A rare disease that is 100% fatal once symptoms appear has been detected in a cow at a farm in the Netherlands. Worryingly, the disease can be passed to humans when they eat beef of cows contaminated with the disease.

The disease called bovine spongiform encephalopathy (BSE) or more commonly as mad cow disease has been reported in the country for the first time in over a decade.

Authorities believe that the cow is not a threat to human health as it was caught before it entered the food chain. However, they are on the lookout for other animals that have come in contact with the cow or were infected by the same source.

“Offspring, and animals that have had the same feed, and animals that have grown up with this bovine are being tracked down, tested for BSE,” and will be put down, Agriculture Minister Piet Adema said, the NL Times reported. “There is a chance that other cattle have also eaten this feed and become infected from it. In that case, measures must be taken to manage risks to food safety and public health.”

BSE is a type of prion disease infecting cows. Prions are the misfolded forms of naturally occurring proteins. Often found in the brain, these unnatural proteins convert normal proteins when they encounter them. The result is a cascading effect that damages the brain eventually. While different incubation periods exist depending on the disease, currently, all prion diseases are 100% fatal once symptoms appear, according to Gizmodo.

The BSE equivalent in humans is Creutzfeldt-Jakob disease or CJD. Most cases of CJD occur sporadically, usually in later life. Yet other forms of the disease can occur as a result of inherited mutations or contaminated surgical equipment or during certain procedures of organ donation. But it is the form of the disease called variant CJD, which is caught by eating beef contaminated with BSE.

This is not our first encounter with the deadly disease.

Hundreds of people developed variant CJD in the 1980s and 1990s from contaminated beef. Interestingly, most of these cases were in the UK. The outbreak is believed to have been caused due to the practice of feeding cows the meat of other infected cows or even from sheep infected with the prion disease called scrapie, as per the outlet.

After prominent bans on British beef, as well as changes in feeding and slaughter regulations, mad cow disease incidence had decreased by the mid-1990s. Large-scale outbreaks of either BSE or variant CJD have not occurred since then. But BSE can still spontaneously occur in cows on farms, in which case containing it becomes a priority.