Lassa fever, also known as Lassa hemorrhagic fever, is a type of viral hemorrhagic fever caused by the Lassa virus. Many of those infected by the virus do not develop symptoms. When symptoms occur they typically include fever, weakness, headaches, vomiting, and muscle pains. Less commonly there may be bleeding from the mouth or gastrointestinal tract. The risk of death once infected is about one percent and frequently occurs within two weeks of the onset of symptoms. Of those who survive, about a quarter have hearing loss, which improves within three months in about half of these cases.
Marburg virus disease (MVD), formerly Marburg hemorrhagic fever (MHF) is a viral hemorrhagic fever in human and non-human primates caused by either of the two Marburgviruses: Marburg virus (MARV) and Ravn virus (RAVV). Its clinical symptoms are very similar to those of Ebola virus disease (EVD).
Viral hemorrhagic fevers (VHFs) are a diverse group of animal and human illnesses. VHFs may be caused by five distinct families of RNA viruses: the families Filoviridae, Flaviviridae, Rhabdoviridae, and several member families of the Bunyavirales order such as Arenaviridae, and Hantaviridae. All types of VHF are characterized by fever and bleeding disorders and all can progress to high fever, shock and death in many cases. Some of the VHF agents cause relatively mild illnesses, such as the Scandinavian nephropathia epidemica, while others, such as Ebola virus, can cause severe, life-threatening disease.
An emerging infectious disease (EID) is an infectious disease whose incidence has increased recently, and could increase in the near future. The minority that are capable of developing efficient transmission between humans can become major public and global concerns as potential causes of epidemics or pandemics. Their many impacts can be economic and societal, as well as clinical. EIDs have been increasing steadily since at least 1940.
Marburg virus (MARV) is a hemorrhagic fever virus of the Filoviridae family of viruses and a member of the species Marburg marburgvirus, genus Marburgvirus. It causes Marburg virus disease in primates, a form of viral hemorrhagic fever. The World Health Organization (WHO) rates it as a Risk Group 4 Pathogen. In the United States, the National Institute of Allergy and Infectious Diseases ranks it as a Category A Priority Pathogen and the Centers for Disease Control and Prevention lists it as a Category A Bioterrorism Agent. It is also listed as a biological agent for export control by the Australia Group.
Ebola, also known as Ebola virus disease (EVD) and Ebola hemorrhagic fever (EHF), is a viral hemorrhagic fever in humans and other primates, caused by ebolaviruses. Symptoms typically start anywhere between two days and three weeks after infection. The first symptoms are usually fever, sore throat, muscle pain, and headaches. These are usually followed by vomiting, diarrhoea, rash and decreased liver and kidney function, at which point some people begin to bleed both internally and externally. It kills between 25% and 90% of those infected – about 50% on average. Death is often due to shock from fluid loss, and typically occurs between six and 16 days after the first symptoms appear. Early treatment of symptoms increases the survival rate considerably compared to late start. An Ebola vaccine was approved by the US FDA in December 2019.
Zaire ebolavirus, more commonly known as Ebola virus, is one of six known species within the genus Ebolavirus. Four of the six known ebolaviruses, including EBOV, cause a severe and often fatal hemorrhagic fever in humans and other mammals, known as Ebola virus disease (EVD). Ebola virus has caused the majority of human deaths from EVD, and was the cause of the 2013–2016 epidemic in western Africa, which resulted in at least 28,646 suspected cases and 11,323 confirmed deaths.
The 2013–2016 epidemic of Ebola virus disease, centered in West Africa, was the most widespread outbreak of the disease in history. It caused major loss of life and socioeconomic disruption in the region, mainly in Guinea, Liberia and Sierra Leone. The first cases were recorded in Guinea in December 2013; the disease spread to neighbouring Liberia and Sierra Leone, with minor outbreaks occurring in Nigeria and Mali. Secondary infections of medical workers occurred in the United States and Spain. Isolated cases were recorded in Senegal, the United Kingdom and Italy. The number of cases peaked in October 2014 and then began to decline gradually, following the commitment of substantial international resources.
