Ebola Outbreaks

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Last reviewed
November 30, 2023
Content Overview
Ebola outbreaks began in 1976 and continued in 2023. The Zaire and Sudan ebolavirus outbreaks are found in Africa.

Ebola Outbreaks 2023

Ebolavirus and Marburg disease outbreaks occur in Africa, with increased frequency in 2023, according to the World Health Organization (WHO). The initial Zaire Ebolavirus disease (EBOV) case was confirmed in 1976 in the African countries of South Sudan and the Democratic Republic of Congo (DRC). An EBOV outbreak occurred in a village near the Ebola River, where the disease takes its name. A study published on August 18, 2023, says the origins of Ebola remains enigmatic. More than 30 EBOV outbreaks have been reported, mostly in west and central Africa, where the disease is endemic. Separately, the U.S. Centers for Disease Control and Prevention (CDC) published a list of EBVD Cases and Outbreaks as of 2023. The WHO also publishes a Chronology of EBVD outbreaks and recommends surveillance for six months following the declaration of an Ebola-free country.

Recent data suggest that some EBOV outbreaks may originate from human-to-human transmission of prior Ebola outbreak strains instead of spillover. A Commentary published by The Lancet Infectious Diseases in August 2023 stated a published observation from the investigation noted that "in one case of the disease, the only possible source of infection was contact with a probable case 48 hours before the latter developed symptoms." The WHO issued new guidelines (August 2023) on infection prevention and control for these related hemorrhagic fever virus outbreaks.

Ebola in the United States

The U.S. CDC updated its Ebola Overbreak History on August 31, 2023. The CDC says eleven people were treated for EVD in the U.S. during Africa's 2014-2016 epidemic. On September 30, 2014, the CDC confirmed the first travel-associated case of Zaire EVD was diagnosed in the U.S. in a traveler from West Africa to Dallas, Texas. The patient (the index case) died on October 8, 2014. Two healthcare workers who cared for him tested positive for EVD, and both recovered. On October 23, 2014, a medical aid worker who had volunteered in Guinea was hospitalized in New York City, NY, and was diagnosed with EVD. The aid worker recovered, and seven others were cared for in West Africa. Six of these EVD patients recovered; one died, reported the CDC.

Zaire Ebolavirus Outbreaks

Africa endured Zaire Ebolavirus outbreaks between 2014, 2016, 2018, and 2022. Over 29,000 people were infected, and more than 11,000 died. The African countries most afflicted were Sierra Leone and Liberia. Since then, the DRC Ministry of Health has announced various outbreaks of EVD. During the 2018–2020 EVD outbreak in the eastern part of the DRC, among those offered vaccination, self-reported uptake of the Ebola vaccine was 99% (95% confidence interval (CI) [98.5–99.4]), As of August 2023, Original Research indicates that EVD surveillance systems in Liberia may fail to detect a new outbreak promptly. Specific improvements are required, and regular evaluations are recommended.

Sudan Ebolavirus Outbreak

On May 8, 2023, North Kivu, DRC, confirmed a positive case of Ebola. This revelation was made by the communicator of the provincial health division of Butembo, Dps-Butembo, Damulo Luhavo, during a press briefing. "Regarding Ebola virus disease surveillance, we received a sample that turned out to be positive from the Kyondo health zone and in the Butembo site. We have received four samples, and among the four, one is positive," said Damulo Luhavo.

The Sudan Ebolavirus (SUDV) outbreak in the Republic of Uganda was declared on September 20, 2022. Since the outbreak declaration, it's the fifth overall for this kind of Ebola; the last outbreak was in 2012; there were 164 cases (142 confirmed and 22 probable), 55 confirmed deaths, and 87 recovered patients. Overall, the case-fatality ratio was 47%. There were 19 cases, with seven deaths occurring among healthcare workers. The last patient was released from care on November 30, 2022, when the 42-day countdown to end the outbreak began. 

