Trypanosomiasis in Cattle

Trypanosomiasis or Surra is an important disease of cattle and buffalo caused by the protozoan parasite. It is transmitted mechanically by biting flies Glossina or needle transmission when the same needle is used for injecting medicines and there is a clinical or sub-clinically infected animal in the herd. The disease is chronic, difficult to get rid of due to antigenic variation. The infected animals have poor productivity, low BCS, immunosuppression and sub-fertility.  In untreated animals, mortality is common due to secondary infections.

Causative agent: T.brucei, T evansi. T.congolense, T.vivax (Heamoprotozoon parasite)

Species affected:  Cattle, Buffalo, Camels, Equines, Elephants, Dogs wildlife like lion, deer and other cloven footed herbivor.

Clinical Symptoms: Pyrexia, anorexia, debility due to anaemic condition, frequent micturition and defaecation, dyspnoea, irritability, moving in circle, extreme fatigue, swollen lymph nodes, and aching muscles and joints. Death in 2-3 days but in chronic cases in 20-30 days, oedema of legs, chest and keratitis in chronic cases.

Clinical Pathology:  Commensurate to parasitic load in blood the classical sign is hypoglycaemia which may go so law as to threaten life. Oligocythaemia and Hypochromicity are other findings.

Post Mortem Lesions: There are no specific post mortem lesions. Commonly recorded lesions are emaciation, subcutaneous yellowish gelatinous oedema, petechiae on serous membrane, hydro pericarditis and ascites, splenomegaly with dark reddish pulp, liver with fatty changes, and necrotic foci enlargement of lymph nodes, necrotic ulcers on tongue and stomach, congestion of intestine.

Specimens required for laboratory:   Blood collected in fluoride for glucose, wet thick blood smear, lymph node aspirates, and cerebral fluid. In cases where parasitaemia is low, smear prepared from the buffy coat after centrifugation increases the chances of detection.

Laboratory Tests:

1. Stained blood smear for examination of parasites.  wet blood smear examination
2. Biological tests in lab animals- suspected blood or fluid is injected intra-peritoneally in rat/mice (preferably rat) and tail blood smear examination during day 3-10.
3. PCRPolymerase Chain Reaction test is available but not suitable for endemic areas as even an insignificant load would give positive results.

Diagnosis:

1. Diagnosis should be based on clinical signs, endemicity of the area, microscopic examination of lymph node aspirate, blood or CSF. A standard method is to identify trypanosomes in the blood of infected animals.
2. ELISAEnzyme-linked Immuno-sorbent Assay- A test to measure antigen or antibodies in biological materials. test

Treatment of Trypanosomiasis in Cattle:

The curative drugs aim to eliminate parasites from sick animals. Inj Diminazene aceturate (Berenil) 0.8 to 1.6 gm per 100 kg body wt. i.m is useful. Drugs like, isometamidium chloride, cymelarsan, suramin and quinapyramine can also be tried. Quinapyramine is also expected to give protection against infection for a short time.

 Prevention and Control:

• Manure management is important since these are the breeding grounds for the flies.
• Bushes in the area should be cleaned since these are the fly breeding sites.

You may like to read: Diagnosis and Treatment of Mastitis in Cattle