A mysterious illness that sickened over 20 people in Liberia is linked to the funeral of a renowned religious leader in Greenville, Sinoe County.

According to the report from the University of Minnesota's Center for Infectious Disease Research and Policy (CIDRAP), the outbreak in Liberia began on April 21, and most of the affected people attended the religious leader's funeral. Patients afflicted with the unexplained illness experience diarrhea, vomiting and mental confusion. The illness also has a case-fatality rate of 55 percent.

As of April 29, 20 cases of the mysterious illness have been reported, inlucing children. Out of those, 12 succumbed to the disease.

"We are still not aware of what killed them," said Sorbor George, communication director for Liberia's Ministry of Health, in a report from CNN. "We don't want to be specific as to the funeral being the reason for the death. We are still investigating and putting our acts together to know what happened."

WHO Regional Office for Africa reported that most of the affected individuals attended in at least one aspect of the funeral, including burial, meal after the funeral and wake. People who attended the funeral came from six counties in Liberia.

Officials noted that the likelihood of food, drink or water poisoning is high. Water samples taken from the Sinoe County has tested negative for chloroform, while food samples from the funeral of the religious leader were collected and preserved at the national reference laboratory for testing.

Health officials have ruled out Yellow fever, Lassa fever and Ebola. Some of the patients tested positive for malaria and were treated accordingly. Lab tests to rule out shigellosis and cholera are still ongoing.

The Liberia Ministry of Health (MOH) already asked for the help of the Centers for Disease Control and Prevention (CDC). Liberia health officials shipped 11 specimens to CDC for testing. The MOH also plans to send specimens to a WHO-affiliated lab in South Africa and a Doctors Without Borders lab in France.