Dr Matshidiso Moeti, the WHO Regional Director for Africa, in a statement in Abuja on Friday, said the speed of escalation remained a great concern to the organisation.

According to Moeti, the five countries affected by the outbreak are Nigeria, Benin, Guinea, Liberia and Togo, while countries at risk of an outbreak include Burkina Faso, Cameroon, Ghana, Mali, Niger and Sierra Leone.

She said that Nigeria was currently facing its largest outbreak of Lassa fever as 16 states were already affected with 213 confirmed cases since the Nigeria Centre for Disease Control (NCDC) declared an outbreak on Jan. 22.

Moeti said that this also includes 42 deaths marking a significant increase as it was already a third of the total cases for all of last year when the country was thought to have experienced its worst outbreak.

With five countries in Western Africa reporting outbreaks of Lassa fever, the World Health Organisation has scaled up efforts to support the regions response to the disease.

While these outbreaks are occurring during the Lassa fever season in countries where the disease is endemic, the speed of escalation is of concern.

The largest outbreak thus far has affected 16 states in Nigeria. The Nigeria Centre for Disease Control declared an outbreak of Lassa fever on 22 January 2019.

The 213 confirmed cases to date including 42 deaths mark a significant increase which is already a third of the total cases for all of last year when Nigeria experienced its worst outbreak of Lassa fever.

Four health workers have been infected so far in this latest outbreak. In Nigeria, WHO is scaling up efforts to support the Federal authorities, NCDC and affected states in responding to the outbreak.

An important focus is on early detection and confirmation of suspected cases, providing optimal supportive care and ensuring infection prevention and control measures in designated healthcare facilities in the affected states, Moeti said.

She said that the organisation has also intensified its technical assistance and was supporting coordination, enhanced surveillance, epidemiological analysis and risk communication.

The regional director said that the organisation was mobilising experts to support case management and infection prevention and control.

She said that to date, a total of 12 cases have been confirmed in Benin, Guinea, Liberia and Togo including two deaths, adding that more suspected cases are being investigated.

She assured that WHO was assisting health authorities in these countries with contact tracing and providing medical and non-medical supplies including technical and financial resources.

Moeti said that this would help in case management, risk communication and logistics.

Dr Ibrahima Soc Fall, the WHO Regional Emergencies Director for Africa, said that the organisation remained concerned over the high number of cases recorded so early in the Lassa fever season as the outbreak was still expected to last the next four months.

Fall assured that the organisation was working with health authorities in the five-affected countries to ensure health workers had the capacity to detect cases.

WHO has set up a regional coordination mechanism for countries to report any suspected case of Lassa fever to expedite the flow of timely information and to assess the situation, recommend actions and help organise assistance.

WHO has also reached out to the six other at-risk countries Burkina Faso, Cameroon, Ghana, Mali, Niger and Sierra Leone, and is supporting prevention and readiness activities as needed, Fall said.

He urged all countries in the Lassa fever belt to enhance preparedness and response capacities especially for early case detection, laboratory confirmation, case management under recommended barrier nursing, risk communication and community engagement.

According to WHO, Lassa fever is an acute viral haemorrhagic illness that occurs predominantly in West Africa caused by human exposure to the urine or faeces of infected Mastomys rats.

WHO says that more than 80 per cent of Lassa fever cases are rodent-to-human transmission with Person-to-person transmission occurring in both community and healthcare settings.

To prevent Lassa fever, the organisation recommends that good community hygiene be encouraged in order to discourage rodents from entering homes.

WHO also recommends that grains and other foodstuffs be stored in roddent-proof containers, dispose of garbage far from the home, maintain clean households and keep cats.

WHO says that persons who have died from the disease should be handled safely, urging healthcare workers to always apply standard infection prevention and control precautions when caring for patients.