The health authorities in Ukraine announced that they will close schools in the central city of Vinnytsia and move to a distance education system via the Internet, starting Monday, after an outbreak of hepatitis A led to the hospitalization of dozens of children and adults.

“The main thing now is to determine the epicenter of the outbreak and the causes in order to stop the spread of hepatitis A among the population as soon as possible,” Ihor Kozin, chief public health doctor, wrote on Facebook on Saturday.

Kozin, who also serves as Ukraine's deputy health minister, said 141 people in the city and region were hospitalized.

According to the US Centers for Disease Control and Prevention, hepatitis A is a highly contagious, short-lived disease that can be spread through close personal contact or consuming contaminated food or drink.

“So far, there is no single cause for the outbreak,” Kozin said.

He added, "We are analyzing the hotspots of spread and working with the population, especially to determine the circle of people who have been in contact."