Lassa fever – Nigeria (update)

Further to current note 52/0902, the latest data from the Nigeria Centre for Disease Control (NCDC) shows that the number of new confirmed and probable cases has been falling for five consecutive weeks, indicating that public health measures are proving effective. However more infections are expected until the end of the dry season. However both NCDC and the World Health Organization (WHO) advised that while the spread of Lassa fever in Nigeria is beginning to slow the epidemic is far from contained.

The current epidemic is Nigeria’s largest on record, with the number of confirmed cases in January and February 2018 alone exceeding the total number reported in the whole of 2017. Between 1 January and 25 March 2018, the NCDC reported 394 laboratory confirmed cases. There were 18 new confirmed cases in the last reporting week (19-25 March 2018), compared to 54 confirmed cases a month earlier (19-25 February 2018).

The cause(s) for the high numbers of infections is not known as yet thought the NCDC is conducting research into the causes of the outbreak in real-time. Researchers at the Irrua Specialist Teaching Hospital, in collaboration with the Bernhard-Nocht Institute for Tropical Medicine, Germany, WHO, NCDC and others, have conducted genome sequencing of the Lassa virus with preliminary results suggesting that the circulating virus is consistent with previous outbreaks and not a new more virulent strain.

WHO recognizes Lassa fever as a priority pathogen which has the potential to cause a public health emergency. The on-going research will provide crucial insights which will help mitigate future Lassa fever outbreaks. WHO has been working with NCDC and other partners to control Lassa fever by deploying teams to hotspots, identifying and treating patients, strengthening infection, prevention and control measures in health facilities, and engaging with communities.

WHO has released US$ 900,000 from its Contingency Fund for Emergencies to quickly scale up operations, and is also supporting preparedness and response capacities in neighbouring countries.

Further information and advice for clinicians advising travellers can be accessed on TRAVAX.

Source: WHO, 26 March 2018