Scientists in Chile say they believe brucellosis, a serious reproductive disease, may have infected a number of seals in the Antarctic.

The scientists, from the Instituto Antartico Chileno, discovered brucella antibodies in five of 16 fur seals and one Weddell seal.

The discovery means new concerns for the Antarctic ecosystem

It is the first time that brucella antibodies have been found in seals in the Antarctic, though other exotic diseases have previously been found in the continent's wildlife.

In 1996, Australian scientists said they had found infectious bursal disease virus in Adelie and emperor penguin colonies near Mawson station in east Antarctica.

Unknown route

Brucellosis is usually found in cattle and other hoofed animals, where it causes sterility in males and prompts females to abort. It can spread to humans, though the effects are usually mild.

With land animals transmission occurs by direct contact and, although brucella bacteria have been found in wild marine mammals off Scotland and in captive ones in the US, the scientists say there is no clear pattern that can explain its transfer from the northern hemisphere to the southern ocean.

Scientists do not know how brucella moved from the northern hemisphere

In a paper to the Antarctic Treaty's Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), they say the discovery "outlines a new element for the conservation problems that affect the southern ocean fauna".

Although the scientists have found antibodies, they have not so far found any evidence of the disease itself in the Antarctic.

Warning to tourists

The infected animals were found at a large fur seal breeding colony at Cape Shirreff, on the northern coast of Livingston Island in the South Shetland group.

Weddell seals are occasional visitors, and the fact that the only one examined for the antibodies tested positive is said to show either that they are highly susceptible, or that the result was a remarkable coincidence.

Antarctic tour guides have been warned to take extra care to prevent any contact with seals or seal remains, and the International Association of Antarctic Tour Operators has sent out an advisory note on disinfection procedures.