Emergencies preparedness, response

Successful Ebola responses in Nigeria, Senegal and Mali

One year into the Ebola epidemic. January 2015

At-risk countries had a distinct advantage by the summer of 2014: they had witnessed the devastation caused by Ebola and were on high alert to respond to an imported case as a national emergency.

WHO and partners are celebrating end of Ebola virus transmission in Nigeria.
WHO/A. Esiebo

Though no clinicians, laboratories, populations, or governments in West Africa had any experience with Ebola virus disease when the outbreaks started, at-risk countries had a distinct advantage by the summer of 2014. They had witnessed the tenacity of the virus, and the social and economic devastation it caused, and were on high alert to respond to an imported case as a national emergency. This high-level of alert characterized the responses in Nigeria, Senegal, and Mali and contributed to their success.

Nigeria's response to the Ebola outbreak

In an unprecedented event, the virus entered Lagos, Nigeria on 20 July in a symptomatic air traveller whose sister had just died from Ebola in Liberia. He vomited during the flight, on arrival and, yet again, in the car that drove him to a private hospital, where he told staff he had malaria. The protocol officer who escorted him later died of Ebola. As malaria is not transmitted from person to person, no staff at the hospital took protective precautions. Over the coming days, 9 doctors and nurses became infected and 4 of them died. No one who shared a flight with the index case developed the disease.

"The Ebola outbreaks and response in Nigeria and Senegal showed the world that the disease can be stopped if a country is adequately prepared from the outset. WHO is now working with all countries at-risk to help them meet the same standards for preparedness."

Isabelle Nuttall, Director, Global Capacities, Alert and Response, WHO

When confirmation of Ebola virus as the causative agent was announced on 23 July, the news rocked public health communities all around the world. No one believed that effective contact tracing could be undertaken in a chaotic and densely populated city like Lagos, with many poor people living in crowded slums and a population that swelled and ebbed every day as people came to the city looking for work or returned home when unsuccessful. Many envisioned an urban apocalypse, with Nigeria seeding outbreaks in several other countries, as had happened in the past with the poliovirus.

The second shock came when a close contact of the index case entered the country’s oil hub, Port Harcourt, on 1 August. A doctor who treated him developed symptoms on 10 August and died of Ebola on 23 August. An investigation undertaken by Nigerian and WHO epidemiologists revealed an alarming number of high-risk and very high-risk exposures for hundreds of people.

In both cities, all the ingredients for an explosion of new cases were in place. That explosion never happened, thanks to the country’s strong leadership and effective coordination of an immediate and aggressive response. As in Senegal, an emergency operations centre was established, supported by the WHO country office. Also like Senegal, Nigeria had a first-rate virology laboratory, affiliated with the Lagos University Teaching Hospital, that was staffed and equipped to promptly diagnose a case of Ebola virus disease.

The government generously allocated funds and dispersed them quickly. Isolation facilities were built in both cities, as were designated Ebola treatment facilities. House-to-house information campaigns and messages on local radio stations, in local dialects, were used to ease public fears. Infrastructures and cutting-edge technologies in place for polio eradication, were repurposed to support the Ebola response, putting GPS systems to work for real-time contact tracing and daily mapping of transmission chains. Contact tracing reached 100% in Lagos and 99.8% in Port Harcourt.

In what WHO described as a “spectacular success story”, the country held the number of cases to 19, with 7 deaths. World-class epidemiological detective work eventually linked all cases back to either direct or indirect contact with the air traveller from Liberia. WHO declared Nigeria free of Ebola virus transmission on 20 October.

Senegal's response to the Ebola outbreak

The first case in Senegal was confirmed on 29 August in a young man who travelled to Dakar, by road, from his home in Guinea, where he had been in direct contact with an Ebola patient. Both the government and WHO treated that news as an emergency and responded accordingly. WHO despatched three senior epidemiologists with extensive frontline experience in containing some of history’s largest Ebola outbreaks. These epidemiologists worked shoulder-to-shoulder with staff from the Ministry of Health, MSF, and CDC to undertake urgent and thorough contact tracing.

