The World Health Organisation has said that Lassa fever outbreak in Nigeria is declining.
WHO said that considering the seasonal peaks in previous years, improvements in community and health care worker awareness, preparedness and general response activities, the risk of a larger-scale outbreak had become low.
It, however, warned that measures such as close monitoring, active case search, contact tracing, laboratory support and disease awareness (both in community in general and specific training for health care workers) should continue.
Also, statistics show that between August 2015 and 17, May 2016, WHO has been notified of 273 cases of Lassa fever, including 149 deaths in Nigeria. Of these, 165 cases and 89 deaths have been confirmed through laboratory testing (CFR: 53.9%). The cases were reported from 23 states in Nigeria. Also recently in June, 2017, five cases were reported in Ondo State.
Since August 2015, ten health care workers have been infected with the Lassa fever virus and two of them have died. Of these ten cases, four were nosocomial infections, according to WHO.
As at 17 May 2016, the WHO disclosed that 8 states were reporting Lassa fever cases (suspected, probable, and confirmed), deaths and/or following of contacts for the maximum 21-day incubation period. Currently, 248 contacts are being followed up in the country. The other 15 previously affected states have completed the 42-day period following last known possible transmission.
Public health response
Currently, two national laboratories are supporting the laboratory confirmation of Lassa fever cases by Polymerase Chain Reaction tests. All the samples were also tested for Ebola, Dengue, Yellow fever and they have so far tested negative. The two laboratories that are currently operational are the Virology Laboratory, Lagos University Teaching Hospital and the Lassa Fever Research and Control Centre at the Irrua Specialist Hospital in Edo State.
Along with other key partners, WHO is supporting the Ministry of Health in surveillance and response of Lassa fever outbreaks, including contacts tracing, follow up and community mobilisation. One of a concern since the onset of Lassa fever outbreaks is the high proportion of deaths among the case still under investigation.
WHO advice
Considering the seasonal flare ups of cases during this time of the year, countries in West Africa that are endemic for Lassa fever are encouraged to strengthen their related surveillance systems.
1. Health-care workers caring for patients with suspected or confirmed Lassa fever should apply extra infection control measures to prevent contact with the patient’s blood and body fluids and contaminated surfaces or materials such as clothing and bedding. When in close contact (within 1 metre) of patients with Lassa fever, health-care workers should wear face protection (a face shield or a medical mask and goggles), a clean, non-sterile long-sleeved gown, and gloves (sterile gloves for some procedures).
2. Laboratory workers are also at risk. Samples taken from humans and animals for investigation of Lassa virus infection should be handled by trained staff and processed in suitably equipped laboratories under maximum biological containment conditions.
3. The diagnosis of Lassa fever should be considered in febrile patients returning from areas where Lassa fever is endemic. Health-care workers seeing a patient suspected to have Lassa fever should immediately contact local and national experts for advice and to arrange for laboratory testing.
However, WHO stated that it had not recommended any travel or trade restriction to Nigeria based on the current information available.
