**7.3 Pathogenesis**

Cryptosporidium parvum infection, cause a malabsorptive diarrhea (Navarre and Pugh, 2002). Cryptosporium life cycle consist of six developmental stages. After ingestion of the oocyt there is excystation, merogony, gametogony, fertilization, oocyst wall formation, and sporogony.In contrast to other protozoal agents, cryptosporidia do not require fecal excretion for sporulation to infective stages, and they sporulate in the intestine (Navarre and Pugh, 2002; Radostits et al., 2008).

Protozoan Diseases in Farm Ruminants 491

livestock, causing diarrhea, weight loss, poor condition and lethargy (Hunter and Thompson, 2005). The parasite is a noninvasive and colonizes the mucosal surface of the

**Specie Affinity site Hosts Geographic** 

Giardia intestinalis Small intestine Cattle, sheep, goats, man Worlwide

Fig. 9. Giardia spp. trophozoit, lamb, Giemsa staining, immersion objective

transient, but infected animals can continue to shed cysts for long times.

prevalence rates of 100% (Xiao and Herd, 1994).

Giardia intestinalis is an important parasite in domestic ruminants also, in human with high levels of infection. Asymptomatic adult animals may act as healthy transporters and may be a source of environmental contamination and infection for young animals. Infection is commonly exhibited by the animals within 2 weaks of birth (Xiao, 1994). Diarrhea may be

Olson et al., (2004) reported a high levels of infection of Giardia in young livestock, specially calves. Giardia occur in both beef and dairy cattle, and studies have demonstrated

**distribution** 

small intestine.

Table 9. Giardiasis

**8.2 Epidemiology** 

The Giardia specie is shown in table 9.