Dakar was in a fortunately position as it is home to a world-class Senegalese foundation, the Pasteur Institute and its laboratory, which is fully approved by WHO to test quickly and reliably for viral haemorrhagic fevers, including Ebola. In an important innovation, Senegal set up a separate centre devoted to emergency Ebola measures, thus freeing the health system to continue to deliver routine services. That measure, backed by massive public information campaigns, helped relieved public anxieties and encourage cooperation with control measures.

All contacts were monitored daily and those with symptoms were immediately tested. All test results were negative. No onward transmission occurred. The single case fully recovered. WHO declared Senegal free of virus transmission on 17 October, 42 days after the second test on that single patient came back negative.

Mali's response to the Ebola outbreak

When Mali confirmed its first case on 23 October, in a two-year-old child from Guinea who later died, the country had been on high alert for months. Mali experienced a dress-rehearsal for imported Ebola cases in early April, when six suspected cases were detected and placed under observation. An isolation facility in Bamako, designed for the management of Lassa fever patients, was repurposed to safely receive the suspected cases for close monitoring. Patient samples were tested at the CDC in Atlanta and the Pasteur Institute in Dakar. All test results were negative.

As in Senegal and Nigeria, the country moved quickly in what the government and WHO regarded as an emergency situation. The child, who was symptomatic upon her arrival, and her family members had travelled extensively throughout the country using public transportation, also spending some hours with relatives in Bamako. Staff from WHO and other partners, already in the country to strengthen preparedness, shifted their work to support outbreak containment. Aggressive contact tracing was undertaken, with several close contacts monitored in a hospital setting. As in Senegal and Nigeria, the country could use is own high-quality laboratory facilities, in Bamako, that had been built, with support from the US National Institutes of Health, to safely handle hazardous samples from tuberculosis and HIV patients.

Days then weeks passed with no contacts showing symptoms. The country looked like it would pass through the event with a single case. Then, on 25 October, a Grand Imam from Siguiri prefecture in Guinea was admitted to Bamako’s Pasteur Clinic with a diagnosis of acute kidney failure. He died on 27 October. That single hospital admission ignited a chain of transmission that eventually led to seven additional cases and five deaths, including a doctor and a nurse who had treated the Imam.

The country was well-rehearsed in the emergency measures that needed to be taken swiftly. Hundreds of contacts were identified and placed under daily surveillance. Isolation facilities and an Ebola-designated treatment centre were constructed. In response to public fears and misperceptions, an innovative telephone hotline was established and began receiving around 6,000 calls per day. All calls were meticulously recorded and analysed each day, with information on the caller’s precise area of work or residence, occupation, and main concerns. Calls were then mined to uncover where public messages about the disease needed to be adjusted. Some callers reported suspected cases. All such reports were investigated. No further cases were identified.

Altogether, 433 contacts were identified and followed up for the 21-day incubation period. The last patient hospitalized in the Ebola treatment centre fully recovered and was released, following two negative tests, on 6 December. The last 13 contacts ended their monitoring period at midnight on 15 December. Vigilance remains high. If no further cases are detected, WHO will declare Mali free from active Ebola transmission on 18 January 2015.

Shared features of a successful response

The three countries shared a high level of vigilance that led to the rapid detection of an imported case and the rapid introduction of classical control measures. They also benefitted from government support at the highest level that treated the first case as a national emergency. Support from WHO epidemiologists at the start of the investigation was warmly welcomed.

All three countries had their own high-quality laboratories, facilitating the rapid detection or discarding of cases. Contact tracing was rigorous and most identified contacts were monitored in isolation. Local staff and existing infrastructures were used in innovative ways. For example, Mali used medical students with training in epidemiology to increase staff numbers for contact tracing. All three countries established emergency operations centres and recognized the critical importance of public information campaigns that encouraged community cooperation.

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