The primary species in sheep (and goats) is potentially zoonotic C. parvum.  A new species - C. xiaoi - has recently been described from sheep, but its occurrence and significance have not yet been fully determined..  In addition, C. bovis and the potentially zoonotic C. hominis and C. ubiquitum have been found in sheep.  Cryptosporidium andersoni of cattle does not appear to infect sheep or goats.  Prevalence of infection in young sheep and goats can be  20 percent or more.  The importance of sheep as a source of  human infection with Cryptosporidium is not known, but in most circumstances is likely to be small. Clinical cryptosporidiosis has been reported in veterinary students and school children who have contact with young ruminants.

The primary clinical sign of cryptosporidiosis in sheep and goats is diarrhea, although there may also be anorexia, depression and abdominal pain.  The disease can be severe in these hosts.  Neonatal animals (4 to 10 days old) and, to a lesser extent, lambs and kids (1-5 weeks) are the most commonly and severely affected.  If the animals are are otherwise healthy, the clinical signs of cryptosporidiosis usually resolve after a week or so.  Infection and disease associated with Cryptosporidium are less common in older sheep and goats.  In these hosts, as in cattle, concurrent infection with other enteric pathogens can exacerbate the clinical effects of Cryptosporidium, especially in lambs and kids.  Animals with these mixed infections will sometimes die.  No treatments are approved in Canada for cryptosporidiosis in sheep and goats, and little information is available for these hosts on the drugs tried in cattle (e.g. paromomycin and halofuginone).

Additional information about Cryptosporidium is available under Cattle.