June 2, 2026 Author : Saraiva da Cunha (Infectious Diseases ) Ebola is a rare, severe, and frequently fatal viral disease caused by viruses of the genus Orthoebolavirus from the Filoviridae family . It is transmitted through direct contact with blood, body fluids, tissues, and organs of infected people and animals. The incubation period ranges from 2 to 21 days; there is no transmission before symptom onset. The first symptoms are nonspecific and include fever, muscle pain, fatigue, and headache. The mortality rate is high (around 50%, but varies with the virus species). There are some effective medicines and vaccines available, but only for Orthoebolavirus Zaire . Ebola outbreaks occur in regions of Africa and are associated with fragile health systems. Prevention is based on strict infection control measures, contact tracing, case isolation, and safe healthcare and funeral practices. The risk to the general population outside affected areas is very low. What is Ebola virus disease and what causes it? Ebola virus disease, commonly referred as Ebola, is a rare but severe and potentially fatal hemorrhagic disease caused by viruses of the genus Orthoebolavirus ( Ebola virus ). It was first documented in 1976 in two simultaneous outbreaks in northern Zaire (now the Democratic Republic of the Congo) and South Sudan. At that time, a new virus was identified and named Ebola, after a river in the region of the Democratic Republic of the Congo where it was isolated. Later, differences were identified between the viruses involved in the two outbreaks, which were then designated Orthoebolavirus Zaire and Orthoebolavirus Sudan . Since then, several Ebola outbreaks have occurred. There are several species of Orthoebolavirus and four are known to cause severe disease in humans: Orthoebolavirus Zaire; Orthoebolavirus Sudan; Orthoebolavirus Bundibugyo; Orthoebolavirus Taï Forest. The largest Ebola outbreak occurred between 2013 and 2016 in Guinea, Liberia, and Sierra Leone. It was caused by Orthoebolavirus Zaire , which is the most aggressive species. Approximately 28,000 cases and 11,000 deaths were recorded. During this period, 9 cases were reported in Europe: 3 in Germany, 3 in Spain, 1 in Italy, 1 in Norway, and 1 in the United Kingdom. To date, Portugal has never reported Ebola cases. Ebola virus disease is notifiable , and the associated viruses are classified at the highest level of biosafety (they should only be handled in laboratories with BSL-4 safety level, which do not exist in Portugal). What are the characteristics of the 2026 Ebola outbreak? In May 2026, an outbreak of disease was identified in the Democratic Republic of the Congo, caused by Orthoebolavirus Bundibugyo , with associated cases in Uganda. On May 17, 2026, the World Health Organization declared this outbreak a public health emergency of international concern (PHEIC), the highest level of alert under international regulations, reflecting the risk of spreading to other countries and the need for a coordinated global response. According to available data, confirmed and suspected cases were reported in several provinces of the Congo, as well as imported cases in Uganda. The outbreak is evolving in a complex context that hinders early case detection and control of transmission, characterized by: Conflicts in the region; High population mobility; Limited access to healthcare. It is important to note that: The actual number of cases may be higher than reported; Transmission chains may not be fully identified; To date, there are no vaccines or specific approved treatments for this virus variant. The Orthoebolavirus Bundibugyo was first identified in 2007 in the Bundibugyo region of Uganda and has an associated mortality rate of 30%–50%. How does Ebola virus infection occur? The natural reservoir of Ebola viruses are some species of bats found in Africa. They have also been isolated in mammals of various species, including primates and hunted animals used as food, which have been the source of human infections. Human infection occurs mainly through direct contact of mucous membranes and skin lesions with blood, other body fluids, organs, and tissues of infected people and animals, including dead ones, or with contaminated surfaces and objects. Transmission may also occur: Through semen for several months after clinical recovery; From mother to child during pregnancy, childbirth, and breastfeeding. Outbreaks generally begin after human contact with infected animals. Subsequently, they are sustained by transmission between symptomatic individuals. People without symptoms do not transmit the infection in a significant way. Are there groups at higher risk of Ebola virus infection? Anyone can become infected when exposed to the Ebola virus, but