Neosporosis In Cattle

Abstract

Neospora caninum is an obligate intracellular coccidian parasite of cattle and dogs that infects 10- 20% of all cattle worldwide and causes up to 20% of bovine abortions. N. caninum cycles at low levels between the definitive host, canids, and a wide range of intermediate hosts, cattle being the most important. Abortion is the only clinical sign observed in adult cattle. N. caninum most commonly causes an endemic increase in a herd’s annual abortion rate and infrequently causes epidemic abortion storms. Rarely, congenitally infected calves are born with neurological disease. Most infected calves are born clinically normal but with a titer. The parasite persists within cattle herds through vertical transmission via transplacental infection of successive pregnancies of chronically infected dams and by infrequent horizontal transmission. All infected cows are at increased risk of abortion. Abortion diagnosis is challenging because Neospora may be present but not the cause. Ruling out other causes of abortion, detecting the characteristic fetal lesions, or establishing an association between abortion and infection within the herd is important. Control options are limited. No antiparasitic drugs are approved or economical for treatment or prevention. Although a killed vaccine is available commercially, it has questionable efficacy. In many instances, tolerating the infection is the most economical option. Testand- cull strategies are often cost-prohibitive. For reducing a herd infection rate, precolostral testing of heifer calves and excluding those with titers from breeding is usually an economical option.