For the first time in more than 30 years an outbreak of anthrax has been
confirmed among cows in Logan County in northeastern Colorado. Last
week 60 cows died on one ranch where one of the cows had testedCows (Public Domain Image)Cows (Public Domain Image) positive
for the disease. Authorities are fairly sure that the rest of the cows
also contracted the disease and succumbed soon after.

Two additional cows have tested positive on adjacent ranches. The animals all were likely to have ingested the disease by grazing in areas where anthrax spores were present in the soil. 

Anthrax is an acute disease caused by the bacterium Bacillus Anthracis. It forms as endospores (or spores for short) and can lie
dormant in soil for decades and possibly even centuries until ingested. These hardy spores are found on all continents, including Antarctica. Humans get anthrax most
commonly by contact with an infected animal while having an open sore or other wound. Without treatment it can
be fatal, but early treatment with antibiotics is very effective.

Bacillus Anthracis (Public Domain Image)Bacillus Anthracis (Public Domain Image)The Colorado Health Department is working to ensure that anyone at risk from possible exposure is receiving treatment. This includes farm workers, farmers, and anyone involved in the cow necropsies at Colorado State University.

The carcasses of the deceased cows have been incinerated. Fire is the only way to ensure that the spores are destroyed. Areas where infected animals have been buried have been known to remain infectious for decades. Animals that have not been infected are being vaccinated to prevent the illness from further destruction of cattle in the area. 

It is not clear why anthrax has surfaced after no reported cases
in decades. The ranches
are located in the South Platte River Valley where floods followed by drought
are common and the region has alkaline soil types. These are conditions conducive to anthrax spores.

None of the animals on any of the ranches involved have left the ranches to enter the food supply.

Sources: ABC News, Wikipedia