A survey of 93 dairy and five beef herds from five regions of the United States revealed that at least one cow in 90% of the herds was seropositive for antibody to Neospora caninum (1). The prevalence of seropositive cattle in these herds was 2 to 65%. WithNeospora caninum, seropositive cattle are infected because the organism is persistent and not cleared.
There are several problems that result from having seropositive cows in a herd. The major problem is production losses from decreased milk production and abortion. Independent studies in the United States demonstrated that seropositive cows had decreased milk production of 2.5 lbs/day/cow in one study (2) and 2.8 lbs/day/cow in another study (3) when compared with seronegative cows. In the later study, decreased milk production caused a $128 loss per lactation period/seropositive cow. Another major problem with having seropositive cows in a herd is that vertical transmission occurs. The frequency of vertical transmission varies considerably, but can reach 100% (4). A recent evaluation of economic considerations for diagnostic and control options for Neospora caninum-induced abortion in beef cattle used a 5-year economic simulation model (5). A seroprevalence of 10% in cow-calf herds decreased mean return to fixed assets by 22.2%. The control strategy with the best economic return involved testing the entire herd for antibodies to Neospora caninum and excluding heifers from seropositive cows as replacements (5).
1. Rodriguez I, L Choromanski, SJ Rodgers, and D Weinstock. Survey of Neospora caninum antibodies in dairy and beef cattle from five regions of the United States. Vet. Ther. 3:396-401, 2002.
2. Thurmond MC, and SK Hietala. Effect of Neospora caninum infection on milk production in first-lactation dairy cows. J. Am. Vet. Med. Assoc. 210:672-674, 1997.
3. Hernandez J, C Risco, and A Donovan. Association between exposure to Neospora caninum and milk production in dairy cows. J. Am. Vet. Med. Assoc. 219:632-635, 2001.
4. Campero CM, DP Moore, H Lagomarsino, AC Odeon, M Castro, and H Visca. Serological status and abortion rate in progeny obtained by natural service or embryo transfer from Neospora caninum-seropositive cows. J. Vet. Med. B Infect. Dis. Vet. Public Health 50:458-460, 2003.
5. Larson RL, DK Hardin, and VL Pierce. Economic considerations for diagnostic and control options for Neospora caninum-induced abortions in endemically infected herds of beef cattle. J. Am. Vet. Med. Assoc. 224:1597-1604, 2004.