Workers in protective suits have begun culling 6,000 pigs at a northern farm in the Phillippines to prevent the spread of the Ebola Reston virus that has infected some of the animals.    

Health officials say six farm and slaughterhouse workers in Bulacan have developed antibodies to the virus after contact with infected pigs, but none of them have had any serious illness in the last 12 months.    

Provincial health officer Dr. Jocelyn Gomez said on March 2 that it would take about a week for all the farm hogs to be slaughtered at a rate of 1,000 a day.