Theileriosis is a big problem in dairy cattle- A report
Dr Sanjay Kumar Bharti1 and Dr Avnish Kumar Gautam
Head1,Assistant Professor-cum-Junior Scientist2 Department of Veterinary Anatomy
Bihar Veterinary College, Bihar Animal Sciences University Patna
Cross ponding Authors- drskbharti24@gmail.com
Introduction
Theileriosis is a tick-borne infections disease to cattle characterized by fever, anaemia and disorders of respiratory and digestive tracts. In India, the disease in cattle is known as Bovine Tropical Theileriosis. In many respects Theileriosis is like Malaria in human beings and so it is also called cattle malaria.
This disease was though recognised in India in 1905 (by Lingard), but its real impact was seen only in mid-sixties when exotic breeds of cattle were imported in large number for cross-breeding in Indigenous cattle to increase the milk production. It has become a disease of economic importance due to high degrees of morbidity, mortality and prolonged convalescent period.
Etiology:
The disease is caused by Theileriaannulata(a blood protozoan parasite) which is transmitted to cattie by the bite of ticks of genus Hyalomma, the most potent of which is Hyalammaanatolicumanatolicum (a3 host tick) Theileriosis is a serious disease incattle mainly transmitted by protozoansTheileriaparvacousing East Coast Fever or Theileriaannulata causing Tropical Theileriosis or Medeterian East Coast Fever both parasite are transmitted by ticks.
Epidemiology:
All the age groups of cross-bred cattle are highly susceptible to Theileriaannulatainfection. The severity of the disease is more in young cross-bred calves with very high mortality rate. This disease has also been attributed to one of the causes of calf mortality. Clinical Theileriosis has also been observed in young indigenous calf. The adult indigenous cattle generally suffer from subclinical infection. But they become potent source of spreading the infection to other healthy cattle through ticks. The cycle of infection from tick to cattle and back to tick (tick-cattle-tick) continues. The clinical cases in Indian buffaloes have rarely been reported. They are considered to be carriers of Theileria organisms.
The occurrence of the disease has been seasonal i.e. in summer and rainy months, which may be due to enhanced activity of vector ticks. The stress factors like hot and humid weather, transportation, malnutrition, pregnancy, lactation and even vaccination precipitate the occurrence of disease. The mortality is variable according to the severity of disease. It has been reported to be as high as 90%
Clinical Symptoms:
The first symptom is enlargement of superficial lymph glands which develops within 8-12 days (incubation period) after the bite of Theileria infected Hyalomma ticks. This symptom s mostly observed is the prescapular lymph gland and occasionally in the parotid lymph gland. The fever develops at this stage and the body temperature rises from 103 to 107º F. There is short sporadic cough, laboured breathing, mucous discharge from eyes and nostrils and depraved appetite. The lungs become filled with fluid and the fluid and the alimentary canal particularly the abomasum develops ulcers. The abortion may occur in pregnant cows.
Severe form of anaemia develops causing marked reduction in the values of haemoglobin (Hb), packed cell volume (PCV) and total erythrocytic count (TEC). In the later stage of disease, the animal develops jaundice. The conjunctive may become icteric. There may be petechial haemorrhages in the conjunctive Diarrhoea also occurs in the last stage with faeces containing bloodtinge. The animal becomes weak and emaciated followed by death in 80-100% of cases. The course of the disease is 6-19 days with an average of 12 days in fatal cases. In mild form of disease, the course is 22-23 days.
Sometimes unusual symptoms are also observed like swelling of eyes with protrusion of eyeballs from the socket leading to conjunctivitis, ulceration and opacity of cornea. These symptoms are generally seen in young calves. Nervous symptoms are found in cerebral from of theileriosis. Cutaneous lesions showing urticarial growths have also been observed occasionally.
Post-mortem Findings:
The important P.M. findings consist of punched necrotic ulcers in the abomasum and occasionally in the small and large intestines and congestion and oedema of lungs. The punched necrotic ulcers in the abomasum are characteristic P.M. lesions and of diagnostic significance.
