Hidden Danger in Cattle? Shocking Differences Between Classical and Atypical BSE Revealed in New Scientific Review!

 

Classical and Atypical Bovine Spongiform Encephalopathy: An Updated Comparative Review

 

Pudjiatmoko

Member of the Nanotechnology Technical Committee, National Standardization Agency, Indonesia

 

ABSTRACT

Bovine Spongiform Encephalopathy (BSE) comprises two epidemiologically distinct forms: classical BSE, transmitted primarily through contaminated feed, and atypical BSE, a sporadic neurodegenerative condition occurring naturally at very low frequency in older cattle. This review synthesizes current scientific knowledge regarding their origins, epidemiological behavior, detection patterns, and public health implications. Evidence shows that classical BSE incidence has declined to negligible levels following global feed bans and enhanced surveillance, while atypical BSE appears to arise spontaneously and remains extremely rare. Understanding these distinctions is crucial for maintaining effective surveillance and safeguarding public health.

 

1. INTRODUCTION

Bovine Spongiform Encephalopathy (BSE) is a fatal transmissible spongiform encephalopathy (TSE) of cattle caused by misfolded prion proteins. Since its initial emergence in the 1980s, BSE has generated global concern due to its zoonotic potential, particularly its causal association with variant Creutzfeldt–Jakob Disease (vCJD) in humans (WHO, 2002; Prusiner, 1998). Two distinct forms of the disease are now recognized: classical BSE, associated with feedborne transmission, and atypical BSE, believed to arise spontaneously in aging cattle (Biacabe et al., 2004; WHO, 2012). This review presents a comparative analysis of both forms using recent epidemiological data and surveillance findings.

 

2. METHODS

This narrative review synthesizes current international literature and official surveillance reports concerning BSE. Literature was identified through searches of PubMed, Scopus, and Web of Science using the terms classical BSE, atypical BSE, prion disease, H-type BSE, L-type BSE, and TSE surveillance. Additional authoritative sources included documents from the World Organisation for Animal Health (WOAH/OIE), the World Health Organization (WHO), and the European Food Safety Authority (EFSA). Reference lists of key articles were screened to identify further relevant materials. Only peer-reviewed articles, official reports, and globally recognized scientific assessments were included.

 

3. RESULTS

3.1 Classical BSE: Origin and Epidemiological Characteristics

Classical BSE is primarily associated with the consumption of feed containing mammalian meat-and-bone meal contaminated with infectious prions (WHO, 2002; WOAH, 2018). This form was responsible for the major epidemic observed in the United Kingdom and other countries during the 1990s. Following implementation of strict control measures—including feed bans, specified risk material (SRM) removal, and intensive surveillance—incidence has declined sharply. Current surveillance data indicate that classical BSE occurrence is now extremely low, with many countries reporting zero cases for several consecutive years (EFSA, 2021; WOAH, 2024).

3.2 Atypical BSE: Molecular and Epidemiological Features

Atypical BSE differs markedly from the classical form. Classified into H-type and L-type based on molecular banding patterns, it is considered a naturally occurring, sporadic condition that arises in older cattle at a very low frequency (Biacabe et al., 2004). Epidemiological evidence indicates that atypical BSE is not associated with feedborne transmission and has never been linked to widespread outbreaks (WHO, 2012). Most detected cases originate from active surveillance involving fallen stock and older animals.

3.3 Detection of Atypical Prion Strains in the Early 2000s

The identification of atypical BSE emerged during the early 2000s as many countries expanded and intensified TSE surveillance programs. These enhancements facilitated the detection of rare prion variants distinct from the classical strain (WOAH, 2018). The number of atypical BSE cases remains negligible compared with classical BSE, reinforcing the hypothesis of sporadic origin and minimal risk of large-scale transmission (EFSA, 2021).

 

4. DISCUSSION

This review highlights clear epidemiological distinctions between classical and atypical BSE. Classical BSE is a feedborne disease that caused major global epidemics but has been effectively controlled through strict regulatory and surveillance measures. Its current incidence—approaching zero in many regions—demonstrates the long-term success of these interventions.

In contrast, atypical BSE appears to occur spontaneously in aging cattle and is detected only at very low frequency. Its sporadic nature, combined with the absence of feedborne spread, suggests a fundamentally different pathogenesis. Although both forms involve misfolded prion proteins, their transmission dynamics and public health implications differ significantly.

Enhanced surveillance remains crucial for early detection of both forms, especially atypical BSE, which can only be captured through systematic monitoring of older cattle populations. Continued vigilance is essential to prevent re-emergence of classical BSE and to improve understanding of the biological origins of atypical prion diseases.

 

5. CONCLUSION

Classical and atypical BSE represent two distinct prion disease entities with different origins, epidemiological profiles, and risks. While classical BSE has been nearly eradicated through comprehensive feed controls, atypical BSE persists at a very low sporadic rate. Maintaining robust surveillance systems is key to sustaining progress in BSE control and safeguarding both animal and human health.

 

REFERENCES

Biacabe, A.-G., Laplanche, J.-L., Ryder, S., & Baron, T. (2004). Distinct molecular phenotypes in bovine prion diseases. EMBO Reports, 5(1), 110–115.

EFSA Panel on Biological Hazards (BIOHAZ). (2021). Scientific opinion on the BSE surveillance system in the EU. EFSA Journal, 19(6):e06629.

Prusiner, S. B. (1998). Prions. Proceedings of the National Academy of Sciences, 95(23), 13363–13383.

WHO. (2002). Bovine Spongiform Encephalopathy (BSE): Public Health, Animal Health and Trade. World Health Organization.

WHO. (2012). Transmissible Spongiform Encephalopathies (TSEs): A Summary of Surveillance and Epidemiological Findings.

WOAH (formerly OIE). (2018). Terrestrial Animal Health Code: Bovine Spongiform Encephalopathy.

WOAH. (2024). WAHIS: BSE Reports and Global Status Overview.

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