Anatomy of an outbreak

August 06, 2018 12:00 am | Updated 03:35 am IST

How Congo learnt from the 2014 Ebola crisis and is dealing with the situation this year

R. Prasad

R. Prasad

The Ebola virus returned to the Democratic Republic of the Congo (DRC) just days after the World Health Organisation (WHO) announced, on July 24, that the Ebola outbreak had ended there. Congo says it has recorded a fresh outbreak in North Kivu province — the tenth instance in the country since the virus was discovered in 1976. At least four samples have tested positive and the majority of cases are in Mangina, about 30 km from Beni city, a densely populated area.

But the outbreak in North Kivu, announced on August 1, appears to be a fresh and unrelated one, having occurred about 2,500 km away from Bikoro in Equateur Province where the last outbreak was first reported this May.

This outbreak, on May 8, was based on two samples testing positive — made possible by a prompt sharing of information by Equateur officials about 21 cases of fever with haemorrhagic signs and 17 deaths on May 3. Again, on July 28, the North Kivu health division shared information about 26 cases of haemorrhagic fever, including 20 deaths, which led to four samples testing positive and the announcement, on August 1, of there being a fresh outbreak.

“The detection of the virus is an indicator of the proper functioning of the surveillance system,” Congo’s Health Minister Oly Ilunga Kalenga said in a statement.

“Ebola is a constant threat in the DRC. What adds to our confidence in the country’s ability to respond is the transparency they have displayed once again… we will fight this one as we did the last,” WHO Director-General, Dr. Tedros Adhanom Ghebreyesus, tweeted.

Contrast in responses

While Congo has displayed its considerable experience and also promptness in its response, WHO has also made similar moves. Hours after the outbreak was declared on May 8, WHO released $1 million from its Contingency Fund for Emergencies. Its multidisciplinary team began an active search for cases and people who had come in contact with those who were infected. Then, treatment facilities and mobile laboratories were set up and the community educated on safe practices. In 2014, when Ebola had struck three West African countries (Guinea, Liberia and Sierra Leone), these measures were delayed and were responsible for the spread and high mortality.

But despite the pro-active measures this time, 14 laboratory-confirmed cases were reported about 10 days after the outbreak was declared. Most were in remote, hard-to-reach areas, which made it a challenge in terms of surveillance, case detection and confirmation, contact tracing, and access to vaccines and therapeutics. But one confirmed case, in Mbandaka city with a population of 1.2 million population, changed the risk perception completely.

In the 2014 West African epidemic, WHO’s Emergency Committee convened only after some 1,000 people had died. This time around, it convened 10 days after the outbreak was declared on May 8.

But despite the heightened global risk, the committee has not viewed it to be a ‘Public Health Emergency of International Concern’, which is a formal WHO declaration. There are two main reasons for this. The first is the “rapid and comprehensive” response by the government, WHO and other partners. According to an editorial in The Lancet , the median time from illness to hospitalisation this time in Congo was just one day. In contrast, in the 2014 outbreak, the average time in West Africa was 5 days; in Congo, it was 4.7 days.

Vaccine power

The second reason is the availability of VSV-EBOV, an investigational vaccine, developed by Canada’s National Microbiology Laboratory and manufactured by Merck. In results of the 2015 vaccination trial carried out in Guinea (and published in The Lancet) , the vaccine offered “substantial protection” against Ebola.

Though the vaccine is still to be approved by a regulatory agency for commercial use, it has been approved for ‘compassionate use’ in outbreaks. “Vaccination will be key to controlling this outbreak,” Dr. Ghebreyesus has said.

In this outbreak, there are several firsts. On May 9, a day after Congo declared an outbreak, WHO and the Ministry of Health set up a specialised cold chain to store the vaccine in the provincial capital Mbandaka. And on May 14, the first batch of more than 4,000 doses of vaccine was on its way to Congo. “This marked the first time vaccines were available so early in a response,” according to a WHO release.

On May 21, vaccination of health workers as well as people in contact with Ebola began in Mbandaka. In total, 3,330 people were vaccinated (May 21-June 30).

The quick and proactive steps were not in vain. On July 24, WHO announced the end of the outbreak when a period of 42 days (two incubation periods) following the last possible exposure to a confirmed case had elapsed without any new confirmed cases being detected.

While it took nearly 30 months to control the 2014 West African epidemic (more than 28,600 people were infected and 11,300 died), it took less than three months in the case of the May 8 outbreak. On July 24, the total number of laboratory confirmed cases was just 38 (and 16 more probable cases) while the number of deaths was 33.

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