The incidence and distribution in Montana and elsewhere, along with the information regarding the spread of the disease.
The virus is excreted 1–2 days before clinical signs are observed. Virus is found in expired air, eye and nose discharges, saliva, faeces, urine and milk. Transmission is mainly through aerosols.
Infection spreads to new areas by movement of infected animals. Recovered animals have a solid immunity and there is no known chronic carrier state. Indirect transmission by clothing, equipment and so on, is unlikely as the virus does not persist in the environment.
The disease occurs in parts of Africa, the Middle East, Pakistan, India and Nepal. An outbreak in Russia was reported to OIE in 1998.
The virus has not become established in either the Americas or Australia/New Zealand.