Introduction
⇒ Bovine
theileriosis is a protozoal, tick-borne, diseases, characterized by fever,
hemolytic anemia, and jaundice
⇒ Bovine
Theileriosis is OIE listed diseases
⇒ Two
diseases
East
Coast Fever (east and central Africa)
Tropical Theileriosis (North Africa and central Asia)
Synonyms
⇒ Corridor Disease,
⇒ January Disease
Etiology
⇒ Order: - Piroplasmida
⇒ Family: - Theileriidae
⇒ Genus: - Theileria
⇒ Species: - 2 most important species
Theileria annulata (Tropical Theileriosis)
Theileria parva (East Coast Fever)
⇒ Horses:-Theileria equi (formerly Babesia equi)
⇒ Cattle:-Theileria annulata, Theileria buffeli, T.
parva
⇒ Sheep
and goats:-Theileria lestoquardi
(formerly Theileria hirci)
Host
⇒ Theileria parva: Cattle; African buffalo;
Water buffalo
⇒ Theileria annulata: Cattle; Yaks; Water
buffalo; Camels
⇒ Indignons
zebu cattle (Bas indicus) have resistance to the disease
⇒ Recovered
animals show a solid, long-lasting immunity, but they remain as carriers
Transmission
⇒ Theileria
parva:
Ticks Rhipicephalus appendiculatus and other
Rhipicephalus (ear is the preferred feeding site)
⇒ Theileria
annulata
Transstadially
by the three-host tick Hyalomma anatolicum
⇒ Iatrogenic transmission can also occur through the
blood (e.g., on re-used needles).
Just for information
⇒ Zoite—a
motile, banana- or cigar shaped cell, rounded at one end and pointed at the
other (apical) end
⇒ Tachyzoites:
divide rapidly
⇒ Bradyzoites:
divide slowly
⇒ Trophozoites:
ring stage/ growing stage in the life cycle
⇒ Sporozoites:
Infective forms found in sporulated oocysts
⇒ Schizogony
(synonym, merogony): Process of asexual reproduction during which the nucleus
undergoes division preceding cell division.
⇒ Schizont.
: here multinucleated sporozoan (as a malaria parasite) that reproduces by
schizogony
⇒ Schizogony
that produces daughter cells it is also known as merozoites, which can develop
in to gametocytes or enter new host cells and undergo another cycle of
schizogony.
⇒ Gametocytes
derived from merozoites, are cells that are capable of developing into gametes
Pathogenesis
Infected Ticks Feeding On The Host
And Transmit Sporozoites Within Their
Saliva
⇓
Sporozoites Enter Lymphocytes (T.
Parva) And Macrophages (T. Annulata)
⇓
Infected Lymphocytes Are Transformed Into Lymphoblastic
Macroschizonts Develop In The
Cytoplasm Of The Transformed Cells
⇓
Infected Cells Proliferate, Dividing
Synchronously With Macroschizonts To Infect Daughter Cells (Clonal Expansion)
⇓
Schizont Infected Cells Multiply In
The Lymph Nodes And Disseminate Rapidly In Tissue Like Liver, Kidney, Lung,
Abomasum, And Brain
⇓
Macroschizonts Enter The
Microschizont Stage And Infected Cells
Destroyed
⇓
Merozoites Released And Invade And
Parasitize Erythrocytes (As Piroplasms)
⇓
Possible Mechanisms Of Anemia In
Theileriosis Include
⇓
Invasion Of Erythroid Precursors By
Merozoite Stages And Fission Of The Piroplasm Forms In Erythrocytes
⇓
Associated Erythroid Hypoplasia (As
Occurs With T. Parva Infection)
Immune-Mediated Hemolysis
⇓
Mechanical Fragmentation Because Of
Vasculitis Or Microthrombi
⇓
Enzymatic Destruction By Proteases
Oxidative Damage
⇓
In
The Acute Phase Of The Disease, More Than 60% Of Lymphocytes May Contain
Schizonts, Also Called Koch’s Bodies Or Koch’s Blue Bodies(KBB).
⇒ Lysis Of Lymphocytes And Rbcs Induce
Leukocytopenia And Anemia
⇒ In T.Parva Infection Parasitized
Lymphocytes Localize By Embolism Or Sequestration In Cerebrospinal Vessels And
Produce Hemorrhagic Infarcts → Produced Nervous Signs Like Circling, Hence Also Known As 'Turning Sickness' Or Cerebral Theileriosis
Clinical Signs
⇒ Incubation
Period: 1 To 3 Weeks
⇒ Enlargement
of Lymph Nodes ( Prescapular lymph node)
⇒ Fever, Depression, Dehydration
⇒ Anemia
– Watery Blood; Pale Mucus Membrane
⇒ Icterus, Anorexia
⇒ Nasal
and Ocular Discharge, Corneal Opacity
⇒ Hemoglobinuria(Theileria annulata)
⇒ Splenomegaly with Diarrhaea,
⇒ Turning
Sickness: Circling In Affected Cattle
⇒ Death
Clinical Pathology
⇒ Piroplasms
In Erythrocytes
⇒ Schizonts
In Lymphocytes
⇒ Leukocytopenia
⇒ Thrombocytopenia
Macroscopic Pathology
⇒ Enlargement
of lymphoid tissues with hemorrhages in cortex
⇒ Cerebrum
Acute:
Multifocal infarcts, meningocerebral congestion, hemorrhage, and thrombosis, yellowish discoloration of brain,
intraventricular hemorrhage
Chronic:
Resorption of necrotic tissue results in
intracerebral cystic spaces
⇒ Splenomegaly
in acute cases; shrunken spleen with chronicity
⇒ Ulcerative
abomasitis; erosive or catarrhal enteritis
⇒ Small
gray-white patches (“pseudo-infarcts”) on surface of liver and kidney that
bulge slightly (proliferative foci of perivascular lymphocytes)
⇒ Severe
pulmonary edema and congestion; copious froth in airways; hydrothorax and hydropericardium
Microscopic pathology
⇒ Lymphoid organs: In early stages, there is diffuse
lymphoid hyperplasia; with progression, there is a general loss of small
lymphocytes which are replaced by numerous parasitized lymphoblasts containing
intracytoplasmic schizonts (Koch’s blue bodies)
⇒ In terminal stages, there is widespread, prominent
lymphocytolysis, especially within germinal centers that is accompanied by
hemorrhage and fibrinous exudate within the cortex of lymph nodes
⇒Lymphocytic infiltrates in liver and kidney
⇒ Lung: Severe pulmonary edema and lymphoid
infiltration of the alveolar septa
⇒ Bone marrow: In terminal stages, marrow is hypoplastic,
and the remaining cells consist of parasitized, blastic lymphocytes
⇒ Turning sickness: Hemorrhagic infarcts in
brain and spinal cord due to thrombi containing parasitized lymphocytes
Diagnosis
⇒ Blood smear examination
⇒ Lymph node aspirate examination
⇒ PCR
⇒ ELISA
⇒ Indirect fluorescent antibody (IFA) tests
Treatment
⇒ Buparvaquone (2.5 mg/kg IM, 2 doses 48 hours apart)
⇒ Parvaquone (10 mg/kg IM 2 doses 48 hours apart)
⇒ Halofuginone lactate (1.2 mg/kg PO)
⇒ Oxytetracycline (20 mg/kg IM)
Control
⇒ Vaccination by infection and treatment method using tetracycline or parvaquone
⇒ Vaccination
by infection with low pathogenicity isolate
Post a Comment