The U.S. CDC reissued  Alert Level 2, Practice Enhanced Precautions notice on November 16, 2022, regarding the SUDV outbreak, as did Uganda's Government. In addition, on November 5, 2022, the U.S. Embassy in Kampala reported the U.S. had channeled more than $22.3 million through implementing partners to support the government of Uganda's led response to the current Ebola virus outbreak. Accordingly, the U.S. Embassy recommends deferral of non-essential U.S. Government employee travel to and through the Mubende and Kassanda districts. The CDC issued Health Alert Network Health Advisory CDCHAN-00477 on October 6, 2022, and CDCHAN-00480 on November 7, 2022. Since October 2022, all U.S.-bound passengers who have been in Uganda have been routed to designated airports for enhanced Ebola screening. The U.S. government conducted similar airport exit and entry screening for Zaire Ebolavirus in 2014.

The UKHSA issued a public health message on November 14, 2022, regarding the Sudan Ebolavirus outbreak in Uganda. All workers returning to the U.K. from areas affected by SUDV should be risk-assessed by the UKHSA. On November 1, 2022, the WHO advised against any travel and/or trade restrictions to Uganda based on available information for the current SUDV outbreak.

Virological.org's preliminary analysis of selected Sudan Ebola Virus isolates from the 2022 Uganda outbreak. Further investigation with more samples will be required to understand better the possible relevance of mutations concerning the current Ebola Sudan outbreak and future outbreaks in Uganda.

Marburg Virus Outbreaks

Marburg virus disease (MVD) outbreaks have been reported since 1967 in Germany and continue in 2023. On February 13, 2023, the Government of Equatorial Guinea declared an MVD outbreak, the country's first of the disease. Tanzania said the end of its first-ever outbreak of Marburg in June 2023. Nine cases, including six deaths, were recorded in the outbreak announced in MaTanzania'sn Tanzania's northwest Kagera region.

Ebola Vaccines 2023

Ebola vaccine information is posted at this Precision Vaccinations link.

Ebolavirus Diagnostic Tests

A novel patch-based ebolavirus diagnostic test was announced on August 18, 2023.

Ebolavirus Disease

The Ebolavirus family Filoviridae includes three genera: Cuevavirus, Marburgvirus, and Ebolavirus. Within the genus Ebolavirus, six species have been identified: Zaire, Bundibugyo, Sudan, Taï Forest, Reston, and Bombali. Ebola viruses (EBOV) assemble into filamentous virions whose shape and stability are determined by the matrix viral protein 40 (VP40). pH-driven structural remodeling of the VP40 matrix acts as a molecular switch coupling viral matrix uncoating to membrane fusion during EBOV entry. According to the WHO, EVD is transmitted to people from wild animals and spread through human-to-human transmission, with case fatality rates varying from 25% to 90%. Infection with the Ebola virus to symptom onset, including fever, fatigue, muscle pain, headache, and sore throat, can range from 2 to 21 days.

Ebola Outbreak News 2023

July 25, 2023 - The journal Frontiers published an Orginal Research: Ebola vaccine uptake and attitudes among healthcare workers in North Kivu, Democratic Republic of the Congo, 2021. The overall uptake of the Ebola vaccine was very high among healthcare workers.

March 28, 2023 - The journal Virology published a Research Article - This study is the first to examine the Kikwit strain of EBOV, the most commonly used strain, in the gold-standard macaque infection model. This is the first description of detecting the virus in the vitreous fluid (eye). This immune-privileged site has been proposed as a viral reservoir following conjunctival challenge. 

February 11, 2023 - Dr. Syra Madad (@syramada') tweeted, 'Cameroon restricts movement after 'several unexplained deaths' in Equatorial Guinea from hemorr'aCameroon's' Cameroon's health ministry recently issued a statement saying it had recorded around 20 deaths in villages inGuinea'sial Guinea's Kie-Ntem province, which borders Cameroon.

January 11, 2023 - The Republic of Uganda endedrent the SUDV outbreak.