neospora positive cattle.
To summarise, neosporosis is a significant parasitic disease affecting cattle, primarily causing reproductive issues that can lead to economic losses. Effective management requires a combination of biosecurity measures, diagnostic testing, and herd management practices.
Mihail
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