An Ebola virus epidemic in Sierra Leone occurred in 2014, along with the neighbouring countries of Guinea and Liberia. At the time it was discovered, it was thought that Ebola virus was not endemic to Sierra Leone or to the West African region and that the epidemic represented the first time the virus was discovered there. However, US researchers pointed to lab samples used for Lassa fever testing to suggest that Ebola had been in Sierra Leone as early as 2006.
In 2014, an outbreak of Ebola virus disease in the Democratic Republic of the Congo (DRC) occurred. Genome sequencing has shown that this outbreak was not related to the 2014–15 West Africa Ebola virus epidemic, but was of the same EBOV species. It began in August 2014 and was declared over in November of that year, after 42 days without any new cases. This is the 7th outbreak there, three of which occurred during the period of Zaire.
An epidemic of Ebola virus disease in Guinea from 2013 to 2016 represented the first-ever outbreak of Ebola in a West African country. Previous outbreaks had been confined to several countries in Sub-Saharan Africa.
Organizations from around the world responded to the West African Ebola virus epidemic. In July 2014, the World Health Organization (WHO) convened an emergency meeting with health ministers from eleven countries and announced collaboration on a strategy to co-ordinate technical support to combat the epidemic. In August, they declared the outbreak an international public health emergency and published a roadmap to guide and coordinate the international response to the outbreak, aiming to stop ongoing Ebola transmission worldwide within 6–9 months. In September, the United Nations Security Council declared the Ebola virus outbreak in the West Africa subregion a "threat to international peace and security" and unanimously adopted a resolution urging UN member states to provide more resources to fight the outbreak; the WHO stated that the cost for combating the epidemic will be a minimum of $1 billion.
Ebola virus disease in Mali occurred in October 2014, leading to concern about the possibility of an outbreak of Ebola in Mali. A child was brought from Guinea and died in the northwestern city of Kayes. Mali contact traced over 100 people who had contact with the child; tracing was completed in mid-November with no further cases discovered. In November, a second unrelated outbreak occurred in Mali's capital city, Bamako. Several people at a clinic are thought to have been infected by a man traveling from Guinea. On January 18, Mali was declared Ebola-free after 42 days with no new cases. There had been a cumulative total of eight cases with six deaths.
Cases of the Ebola virus disease in Nigeria were reported in 2014 as a small part of the epidemic of Ebola virus disease which originated in Guinea that represented the first outbreak of the disease in a West African country. Previous outbreaks had been confined to countries in Central Africa.
The 2018 Équateur province Ebola outbreak occurred in the north-west of the Democratic Republic of the Congo (DRC) from May to July 2018. It was contained entirely within Équateur province, and was the first time that vaccination with the rVSV-ZEBOV Ebola vaccine had been attempted in the early stages of an Ebola outbreak, with a total of 3,481 people vaccinated. It was the ninth recorded Ebola outbreak in the DRC.
The Kivu Ebola epidemic was an outbreak of Ebola virus disease (EVD) mainly in eastern Democratic Republic of the Congo (DRC), and in other parts of Central Africa, from 2018 to 2020. Between 1 August 2018 and 25 June 2020 it resulted in 3,470 reported cases. The Kivu outbreak also affected Ituri Province, whose first case was confirmed on 13 August 2018. In November 2018, the outbreak became the biggest Ebola outbreak in the DRC's history, and had become the second-largest Ebola outbreak in recorded history worldwide, behind only the 2013–2016 Western Africa epidemic. In June 2019, the virus reached Uganda, having infected a 5-year-old Congolese boy who entered Uganda with his family, but was contained.
Michael Joseph Ryan is an Irish epidemiologist and former trauma surgeon, specialising in infectious disease and public health. He is executive director of the World Health Organization's Health Emergencies Programme, leading the team responsible for the international containment and treatment of COVID-19. Ryan has held leadership positions and has worked on various outbreak response teams in the field to eradicate the spread of diseases including bacillary dysentery, cholera, Crimean–Congo hemorrhagic fever, Ebola, Marburg virus disease, measles, meningitis, relapsing fever, Rift Valley fever, SARS, and Shigellosis.
In August–November 1976, an outbreak of Ebola virus disease occurred in Zaire. The first recorded case was from Yambuku, a small village in Mongala District, 1,098 kilometres (682 mi) northeast of the capital city of Kinshasa.
