Last September, while COVID-19 was still raging around the world and across Africa, Uganda identified a case of Ebola Virus Disease (EVD) in Mubende, a district west of the capital, Kampala. It took only three weeks for the disease to spread to Kampala, a well-connected city of 1.5 million people. From there, it could easily have traveled to other countries, but thanks to dedicated and well-coordinated efforts, the outbreak was officially declared over by the country’s Ministry of Health on January 11, 2023. They reported 142 confirmed cases and 55 deaths, contrasting with the 11,000 deaths during the world’s deadliest Ebola epidemic in west Africa, from 2014 to 2016.
There have been annual outbreaks of EVD in the neighboring Democratic Republic of Congo (DRC) and west Africa over the last couple of decades, but the 2022-23 epidemic in Uganda was different. Ugandan health authorities confirmed that the latest outbreak was linked to the Sudan strain of the virus which is less transmissible and less deadly than other EVD viral strains – this is the first appearance of the Sudan strain in Uganda since 2012. The Sudan strain is one of four strains of the Ebola virus that are known to infect humans, the most common being the ‘Zaire’ strain.
Ugandan officials imposed a lockdown in the districts of Mubende and Kassanda with measures including an overnight curfew, closing of places of entertainment and worship, and the restriction of movement in and out of these districts. These measures, though they caused hardship to local people, were crucial implementations in halting the spread to the extent that there was no reported cross-border contamination to neighboring countries. The last case of EVD was reported on November 27, 2022 and 42 days later, respecting the World Health Organization convention, the authorities were able to declare an end to the outbreak.
What is the Ebola Virus Disease?
The Ebola virus was first discovered in 1976 near the Ebola River in what is now the Democratic Republic of Congo (DRC). It is one of a class of viruses that cause hemorrhagic fever and is often fatal. There have been multiple outbreaks in the intervening years in many African countries across a sub-Saharan belt from west to east. High-risk regions include areas in Uganda, the DRC, Gabon, Sierra Leone, Liberia, South Sudan, the Ivory Coast, and Ghana. The natural reservoir of the Ebola virus is thought to be in animals, with bats or non-human primates being the most likely source. Infected animals carrying the virus can transmit it to other animals, like gorillas, monkeys, fruit bats, and humans.
How Does the Virus Spread?
The virus first spreads to people through direct contact with animal blood, bodily fluids, and tissues. Traditionally, the Ebola virus would spread from hunters, butchers, and then consumers of bush meat to other people through direct contact with the body fluids of a person who is sick and then during the very elaborate funeral rituals. A person can only spread EVD to others after developing signs and symptoms. The virus enters the body through broken skin or mucous membranes in the eyes, nose, or mouth. The virus also spreads through sexual contact with someone sick with or who recovered from EVD.
What Are the Symptoms?
Symptoms may appear anywhere from 2 to 21 days after contact with the virus, and the illness typically progresses from typical flu-like symptoms to diarrhea and vomiting as the patient becomes more unwell. It is often difficult to differentiate between malaria, typhoid, influenza, or Covid. In the later stage, patients develop unexplained hemorrhaging, bleeding, or bruising and need intensive supportive care. In many cases, the disease is fatal.
Treatments and Immunization
As of 2020, there are two approved treatments by the World Health Organization (WHO) to treat EVD, but only when caused by the Zaire strain of Ebola virus. They were evaluated during the Ebola outbreak of 2018-2020 in the DRC, and both are based on expensive ‘monoclonal’ antibody treatments designed to bolster the body’s natural immune defense. Survival is significantly higher for patients who were able to receive the medication.
There is also an approved vaccine given as a single dose, found to be safe and protective against the Zaire strain of Ebola virus. During an outbreak, it is used in a ‘ring vaccination’ protocol, utilized in the program that eventually eradicated smallpox. Teams of health workers identify close contacts of confirmed cases for vaccination and then move outwards in rings to more distant contacts. Pre-exposure immunization is also possible for healthcare workers and others at potential occupational risk of exposure to the Zaire strain of the Ebola virus.
Public Health Principles Halt Epidemics
Since the first Ebola outbreaks in 1976, we have learned many lessons, and several tools have been developed to control and eradicate the outbreaks:
- Contact tracing
- Risk communication and community engagement
- Community-based surveillance
- Quarantine of confirmed cases in an isolation facility for 21 days
- Safe eating and hunting practices and dignified burials
- Lockdowns of affected populations
Where the strain is confirmed as the Zaire species, additional monoclonal antibody treatments and the vaccine help reduce the mortality and contain the outbreaks.
The Future of Ebola Virus Disease
There is an urgent need for further research into preventive vaccines to protect vulnerable populations from strains of the Ebola virus other than the Zaire Ebola virus. Frustratingly, it takes an outbreak to be able to conduct human trials and gather data on the efficacy of the approved monoclonals and vaccines - the latest outbreak of the Sudan Ebola virus was so well managed that only limited trials were possible. More than 5,000 doses of trial vaccines arrived in Uganda just as the outbreak was ending, and the planned clinical trials must be redesigned to generate more safety and data effectiveness.
In the meantime, surveillance of high-risk areas through testing human and animal blood samples for the Ebola virus will allow the use of disease-modeling methods to map high-risk areas. It will enable public health experts to develop vaccination programs targeting the most vulnerable populations to stave off future epidemics rather than waiting for the next outbreak. Further outbreaks are otherwise inevitable, given the widespread animal reservoir and the ongoing habitat destruction and encroachment that brings humans in closer contact with animals.
This plan assumes that there are sufficient stocks of Zaire strain Ebola vaccine and that governments of affected countries can tailor communication strategies and enable culturally sensitive ways to engage with communities to gain their trust. African nations cannot rely solely on lockdowns, quarantines, and contact tracing to fight the Ebola virus in the future. Research into suitable treatments and vaccines for all strains of the Ebola virus needs to continue, and if a universal Ebola vaccine can be developed, we may be able to prevent future outbreaks of this devastating disease. We have seen how quickly ‘mRNA’ vaccines (the type of vaccine platform used by Pfizer and Moderna for COVID-19) can be designed and produced for COVID-19 - even a fraction of that finance and determination would go a long way to making EVD a preventable disease.
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