World Health Organization says as many as 450 people may have been infected with Lassa fever in Nigeria in less than five weeks.

In a statement Tuesday, WHO says 43 suspected deaths from the viral hemorrhagic fever were reported between Jan. 1 and Feb. 4 and 37 of them have been confirmed.

Mr Wondimagegnehu Alemu, WHO Representative to the West African nation, calls it an "unusually high number of cases for this time of year."

The disease is spread through contact with the bodily fluids of sick people. Humans often contract the virus from eating food contaminated by the urine or feces of rodents.

The disease starts as a fever with body aches and can progress to patients bleeding from the nose or mouth. There is no vaccine.

AP