Foot and Mouth disease
Synonym : Aphthous fever,Aftosa,Enzootic apthiae
Definition
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Acute highly contagious febrile disease of cloven footed animals
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Formation of vesicles in mouth and feet of cattle,sheep, goat and swine
Etiology
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Picorna virus group,
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GENUS-APHTHOUS VIRUS
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Serotypes – O, A,C, and South African type SAT1, SAT2, SAT 3 and Asia 1 of which O,A,C and Asia 1 - prevalent in India
Incubation period/span>
Susceptibility
Transmission
Pathogenesis
Vrius is epitheliotropic
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Virus invades epithelial cells, multiplies resulting in vesicle firmation finally causing focal areas of inflammation
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Invades lymph and blood results in viremia and reaches epithelium of other mucous membrane, interdigital space, dorsum of tongue, gums etc.producing vesicles
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Causes myocardial degeneration in young calves
Clinical signs/span>
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High temperature
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Vesicles appear on mouth
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Rupture leaving ulcer - refuses feed and water
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Vesicles on cleft of feet leading to lameness
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Also seen in lightly haired parts (Udder and teat)
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Produces smacking noise or smacking of tongue
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Drooling of saliva
Gross lesions
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Vesicles on the mucosa of lips, dorsum of tongue and palate in cattle and also in coronet, udder and teat
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Lesions also seen – Rumen, reticulum and omasum
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Haemorrhage and diffuse oedema in mucosa of abomasum and small intestine
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Death may be due to gastroenteritis and myocardial lesions in young calves -"Tigroid heart"
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In sheep: Oral lesions appear on the dental pad only
Microscopic lesions
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Vacuoles appear in the cells of epithelium with eosinophilic cytoplasm and pyknotic nuclei. These small vesicles coalesce to form larger ones and the epithelium gets detached
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Hyaline degeneration and necrosis of myocardial fibres and also in sketetal muscles - "Tigroid heart appearance"
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Secondary bacterial infections produces osteomyelitis and suppurative arthritis
Secondary Effects
Important sequelae of FMD is infertility and decreased production probably due to endocrine damage especially the thyroid gland
Diagnosis
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Last modified: Saturday, 17 December 2011, 9:54 AM