加拿大人到南方解决精子需要 Canadians looking south to meet sperm demand TORONTO, Nov 21 (Reuters) - A human sperm shortage in Canada, caused by new rules on donor screening, has forced doctors, and their patients who want to be artificially inseminated, to look south of the border for frozen semen, according to fertility specialists.  A government investigation of Canadian sperm banks last year uncovered widespread irregularities in the donor screening process, forcing the federal Department of Health to quarantine tens of thousands of samples.  The investigation was prompted by a woman who became infected with chlamydia, a common sexually transmitted disease that can cause sterility in women, after receiving sperm from a clinic--the only known case of its kind in Canada.  New government requirements for more stringent and frequent testing have forced many small and university-based clinics, which operate on a cost-recovery basis, out of business as their store of frozen semen is rendered unusable.  "The stocks have decreased dramatically," said fertility specialist Roger Pierson, president of the Canadian Fertility and Andrology Society, told Reuters.  Pierson said the demand previously met by Canadian sperm banks is now increasingly being filled by large US firms that can afford to adhere to the tougher new standards. He said US orders from Canada have grown a hundred-fold this year alone.  Pierson said the sperm shortage, which he estimated could last for several years, might require patients to fly to the United States to get treatment or to act as their own importers.  In addition, Canadians must pay about four or five times more for US semen--which often comes from clinics that operate on a for-profit basis--than they would for a domestic supply.  With an eye on the expanding Canadian market, US-based Xytex Corp. set up a office in Toronto this month. Company spokesman David Towles said the company has seen an increase in business of 5 to 10 percent over the past year.  "We have more people using us in Canada than ever before," said Towles.