“Trypanosomiasis” is a protozoan disease of livestock commonly called as Surra caused by a protozoan organism Trypanosoma evansi. The disease is transmitted by Tabanid flies. It affects most of the livestock and wild animals also. It is distributed throughout India and found as endemic. The disease is seen as an outbreak in pre monsoon and in monsoon seasons due to active breeding of the Tabanid flies. In most of the animals the disease runs in a subclinical form making its diagnosis rather difficult. The disease is characterized by anemia, nervous complications, emaciation and death. It causes severe loss to the farmers by way of poor milk and meat production, reduced ability to work and high mortality. The disease also interferes with immunity and causes immunosuppression of bacterial and viral infections.
Transmission and pathogenesis of the disease:
Trypanosiasis is transmitted by a vector Tabanid fly (Horse fly).The fly passively transfer the parasites from the infected animal by sucking along with the blood and regurgitating into another animal. Development of parasite does not take place in the body of the vector. However the parasites can briefly live in the gut of the fly. Other vectors capable of infecting are Stomaxys, Lyperosia, Hematopota (Flies), Ornithodorus (Ticks). Trypanosomes after reaching the blood stream of the host quickly deplete the blood sugar levels by consuming large quantities of sugar and develop hypoglycemia. They also produce disturbances in protein metabolism in the host’s body. They also cause destruction of the red blood cells and produce anemia.
- The disease in cattle and buffaloes runs in per acute, acute and chronic forms depending on the strain of the parasite.
- In acute form there will be intermittent fever ranging from 39 to 41 degrees Celsius, conjunctivitis, and lachrymation
- Sudden drop of milk yield
- Labored breathing
- Nervous symptoms like walking in circles, beating the head on mangers, or walls, twitching of the muscles and the animal may go coma leading to death of the animal.
- In per acute cases the animal may die in 2-3 days
- In sub acute and chronic cases the symptoms develop slowly and the owner may not be able to notice the symptoms in the early stage of the disease. The animal will be dull, reduction in the milk yield, intermittent fever, and the pregnant animals may abort. The mortality will be around 20-90%.
The diagnosis can be made by demonstrating the Trypanosomes in the peripheral blood. A wet drop of blood can be obtained from the ear or tail vein and examined in high power. The moving parasites can be seen in the wet blood. The drop should be examined before it dried. Quick examination is necessary. Blood smears can also be stained with Giemsa stain and the parasite can be observed. Both the tests are good tests but they should be examined at the height of temperature.
Biological tests can also be made in the laboratory by inoculating infected blood into mice, rabbits or guinea pigs. The parasites multiply in them and they can be demonstrated.
Serological tests can also be made to identify the antibody formation using PCR, ELISA, agglutination tests for laboratory diagnosis of the disease.
Treatment of affected animals can be made with suitable drugs like Quinapyramine sulfate, Quinapyramine chloride (Antrycide and Antrycide prosalt), Demenazene aceturate (Berenil), Suramin (Naganol). All these drugs are highly useful for treating of the disease. Antrycide prosalt can also be used as a prophylactic drug to protect the animals in endemic areas during pre monsoon periods.
Prevention of the disease:
- Quick diagnosis and prompt treatment of affected animal controls the disease to some extent.
- In endemic areas prophylactic treatment with Antrycide prosalt administration controls the disease.
- Effective methods for fly control should be followed to control breeding of the flies. Spraying of the dung pits, clearing of the bushes around the cattle sheds by burning, spraying insecticides on the animals etc should be followed.