McMaster Friends of MSF

What are Hemorrhagic Fevers?

Hemorrhagic fever, more commonly known as viral hemorrhagic fevers (VHFs), is a group of viral infections that can cause fever, inflammation, and eventually excessive bleeding.¹ Some well-known types of hemorrhagic viruses include Ebola virus, Marburg virus, Lassa virus, yellow fever virus, and Crimean-Congo hemorrhagic fever (CCHF).² These VHFs are usually distributed in West and Central Africa, Central and South America, parts of Asia, and Europe.²

While the early symptoms of VHFs are non-specific, involving fever, body aches, fatigue, and rash, as the disease progresses, symptoms like severe bleeding in the nose and eyes, vomiting, and diarrhea may occur.² These ongoing symptoms may also increase transmission risks within households or hospital facilities. Thus, the two main methods of transmission in VHF are:³

1. Human-to-human transmission, which takes the form of exchange of blood, feces, saliva, breast milk, semen, or vaginal fluids.
2. Human-to-human transmission, which takes the form of exchange of blood, feces, saliva, breast milk, semen, or vaginal fluids.

​The primary transmission of VHF outbreaks often begins with contact with a host animal,³ and can spread from person to person through contact with an infected individual’s bodily fluids. In different regions of the world, the factors causing the outbreaks vary.

VHFs can usually be diagnosed with blood tests or throat swabs for detections of the viral genome. They are also well known for their high mortality rate in certain viruses. For example, the average mortality rate for CCHF is 30%,⁴ and for Ebola diseases is 50%,⁵ suggesting that 1 in 2 people infected with Ebola will die from it. Thus, prevention measures need to be taken, usually through effective vaccination, which are available for Ebola, yellow fever, and dengue. It can also be prevented by avoiding interaction with carriers of VHFs, or via antiviral treatments, such as Ribavirin, pyrazinecarboxamide compounds, and monoclonal antibodies.²

Global Patterns of Outbreak

​

Fig. 1 Worldwide Distribution of VHF.³ The number represents the number of VHF outbreaks reported by the country. The acronym represents the name of VHFs.

In Africa, frequent interaction between humans with infected arthropods, usually mosquito or tick, increases the risk of exposure and transmission of VHF. Climate changes in those tropical areas like heavy rainfall and flooding, will also increase mosquito breeding, which further increases the transmission of VHF, a classic example being the yellow fever. Moreover, deforestation and expanding agriculture in those areas may also increase exposure to tick habitats, which escalates the spread of disease like the CCHF.⁶

In central and west Africa, Ebola and Marburg viruses are responsible for several severe outbreaks. Outbreaks usually initiate from a zoonotic transmission, often from a bat, and will be further spread out in humans. The crisis will be worsened in areas with a lack of proper infection control measures. This is important as studies have shown that the Ebola virus can persist in immunoprecipitated sites like the eye and testicles of survivors; thus, it is important to keep high vigilance and follow up with Ebola survivors.⁷ Another disease that raises concern is the Lassa Virus (LASV), which is carried by Mastomys natalensis rodents, an animal that lives closely to human residential areas. LASV have caused several seasonal outbreaks, especially during the dry season, as rodents will approach near residential areas in search of food. The most severe outbreak occurred in 2018 and is due to the lack of robust infection control in hospital settings.⁷

VHFs are less commonly prevalent in Europe, but cases of CCHF and Dobrava-Belgrade virus (DOBV) have been reported. Some researchers suggest that it could be due to migratory birds bringing ticks from Africa to Europe.⁸

In South America, the VHF activity is highly relevant to the agricultural practices that enhance human contact with rodent vectors. The predominant pathogen in the area is Junin virus (JUNV), which is transmitted through aerosol particles or direct contact with infected rodents.⁹ The number of infected people increases during the maize-harvesting period, given the increased potential contact with the rodents.

In Asia, there is a diverse variety of VHFs mainly distributed in the rural areas, like Hantaviruses (HTNV), which is known to cause renal and pulmonary syndrome when infected. It is mainly determined by the specific vectors and environmental conditions that influence the specific VHFs’ spread and impact, and it varies in each country and region.⁸

MSF’s role in combating the crisis – what are some initiatives that have been done?

