Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


BSE’s epidemic proportions


While prion diseases seem to be waning in humans, they could be waxing in sheep.

The BSE epedemic in cows could be repeated in sheep.
© AP

Variant Creutzfeldt-Jakob disease (vCJD) may claim only around 200 victims, a new model predicts1. This degenerative brain disease is thought to occur when people are exposed to misfolded prion proteins from meat infected with bovine spongiform encephalopathy (BSE or ’mad cow disease’).

Meanwhile, another study warns that a huge BSE epidemic could be brewing in the UK sheep flocks2.

A team of French and British researchers has formulated a new model for the UK vCJD epidemic - the first to take into account the unusual age distribution of the victims. The average age of people with vCJD is just 28.

The researchers assumed that people below the age of 15 are most susceptible to the disease, and that the incubation period is about 17 years. Most victims of the disease are thought to have been infected between 1980 and 1989, when about 500,000 infected cows were in the British food chain.

The model predicts that the epidemic has reached its peak and will soon start to decline. It puts the probable number of victims at about 205 in total (111 have been diagnosed already), with a 95% chance of no more than 403 victims.

"I’m surprised they can say with such certainty that there aren’t going to be more than 400 cases," says Simon Cousens of the London School of Hygiene and Tropical Medicine. Cousens’ team recently estimated that the epidemic could claim thousands3. Earlier models suggested that hundreds of thousands might contract the disease.

It is not surprising that the estimates are going down, says Graham Medley, an epidemiologist at the University of Warwick, UK, because the number of reported cases has not been increasing as fast as was originally expected. But any predictions about the extent of the epidemic must be taken cautiously, he warns, since so little data are available. "It’s impossible to provide accurate predictions," he says.

The new study is the first to forecast that the age distribution will change as the epidemic continues. Infections in older people might emerge later on, suggests Alain-Jacques Valleron of the National Institute of Health and Medical Research in Paris, a member of the team that performed the study.

This is because, if older people are less susceptible to the disease, they might not have caught it until the late 1980s. There was more infected meat in circulation then than earlier in the decade.

Sheep to sheep

Because sheep ate the same meat and bone-meal believed to have caused BSE in cattle, some experts fear that they may also have become infected with BSE. In that case, the disease could be in the early stages of a large epidemic, a second study suggests.

Sheep have long been prone to scrapie, another transmissible spongiform encephalopathy not believed to infect humans. Unlike BSE in cattle, scrapie can be transmitted from one sheep to another, raising the possibility that BSE might also spread through sheep flocks.

"Since BSE may be transmissible from sheep to sheep, getting rid of the meat and bone matter might not get rid of BSE in sheep," says Rowland Kao of Oxford University, a member of the team that performed the study. "That’s the thing that really concerns everyone."

Kao’s team found that if BSE is transmissible in this way, the number of sheep infected could soar in future years even if it is very low now. "There’s no cause for panic, but not for complacency either," he says.

"If their scenario is correct and BSE is spreading through the sheep population, we need to do something about it," agrees Cousens, commending the model’s "sensible approach".

No one knows whether sheep have been infected with BSE because the symptoms of BSE resemble those of scrapie, which is unique to sheep. A recent five-year study to determine whether the British sheep flock was infected ended in fiasco last month when it emerged that the study had been performed on cattle brains by mistake.

Science Express advanced online publication


  1. Valleron, A.-J. et al. Estimation of epidemic size and incubation time based on age characteristics of vCJD in the United Kingdom. Science, 294, 1726 - 1728, (2001).
  2. Kao, R. R. et al. The potential size and duration of an epidemic of bovine spongiform encephalopathy in British sheep. Science, Published online 22 November (2001); DOI: 10.1126/science.1067475
  3. Huillard d’Aignaux, J. N. et al. Predictability of the UK variant Creutzfeldt-Jakob disease epidemic. Science, Published online 25 October (2001); DOI: 10.1126/science.1064748

ERICA KLARREICH | © Nature News Service
Further information:

More articles from Health and Medicine:

nachricht Inflammation Triggers Unsustainable Immune Response to Chronic Viral Infection
24.10.2016 | Universität Basel

nachricht Resolving the mystery of preeclampsia
21.10.2016 | Universitätsklinikum Magdeburg

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>