**8.2 Epidemiology**

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

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

Protozoan Diseases in Farm Ruminants 493

Disease occur as outbreaks in tropical and subtropical countries and sporadically in other countries (Radostits et al., 2008). Bovine besnoitiosis is common in Africa, Asia and in the South of Euroup ( Jacquiet et al., 2010), Caprine besnoitiosis in Kenya, Uganda, Iran, and Kazakhastan. In livestock, cattle and goats are intermediate host, and cats are their definitive hosts (Radostits et al., 2008). It is thought that agent is transmitted mainly by

Following infection in cattle or in goats, the tachyzoites proliferate in macrophages, fibroblasts, and endothelial cells and causing vasculitis. Subsequently they develop to form bradyzoite cysts in fibroblasts in the dermis, subcutaneous tissues, fascia, nasal and laryngeal mucosa (Taylor et al., 2007; Radostits et al., 2008). After developing cysts in the skin, painful subcutaneous swelling, thickening of the skin, alopecia, and necrosis can be

Clinical signs occur in two stages: acute and chronic. In acute stage clinical signs include fever, increase in pulse and respiratory rates, painful swelling on the ventral aspects of the body, edema of the skin, sometimes diarrhea, lacrimation and nasal discharge. In chronic

Thickening of the skin over the lower limbs, around the eyes, nose, face and scrotum, alopecia in all of these areas, and white granular cysts in the sclero-conjunctiva can be seen

Besnoitiosis can be diagnosed by demonstration of B. bradyzoites in skin biopsy smears or

Control is effected by the elimination of infected animals and carriers, and early diagnosis (

Toxoplasma gondii is a systemic coccidian, a universal parasite that causes rarely abortion in cattle but is a major abortifacient in sheep and goats (Radostits et al., 2008; Christensen et

stage, there is a severe dermatitis over most of the body (Radostits et al., 2008).

**9.2 Epidemiology** 

**9.3 Pathogenesis** 

occur (Taylor et al., 2007).

**9.4.1 Bovine besnoitiosis** 

**9.4.2 Caprin besnoitiosis** 

(Oryan and Azizi, 2008).

**9.6 Treatment and control** 

Antonio Castillo et al., 2009 ).

**10. Toxoplasmosis** 

**10.1 Etiology** 

scleral conjunctival scrapings (Radostits et al., 2008).

There is no known treatment for this disease (Taylor et al., 2007).

**9.5 Diagnosis** 

**9.4 Clinical findings** 

hematophagous insects (Jacquiet et al., 2010).
