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Mannheimia: New Disease or Old Enemy?

Livestock Update, September 2000

Dr. John Currin, Extension Veterinarian, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech

How many cattle producers have heard of Mannheimia? If you haven't chances are you will soon be running across it in either an article from a popular farm magazine or on a drug or vaccine bottle. Mannheimia is not a new disease causing organism but rather a bacteria that has been around for a long time: Pasteurella haemolytica the major cause of shipping fever.

Bacteriologists have begun to use DNA typing, a technique similar to the DNA tests police use, as a means of classifying bacteria that have been thought to be the same bacterium. For several years we have thought that cattle carry a certain type of Pasteurella haemolytica as part of the normal bacteria of the upper respiratory tract (nose and throat). Only when the cattle were stressed in some way did this Pasteurella undergo changes and move down to infect the lung. It now looks like there are two separate bacteria involved; Mannheimia glucosida, a part of the normal flora of the upper respiratory tract and Mannheimia hemolytica the primary pathogen that causes the severe pneumonia of Bovine Respiratory Disease Complex (shipping fever).

There are three important issues to understand. First, when you read an article or a label on a bottle understand that Mannheimia hemolytica is basically the same bug as the Pasteurella haemolytica with which you are more familiar. Second, current recommendations have not changed for controlling and treating this disease. Third, our understanding of this family of bacteria is increasing which will hopefully lead to better control measures for this disease that is of such economic significance to both beef and dairy cattle producers.

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