MAD COW DISEASE (BSE): THE SILENT THREAT ILLUMINATED BY SCIENCE

Mad cow disease is a rare yet profoundly instructive condition that challenges the limits of modern medicine and simultaneously concerns biology, food safety, and public health.

Mad cow disease, scientifically known as Bovine Spongiform Encephalopathy (BSE), is a progressive and fatal disease of the central nervous system observed in cattle. The disease causes the formation of “spongy” holes in brain tissue, which is why the term spongiform is used. The most striking feature of BSE is that it is caused neither by bacteria nor by viruses. Instead, the causative agent is a prion, an abnormally folded form of a protein that normally exists in the body. Prions induce healthy proteins to misfold in the same way, triggering a chain reaction of destruction. This process progresses slowly; by the time clinical symptoms appear, brain damage is largely irreversible.

The disease typically begins with behavioral changes: restlessness, sudden fright responses, aggression, balance disturbances, and loss of coordination. Over time, difficulty walking, tremors, and frequent falls increase, and the outcome is most often death. Because BSE has a long incubation period—often lasting years—the disease can enter the food chain unnoticed. This characteristic places BSE at the center not only of veterinary medicine but also of public health. The outbreaks that occurred in Europe during the 1990s fundamentally transformed global feed policies and animal food safety controls. BSE taught us that scientific ethics and biosecurity are indispensable in food production processes.

Prions are fundamentally different from classical infectious agents. They contain no DNA or RNA; they consist solely of protein. Under normal circumstances, prion proteins (PrP) in cells have a specific three-dimensional structure. When this protein misfolds into the abnormal form (PrP^Sc), it forces surrounding healthy proteins to adopt the same abnormal structure. A chain reaction ensues, leading to the accumulation of insoluble protein aggregates in brain tissue. These aggregates disrupt neuronal function and ultimately cause cell death.

Another feature that makes prions particularly dangerous is their extraordinary resistance. High temperatures, radiation, and most chemical disinfectants are ineffective against prions. As a result, standard cooking methods, pasteurization, or sterilization are insufficient. Furthermore, the immune system does not recognize prions as “foreign,” preventing the activation of normal defense mechanisms. In the scientific literature, prions are considered exceptional entities that challenge fundamental assumptions of biology. These characteristics create unique difficulties in both diagnosis and prevention. The nature of prions clearly demonstrates why a preventive approach in food safety is vital.

Yes, mad cow disease can be transmitted to humans. The human counterpart is called variant Creutzfeldt–Jakob disease (vCJD). Transmission is associated with the consumption of prion-containing tissues obtained from infected cattle. Brain, spinal cord, eyes, and certain nervous tissues pose the highest risk. The vCJD cases reported in the United Kingdom during the 1990s provided scientific confirmation of this link.

In humans, the disease typically appears at a younger age, and early symptoms are often psychiatric. Depression, anxiety, and personality changes may precede neurological signs by months. The disease is progressive, and there is currently no known definitive treatment. Therefore, preventing transmission through the food chain remains the only effective means of protecting human health. For this reason, international health authorities have mandated the complete removal of high-risk animal tissues from food and banned ruminant-derived proteins in animal feed. vCJD stands as a striking example of the inseparable connection between animal health and human health.

The symptoms of vCJD in humans differ from those of classical neurodegenerative diseases. In the early stages, psychiatric and behavioral changes are prominent. Depression, anxiety, social withdrawal, difficulty concentrating, and personality changes are common. These features may cause the disease to be initially mistaken for a purely psychological disorder.

In subsequent months, neurological symptoms become more apparent. Loss of balance, difficulty walking, involuntary muscle contractions, speech disturbances, and memory impairment develop. Over time, severe dementia ensues, and the patient becomes unable to perform daily activities independently. The disease is progressive and typically results in death within 12–18 months after diagnosis. This severe clinical course highlights the importance of early recognition and preventive public health measures. As there is no curative treatment for vCJD, management is limited to supportive care aimed at symptom relief.

Diagnosing BSE and vCJD is challenging due to the biological properties of prions. Definitive diagnosis in living individuals is often not possible. In animals, diagnosis is typically established post-mortem through histopathological examination of brain tissue. In humans, magnetic resonance imaging (MRI), electroencephalography (EEG), and the analysis of certain biomarkers in cerebrospinal fluid can support the diagnosis.