VHFs outbreaks continue to emerge and re-emerge. We can examine MSF’s role in combating the crisis through the case study below, which emphasizes on the importance of surveillance and early detection.

Just recently, in September 2025, MSF supported the Ebola outbreak in the Democratic Republic of Congo.¹⁰ Currently, the WHO has confirmed that 2,000 Ebola vaccine doses are available in the country, with additional shipments expected in the coming days.¹² MSF stands ready to support vaccination efforts if requested by health authorities.

Moreover, MSF continued to coordinate with the Congolese Ministry of Health (MoH) and, alongside the World Health Organization (WHO), rapidly mobilized teams and joined a multi-agency emergency project in the area to assess the situation and support immediate response efforts.¹⁰

Here are some outbreak management efforts the MSF team has done:¹⁰

• Reinforce triage protocols
• Supplied essential medicines and personal protective equipment
• Conducted training in infection prevention and control (IPC) and symptomatic care
• Assesses the need for surveillance, community engagement or vaccination

Looking forward

Currently, MSF faces many challenges to combat the VHF crisis, one of them being that the international response to the VHF outbreaks are insufficient, derisory, and at times irresponsible.¹¹ Not enough international organizations are engaged, the promises of funding and political statements are inadequate, and the closure of international borders made evacuation of infected medical personnel increasingly difficult. Furthermore, given that many regions of the crisis outbreak are relatively rural, there is a lack of medical facilities to support the people in need.¹¹To confront these challenges, enhanced global collaboration is essential. This approach suggests interdisciplinary research integrating various topics like virology, ecology, and epidemiology,³ as well as combined with emerging technologies to improve preparedness for future outbreaks. For MSF and the global health community, the path forward demands sustained investment, stronger cross-border partnerships, and an unwavering commitment to ensuring that communities most vulnerable to VHFs receive timely, effective, and equitable care.

References

1. Haemorrhagic fevers, Viral. World Health Organization. https://www.emro.who.int/health-topics/haemorrhagic-fevers-viral/.
2. Viral Hemorrhagic Fevers. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/17973-viral-hemorrhagic-fevers. September 14, 2025.
3. Belhadi D, El Baied M, Mulier G, Malvy D, Mentré F, Laouénan C. The number of cases, mortality and treatments of viral hemorrhagic fevers: A systematic review. Carabali M, ed. PLoS Negl Trop Dis. 2022;16(10):e0010889. doi:10.1371/journal.pntd.0010889
4. Crimean-Congo haemorrhagic fever. World Health Organization. https://www.who.int/news-room/fact-sheets/detail/crimean-congo-haemorrhagic-fever. February 20, 2025.
5. Ebola Disease. World Health Organization. https://www.who.int/news-room/fact-sheets/detail/ebola-disease. April 24, 2025. Accessed November 15, 2025.
6. Isaäcson M. Viral Hemorrhagic Fever Hazards for Travelers in Africa. Clin Infect Dis. 2001;33(10):1707-1712. doi:10.1086/322620
7. Diallo B, Sissoko D, Loman NJ, et al. Resurgence of Ebola Virus Disease in Guinea Linked to a Survivor With Virus Persistence in Seminal Fluid for More Than 500 Days. Clin Infect Dis. 2016;63(10):1353-1356. doi:10.1093/cid/ciw601
8. Hewson R. Understanding Viral Haemorrhagic Fevers: Virus Diversity, Vector Ecology, and Public Health Strategies. Pathogens. 2024;13(10):909. doi:10.3390/pathogens13100909
9. Gallo GL, López N, Loureiro ME. The Virus–Host Interplay in Junín Mammarenavirus Infection. Viruses. 2022;14(6):1134. doi:10.3390/v14061134
10. Democratic Republic of Congo: MSF supports Ebola outbreak response in Kasaï. Medicines Sans Frontiers – Doctors Without Borders. https://www.doctorswithoutborders.ca/democratic-republic-of-congo-msf-supports-ebola-outbreak-response-in-kasai/. September 16, 2025.
11. The failures of the international outbreak response. Medicines Sans Frontiers – Doctors Without Borders. https://www.msf.org/ebola-failures-international-outbreak-response. August 29, 2014.
12. Ebola virus disease – Democratic Republic of the Congo. World Health Organization.https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON580. September 5, 2025.