Deadly Marburg Virus Found in Sierra Leone Bats
First Time the Virus Has Been Identified in West Africa
Los científicos han descubierto el virus de Marburgo en murciélagos de la fruta en Sierra Leona. Es la primera vez que se encuentra el mortal virus en África Occidental. Cinco murciélagos frugívoros de raza egipcia han dado positivo en la infección activa por el virus de Marburgo. Los científicos capturaron los murciélagos por separado en tres distritos sanitarios: Moyamba, Koinadugu y Kono.
El virus se detectó antes de que se registraran casos de enfermedad en personas en Sierra Leona, y todavía no se han registrado casos de Marburgo en humanos en ese país. Sin embargo, la presencia del virus en los murciélagos significa que las personas que viven cerca podrían correr el riesgo de infectarse con el virus de Marburgo, un primo del virus del Ébola que causa una enfermedad similar en las personas.
El codescubrimiento del virus de Marburgo se produjo gracias a dos proyectos: uno del proyecto PREDICT, financiado por USAID y dirigido por la Universidad de California, Davis, y la Universidad de Makeni; y otro de los Centros de Control y Prevención de Enfermedades y la Universidad de Njala.
El hecho de que el descubrimiento se produjera en murciélagos antes de que se reconociera cualquier enfermedad o muerte humana conocida es exactamente lo que el enfoque de "Una Salud" de PREDICT para la vigilancia de la enfermedad y la creación de capacidad están diseñados para hacer", dijo Brian Bird, del Instituto de "Una Salud" de la UC Davis y líder global para Sierra Leona y las operaciones multinacionales de ébola para PREDICT-USAID.
Reservorio natural
Los científicos ya habían demostrado que el murciélago egipcio (Rousettus aegyptiacus) es el reservorio natural del virus de Marburgo, lo que significa que los murciélagos pueden ser portadores del virus a largo plazo y transmitirlo a animales o personas sin enfermar ellos mismos. La secuenciación del material genético del virus de los cinco murciélagos que dieron positivo en la prueba de Marburgo encontró múltiples cepas genéticamente diversas, lo que sugiere que el virus de Marburgo ha estado presente en estas colonias de murciélagos en Sierra Leona durante muchos años.
"Hace tiempo que sabemos que los murciélagos portadores del virus de Marburgo viven en África Occidental, así que tiene sentido que encontremos el virus en murciélagos de allí", dijo el ecólogo de los CDC Jonathan Towner, que dirigió el equipo de los CDC. "Este descubrimiento es un excelente ejemplo de cómo este tipo de trabajo de ecología puede ayudarnos a identificar una amenaza y advertir a la gente antes de que enferme".
Murciélagos en una cueva de Uganda
Miles de murciélagos frugívoros egipcios se posan en una cueva del Parque Nacional Queen Elizabeth de Uganda. (Getty)
Los murciélagos frugívoros egipcios viven en cuevas o minas subterráneas en gran parte de África. El virus de Marburgo se ha detectado en murciélagos fruteros egipcios capturados en el África subsahariana, principalmente en Uganda y la República Democrática del Congo, pero también en Gabón, Kenia y Sudáfrica. En África oriental y central, estos murciélagos pueden posarse en colonias de más de 100.000 animales.
Sin embargo, las colonias de murciélagos frugívoros egipcios identificadas en Sierra Leona hasta ahora han sido mucho más pequeñas, lo que puede explicar por qué no se han conocido brotes de la enfermedad del virus de Marburgo en personas en Sierra Leona como los encontrados en África oriental y central.
Se detectan por primera vez cepas angoleñas en murciélagos
Hasta la fecha, se han conocido 12 brotes del virus de Marburgo con vínculos directos con África, el más reciente en Uganda en 2017. El mayor y más mortífero brote del virus de Marburgo se produjo en Angola en 2005. Causó la muerte de 227 de los 252 casos, es decir, cerca del 90% de los infectados. Dos de las cuatro cepas identificadas entre los cinco murciélagos positivos a Marburgo en Sierra Leona son genéticamente similares a la cepa que causó el brote en Angola. Es la primera vez que los científicos detectan estas cepas angoleñas en los murciélagos.
Los murciélagos egipcios se alimentan principalmente de fruta. Cuando se infectan, los murciélagos eliminan el virus en su saliva, orina y heces. Se sabe que estos murciélagos rousette egipcios prueban la fruta, orinan y defecan donde comen, contaminando potencialmente la fruta u otras fuentes de alimento consumidas por otros animales como los monos o las personas, especialmente los niños. Debido a su gran tamaño, este tipo de murciélagos a veces también sirven de fuente de alimento para las poblaciones locales. Las personas pueden estar expuestas al virus de Marburgo a través de las mordeduras de los murciélagos al contagiarse.
