Foot and Mouth Disease

This is a power point presentation for FMD

1. FOOT & MOUTH DISEASE ABHIJITH SP CVAS, POOKODE

2. FOOT & MOUTH DISEASE Highly contagious febrile infectious viral disease of many wild and domestic cloven footed mammals. Formation of vesicles in the epithelial tissue especially in squamous epithelium (Stratum spinosum is involved). Vesicles are formed in lips,muzzle,tongue,udder, fore-stomach, interdigital space, coronary band of feet, teats etc. Low mortality, but high morbidity

3. Etiology Agent- Picornaviridae family-Aphthous virus genus—FMDV Seven immunologically different serotypes- O,A,C, Asia –I, SAT- I, SAT-II & SAT-III ( Different antigenic subtypes under each serotype, no cross protection hence vaccination failure is common) O,A,C, Asia –I – Asian countries SAT- I, SAT-II & SAT-III O,A,C, SAT- I, SAT-II & SAT-III – African countries Synonyms-Aphthous fever, Panters In India after 1995, strain C was absent.

4. Susceptible Host Cloven footed animals- ruminants, pigs etc. Cattle is most affected Cattle- Indicator host Pigs – Replicator host, Amplifier Host Goats & Sheep- Maintenance host

5. Route of infection Ingestion of feed and water contaminated by infected material like saliva, urine, feces, milk and discharges from lesions of infected animal. Inhalation as virus will be present in the exhaled air ( Esp. in pigs) and carried as aerosols ( Via dust) Contact with contaminated bedding materials and other fomites Rapid spread due to small size of virus

6. INCUBATION PERIOD OIE recognizes IP as 2-14 days. The viral dose, susceptible species, and route of infection all influence the speed with which signs of illness appear. Also IP varies according to the serotypes. OIE List A Disease

7. Pathogenesis Through inhalation or ingestion, virus get into the body of animal. Initial replication in the pharyngeal lymphoid tissue or tonsils and they replicate in the lymph node. They move to lymphatics and through veins they get into systemic circulation. Now its viremia stage (Virus in blood). Since it is epitheliotropic, localization in the regions of epithelial tissues of mouth, skin and feet and in organs like mammary gland, lymph nodes, thyroid glands, adrenals etc. Second phase of replication in areas of localization and forms lesions. Recovered animals may become panters because thyroid is affected and BMR is altered.

8. Clinical signs Onset of disease is by sharp rise of temperature (104 to 106). Anorexia, Sudden drop in milk yield. Formation of vesicles- inner lips, cheeks, gums, hard palate, dental pad, sides and dorsum of tongue, muzzle, external nares, interdigital cleft, coronary band, teats etc. Usually, Blisters produce secondary bacterial infection. Smacking of lips, Grinding of teeth, Drooling of saliva, Kicking of feet etc. (due to blisters) Loss of heat control (panters)

9. Clinical signs Vesicles in mouth causes excess salivation – Stringy/ ropy salivation. Lameness due to foot lesions, hooves may slough off. Mastitis will occur if teats are affected. Pregnant animals may abort. Islets of pancreas can get affected leading to diabetes mellitus. High Mortality occurs in pigs. Blister are common in snout region for pigs. Since vesicles occur at pressure points in pigs-Knuckling. In cattle, Milk may have virus up to 3 months

10. Gross lesions In the oral cavity, there is buccal hyperemia with development of vesicles on inner lips, cheeks, gums, hard palate, dental pad, sides and dorsum of tongue and muzzle. Foot lesions are also in the form of vesicles in the interdigital cleft and coronary band. In udder, vesicles may form on teats and they may burst. Sometimes the epithelium sloughs off forming ulcers with raw red bases. Mottled myocardial lesions. Thyroid atrophy. Myocardial hemorrhage. Fluid presence in myocardium.

11. Gross lesions In young animals/ calves, FMD is characterized by grayish white streaks on the ventricular and papillary musculature and septal wall especially of left ventricle – TIGROID HEART due to special pattern in ventricular musculature. Cause of Death in Suckling calves-Acute Myocarditis.

12. Microscopic lesions Cells of stratum spinosum are affected, virus replicate in the cytoplasm. Ballooning/ Hydropic degeneration, spongiosis, acantholysis, finally forming vesicles. Roof of the vesicle- Stratum granulosum, lucidum and corneum, Base- Stratum germinativum Vesicles coalesce and form bullae. Sometimes the epithelium sloughs off forming ulcers. Lesions in mouth can be described as vesicular & ulcerative stomatitis.

13. Microscopic lesions In young calves- Hyaline degeneration and necrosis of myocardial fibers with large numbers of infiltrating lymphocytes and a very few neutrophils – Mononuclear/lymphocytic and necrotizing myocarditis No inclusion body formation. Microscopic image of calf ’s heart (“tiger-heart”) from a calf that died from an acute form of FMD, showing severely affected muscle fibers with coagulative necrosis), with infiltration of lymphocytes. (PAS stain, 600x)

14. Diagnosis Tentative Diagnosis: History, Clinical Signs, Details from owner . Laboratory Diagnosis : Swab Test-Swabs from mucosal eruptions and Pharynx are taken and cultured to check the presence of virus. Complement Fixation Test Virus Neutralization Test PCR,RT-PCR, ELISA, Electron Microscopy.

15. Differential Diagnosis 1.Vesicular Stomatitis 2.Rinderpest 3.Blutongue 4.Malignant Catarrhal Fever

16. Prevention and Control Proper Hygiene measure should be practiced. Vaccination should be properly practiced. Ring Vaccination is practiced Vaccine: Raksha “O”VAC Vaccination started at 4 months of age.

17. Special Points 1.Most Common strain-O 2.Immunogenic viral polypeptide-VP1 3.Cause of death in neonates-Acute myocarditis. 4.Size of virus-very small (Pico) 5. Semen and Urine can also carry virus, so during mating it can be spread. 6.It is a zoonotic disease with very little problems in human.

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