Babesia bigemina - Pedigogy

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Babesia bigemina

Introduction

These parasites are found to erythrocyte of cattle.
It causes cattle tick fever, red water disease or protoplasmosis in cattle and buffalo.
Earlier, it was called ‘Texas fever’ in North America.
Distributed widespread throughout tropical and sub-tropical areas.

Morphology

Large, pleomorphic Babesia but characteristically seen and identified by pear-shaped bodies joined at an angle within mature erythrocytes.
Round form measure 2 µm and pear-shaped elongated ones are 4-5 µm.
Erythrocytic stages lack conoid, micropores and typical mitochondria, but have anterior and posterior ring and typically two rhoptries ( Specialized secretory organelles characteristic of motile stage of Apicomplexa protozoans).

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Life-cycle

Transovarian transmission is seen in tick host.
Transmission is through various species of ixodid ticks: Boophilus annulatus, micropkus, B. australis, Rhipicephalus appendiculatus, R. bursa, R. evertsi.
Infection acquires through tick
Multiplication in host and form trophozoite
Trophozoites release infected cells and invade other new cells.
After repeated multiplication, gamonts forms.
Gametes taken by tick
Invades gut of tick and multiplies
Fusion of gamete to form zygote
Vermicules released and invade ova of egg and gut epithelium of larva
Transfer to salivary gland during tick development.

Pathogenesis

Due to repeated multiplication inside erythrocyte of vertebrate, there is rapid destruction of erythrocyte. This results in hemoglobinemia, Hemoglobinuria and fever.
Not as much virulent as bovis.

Clinical signs

Calves are relatively resistant to infection and do not show clinical signs
Clinical signs are severe in adult animals.
Fever is first sign with temperature reaching 41.5⁰C (106.7 ⁰F). During early phase of fever, blood smears show parasllemia.
Anorexia
Ruminal atony
Animal isolates themselves from herd, becomes uneasy , seeks shade and lie down.
Cattle stand with arched back, have roughened hair coat and shows dyspnoea and tachycardia.
Mucous membrane is first inflamed and reddened but as erythrocyte lysis occur, they become pallid and shows signs of anemia. Anemia is hyperchromic, normocytic anaemia.
Death may occur due to destruction of large number of RBCs because of autoimmune mechanism, cerebral anoxia and accumulation of toxic byproducts.
In chronic infection, animal lose condition rapidly and remain thin, weak and emaciated for weeks.

PM findings

Subcutaneous and intramuscular oedema.
Icterus; pale yellow to distinct yellow discoloration of subcutis
Swelling and congestion of internal organs.
Ecchymotic hemorrhages in serosal surface of intestine.
Marked enlargement of spleen
Enlargement of liver with pale appearance
Distension of gall bladder.
Lymph-node enlargement.
Urinary bladder are congested and enlarged containing reddish brothy fluid and perivascular, perineuronal and interstitial oedema throughout brain and spinal cord.

Diagnosis

History and clinical signs of fever, anemia, jaundice and hemoglobinuria in cattle located in enzootic areas where Boophilus ticks occur are usually sufficient to justify the diagnosis.
Confirmatory diagnosis is through examination of blood smear with a Giemsa stain. This examination reveals parasite in red cells.
In chronic case, diagnosis is made through serological tests by detection of specific Ab, CFT, IFA, agglutination test can be done.

Treatment

Treatment success depends on early diagnosis and administration of effective drugs.
Trypan blue is one of the effective drug used in babesiosis, bigemina is susceptible.
Diminazene diaccoturate @ 3-5 mg/kg, imidocarbe @ 1-3 mg/kg, amicarbalide @ 5-10 mg/kg.

Immunoprophylaxis

Premunity occurs. Premunity is host response that protects against high numbers of parasites and illness without eliminating the infection.
Animal recovered from disease remain immune to reinfection for more than a year.

Prevention and control