Diagnosis:
The diagnosis of the disease is based on the clinical symptoms and demonstration of parasites in the lymph node biopsy smears and peripheral blood smears after stainingthem with Giemsa or Leishman stain. At the initial stage of the disease, the schizont stage of the parasite is detected in the stained lymph node biopsy smears which appear in the cytoplasm of the lymphocytes.
In the later stage of the disease, piroplasm stage develop in the R.B. Cs the piroplasms appear in the stained bloodsmears in R.B.Cs. as a ring or oval shaped organisms either singly or in pairs. In heavy infection, the parasites may be 4-6 in number in one R.B.Cs. For diagnosis of subclinical cases, serological tests are used.
Treatment:
The drug of choice is “Buparvaquone: marketed as Butalex/zubion. A single injection of Butalex as Zubion at the dose rate of 1ml. Per 20 kg. Body wt. i/m is usually sufficient, but in some cases, a second injection may be required within 48-72 hours of initial injection. Not more than 10 ml should be injected at one site. Milk from lactating animals should not be used for 2 day following the treatment for humanconsumption. Butalex/Zuubion is effective against both schizont and piroplasm stages of Theileriaannulata. Since, it is very costly drug, it is desirable to use after the confirmation of diagnosis.
In the absence of Buparvaquone (Butalex/Zubion), drug combinations consisting of antibiotic (Oxytetracycline), antiblood protozoal (Dimenazene – Diaceturate) including antimalarial like Chloroquine (Nivaquine) may be used. Oxytetracycline is used at the dose rate of 5-10mg/kg body wt. i/m for 5 days.
Long acting Oxytetracycline may be used in place of plainone at the dose rate of 20 mg/kg body wt. i/m and to be repeated after 72 hrs. on 2-3 occasions. Diminazene-Diaceturate (Berenil / Nibery/ Prozomin) is used at the dose rae of 10 – 15 mg/kg body wt. deep i/m on 2 – 3 occasions at the interval of 48 hrs. Nivaquine is used at the dose rate of 8 – 10 mg/kg body wt. i/m daily for 3 – 4 days. Oxytetracycline has effect on schizonts, whereas Diminazene and Chloroquine have effect on piroplasms. Antipyretics like Paracetamol or Meloxicam may be used to reduce fever. Antihistaminics (Avil/ Cadistin) should be given to prevent the reactions of Oxytetracecycline and Diminazene-diaceturate if any.
The supportive therapy consists of haematinic, such as Vit. B-Complex, Liver extract and Iron preparations parenterally in required doses to overcome anaemia. In severely anaemic cases, when the haemoglobin level comes down to 3-4 g/100ml of blood, in that case blood transfusion may be of much value. For this, blood is collected from the jugular vein of normally healthy cattle in to a sterilized empty glucose saline bottle containing anticoagulant solution- sodiumcitrate 3.85% at the rate of 10ml for each 100ml of blood. The blood is transferred immediately to sick animal by slow drip method. 400-500ml of blood can be transferred cross-matching may be needed to determine the compatibility. For this, a small amount of blood (50 – 100 ml) should be injected at first and the animal should be observed for half an hour, if no transfusion reaction occurs, the rest of the blood can be injected slowly.
Control:
The control measures consists mainly of two methods – (1) Control of vector ticks (2) Immunisation of susceptible animals. For the control of vector ticks, ectoparasiticdes viz. Deltamethirin / Cypermethrin (Butox/Clinar) are used effectively as spray in the required concentration. The spraying should be done regularly on the body of animals infested with ticks particularly in the rainy season. The spraying should also be done on the floor of animal shed including the crevices in the walls where ticks generally hide.
For immunisation, schizont vaccine has been developed which is lymphoid cells grown schizonts attenuated after passages. But this vaccine has not become popular due to certain limitations. However, there is need for development of safe and effective vaccine which can be used in all age group of susceptible cattle including the young calves producing longer immunity.
