Anthrax is a serious disease that’s rare in humans, but earlier this year an unexpected outbreak occurred when a Texas rancher picked up the bug. The Centers for Disease Control and Prevention (CDC) have now detailed the circumstances behind the event that made it what they describe as “unusual”.

It began when a male in his 50s presented to his GP with a soft tissue infection and was sent home with a course of antibiotics. The infection, however, didn’t go away; three days later, he was sent to hospital after developing a fever, blisters, and a black piece of dead tissue characteristic of an anthrax infection.

After being sent to a larger hospital, swabs of the wound then tested positive for the DNA of Bacillus anthracis, the bacterium that causes anthrax. Though the skin form of the disease can be fatal if left untreated, the rancher was successfully treated and discharged from hospital a week after being admitted.

So what was the source of his infection? The clue is in his job.

Anthrax is zoonotic, meaning it can be passed from animals to humans. While such cases are rare on the whole, there’s a region of Texas known as the “Anthrax Triangle” where it’s considered to be enzootic, a disease that’s constantly present in animals – essentially their equivalent of endemic. The case in question occurred on a ranch in a county adjacent to the triangle.

Outbreaks in this region usually occur sporadically in the summer months when there’s hot, dry weather, followed by human cases. What made this case particularly “unusual”, as the CDC described it, was that the rancher turned up in hospital in January.

Upon investigation, it was suspected that the source of the infection had been a lamb on the ranch that had died suddenly, 11 days prior to the rancher winding up in hospital. After the rancher butchered the lamb, its meat was then cooked and eaten by himself and four others.

With only the rancher becoming ill, it’s likely that the man picked up the skin infection handling the lamb, as he’d reported not using any personal protective equipment to do so. 

Although no one else got sick, the CDC reported that cooked meat from the lamb that had been frozen did test positive for B. anthracis and cautioned that “there is no safe way to prepare meat for human consumption from an animal that has died of anthrax.”

“Processing animals that die suddenly from unknown causes should be avoided, irrespective of the season.”