Blood Protozoan and Ricketsial Diseases
It is also known as surra in equines and tibarsa in camel and results in intermittent fever, loss of condition, edema and nervous signs.
Etiology: It is caused by Trypanosoma evansi in cows, buffaloes, horses, camel, dog, elephant and wild ruminants.Spread of the disease occurs through mechanical carriers. Tabanus and stomoxys fly play important role in the spread of the disease.
Pathogenesis: The organisms gain entry into blood by biting of the flies and multiply there as well as in the body fluid like cerebrospinal fluid.
Clinical signs: The affected animals reveal intermittent fever, progressive anaemia and edema mainly of dependant parts of body. The animals become dull, depressed and weak. There is ocular and nasal discharge and haemorrhages occur at the junction of skin and mucus membrane. Urticarial plaques with necrotic foci in centre are also noticed. In the later stages, animals reveal nervous signs like paraplegia, paralysis, circling, head pressing against fixed objects and convulsions. Performance of animals become low while pregnant animals abort and show irregular estrus. Disease in horses and camel is usually fatal if not treated early.
On postmortem examination, the carcass appears emaciated, pale and icteric. There is infiltration of lymphocytes and plasma cells in different tissues including brain and spinal cord.
Diagnosis: It is diagnosed by clinical sign and confirmed by serological tests like indirect fluorescent antibody test, capillary agglutination and ELISA test, and by seeing the organisms in blood smears prepared from affected cases. If the number of organisms is low in circulation, glucose saline can be injected intravenously and then the blood is collected for preparing smear. It can also be confirmed by animal inoculation test by injecting suspected blood into rat or mice intravenously or intraperitoneally. These animals die within 2-3 days.
Treatment: The affected animals can be given suramin @ 9 g/100 kg dose body weight as single intramuscular injection or diminazene aceturate @ 0.8-1.6 g/100 kg dose body weight by deep intramuscular route. A maximum of 6 g diminazene aceturate can be given once and it should be repeated after 3 days. Quinapyramine prosalt containing quinapyramine methyl sulphate and chloride salts are also highly effective. It is given @ 2.5 g/dose by intramuscular route as single injection. Its sulphate salt has curative action while chloride has prophylacting action. Use of haematinic and liver tonics is helpful in early recovery of the cases. Occurrence of the disease can be reduced by checking the vector population and protecting the animals from biting flies.