According to experts, the mad cow virus usually makes its way into a country through imports of bone dust and meat and bone meal (MBM) made from infected cattle.

Since January 1, China has stopped the import of feed made with ground-up animal carcasses from the European Union.

This ban, however, could not prevent possibly infected cow parts from sneaking in as unlisted ingredients in other products such as flesh bone dusts.

To remedy this problem, the Shanghai Entry-Exit Inspection and Quarantine Bureau and the Shanghai Institute of Agricultural Science began working earlier this year on a gene-based technique that would make detection of cow components easier.

The genetic technique, called "DNA detection," may allow quarantine officials to find the mad cow virus in products with invisible cow components.

"The result of the past two months of research is a technique that is highly sensitive to cattle components and capable of detecting 1 gram of material derived from cows in 1,000 grams of product," said Zhang Dabing, director of the research group at the Shanghai Academy of Agricultural Science.

So far, researchers have used the technique to find cattle components in five batches of imported bone dust mixtures in the Shanghai port.

None of the batches was found contaminated with the mad cow virus.

The virus was first found in Britain in 1986 and has spread to a number of countries in Europe and elsewhere, causing local cattle industries to sustain huge losses.

Authorities said the use of gene-based technology for detection of the mad cow virus is very important in Shanghai, which is one of the main ports in China. The total volume of imports and exports that went through Shanghai's port last year accounted for one-fourth of the national total.

(Eastday.com 03/27/2001)