London

Thousands of badgers may die as a study into bovine tuberculosis is resumed in Britain. Credit: V. LATFORD/NFBG

Trials in which thousands of badgers will ultimately be killed to investigate their role in spreading bovine tuberculosis (TB) have resumed in Britain amid fresh arguments over the study's aims and effectiveness.

The trials — suspended early last year because of the country's outbreak of foot-and-mouth disease — are intended to show whether strategic culls of badgers could combat the spread of TB in cattle, which is a growing problem in parts of Britain.

“It is a tragedy that these trials are resuming when a growing body of scientific evidence indicates that cattle-to-cattle transmission is the major cause of the increase in bovine TB,” says Elaine King, a zoologist and chief executive of the National Federation of Badger Groups.

Other scientists say that the situation is not so straightforward. “Badgers are part of the problem and continuing these trials is the only way to quantify how big a part they play,” says Tim Roper, an animal-behaviour researcher at Sussex University.

The trials are designed to compare three strategies: killing all badgers in an area; removing them only if a case of bovine TB is spotted; and no culling at all. But they have been dogged by delays and controversy since they were first proposed in 1997 (see Nature 394, 821; 1998). In a 1999 report, the House of Commons Select Committee on agriculture questioned whether the trials will produce statistically meaningful results.

Stephen Harris, a zoologist at Bristol University who runs the UK National Badger Survey and is a long-standing critic of the trials, describes them now as a “farce”. Large numbers of cattle will have been replaced in trial areas since the outbreak of foot-and-mouth, he says, making it impossible to relate test results to the culling of badgers.

John Bourne, head of the government's Independent Scientific Group on bovine TB, which is running the trials, dismisses Harris's criticisms, saying that only about 5% of farms in trial areas were affected by foot-and-mouth, and that trial results — due in 2005 — will still be valid.