Montana cow tests positive for brucellosis

Montana officials said Monday that a cow has tested positive for brucellosis -- a serious livestock disease that had been declared nonexistent in U.S. cattle earlier this year.

The infection means Montana ranchers must undergo an expensive testing program before shipping cattle out of state and will have to increase vaccinations. The state will lose its federal brucellosis-free status until it can demonstrate it has the disease under control.

Brucellosis is a disease carried by wild animals including bison and elk in the greater Yellowstone area. It can cause pregnant cows to abort their calves but transmission to humans is rare.

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In February, the U.S. Department of Agriculture declared all 50 states to be brucellosis-free in their commercial herds -- the first time that had happened in 74 years.


chicagotribune.com

Biological warfare

In 1954, B. suis became the first agent weaponized by the U.S. at its Pine Bluff Arsenal in Arkansas. Brucella species survive well in aerosols and resist drying. Brucella and all other remaining biological weapons in the US arsenal were destroyed in 1971-72 when the U.S. offensive biological weapons (BW) program was discontinued. <10>

The United States BW program focused on three agents of the Brucella group:

* Porcine Brucellosis (Agent US)
* Bovine Brucellosis (Agent AB)
* Caprine Brucellosis (Agent AM)

Agent US was in advanced development by the end of the Second World War. When the USAF wanted a biological warfare capability, the Chemical Corps offered agent US in the M114 bomblet, based after the 4-pound bursting bomblet developed for anthrax in the Second World War. Though the capability was developed, operational testing indicated that the weapon was less than desirable, and the USAF termed it an interim capability until replaced by a more effective biological weapon. The main drawbacks of the M114 with agent US was that it was incapacitating (the USAF wanted "killer" agents), the storage stability was too low to allow for storing at forward air bases, and the logistical requirements to neutralize a target were far higher than originally anticipated, requiring unreasonable logistical air support.

Agents US and AB had a median infective dose of 500 org/person, and AM was 300 org/person. The rate-of-action was believed to be 2 weeks, with a duration of action of several months. The lethality estimate was based on epidemiological information at 1 - 2%. AM was always believed to be a more virulent disease, and a 3% fatality rate was expected.

http://en.wikipedia.org/wiki/Brucellosis