Scientists have discovered Marburg virus in fruit bats in Sierra Leone. This is the first time the deadly virus has been found in West Africa. Five Egyptian rousette fruit bats tested positive for active Marburg virus infection. Scientists caught the bats separately in three health districts: Moyamba, Koinadugu and Kono.
The virus was found in advance of any reported cases of illness in people in Sierra Leone, and there remain no reported cases of Marburg in humans there. However, the virus’s presence in bats means people who live nearby could be at risk for becoming infected with Marburg virus, a cousin to Ebola virus that causes similar disease in people.
The Marburg virus co-discovery occurred through two projects — one by the USAID-funded PREDICT project led by University of California, Davis, and the University of Makeni; and another by Centers for Disease Control and Prevention and Njala University.
“That the discovery was made in bats before the recognition of any known human illnesses or deaths is exactly what PREDICT’s One Health approach to disease surveillance and capacity building are designed to do,” said Brian Bird from the UC Davis One Health Institute and global lead for Sierra Leone and Multi-Country Ebola operations for PREDICT-USAID.
Natural reservoir
Scientists had previously shown that the Egyptian rousette bat (Rousettus aegyptiacus) is the natural reservoir for Marburg virus, which means the bats can carry the virus long-term and pass it on to animals or humans without getting sick themselves. Sequencing of virus genetic material from the five Marburg-positive bats found multiple genetically diverse strains, suggesting Marburg virus has been present in these bat colonies in Sierra Leone for many years.
“We have known for a long time that the bats that carry Marburg virus live in West Africa, so it makes sense that we’d find the virus in bats there,” said CDC ecologist Jonathan Towner, who led the CDC team. “This discovery is an excellent example of how this type of ecology work can help us identify a threat and warn people before they get sick.”
Egyptian fruit bats live in caves or underground mines throughout much of Africa. Marburg virus has been detected in Egyptian rousette bats caught in sub-Saharan Africa, primarily in Uganda and the Democratic Republic of Congo, but also Gabon, Kenya and South Africa. In eastern and central Africa, these bats can roost in colonies of more than 100,000 animals.
However, the colonies of Egyptian fruit bats identified in Sierra Leone so far have been much smaller, which may explain why there haven’t been any known Marburg virus disease outbreaks in people in Sierra Leone like those found in eastern and central Africa.
Angolan strains detected in bats for first time
To date, there have been 12 known Marburg virus outbreaks with direct links to Africa, with the most recent in Uganda in 2017. The largest and deadliest Marburg virus outbreak occurred in Angola in 2005. It killed 227 of 252 cases, or about 90 percent of those infected. Two of the four strains identified among the five Marburg-positive bats in Sierra Leone are genetically similar to the strain that caused the outbreak in Angola. It is the first time scientists have detected these Angolan strains in bats.
Egyptian rousette bats primarily feed on fruit. When infected, the bats shed the virus in their saliva, urine and feces. These Egyptian rousette bats are known to test-bite fruits, urinate and defecate where they eat, potentially contaminating fruit or other food sources consumed by other animals like monkeys or people, particularly children. Due to their significant size, these types of bats sometimes serve as a food source for local populations, as well. People may be exposed to Marburg virus through bat bites as they catch the bats.
Community engagement
In Sierra Leone, researchers and government officials are in the process of meeting with local communities to present their findings, answer questions about Marburg virus, and address how to reduce people’s risk of exposure and live safely with bats.
Bats play important ecological and agricultural roles. Fruit bats pollinate important crops, and insect-eating bats eat thousands of insects each night, including mosquitoes, which helps control pests that transmit disease and damage crops.
Scientists emphasize that people should not attempt to kill or eradicate bats in response to the discovery. Killing and coming into direct contact with bats can actually increase the risk of virus transmission, not halt it.
Finding viruses before they find us
The PREDICT team at UC Davis/University of Makeni and the team led by CDC/Njala both began work in Sierra Leone in 2016 following the massive Ebola outbreak in West Africa. They each sought to discover the Ebola reservoir, the animal that helps maintain the virus in nature by spreading it without getting sick.
The Marburg discovery and the PREDICT-team’s report earlier this year of the discovery of a new ebolavirus species, Bombali virus, illustrate the strengths and mission of USAID’s PREDICT project, which is to find viruses before they spill over into humans and become epidemics.
Media Resources
Brian Bird, UC Davis PREDICT and One Health Institute, 530-752-7544, bhbird@ucdavis.edu
Tracey Goldstein, UC Davis PREDICT and One Health Institute, 415-902-1486, tgoldstein@ucdavis.edu
Kat Kerlin, UC Davis News and Media Relations, 530-750-9195, kekerlin@ucdavis.edu
West Africa’s first-ever case of Marburg virus disease confirmed in Guinea
Se confirma en Guinea el primer caso de enfermedad por el virus de Marburgo en África Occidental
Brazzaville/Conakry – Health authorities in Guinea today confirmed a case of Marburg virus disease in the southern Gueckedou prefecture. This is the first time Marburg, a highly infectious disease that causes haemorrhagic fever, has been identified in the country, and in West Africa.
