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From Ron DeHaven, Animal and Plant Health Inspection Service, US Department of Agriculture

Debora MacKenzie makes claims about US efforts to prevent bovine spongiform encephalopathy, despite the fact that no evidence of BSE has ever been found in the US (31 May, p 6).

Since 1989, the US Department of Agriculture’s Animal and Plant Health Inspection Service has put in place numerous safeguards to prevent BSE from entering the US. These safeguards include stringent import requirements and BSE surveillance levels that far exceed international standards.

In the fiscal year 2002, the US tested more than 19,900 “high-risk” cattle. Experience from Europe confirms that testing non-ambulatory cattle and cattle that show signs of central nervous distress is the best way to discover whether BSE is present. At our current surveillance level, we would detect BSE at a rate of one case per million head of cattle.

In addition to targeted surveillance efforts, the US prohibits the use of most mammalian protein in the manufacture of animal feeds given to ruminants. This feed ban effectively addresses the way scientists believe BSE is spread. The US is one of only a few countries that have imposed a feed ban despite having no recorded BSE.

An independent risk assessment by Harvard University in 2001 confirmed that the US is taking all the necessary and appropriate actions to prevent BSE. The assessment showed that the risk of BSE occurring in the US is extremely low. The report recognised that the early protection systems put into place by the Department of Agriculture and the Department of Health and Human Services have been largely responsible for keeping BSE out of the US and would prevent it from spreading if it ever did enter the country.

Riverdale, Maryland, US