This photomicrograph depicts FMD virus (stained black-brown) within epithelial cells surrounding a vesicle.
| Pathogenesis: | |
| Under natural conditions, the most common form of transmission is by aerosol, with infectious particles exhaled by an animal in the acute phase of the disease being carried on the air to the respiratory tract of a susceptible animal. | |
| The incubation period from point of contact to observable disease is 2-8 days.The virus first replicates in the pharyngeal tissue and/or lung. Twenty-four to 72 hours later, there is a high titered viremia, with dissemination to and replication in stratum spongiosum at multiple epithelial sites. | |
|
Vesicles develop as the virus grows within a group of
contiguous epithelial cells, rupturing them, and creating a large lake of fluid within the
epithelium. This vesicular fluid contains abundant viral particles and the virus persists
in the surrounding cells for 3-8 days, diminishing at about the same time antibodies
develop. This photomicrograph depicts FMD virus (stained black-brown) within epithelial cells surrounding a vesicle. |
| Replication in mammary gland epithelium occurs as well, and the virus can be detected in milk for at least 10 days post-exposure at which point antibodies have been produced which neutralize the virus. | |