Marburg, which is in the same family as the virus that causes Ebola, was detected less than two months after Guinea declared an end to an Ebola outbreak that erupted earlier this year. Samples taken from a now-deceased patient and tested by a field laboratory in Gueckedou as well as Guinea’s national haemorrhagic fever laboratory turned out positive for the Marburg virus. Further analysis by the Institut Pasteur in Senegal confirmed the result.
The patient had sought treatment at a local clinic in Koundou area of Gueckedou, where a medical investigation team had been dispatched to probe his worsening symptoms.
“We applaud the alertness and the quick investigative action by Guinea’s health workers. The potential for the Marburg virus to spread far and wide means we need to stop it in its tracks,” said Dr Matshidiso Moeti, World Health Organization (WHO) Regional Director for Africa. “We are working with the health authorities to implement a swift response that builds on Guinea’s past experience and expertise in managing Ebola, which is transmitted in a similar way.”
Gueckedou, where Marburg has been confirmed, is also the same region where cases of the 2021 Ebola outbreak in Guinea as well as the 2014–2016 West Africa outbreak were initially detected.
Efforts are underway to find the people who may have been in contact with the patient. As the disease is appearing for the first time in the country, health authorities are launching public education and community mobilization to raise awareness and galvanize support to help curb widespread infection.
Las autoridades sanitarias de Guinea han confirmado hoy un caso de enfermedad por el virus de Marburgo en la prefectura meridional de Gueckedou. Se trata de la primera vez que se identifica en el país, y en África Occidental, el Marburgo, una enfermedad altamente infecciosa que causa fiebre hemorrágica.
El Marburgo, que pertenece a la misma familia que el virus que causa el ébola, se detectó menos de dos meses después de que Guinea declarara el fin de un brote de ébola que estalló a principios de este año. Las muestras tomadas de un paciente ya fallecido y analizadas por un laboratorio de campo en Gueckedou, así como por el laboratorio nacional de fiebre hemorrágica de Guinea, dieron positivo para el virus de Marburgo. Los análisis posteriores realizados por el Instituto Pasteur de Senegal confirmaron el resultado.
El paciente había acudido a una clínica local de la zona de Koundou, en Gueckedou, donde se había enviado un equipo de investigación médica para sondear el empeoramiento de sus síntomas.
"Aplaudimos la alerta y la rápida acción investigadora de los trabajadores sanitarios de Guinea. La posibilidad de que el virus de Marburgo se extienda a lo largo y ancho significa que tenemos que detenerlo en seco", dijo el Dr. Matshidiso Moeti, Director Regional de la Organización Mundial de la Salud (OMS) para África. "Estamos trabajando con las autoridades sanitarias para poner en marcha una respuesta rápida que aproveche la experiencia y los conocimientos de Guinea en la gestión del ébola, que se transmite de forma similar."
Gueckedou, donde se ha confirmado la presencia de Marburgo, es también la misma región donde se detectaron inicialmente los casos del brote de ébola de 2021 en Guinea, así como el brote de África Occidental de 2014-2016.
Se están realizando esfuerzos para encontrar a las personas que puedan haber estado en contacto con el paciente. Como la enfermedad está apareciendo por primera vez en el país, las autoridades sanitarias están poniendo en marcha la educación pública y la movilización de la comunidad para concienciar y galvanizar el apoyo para ayudar a frenar la infección generalizada.
An initial team of 10 WHO experts, including epidemiologists and socio-anthropologists is on the ground helping to investigate the case and supporting the national health authorities to swiftly step up emergency response, including risk assessment, disease surveillance, community mobilization, testing, clinical care, infection prevention as well as logistical support.
Cross-border surveillance is also being enhanced to quickly detect any cases, with neighbouring countries on alert. The Ebola control systems in place in Guinea and in neighbouring countries are proving crucial to the emergency response to the Marburg virus.
Marburg is transmitted to people from fruit bats and spreads among humans through direct contact with the bodily fluids of infected people, surfaces and materials.
Illness begins abruptly, with high fever, severe headache and malaise. Many patients develop severe haemorrhagic signs within seven days. Case fatality rates have varied from 24% to 88% in past outbreaks depending on virus strain and case management.
Although there are no vaccines or antiviral treatments approved to treat the virus, supportive care – rehydration with oral or intravenous fluids – and treatment of specific symptoms, improves survival. A range of potential treatments, including blood products, immune therapies and drug therapies, are being evaluated.
In Africa, previous outbreaks and sporadic cases have been reported in Angola, the Democratic Republic of the Congo, Kenya, South Africa and Uganda.
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