WHO

EVENT DESCRIPTION Nigeria experienced a large yellow fever outbreak from September 2017 to late-March 2018 and since then, sporadic cases continued to occur. However since late-September 2018, a new cluster of suspected yellow fever cases emerged in Edo State, located in the southern part of Nigeria. In week 41 (week ending 14 October 2018), one presumptive yellow fever case was confirmed, followed by three presumptive cases in week 42, and more cases occurred subsequently. Between 22 September and 10 December 2018, a total of 97 suspected yellow fever cases, including 23 deaths (case fatality ratio (CFR) 23.7%) were reported across 15 (out of 18) local government areas (LGAs) in Edo State. More than half of these cases occurred in the last two weeks. …..

    
Since the beginning of the yellow fever outbreak on 12 September 2017, a total of 3 510 suspected cases including 74 deaths (CFR 2.1%), have been reported from all 36 states and the Federal Capital Territory……

Males constitute 58% of all cases and the most affected age groups are 1-10 years (41%), followed by 11-20 years (22%) and 21-30 years (19%).

PUBLIC HEALTH ACTIONS The International Coordinating Group (ICG) has approved 1.38 million doses of yellow fever vaccine from the global emergency vaccine stockpile for an immediate reactive mass vaccination campaign, targeting 1.24 million people in eight LGAs. Active surveillance has been enhanced across the country, including active case search and case investigations of alerts. A National Rapid Response Team (RRT) has been deployed to Edo State to conduct epidemiological, entomological and laboratory investigations and support local response efforts. The RRT is working with the state health authorities, WHO and other partners to implement outbreak response activities, including active case search, sensitization of health workers and communities, and entomological surveillance. Implementation of vector surveillance and targeted vector control activities are ongoing, with emphasis on managing Aedes species. WHO is providing technical support to the state and national authorities, including deploying yellow fever experts to support the country response in Edo State.

SITUATION INTERPRETATION A new focus of yellow fever outbreak has been confirmed in Edo State, Nigeria, following the large outbreak that started in September 2017 up to late-March 2018. While Nigeria introduced yellow fever vaccine into routine immunization in September 2016, the country remains vulnerable to the disease. The global strategy to Eliminate Yellow Fever Epidemic (EYE) identified Nigeria as a high priority country for large preventive mass vaccination campaigns. Entomological investigations conducted in various parts of the country identified the presence of competent mosquito vectors (Aedes aeqypti). In response to the 2017 outbreak, several rounds of reactive vaccination campaign have already been conducted in a number of states, while a scheduled preventive vaccination campaign is currently ongoing in six states.
In Edo State, yellow fever vaccination coverage in children below one year of age is about 69% and approximately 60% in the rest of the population, leaving a significant number of people susceptible to the disease. The current outbreak has occurred close to the state capital, Benin city, which is moderately cosmopolitan, with high population movements due to trade.

An influx of persons with low immunity to yellow fever coming from other parts of the country, Europe and America into Edo state for the Christmas holidays is expected. All these underlying issues are significant, calling for the rapid implementation of the upcoming reactive vaccination campaign.
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