EPIZOOTIC LYMPHANGITIS(PSEUDOGLANDERS, EQUINE

BLASTOMYCOSIS, EQUINEHISTOPLASMOSIS)

Chronic contagious zoonotic disease infected horse characterized by supurative lymphangitis and lymphadenitis and ulcers on skin ,there is also keratitis and or pneumonia.

ETIOLOGY

The cause is a fungus,

Histoplasma farciminosum

The disease is listed by the OlE, to which it is notifiable.

EPIDEMIOLOGY

The disease occurs as outbreaks in horses, donkeys and mules in parts of Iran, Asia, India, and Northern Africa . Most outbreaks occur in autumn and winter.The disease was detected in 1.0 to 19% of horses in Ethiopia over a 6-month period The mortality rate is 10-15 %, but the course is prolonged. Cattle and camels are rarely affected.

Sourse of infection1-infected animals. 2-soil during saprophytic stage. 3-Biting fly.

Transmition1-direct contact with infected animals. 2-contact with the soil.3-skin abrasion. 4-fly.

PATHOGENESISAfter gaining entry through wounds, the fungus invades subcutaneous tissue, sets up a local granuloma or ulcer and spreads along the lymphatic vessels. The ocular form of the disease results from inoculation of the organism into the eye, likely by biting flies.

CLINICAL FINDINGS

In General:-Ulcerating. Suppurative pyogranulomatous dermatitis. in most cases, lymphangitis . An ocular form of the disease is characterized by an ulcerating conjunctivitis.

1-In the cutaneous form of the disease an indolent ulcer develops at the portal of entry, making its appearance several weeks to 3 months after infection occurs.2-A spreading dermatitis and lymphangitis, evident as corded lymphatics with intermittent nodules, develops. 3-Nodules rupture, discharging a thick creamy pus.4-Local lymph nodes also enlarge and can rupture.

5-Thickening of the skin in the area and general swelling of the whole limb are common. The lesions are quite painless.The lesions usually develop on the limbs, particularly about the hocks, but may also be present on the back, sides, neck, vulva and scrotum. 6-Occasionally lesions appear on the nasal mucosa just inside the nostrils and do not involve the nasal septum. The disease is chronic, persisting for 3-12 months. Spontaneous recovery occurs and immunity is solid after an attack but many animals are destroyed because of the chronic nature of the disease.

D.Diagnosis1-Cutanous Glander2-Ulcerative Lymphadenitis 3-Sporotrichosis.

Diagnosis1-Clinical signs.2- Gram-positive, yeast-like cells, with a characteristic double-walled capsule, are easily found in discharges. The organismsare located both extracellularly and intracellularly in giant cells and macrophages.The agent can be cultured on special media but the fungus dies quickly in specimens unless these are collected in antibiotic solutions, refrigerated and cultured promptly. The specimen should be collected into a solution containing 500 units/mL penicillin.3- The mallein test is negative4- serological tests, including a fluorescent antibody test.

TREATMENT Many treatments have been tried, largely without success.1- Amphotericin at a dose of 0.2 mg/kg body weight every 48 hours for 3 treatments. . 2-Sodium iodide is administered as a 10% solution at a dose of 1 mL per 5 kg intravenously once weekly for 4 weeks.

CONTROL

1-slaughter of affected animals.2- In enzootic areas severe cases should be destroyed and less severe cases kept in strict quarantinewhile undergoing treatment. 3-All infected bedding, harness and utensils should be destroyed or vigorously disinfected.Formalinized aluminum hydroxide adsorbed 4-heat-attenuated vaccines have been widely used, apparently with success.