November 1, 2006

 

Mexican bovine TB system to undergo changes

 

 

Mexican bovine tuberculosis (TB) surveillance and eradication programme could see key changes in the coming months in the wake of a report by the US Department of Agriculture's inspector general (IG).

 

One such change includes posting all positive cases of bovine TB, those found at slaughter testing and elsewhere on the USDA website beginning Oct 30. This has been entrusted to the USDA's Animal and Health Inspection Service (APHIS).

 

Additionally, the agency would propose a rule to modify its TB status classification guidelines, and the proposal to be published in the Federal Register by April 2007.

 

In the four years ending 2005, three in four TB cases detected in US slaughter plants originated from Mexican  cattle, according to the IG report. US imports more than 1 million cattle from Mexico annually and therefore most of the positive TB cases found in APHIS's slaughter surveillance could be traced to Mexico.

 

Although the two countries worked jointly on the issue through the classification and testing programme, their efforts were undermined by the disease's 3 to 12-month incubation period, warned the report. This meant cattle which tested negative for the disease prior to export could catch the disease later and infect US cattle after import.

 

Despite the risk, APHIS did little to restrict the movement of cattle or carry out additional testing to compensate for the disease's incubation period, said the IG.

 

The APHIS administrator, Dr Ron DeHaven responded by saying that they were working to ensure that they did not inappropriately penalise states with majority of slaughter and/or feedlot facilities.

 

The new guidelines would propose herds to be placed on a high-risk herd list for further testing and be tested whenever another epidemiological trace identified them as a possible source, said DeHaven.

 

Other areas pointed out included a lack of a national animal identification system while investigating TB cases in the domestic US herd and the agency's management of the bovine TB programme.

 

While APHIS made improvements in recent years, weaknesses of the programme made it difficult for APHIS to detect and eradicate TB in a timely manner, the report said.

 

However, there had been "no widespread outbreaks," and conversely there was a decline in the known incidence of bovine TB in the US, concluded the report.