Yellow fever has killed about 45 people in the north of Uganda.
The ministry of health told the BBC that people began falling ill about a month ago in nine districts and the outbreak was confirmed as yellow fever on Christmas Eve.
Officials say the disease was last recorded in Uganda almost 40 years ago. It is transmitted by infected mosquitoes.
Task forces have been put in place in the affected districts and isolation units set up.
Kitgum task force chairman Bosco Ochola said his staff were treating about 65 infected patients.
Yellow fever is transmitted by a type of mosquito which is active only during the day.
Symptoms range from nausea and vomiting to kidney failure, jaundice and bleeding.
The BBC reports that about half of those who develop severe symptoms and are untreated die from the disease.