The UN is sending health officials to Mexico this week to investigate whether the swine flu outbreak is in fact linked to pigs.

The UN’s Food and Agriculture Organization said yesterday (27 April) that, at present, the disease is spreading between humans.

“So far evidence that the new strain of influenza A virus has entered the human population directly from pigs has not been established,” the FAO said. “Further analysis is planned to gain better insight into the situation.”

Chief veterinary officer Joseph Domenech added: “There is no evidence of a threat to the food chain; at this stage it is a human crisis and not an animal crisis, but we have to be alerted and prepared.”

The US pork industry has moved to assure consumers and the trade that its products are safe in light of the outbreak, which has already claimed over 100 lives and cases have also been detected in the US.

Meanwhile, Smithfield Foods, the leading processor and marketer of fresh pork and packaged meats in the US, said it has found no clinical signs or symptoms of the presence of swine influenza in the company’s swine herd or its employees at its joint ventures in Mexico.

Shares in Smithfield tumbled by more than 12% yesterday amid fears in the market over the impact of the swine flu scare on the meat processing sector.

Smithfield shares dropped 12.4% to US$9.04 by the close of trading and led a number of fallers among US meat firms.

Tyson Foods saw its shares fall 8.9% to $9.96, while Hormel Foods‘ stock dipped 2.1% to $29.99.