Three pediatric patients died of acute hepatitis in April, bringing the global death toll from the unexplained liver disease impacting youngsters from the United States to Asia to at least four, according to Indonesia’s health ministry.

The children, who were hospitalized in Jakarta’s capital, suffered symptoms such as nausea, vomiting, heavy diarrhea, fever, jaundice, seizures, and loss of consciousness, according to the ministry. It is asking parents to take their children to the hospital as soon as possible if they develop these symptoms.

The ministry is running a full panel of tests to determine the cause of the disease and has issued a circular to step up nationwide surveillance for the illness, it said.

Over the weekend, Singapore confirmed a case of acute hepatitis in a 10-month old baby and is investigating whether it has a similar presentation to other cases reported worldwide.

At least one other child has died from acute hepatitis, and more than a dozen others globally have undergone liver transplants after coming down with the disease, according to the World Health Organization.

While the cause of the sickness is yet to be determined, investigators are studying a family of pathogens called adenoviruses that cause a range of illnesses including the common cold.