Measles is an example of extremely contagious acute respiratory viral infection. It is caused by a specific morbillivirus of a single serotype. Measles is a human illness that usually affects children. It is spread by airborne and droplet routes with an incubation period of 10–12 days.
The virus replicates in respiratory tract epithelium and moves to regional lymphatic nodes (primary viremia). After second propagation in the lymphoid tissue, it spreads throughout the body penetrating endothelium of vessels and epithelial cells in the skin, conjunctiva, respiratory tract, and oral cavity.
Characteristic lesions of the oral cavity in measles are known as Filatov’s-Koplik’s spots. They appear upon the buccal mucosa two to three days earlier than the measles rash. The spots are the sites of intensive viral replication with the formation of giant cells.
Koplik’s spots can be discerned as firm white lesions on the buccal epithelium opposite to the lower 1st and 2nd molars. They are highly specific for the disease, sometimes described as “grains of salt on wet background”.
As Koplik’s spots emerge at the beginning of measles, their discovery makes possible timely isolation of contact individuals thus preventing further disease spread. Laboratory examination is necessary mainly for diagnosis of unclear measles cases