Agricultural Disaster Preparedness and Recovery November 04, 2011 Print Friendly and PDF

Maedi-visna, or ovine progressive pneumonia, is an infectious viral disease of sheep and goats. The disease can take two forms, which get their names from the Icelandic words for difficulty breathing (maedi) and wasting (visna).

The maedi form is the most common manifestation of the disease. It affects the lungs and causes difficulty breathing. The visna form is rare. It affects the central nervous system. Both forms of the disease are fatal.

The maedi-visna virus is transmitted most often from ewe to lamb through ingestion of milk or colostrum contaminated with the virus. It is also believed that the virus can be transmitted among adult animals through inhalation of virus or ingestion of feces-contaminated water.

Maedi-visna is an economically significant disease due to premature culling of animals and export restrictions.


Endemic Areas

The maedi-visna virus is found worldwide. Only Australia, New Zealand and Iceland are considered free of the disease.


Clinical Signs


  • Increasing difficulty breathing
  • Coughing
  • Nasal discharge
  • Enlarged, firm udder with little or no milk



  • Hindlimb weakness
  • Incoordination
  • Muscle tremors
  • Progressive paralysis
  • Weight loss



There is no specific treatment for maedi-visna, and the mortality rate approaches 100 percent. Any animal suspected of having maedi-visna should be reported to the State Veterinarians or USDA Area Veterinarian in Charge immediately.



Maedi-visna can be prevented by following sound biosecurity practices, including quarantining animals of unknown health status and feeding newborns colostrum and milk known to be free of the virus.


Public Health

Maedi-visna is not a public health threat.



Maedi-Visna -Iowa State University

Connect with us

  • Twitter
  • Facebook
  • YouTube
  • Pinterest
  • Google+


This is where you can find research-based information from America's land-grant universities enabled by



This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.