Final answer:
EPM is a neurologic disease in horses caused by the protozoal parasite Sarcocystis neurona, not to be confused with Toxoplasma gondii which causes neurotoxoplasmosis in immunocompromised humans.
Step-by-step explanation:
EPM is a neurologic disease caused by a protozoal parasite called Sarcocystis neurona. This parasitic disease primarily affects horses, causing a variety of neurological symptoms due to the parasite's ability to invade the nervous system. Sarcocystis neurona is different from Toxoplasma gondii, which causes neurotoxoplasmosis, a disease that typically affects immunocompromised patients and is one of the most common causes of brain abscesses in these individuals. Toxoplasma gondii enters the circulatory system and crosses the blood-brain barrier, causing brain abscesses and lesions. This disease can be detected through radiographic imaging such as MRI or CAT scans.