Transmissible spongiform encephalopathies (TSEs)

Introduction

Transmissible spongiform encephalopathies (TSEs) are a group of neurodegenerative diseases that affect humans and animals. They are always fatal.

TSEs are caused by a transmissible agent called a prionAn infectious agent, prions are abnormal proteins that can be transferred between species attacking cellular proteins found mostly in the brain., which is an abnormal form of a protein.

TSEs include:

  • Classical and atypical bovine spongiform encephalopathy (BSE) in cattle;
  • Classical and atypical scrapie in sheep and goats;
  • Chronic wasting disease (CWD) in cervids;
  • Transmissible mink encephalopathy (TME) in mink;
  • Feline spongiform encephalopathy (FSE) in cats;
  • Creutzfeldt-Jakob disease (CJD); variant Creutzfeldt-Jakob disease (vCJD); Gerstmann-Sträussler-Scheinker syndrome; Fatal Familial Insomnia; Kuru in humans.

With the exception of the BSE agent, which can be transmitted to humans through consumption of contaminated meat causing vCJD, there is no scientific evidence that other animal TSEs can be transmitted to humans.

Latest

In December 2019 EFSA published its latest summary on the monitoring of transmissible spongiform encephalopathies (TSEs) in the EU. The report provides results on data collected in 2018 by all EU Member States, Iceland, North Macedonia, Norway and Switzerland.

The main findings are:

  • One case of classical BSE in cattle (out of 1,181,934 animals tested) was reported in the EU. Three cases of atypical BSE were reported.
  • There were 934 cases of scrapie in sheep (out of 325,386 tested) and 523 cases in goats (out of 138,128 tested).
  • One case of chronic wasting disease (CWD) was reported in a wild moose, the first reported CWD case in the EU (out of 8,185 cervids tested).

Milestones

July 2018 EFSA publishes a scientific opinion on the risk of BSE posed by processed animal protein (PAP) in feed.

August 2017 EFSA publishes a scientific opinion on genetic resistance to TSEs in goats. The evidence provided in the opinion led to the inclusion in EU legislation of the genetic resistance option to control outbreaks of scrapie in goat herds.

July 2017 EFSA publishes a scientific opinion on the origin of the 60 cases of classical BSE reported in cattle born after the EU ban on the use of animal proteins in livestock feed was enforced in 2001. M Experts concluded that contaminated feed is the most likely source of infection. A second possibility is that contaminated feed ingredients may have been imported from non-EU countries. They could not rule out other causes due to the difficulty of investigating individual cases.

January 2017 In a scientific opinion, EFSA experts identify monitoring activities and measures to prevent the introduction and spread of chronic wasting disease into and within the EU. They propose a three-year monitoring system across eight countries to detect if the disease is present, which leads to the detection of the first cases in the EU: in Finland (2018) and Sweden (2019). Chronic wasting disease had been discovered in one wild reindeer and one wild moose in Norway in 2016. It was the first time the disease had been detected in Europe and in reindeer in the wild.

December 2016 EFSA publishes for the first time the annual EU summary report on the monitoring of TSE in cattle, sheep, goats, cervids and other species. Previously, the annual reports on TSEs were produced and published by the European Commission.

September 2014 EFSA assesses the state of scrapie in the EU since the introduction ten years earlier of a series of measures to monitor and control the disease.

January 2011 EFSA and ECDC review the latest available scientific information on possible links between TSEs in animals and humans. The findings confirm that at present the only TSE proven to be zoonoticA term given to diseases and infections that can be transmitted between animals and humans., remains BSE, known in humans as variant Creutzfeldt-Jakob disease (vCJD).

December 2010 EFSA reviews the distribution of TSE infectivity in small ruminant tissues and provides for the first time a quantification of the impact of specified risk material measures in managing TSE-related risks in small ruminants. The removal of materials such as the brain and spinal cord from animals going into the food chain protects consumers from TSE-related risks.

Role

EFSA’s role is to provide independent scientific advice to risk managers on all animal and public health related aspects of TSEs in the EU. Most of EFSA’s work is based on requests from the European Commission.

EFSA’s advice provides the scientific basis for EU measures to reduce the risks from TSEs and to maintain a high level of consumer protection in Europe.

Risk assessments and recommendations

EFSA has carried out comprehensive scientific work on different TSEs, especially on BSE, scrapie and CWD.

EFSA’s scientific work on TSEs is managed by the Panel on Biological Hazards (BIOHAZ), relying on the advice of leading experts in all aspects of TSEs, including epidemiologists, pathologists, molecular biologists.

This work includes reviewing the scientific evidence on the zoonotic potential of animal TSEs, like classical scrapie and CWD.

EFSA has also carried out several country-specific assessments. These include the evaluation of the revision of the BSE monitoring regime in Norway and Croatia, and the evaluation of the applications of Finland, Sweden and Denmark to be recognised as having a “negligible risk” of classical scrapie.

Evaluation of TSE rapid tests

EFSA is also involved in preparing protocols for evaluating new rapid tests used to detect TSEs in animals, including ante- and post-mortem tests, as well as in the different steps of the test evaluation procedure, and the review of the diagnostic methods for CWD.

EU framework

The European Commission and EU Member States have taken a series of measures to manage the risk of TSEs in the EU. There is a large body of legislation in place to protect humans and animals from these diseases.

All EU measures on animal TSEs are consolidated in the Regulation (EC) 999/2001.