A study of neonatal cryptosporidiosis of foals in New Zealand

A study of neonatal cryptosporidiosis of foals in New Zealand
Peer reviewed


AIM: To assess the occurrence of Cryptosporidium  oocysts in faecal specimens from foals, and investigate an outbreak of neonatal  cryptosporidiosis in foals revealed in the course of the study.  
METHODS: Faecal specimens from  foals received by a diagnostic veterinary laboratory in New Zealand between 2006 and 2007 were submitted to Massey University and tested microscopically for  the presence of Cryptosporidium oocysts. The Cryptosporidium isolates  in the oocyst-positive specimens were genetically identified to species  level. In addition, specimen submission data from the participating  laboratory for 2005–2007 were examined. In the course of the study, the  identification of one Cryptosporidium-positive specimen triggered an  on-farm investigation.  
RESULTS: Twelve faecal specimens  submitted by the participating laboratory between 2006 and 2007 were tested  further, and three were positive for C. parvum. Specimen submission records  indicated a total of 67 faecal specimens were tested for Cryptosporidium by  the participating laboratory between 2005 and 2007; 12 (18%) were positive.  The on-farm investigation on a broodmare farm revealed a high incidence of  neonatal diarrhoea in foals; C. parvum was the only enteropathogen  found in the faeces of 4/4 affected foals examined. The diarrhoea in all  those foals was self-limiting, manifesting during the second week of life,  resembling foal heat diarrhoea, and accompanied by a short but intense period  of shedding oocysts.  
CONCLUSIONS AND CLINICAL  RELEVANCE: The fact that Cryptosporidium parasites were identified in  18% of faecal specimens from foals analysed for this agent in 2005–2007 by the  participating laboratory indicated that infection with this agent in foals is  not uncommon. Collectively, the results of this and previous studies  performed in New Zealand indicate C. parvum is a cause of diarrhoea in  newborn foals, potentially accounting for a proportion of cases empirically  diagnosed as foal heat diarrhoea. It is therefore advisable to take  precautions when handling diarrhoeic foals, until this potentially zoonotic  agent is ruled out in the laboratory.  
KEY WORDS: Foals, diarrhoea,  diarrhea, Cryptosporidium parvum

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