Avian coccidiosis remains one of the major parasitic diseases that threaten the global
poultry industry. Since prevention is superior to treatment, this study focuses on eliminating the
infection outside the host. To determine their effect on the viability of Eimeria tenella oocysts in vitro,
allicin and alcoholic garlic extract, which are natural, less toxic, and inexpensive products, were
compared to KOH 5% (chemical disinfectant) using an in vitro culture system. Three concentrations
of allicin (45, 90, and 180 mg/mL) and alcoholic garlic extract (90, 180, and 360 mg/mL, were used.
Subsequently, destructive and sporulation-inhibiting effects on Eimeria oocysts were detected using
light and electron microscopy. Young chickens were infected with treated sporulated oocysts to
determine their effect on infectivity. After 7 days pi, the percentage of excreted oocysts (oocyst
shedding) was determined, and the chickens were slaughtered for histopathological examination of
the cecal tissues. Under an electron microscope, allicin at a concentration of 180 mg/mL and alcoholic
garlic extract at a concentration of 360 mg/mL demonstrate a high oocysticidal activity with severe
destruction of the oocyst wall and the appearance of pores. In addition, both concentrations directly
affected the infectivity of sporulated oocysts by reducing the shedding of oocysts and the pathological
lesions of infected young chickens. We concluded that the ability of Allicin and alcoholic garlic extract
to eliminate Eimeria oocysts makes them superior to chemical disinfectants as a disinfectant.