LONDON — British health officials say they will start a small study later this year to find out how common mad cow disease is.

Health experts have long recommended coroners take samples from dead people to test for the potentially fatal neurological illness.

Mad cow disease was first identified in Britain, which has the world's highest tally at 164 deaths. Without testing tissue samples, scientists don't know how many people who haven't developed symptoms might be infected.

Having a more accurate idea would allow experts to better prevent the disease's spread.

Until now, British coroners say the law only allows them to test for a person's cause of death, not for coincidental infections.