Four health workers who were part of a polio vaccination team were killed in Pakistan on Wednesday.
The attack killed the three women and one man, and, according to reporting by Agence France-Presse, three other women were also wounded.
Reuters described the event as "the most deadly attack on health workers in two years."
Pakistan joins Nigeria and Afghanistan as being on the list of just three countries in the world where the incurable and crippling disease remains endemic. But, according to reporting by UPI, Wednesday's attack "is being considered part of a targeted campaign" by some in the country against a polio vaccination drive.
Contributing to mistrust of polio eradication efforts and legitimate health workers is the CIA's false vaccination campaign conducted as part of the hunt for Osama Bin Laden. Earlier this year, a spokesperson for Pakistan's Ministry of Foreign Affairs criticized that scheme for fueling the "negative perception" about vaccination efforts.
The World Health Organization (WHO) stated this month that the "international spread of wild poliovirus continued to constitute a Public Health Emergency of International Concern," a rare designation it first made in May.
The WHO warns: "Failure to eradicate polio could result in as many as 200,000 new cases every year, within 10 years, all over the world."
Dr. Margaret Chan, head of the WHO, said in September: "Pakistan is the single most important stumbling block along the road to ending polio, once and for all. Right now, a massive polio outbreak is sweeping across the country. Worldwide, nearly 9 out of every 10 children paralyzed by polio live in Pakistan. In numbers, that means 166 from Pakistan out of this year’s global total of 178 cases. Think about it. These figures are dramatic."