Synonyms and introduction

INTRODUCTION

Synonym
  • Aphthous fever, Epizootic aphthea, Aftosa, Fast Moving Disease

Introduction

  • Foot and Mouth Disease (FMD) is an acute, febrile, highly contagious disease of almost all cloven hoofed animals characterized by the formation of vesicles (fluid-filled blisters) and erosions in the mouth, nose, teats and feet with high morbidity and low mortality.
  • The causative agent is Apthovirus, is an infectious, positive sense, ss-RNA virus. There are 7 serotypes of the virus: Types O, A, C, South African Territories 1, 2 and 3 (SAT-1, -2, -3) and Asia-1. Large numbers of subtypes were also identified.
  • In our country only four major serotypes, O, A, C and Asia 1 are known to occur. Among which A 22, A 5 & A 10 subtypes are more commonly occur.
  • Infection with one serotype does not confer immunity against another. This disease occurs naturally in cloven-hoofed animals (Both domestic and wild animals).
  • Cattle are most susceptible followed by pigs and the disease is rare in sheep and goats. Several wildlife species including African buffalo, elephants, hedgehogs, deer and antelopes are also susceptible. Man may contact the disease with mild symptoms such as vesicles on the hand.
  • Horse is refractory to Foot and Mouth Disease virus (FMDV) infection.
  • The healthy animals are infected by contact with the secretions and excretions of the FMD affected animals.
  • The main route of transmission is by inhalation and aerosol route. In addition to inhalation, transmission also occurs by direct or indirect contact with infected animals such as through abraded skin, conjunctiva, ingestion of contaminated garbage, inoculation with contaminated vaccines and insemination. Mechanical transmission may also occur with wild animals, birds and other non-susceptible domestic animals.
  • The virus grows very well in cell cultures.
  • The cell cultures that are commonly used are primary bovine tongue epithelium or bovine thyroid cells, primary pig kidney, calf kidney and lamb kidney cells.
  • Cell lines such as Baby Hamster Kidney-21 (BHK-21) and IB-RS-2 cells are highly suitable. Most strains of the virus multiply to produce cytopathic effect within 24-48 hrs. This virus is highly cytolytic. Guinea pigs, suckling mice, hamsters and rabbits are used as experimental animals . Some strains grow in embryonated eggs (14 days old). Route is chorioallantoic membrane or intravenous route.
Last modified: Sunday, 3 June 2012, 6:51 AM