Countermeasures Against Viral Hemorrhagic Fevers

Viral hemorrhagic fevers (VHFs) are a group of viruses from four different virus families that are characterized by coagulation abnormalities with often fatal outcomes. VHFs can cause both internal and external bleeding. The virus families include: Filoviridae, Arenaviridae, Bunyaviridae, and Flaviviridae. All these viruses are enveloped and contain a single-stranded RNA genome. However, the viruses differ in their pathogenesis, transmissibility, natural host, and geographical distribution.

VHFs usually begin presentation with marked fever, fatigue, dizziness, nausea, vomiting, abdominal pain, muscle aches, loss of strength, and exhaustion. Patients can also experience bleeding under the skin, internal organs, and/or from other orifices (mouth, eyes, or ears). Finally, patients can progress into shock, neurological involvement, coma, delirium, seizures, renal failure and even death.

The route of transmission of VHFs depends on the agent. Some VHFs are spread by close contact with infected animals or humans, while others are spread by insects. The main reservoirs can range from rodents to arthropods. Some of the vectors include: the multimammate rat, cotton rat, house mouse, deer mouse, ticks, and mosquitoes. Ebola, Marburg, Lassa, and Crimean-Congo viruses are known to spread from person to person contact. However, airborne transmission of VHFs is thought to be very rare (CDC, 1988, Baron RC, 1983). Transmission is more likely to happen late in infection when patients experience vomiting, diarrhea, shock, and hemorrhage, occurring with high levels of virus present in bodily fluids. Nosocomial transmission can occur through unprotected contact with infectious body fluids, contaminated medical equipment or supplies, or an accidental needle stick. Infections can be significantly reduced with proper hand washing, safe sharp handling, and isolation precautions. Several outbreaks of Ebola have been attributed to improper personal protective precautions or contaminated needles.

This capstone determined the countermeasures available against VHFs in clinical trials, the vaccines tested in non-human primates, the tested in non-human primates as well as treatment strategies tested in humans.