there are particular risk groups : Healthcare professionals caring for infected people, particularly when they do not use appropriate personal protective equipment for any reason. Family members and caregivers of patients due to direct contact with body fluids, particularly when they are not aware of the severity of the disease and the need for protective equipment. Participants in funeral ceremonies, particularly in cultures where touching or washing the bodies is part of rituals. People who come into contact with or handle animals or meat from potentially infected wild animals. Populations in regions with active outbreaks, especially in conflict settings. Close contacts of infected individuals. The risk of infection is very low for people outside affected areas and without direct contact with cases. Incubation period, symptoms, diagnosis, and treatment Between infection and the first symptoms of Ebola (incubation period) 2 to 21 days may pass, with an average of 6.4 days. Until symptoms appear, an infected person does not transmit the infection. Symptoms appear suddenly and are not specific , resembling those of flu, including: High fever; Fatigue; Muscle and joint pain; Headache. This may be followed by increasing weakness, loss of appetite, and digestive symptoms such as nausea, vomiting, and diarrhea, sometimes with blood. Not all patients present visible external or internal bleeding, but these may occur in more advanced stages. Progression to shock and organ failure is common in fatal cases. Clinical suspicion is based on epidemiological context (travel, exposure to cases or animals). Diagnosis is always confirmed in the laboratory through detection of the virus genetic material. There are some rapid antigen detection tests for professional use, but there are no approved self-tests for home use. Treatment mainly consists of supportive measures aimed at controlling symptoms and complications . There are effective medicines with monoclonal antibodies, but only for infections with Orthoebolavirus Zaire . New medicines are under development. The Ebola mortality rate is about 50% of infected patients, with wide variation mainly related to the virus species. For disease caused by the Orthoebolavirus Zaire it is estimated at 60%–90%, and for Orthoebolavirus Bundibugyo at 30%–50%. After recovery, the virus may persist in some bodily fluids, such as semen, for prolonged periods, making transmission possible in these cases. Outbreak control and prevention of Ebola virus disease There are two vaccines authorized in several countries, but only against Orthoebolavirus Zaire. Healthcare professionals in at-risk regions and specific population groups are usually vaccinated as part of outbreak containment strategies. Control of Ebola outbreaks is based on infection prevention and control measures aimed at interrupting human transmission chains and containing outbreaks: Isolation and treatment of confirmed cases; Contact tracing and monitoring; Awareness and education of populations; Ring vaccination (when applicable) and vaccination of risk groups; Strict application of infection control measures in healthcare settings; Proper use of personal protective equipment; Safe funeral practices. Although they can survive for some time in body fluids and biological materials, Orthoebolavirus are sensitive to: Sodium hypochlorite (bleach) and other disinfectants; Heat: heating at 60ºC for 60 minutes and boiling for 5 minutes; Gamma radiation. People who have recovered from Ebola should not donate blood, other tissues, or cells. In the case of men, they should not have unprotected sexual intercourse until the absence of the virus in semen is documented in two consecutive tests or, if testing is not possible, for a minimum period of one year. Note as of June 1, 2026 As of May 31, Congo had 282 confirmed cases, 42 deaths, and 220 suspected cases. In Uganda, 9 cases and 1 death were confirmed. To prepare the National Health Service (SNS) for this new threat, the Direção Geral da Saúde issued on May 30 orientation 002/2026 : Ebola or Marburg virus disease outbreaks | Revision of procedures – clinical and public health approach to suspected cases of filovirus hemorrhagic fevers. Sources European Centre for Disease Prevention and Control. Ebola disease outbreak in the Democratic Republic of the Congo and Uganda . 1 de junho 2026. European Centre for Disease Prevention and Control. Factsheet about Ebola disease . Umar SK, Diggle MA. The Ebola virus - going beyond the bleeding edge . J Med Microbiol 2025;74:001998. World Health Organization. Ebola disease . World Health Organization. Ebola. The Democratic Republic of Congo 2026 . Meet the infectious diseases clinical team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
