Abuja — At least 42 people have died in the worst outbreak of Lassa fever to hit Nigeria.
The death toll is from 213 confirmed cases to date since the latest outbreak was reported in late January. Some 16 states, out of 36, are affected.
This marks a significant increase as the outbreak accounts for one third of the caseload recorded throughout last year.
The World Health Organization (WHO) is stepping up its efforts to support the response to the disease which has also been reported in four other countries in West Africa.
A total of 12 cases have been confirmed so far in Benin, Guinea, Liberia and Togo, including two deaths.
"We are concerned about the high number of cases recorded so early in the Lassa fever season, which is expected to last another four months," said Dr Ibrahima Socé Fall, WHO regional Director of Emergencies.
WHO is working with health authorities in the five affected countries to ensure health workers have the ability to detect cases and monitor the regional spread of the disease.
To date, four health workers are among those infected during the current outbreak.
Lassa fever is an acute viral haemorrhagic disease used by human exposure to the urine or feces of infected rats.
More than 80 percent of cases are rodent-human transmission.
Person-to-person transmission occurs both in the community and in health care settings.
Prevention is based on good community hygiene.