Review on Epizootic Lymphangitis: Epidemiology and its Diagnosis

Abstract

Epizootic lymphangitis is a contagious fungal disease principally of equines that results from infection by a dimorphic fungus, Histoplasma capsulatum var. farciminosum. The disease commonly develops into a chronic debilitating condition that can manifest itself in one of three clinical forms: cutaneous, ocular and respiratory forms. The disease is primarily an ulcerating, suppurative, pyogranulomatous dermatitis and in most cases lymphangitis. Epizootic lymphangitis is a relatively common infectious disease of horses and other equids in certain parts of the world. The infection rate of EPL varies with the geographic area and the age of the animal. The disease has the potential to significantly impact the health and welfare of equids in countries in which it is endemic. EPL is second only to African Horse Sickness as a most important disease of horses in Ethiopia. The wounds caused by harness are reported as major predisposing factors of EPL in carthorses in Ethiopia. Currently, due to limited available diagnostic technologies, veterinarians in Ethiopia diagnose the disease based on clinical appearance and microscopic examination for yeast cells within pus. This has the potential for misdiagnosis, as the clinical appearance can mimic that of other diseases. Diagnosis is possible by direct visualization of the yeast form of the fungus in pus from infected lymphatic nodules and by culture or histopathologic examination of tissues from clinically affected cases. It is also possible to visualize the organism in stained histological sections of matured or developing lesions. EPL is an economically important disease in some areas of the world, particularly where large numbers of horses, donkeys, or mules are assembled. Different treatment modalities are available some of which are successful in treating early cases of the disease. Effective prevention and control of epizootic lymphangitis is based on euthanizing infected equids and the application of strict biosecurity measures.