Page 3 - Cryptosporidiosis in neonatal calves

Cryptosporidiosis in neonatal calves PAGE 3

Life cycle of parasite

The oocyst infectve stage once ingested invades the cells lining the wall of the small intestne. There it undergoes
numerous asexual multplicaton stages and a fnal sexual reproductve stage before further infectve oocysts are excreted
in the faeces. There is also an endogenous infectve cycle, where a proporton of the oocysts are thin walled and excyst
in the intestne. The freed sporozoites then initate an auto-infecton cycle which may prolong the disease (See Figure 1).

Disease transmission

The parasite is transmited via the faecal-oral route through the ingeston of oocysts from infected animals. Oocysts
may be present in faecal mater on the foors of trailers, on walls and foors of calf pens and houses and protectve
garments of owners and handlers. Other sources of oocysts include contaminated feeding utensils and anything else
calves may fnd to lick and suckle.

Calves become infected by:
(i) Being reared in calf pens/houses that have been previously contaminated by infected calves

(ii) Ingestng food and water contaminated with oocysts
(iii) Contact with faeces from older infected calves

(iv) In rare circumstances, where husbandry is inadequate prior to and during calving, transmission may occur
via the dam

Life Cycle of Cryptosporidium parvum

Figure 1