Nigerian and international health officials say a meningitis epidemic has killed 336 children amid fears it could spread across the border to Niger.

The Nigerian Centre for Disease Control and U.N. agencies say 2,997 cases have been reported in the states of Zamfara, Katsina, Kebbi, Niger and Sokoto in northwest and north-central Nigeria since the surfaced in December.

A statement Tuesday says most victims are between 5 and 14.

Some 500,000 doses of vaccine have arrived in Zamfara, where the disease surfaced. But officials say 2 million doses are needed and there's a worldwide shortage for the strain, which inflames the and brain.

The statement notes the "risk of international border transmission."

Meningitis killed 1,100 people and infected more than 10,000 in Nigeria and Niger in 2015.