Case 6: Neosporosis

Linda Behling Sarah Galdi

Jamie Jergenson

Case Summary

• Herd manager for a 3,000 cow dairy located in Southern California

• Abortions in 20% of first lactation heifers during first 4-6 months of pregnancy and cows aborting at 5 months

• Blood test is being run, but results not back yet

• Suspected cause of abortions is Neosporosis

Cause and Transmission

• Caused by protozoan Neospora Caninum

• Transmitted two ways– From cow to calf (across placenta)– From host to cow

(ingestion of contaminated feed)

Transmission

Results of Neospora

• 3 possibilities for fetus:– 1.) Fetus becomes infected early and is

aborted– 2.) Fetus is infected late, pregnancy

maintained but calf is born with neurological diseases

– 3.) Fetus is infected late, pregnancy is maintained, calf is born normally but is more likely to abort during first gestation than heifers not infected

Economic Impact on Dairy Herd

• Cows with Neospora have:– Decreased milk yield– Decreased reproductive efficiency– Decreased weight gain and feed efficiency– Decreased value as breeding stock

• In California, the approximate economic loss from both abortion and other factors (semen, breeding, vet costs, open/not milking) is $35,000,000/yr

Treatment

• No effective drug or vaccine available• Suggestions to reduce incidence:

– Remove all cows infected with Neospora– Test replacement heifers and newborn

calves– Reduce stressors (low quality feed stuffs,

overcrowding and excessive heat)– Prevent horizontal transmission by

preventing fecal contamination of cattle feed

Diagnosis

• ELISA test• Blood samples

Likely Situation at CA Dairy

• Wildlife infected with Neospora by consuming an infected aborted fetus

• Wildlife are contaminating feed supply• First lactation heifers and cows (that are housed

together) are ingesting the feed• Cattle are passing disease on to fetus (some of

which survive and carry the disease to their offspring)

Should the herdsman be fired?

• No, Neospora is not tied directly to his or her herd management responsibilities – He just began this past year and the initial infection would

have started with the later lactation cows before he was hired.

• Improved pest control methods must be implemented to control the presence of wildlife around the dry lot

Coyote/Dog Fencing Live Traps

Sources

• Washington State University College of Veterinary Medicine http://www.vetmed.wsu.edu/depts_waddl/Neosporosis.asp

• United States Department of Agriculture Agricultural Research Service http://www.ars.usda.gov/Main/docs.htm?docid=11007

• The Merck Veterinary Manual http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/51600.htm