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New reports of Ebola in Guinea are causing anxiety given the history of the 2014-2016 West African outbreak. This was the largest Ebola outbreak to date: 28,000 cases were recorded, including 11,000 deaths. It originated in Guinea and later spread to Sierra Leone and Liberia. Confirmed cases this time have been reported from southeast Guinea about 800 km by road from the capital Conakry, but only about 100 km from various border points with Liberia and Côte d’Ivoire. The concern is that the virus could spread to other parts of Guinea, as well as neighboring countries, if it is not contained quickly. Jacqueline Weyer answers questions about the latest outbreak.
What has been done to prevent new outbreaks from developing since 2016?
The development, evaluation, and registration of Ebola vaccines and antivirals have been important activities in the years since the 2014-2016 outbreak. Since then, two vaccines have been previously approved by the World Health Organization (WHO) and registered with different regulatory bodies.
Read more: Ebola hits West Africa again: key questions and lessons from the past
During the 2018-2020 Ebola outbreak in the Democratic Republic of the Congo (DRC), several countries in the region also established a national registry of these products. About 50,000 people were vaccinated as part of containment efforts in the Democratic Republic of the Congo. Ring vaccination (vaccination of individuals circled around cases) with the Ebola vaccine is a vital tool in preventing the spread of infection, as it produces an immunity barrier that interrupts the chain of transmission of the virus. virus.
Why has the disease returned?
The natural transmission cycle of the virus involves certain species of fruit bats that live in forests. These act as a reservoir for the virus in nature and this cycle is continuous, ensuring that the virus remains in nature over time. However, the virus can spread from its natural reservoir to other forest-dwelling animals or directly to humans to trigger an epidemic in the human population.
Read more: Ebola vaccine is key in ongoing efforts to contain outbreak in the Democratic Republic of the Congo
Animals infected with Ebola, such as nonhuman primates, monkeys, and antelopes, have been reported previously and could represent a source of exposure for humans. For example, hunters or people who slaughter these animals come into contact with infected blood and tissues. But it is also believed that contagion can occur through direct contact of infected bats with humans. The exact mechanism has not yet been defined, but contact with infected blood and tissues is likely a source of infection.
The virus is always present in nature and, when circumstances permit, it can jump from one species to another.
What lessons from previous outbreaks are being applied now?
There are many important lessons, but possibly quick and safe action will make a difference. In the wake of the 2014-2016 outbreak, the apparent delay in initial responses was a major criticism of response efforts.
It is essential to contain the outbreak early before it spreads beyond ground zero to other parts of Guinea and neighboring countries. If this happens, longer and more complicated containment efforts will be required.
One distinguishing feature of this outbreak is that it is occurring in the context of the global COVID-19 pandemic, which has medical care and other resources around the world under heavy pressure.
Read more: The coping mechanisms that the Democratic Republic of Congo is implementing against Ebola, measles and COVID-19
International support has been a mainstay in containment efforts in West Africa, but also in most of the Ebola outbreaks reported to date. Time will tell how efforts to tackle the COVID-19 pandemic impact Ebola containment efforts.
Does Guinea have the health infrastructure to manage the disease?
Access to healthcare in Guinea has improved slightly over the years. But the country struggles with one of the worst healthcare infrastructures in the world. Most deaths in Guinea remain associated with communicable, maternal and neonatal diseases and nutritional disorders. The 2014-2016 Ebola outbreak galvanized intensified efforts to improve health systems in the country, but progress is slow.
Given that the Ebola outbreak in West Africa ended only five years ago, it could be assumed that some of the infrastructure that was developed during the outbreak remains and could be quickly used again. The “muscle memory” for the public health response to Ebola gained from the previous outbreak in Guinea will be put to the test in the coming weeks.
What is the relationship between the outbreak in West Africa and Central Africa?
Studies conducted during and after the 2014-2016 outbreak show that the Zaire Ebolavirus The species was circulating in local bat populations in West Africa prior to the outbreak. The genomic similarity of the Ebola viruses associated with the West African outbreak and the Ebola viruses that have caused outbreaks in Central Africa since 1976 supports the hypothesis that the virus spread at some point from Central Africa to West Africa.
On the other hand, when analyzing the differences between these viruses, there is evidence of a separate evolution in space and time. The exact mechanism of spread from Central to West Africa remains unclear. But the transfer is plausible given, for example, that many species of fruit bats, some of which are implicated as natural reservoirs for the Ebola virus, are migratory and can migrate long distances.
Efforts are underway to determine the genomic sequence of the virus associated with the recently reported cases. This could point to the potential source of the outbreak and indicate the link between these viruses associated with recent cases and the viruses that circulated during the previous outbreak. Another consideration is that currently available Ebola vaccines have not been tested against strains other than Zaire Ebolavirus. The efficacy of these vaccines against other virus species is therefore uncertain.
Jacqueline Weyer does not work, consult, own stock, or receive funds from any company or organization that benefits from this article, and has disclosed no relevant affiliations beyond her academic appointment.
By Jacqueline Weyer, Senior Medical Scientist, National Institute of Communicable Diseases