MRI may reveal characteristic signal changes in specific brain regions. EEG can show typical wave patterns in some patients, although these findings are not always present. Biomarkers such as the 14-3-3 protein in cerebrospinal fluid may provide supportive evidence. Definitive diagnosis is often confirmed through post-mortem examination. These diagnostic limitations explain why preventive strategies are prioritized in disease control.

Currently, there is no definitive treatment or vaccine for either BSE or vCJD. Existing approaches focus on alleviating symptoms. Pain control, reduction of muscle spasms, and psychiatric support constitute the main components of care. However, these measures do not halt disease progression.

Scientific research is focused on methods to inhibit prion formation or eliminate misfolded proteins. Nevertheless, the biological resilience of prions and their ability to evade the immune system make these efforts particularly challenging. Consequently, the most effective strategy remains preventing the disease from occurring in the first place by blocking transmission.

Scientific evidence indicates that industrial livestock practices played a decisive role in the emergence of BSE. Feeding cattle with protein-rich feed containing tissues from infected animals facilitated the spread of prions. This practice represented a deviation from the natural feeding chain.

This situation revealed how delicate the balance is between economic efficiency and biosecurity in animal production. BSE serves as a historical lesson emphasizing the ethical and scientific oversight required in modern agriculture and livestock systems.

The highest risk for BSE lies in tissues classified as specified risk materials, including the brain, spinal cord, eyes, and certain nervous tissues. Muscle meat is generally considered low risk; however, production processes are strictly controlled to prevent contamination.

In many countries, these high-risk tissues are completely banned from entering the food chain. Slaughterhouses and processing facilities implement measures to prevent cross-contamination. This approach forms a cornerstone of public health protection.

To date, no confirmed indigenous BSE cases have been reported in Turkey. However, the risk theoretically exists due to imported animals and feed. Therefore, the Ministry of Agriculture and Forestry conducts regular surveillance and inspection programs.

Turkey’s status as a “low-risk country” for BSE reflects the effectiveness of strict controls and compliance with international standards. This demonstrates the success of preventive policies.

BSE is not a genetic disease; it is associated with environmental and dietary factors. However, rare genetic forms of prion diseases exist in humans. vCJD, by contrast, is primarily linked to the consumption of contaminated food products.

This distinction is important for accurate genetic counseling and public health planning.

No. Prions are extremely resistant to high temperatures. Normal cooking, frying, or boiling does not inactivate prions. Therefore, “cooking the final product” is not a sufficient protective measure in food safety.

The real preventive strategy lies in preventing risky tissues from entering the food chain in the first place. This reality underscores the importance of every stage of the food production process.

BSE occupies a unique position in food safety due to its long incubation period, diagnostic difficulty, and fatal course. Even a single uncontrolled case can cause widespread public panic and significant economic losses.

For this reason, BSE represents one of the clearest examples of preventive public health. Scientific oversight of the food chain protects not only individual health but society as a whole.

Today, thanks to strict feed policies, comprehensive animal traceability systems, the removal of specified risk materials from the food chain, and robust international surveillance mechanisms, the risk of bovine spongiform encephalopathy (BSE) re-emerging as a major global epidemic is considered quite low. However, this does not mean that the threat has been completely eliminated. The long incubation period of BSE and the extraordinary resistance of prions allow the disease to persist unnoticed for years. The expansion of global food trade, increased movement of animals and feed, and inadequate inspection and record-keeping systems in some countries keep the theoretical risk alive. Moreover, even minor violations in production processes driven by economic pressures could, as seen in the past, lead to cascading consequences. From a scientific perspective, BSE is regarded as being “under control” today, yet experts emphasize that it remains a public health threat requiring continuous monitoring. For this reason, BSE should be viewed as a silent risk in the modern world—one that could return if preventive measures are relaxed.

Ruminants are prohibited from being fed ruminant-derived proteins. Risky tissues are destroyed, animals are registered and monitored, and strict hygiene and traceability rules are enforced in slaughterhouses.

These measures represent a successful example of evidence-based policy making.

Mad cow disease exposed the consequences of humanity’s relationship with nature. Scientific ethics, sustainable production, and the One Health approach gained renewed importance through this disease.

This experience clearly demonstrates that science must guide us to prevent similar threats in the future.