Ebola virus is the most well-known infectious agent to cause hemorrhagic fever; however, several different viruses can cause viral hemorrhagic fever. The pathophysiology of hemorrhage in viral hemorrhagic fever is due to increased capillary permeability. The clinical presentation of hemorrhagic fever ranges from mild illness to a deadly infection with a high case mortality rate depending on the infectious agent. Some of the most well-known viral hemorrhagic fever diseases are: 

• Ebola hemorrhagic fever, caused by the Ebola virus (a Filoviridae)
• Lassa fever, caused by the Lassa virus (an arenavirus)
• Marburg hemorrhagic fever, caused by the Marburg virus (a Filoviridae)
• Dengue hemorrhagic fever, caused by the Dengue virus (a Flavivirus)
• Yellow fever, caused by the Yellow fever virus
• Hemorrhagic fever with renal syndrome, caused by the hantavirus (an Orthohantavirus)

Lassa Fever is a rare disease that is endemic in West Africa. The primary reservoir for the Lassa virus is rodents and mice. Cases of Lassa Fever range from mild to severe and fetal death is seen in around 95% of pregnancies of infected mothers. Sequala of deafness is a possible long-term adverse outcome of Lassa Fever. Ebola hemorrhagic fever is a concerning disease due to the severity of symptoms, ability to cause large outbreaks, and high case fatality rate of around 50%. In 2014 there was a large Ebola outbreak in Guinea, Sierra Leone, and Liberia resulting in over 11,000 deaths. The primary reservoir for the Ebola virus is bats, and once infected, human, person-to-person transmission is possible through direct contact with body fluids (sweat, vomit, urine, diarrhea, semen, breast milk, and blood). Direct contact with dead bodies from individuals infected with Ebola also spread the Ebola virus. It was a significant transmission mode in previous Ebola virus outbreaks in West Africa due to cultural burial practices where deceased bodies are touched by those grieving their loss. The incubation period for the Ebola virus is 2 to 21 days. There is a live attenuated vaccine for the Ebola virus, which the FDA approved in 2019. There are no FDA-approved treatments for Ebola. However, more than one monoclonal antibody has demonstrated effectiveness in Ebola outbreaks. ZMapp is a triple monoclonal antibody medication used to treat Ebola. Ebola virus is likely to emerge as Ebola virus outbreaks in West Africa over time as the primary reservoir for the disease is bats. It's impossible to predict when or where the next Ebola outbreak will occur. Hopefully, future outbreaks were be controlled more easily through educational campaigns on how the Ebola virus is transmitted, ring vaccination campaigns during an outbreak to prevent spread, and improved treatments for Ebola to decrease the morbidity and mortality during outbreaks. 

Reference:

Choi MJ, Kofman AD, Graziano J. Other Zoonotic and Vector-Borne Illnesses: Ebola and Other Viral Hemorrhagic Fevers. In: Boulton ML, Wallace RB. eds. Maxcy-Rosenau-Last Public Health & Preventive Medicine, 16e. McGraw Hill; 2022.