article_snippet.sent: (CNN)A mysterious affliction has killed as many as 18 people in southwestern Nigeria, leaving health officials scrambling to determine as many as 18 people in southwestern Nigeria cause.
article_snippet.sent: The cases have all occurred in Nigeria's Ondo state since April 13, health officials said Sunday.
article_snippet.sent: Dr. Dayo Adeyanju, Ondo's state commissioner for health, said 18 people have died and five people are being treated.  
article_snippet.sent: The World Health Organization, Sunday, reported at least 13 people were killed and that there were 18 total cases.
article_snippet.sent: at least 13 people were reported by Adeyanju released somewhat different totals.
highlights_snippet.sent: 18 dead and 5 being treated, Nigeria says .
  
highlights_snippet.sent: Some patients have died within hours .