Diagnosis of Cryptosporidium on a sheep farm with neonatal diarrhea by immunofluorescence assays

An outbreak of diarrhea in neonatal lambs occurred on a a sheep farm in northern Ohio. Diarrhea commenced as early as 1 week of age and lasted for about 3–4 days. Although 100% of the newborn lambs were affected, most had recovered by 3 weeks of age. Cryptosporidium infection appeared to be the cause of diarrhea. Fecal examination of nine diarrheic newborn lambs (5–10 days old), 23 older lambs (2–3 weeks old, six with diarrhea) and 23 clinically normal ewes by immunofluorescence assays revealed infection rates of 100%, 78.3% and 17.4%, respectively. Most newborn lambs had high oocyst counts. Ewes were considered to be an important source of infection for lambs.