At least 20 children are believed to have died in an outbreak of measles in Nigeria's north-eastern Borno State.
About 400 children were affected by the epidemic which broke out last week.
Measles is quite common in northern Nigeria early in the rainy season.
Children with reddish spots on their skin are being taken to hospitals in Maiduguri.
A doctor at a teaching hospital there told the BBC he feared the toll could be higher.
Areas that are worst hit by the measles epidemic include Konduga, Jere, Damboa and Bama local government areas.
State public health workers have been deployed to the affected areas to try to prevent a further spread of the disease, officials say.
Air-borne epidemics are common in Borno State, a semi-arid region with poor health services.