WASHINGTON, Nov 15: One of the two types of polio viruses circulating in Pakistan could be on the verge of extinction, said a report presented at a medical conference in Atlanta, Georgia, earlier this week.

Dr Steven Wassilak, of the US Centres for Disease Control (CDC), told the conference that “no Type-3 cases have been reported for six months, which is the longest gap in incidence there to date.”

Scientists at the CDC studied the molecular make-up of polio viruses and said the Type 3 viruses were down to one remaining chain of transmission.

“The Type 3 (virus) is approaching a point where it’s never been before. It’s a single family that’s been in circulation over the last year and a half, in an isolated place,” Dr Wassilak said.—Correspondent