The list of infectious agents that have ruled out in the “mystery illness” in Ondo State, Nigeria is extensive:  Ebola Virus, Yellow Fever, Lassa Fever Virus, Rift Valley Fever Virus, Dengue Virus, West Nile Virus and possibly more.

ondoNow it appears the focus will be on toxins and poisons, according to WHO spokesman Tarik Jasarevic. Doctors plan to carry out toxicological tests on one of the victims who died in a hospital, Jasarevic said.

One WHO spokesman tweeted Sunday that herbicides are the current agent officials are looking at as the cause of the mystery illness, known unofficially as OndoX.

Head of Public Relations/Social Media for the World Health Organization, Gregory Härtl tweeted: : current hypothesis is cause of the event is . Tests done so far r negative for viral and bacterial infection

The symptoms of this mystery illness, which has killed depending on who you read, 13-30 people, include headache, loss of sight and restlessness. Death has followed in most cases within six to eight hours.