Tick-Borne Diseases: Epidemiology and Diagnosis

Transmission:Various spp. of Ticks – Hyalomma anatolicum anatolicumH. dromedarii, H. marginatum, H. detritum

Epidemiology : 1) All age group exotic and cross bred are highly susceptible 2) Young indigenous calves highly susceptible 3) Indigenous cattle and buffaloes –inherent resistant 4) Favourable climate and habitat for the survival of ticks, responsible for transmission 5) Bos Taurus X Bos indicus crosses susceptible to the disease 6) Adult indigenous cattle are generally do not suffer clinically but are the constant source of infection

Diagnosis : • Clinical simptoms, knowledge of the disease and tick distribution of the area 1) Clinical symptoms a) High rise of temp.(40.50C to 41.50C). Theileriosis should be suspected in tick infested animals with fever. b) Prepatent period – attachment of ticks to onset of fever 10-13 days c) Enlargement of prescapular lymph nodes

Enlargement of prescapular lymph nodes

d) Decreased rumination e) Decrease of temp. and development of anaemia with high coloured urine in later stage f) Reduced milk yield and may abortion g) Constipation / diarrhoea h) Lies neck curved back to the shoulder i) The course of the disease from fever to death ranges from 1-2 wks.

2. Exam. of Giemsa-stained blood and lymph node smears a) Detection of schizonts in WBC and piroplasms in RBC b) Schizont is a characteristic diagnostic feature of acute infections * Negative results of microscopic examination of blood films do not exclude latent infection

Peripheral blood smear with Theileria spp.

3. P.M. Lesions a) Enlargement of lymph nodes b) Enlargement of liver and spleen c) Numerous ulcers in the m.m. of the abomasums d) Schizonts may be found in impression smears from most internal organs

Collection of materials a) Blood and lymph node biopsies should be submitted for the detection of Theileria schizont b) Blood or buffy coat smears and lymph node impressions should be air dried and fixed in methanol c) Lymph node, spleen, liver should be collected for histopathology d) Serum for serological tests

Stained impression smear from an enlarged lymph node of a cow with Theileriosis.

BABESIOSIS • ‘Tick borne’ haemoprotozoan disease • Cattle Worldwide– B. bovis, B. bibemina, B. divergens, B. major • India – B. bovis and B. bigemina • First reported in India by Lingard and Jennins (1904) – Buffalo • Transmission : 1) Boophilus spp. • Hyalomma, Haemaphysalis, Rhipicephalus, Dermacentor, Ixodes spp. • 2) Blood transfusion, vaccination

Epidemiology : 1) Young animals suffer less 2) Adult – Acute and chronic forms 3) Recovered animals – immune for life 4) Indigenous cattle tend to be more resistant than exotic cattle • Zoonotic importance: Several human cases of babesiosis have been recorded

DIAGNOSIS • A. Clinical symptoms 1) Acute disease generally runs for about 1 week 2) The first sign is fever (105.80F) 3) Inappetance 4) Anaemia 5) Weight loss 6) Haemoglobinurea 7) CNS involvement 8) Late term pregnant animal may abort 9) Bulls may undergo temporary infertility

B. Examination of thin blood smears a) Blood should be collected from tip of the ear or tail b) Jugular blood EDTA (1 mg/ml) c) Kept cool (50C)- until delivery to the Lab. (preferably within hours of collection) d) Stain blood films as soon as possible to ensure proper stain definition e) Unstained blood smears should not be stored with formalin solutions as it may affect staining quality

Babesis bigemina parasites in two erythrocytes (top left and bottom right)

Diagram of Giemsa stained Babesia bovis infected erythrocytes.

C. Exam. of P.M. materials Collection of samples from dead animals a) Thin blood films as well as smears from b) Cerebral cortex c) Kidney d) liver e) Lung f) Unreliable if death occurred 24 hours previously

Giemsa stained liver impression smear from B. bovis field case. Note clumping of infected erythrocytes (X1000)

ANAPLASMOSIS • Anaplasmosis – Form of ‘Tick Fever’ • A. marginale, A. centrale (sometimes) • Protozoan Parasite • Family: Anaplasmataceae (Since 1957) • Order :Rickettsiales • Genera : Anaplasma, Aegyptianella Haemobartonenella, Eperythrozoan • Characterized by High fever & progressive anaemia

Transmission • Ticks (Boophilus, Dermacentor, • Rhipicephalus, Hyalomma) • Mechanical transmission – Dipteran Flies • Transplacental Transmission • Contaminated needle

Epidemiology • All ages of cattle may become infected but the severity of illness increases with age. • 6 months to 3 yrs – increasingly ill • > 3 yrs – 30-50% die • After recovery- Chronic • Inadequate treatment – carrier • Carriers rarely become ill in second time • Unidentified carriers – source of infection for future outbreak • Outbreaks related – Lack of control programme, the ratio between anaplasmosis carriers, the amount of vector • Serious illness – with no previous exposure

Diagnosis 1) By clinical symptoms a) In cattle the incubation period varies from 15-45 days or more after tick infection b) Experimentally: C.B. – 24 Days, Indigenous cattle – 29 Days c) High rise of Temp (40.50C) d) Constipation e) Decrease milk yield f) May be abortion g) Anaemic h) Jaundice but no haemoglobinurea 2) Exam. of thin blood smears

Anaplasma marginale in bovine bloodg, located near the margin oferythrocytes.

3) Animal sub-inoculation Test 4) Spleenectomy 5) Serological Tests a) Complement Fixation Test b) Capillary Tube Agglutination Test c) FAT d) Card Agglutination Test e) ELISA 6) PCR

Tick-Borne Diseases: Epidemiology and Diagnosis