COUNTRIES detecting rare cases of atypical bovine spongiform encephalopathy (BSE) in cattle are no longer obliged to report the incidents to the international animal health authorities.

The World Organisation for Animal Health (WOAH) has removed atypical BSE from its list of diseases that require a compulsory worldwide notification.

Reports of atypical (spontaneous) BSE cases are now rare, but still occur. The US reported a case last month, it’s seventh overall in the past 20 years and the first since 2018. The UK and Switzerland also reported single atypical cases earlier this year – both picked up in routine screening. In February, Brazil reported an atypical case, leading to a month-long suspension from key export markets including China.

In its recent decisions, the WOAH also made changes to the complete disease risk assessment, including entry and exposure assessments, to determine the risk status of a country or a zone for BSE.

It also made allowance for a simplified surveillance to “better match with the reality in the field,” while ensuring that minimum sanitary requirements are put in place by countries.

In a statement, the WOAH said the new BSE standards were not expected to impact the already recognised official BSE risk status of member countries.

“Thanks to the successful implementation of effective control measures, BSE has turned from a public health emergency of international concern to a disease with contained presence and sanitary impact,” the organisation said.

What is the impact of BSE today?

Dr Cristóbal Zepeda, president of the WOAH’s Scientific Commission for animal diseases and Dr Etienne Bonbon, president of the Terrestrial Animal Health Standards Commission provided comment.

“At the beginning of the BSE epidemic in the late 1980s and early 1990s, the majority of cases were detected in a few countries, most predominantly in Europe,” Dr Zepeda said.

“Today, the incidence has dropped to nearly zero, as most countries have implemented measures to avoid the recycling of specified risk materials,” he said.

Dr Bonbon said in the past, the uncertainty around the epidemiology of BSE justified an important level of precaution taken to handle the disease.

“Today, its quasi-zero incidence worldwide minimises the risk of disease and calls for a different level of precaution to face a novel scenario,” he said.

The standard on BSE was updated to align it with the current scientific knowledge and an evolving epidemiological context.

Several changes were proposed – the first covering the need for a complete disease risk assessment, including entry and exposure assessments, to determine the risk status of a country or a zone.

The second allowed for a simplified surveillance to better match with the reality in the field, while ensuring that minimum sanitary requirements are put in place by countries.

Dr Zepeda said the cost of implementing a point-based surveillance system was significant and some countries with small cattle populations simply could not comply with such requirements. Guidelines had been developed to support countries in the transition to this new system.

Explaining the decision to remove atypical BSE from the list of diseases which require a compulsory notification to WOAH, Dr Zepeda said atypical BSE occurred spontaneously in cattle populations at a very low rate.

“In addition, the only evidence of potential recycling of specified risk materials was found under experimental conditions that would be extremely unlikely to be replicated under field conditions,” he said.

“Atypical BSE has been delisted also because it was found to be a very rare and sporadic condition, with no significant impact on animal or public health.”

Dr Bonbon said the justified simplification and cost reduction of surveillance methods would not lead to a reduction in their effectiveness. Rather, this more flexible system based on field clinical screening reflected current scientific information and responds to a diversity of needs across countries.

“The achievement made with the BSE standard is the result of a multi-step process which involved many dedicated expert discussions and extensive consultations with members. It shows how the different governance bodies work at the Organisation, and highlights the role of the Specialist Commissions in the process.

“These Commissions play a key role to ensure that the standards are scientifically sound, and to build a common understanding trough consultation with Members.

What will the impact of this new standard be on international trade?

Dr Zepeda said the changes in the surveillance requirements would provide an incentive for countries that have not gained an official risk status to apply for one. By removing atypical BSE as a listed disease, countries will not impose unwarranted trade restrictions, he said.

“With the adoption of the revised standard, the benefits will be much higher than any risks of disease introduction or emergence,” Dr Bonbon said.

“If it is well applied, access to trade will be facilitated thereby accelerating economic development, food security will be improved, while the likelihood of new BSE cases will continue to decrease.”

A growing number of countries (including Australia, which has been on the list since day one) now sit within the “Negligible Risk” category for BSE, indicating:

• Negligible risk of the classical BSE agent being recycled within the bovine population for at least the preceding eight years
• Ongoing implementation of a surveillance programme for at least the preceding eight years
• The history of occurrence, investigations and management of cases of BSE (classical and atypical) demonstrate either the absence of indigenous case of BSE or the control of the risk of BSE agents being recycled for at least the preceding eight years.

Despite extensive routine testing, Australia has never detected a case of BSE – atypical or otherwise. It was one of the first countries in the world to ban the feeding of mammalian protein (mostly in the form of meat and bone meal) to cattle in the 1980s.