The United States health authorities are considering whether to ban imports of blood from Switzerland, over fears that they may be contaminated by the human form of mad cow disease, or BSE.
The city of New York is mooting a recommendation by the US Food and Drug Administration (FDA), which called for blood imports from Switzerland and Europe to be stopped.
The FDA says there is a risk that the human form of BSE, known as variant Creutzfeld-Jakob disease (vCJD), could reach US shores.
Only New York would be affected. The city gets around a quarter of its blood supply from a European network, Euroblood, which distributes the precious liquid from sources in Switzerland, Germany and the Netherlands.
Serious implications for health system
This ban on imports could have serious effects on the local health system, according to Rudolf Schwabe, head of the Swiss Red Cross' transfusion unit. He says New York's hospitals could be forced to delay urgent operations because of a lack of fresh blood.
No scientific evidence exists to prove that the disease can be transmitted through blood transfusions. The European authorities have also taken measures to reduce theoretical risks, such as eliminating white cells from blood packages in case they turn out to be contagious.
The association of American blood transfusion centres says the FDA recommendation is over-cautious, but the US Red Cross favours a better safe than sorry approach.
"There is too much uncertainty," say Bernardine Healy of the American Red Cross. "We believe security must not be compromised by a shortage of blood."
For his part, Schwabe does not condemn the FDA's decision either. "Each country is right in acting according to its own risks," he says, adding that Switzerland imposed a similar ban on blood donated by people travelling to and from Britain last spring.
Ban on donors who have lived in Europe
In September, the organisation is planning to apply even more restrictive measures than those recommended by the FDA. As well as proposing a ban on European blood imports, the US health authorities want to exclude donors who have spent five or more years in Europe after 1980.
Switzerland exports around 10 per cent of the blood it collects. The Red Cross usually has more than is required for local needs, except in summer.
Nearly 90 per cent of the exported blood goes to New York, with the rest heading to Greece. However, Schwabe says there are plenty of other markets open to blood imports, if New York should renege on its contract with Euroblood.
"We have several contacts, mainly in southern Europe and central Africa, to which we could export blood," he says. "Financially speaking, the export of blood is not that vital to us."
swissinfo with agencies