Trypanosomiasis
Basic Information 
Epidemiology
Geography and Seasonality
• The actual trypanosome and syndrome are geographically related. Surra is a syndrome of South and Central America, Northern Africa, the Middle East, Asia, Indonesia, and Philippines.
• African animal trypanosomiasis occurs in Central and Southern Africa starting mainly along the southern edge of the Sahara, Angola, Zimbabwe, and Mozambique.
Clinical Presentation
Physical Exam Findings
• Surra can be an inapparent infection, yet these animals are capable of transmitting the disease to vectors. With clinical disease, the onset is variable with insidious signs composed of fever, progressive anemia, and weight loss with a normal appetite. Edema is common on the ventral abdomen and distal limbs. There are frequently petechial hemorrhages on the mucous membranes. Horses commonly have neurologic signs such as weakness and ataxia.
• African animal trypanosomiasis usually starts with an initial infection of skin that is called a chancre. The animal progresses to systemic signs of intermittent fever with accompanying anemia, edema, and weight loss. Trypanosoma brucei infection may be associated with neurologic signs similar to surra. Abortion and infertility may occur.
• Dourine is mainly a sexually transmitted disease with transmission from male to female most commonly occurring. After incubation (short or prolonged), animals can become asymptomatic carriers. Clinical disease is characterized by paraphimosis and cutaneous plaques with accompanying neurologic signs in males. Females have swollen vulvar and vaginal tissues and mucopurulent discharge. Mares are frequently uncomfortable and polyuric. The genital symptoms usually are cyclical. The development of characteristic cutaneous lesions follows. These lesions are circular, elevated plaques of thickened skin ranging from 1 to 10 cm in diameter that are observed mostly on the neck, hip, and ventral abdomen.
• With neurologic signs in these diseases, horses become restless and exhibit leg shifting, progressive weakness, and incoordination, and they eventually progress to recumbency. Cranial nerve paralysis, usually cranial nerve VII, may occur.
