The global effort to eradicate polio, a disease that has been on the brink of extinction for years, is facing serious setbacks on two continents. The virus is surging in Somalia and the Horn of Africa, which had been largely free of cases for several years. And a new outbreak has begun in a part of Pakistan that a warlord declared off limits to vaccinators 14 months ago.

The African outbreak began in May with just two cases of polio paralysis: one in Mogadishu, Somalia’s capital, and another in the huge Dadaab refugee camp in Kenya, where thousands of Somalis have fled fighting between Islamic militants, clan militias, government troops and African peacekeepers.

Now there are 121 cases in the region; last year, there were only 223 in the world.

The new Pakistan outbreak is in North Waziristan, near the frontier with Afghanistan. It is in an area where a warlord banned polio vaccinations after it was disclosed that the C.I.A. had staged a hepatitis vaccination campaign in its hunt for Osama bin Laden. The warlord, Hafiz Gul Bahadur, banned all efforts until American drone strikes ended.

Although only three North Waziristan children have suffered polio paralysis since then, even one case shows that the virus is in the area and could spread.