refer to a group of illnesses that are caused by several distinct families
of viruses. In general, the term "viral hemorrhagic fever" is
used to describe a severe multi-system syndrome, where multiple organ
systems in the body are affected.
include four families of viruses: filiviruses such as the Ebola and Marburg
viruses, arenaviruses such as Lassa, bunyavirus such as Rift Valley Fever
and flaviviruses such as yellow fever and dengue. They can all cause serious,
life-threatening illnesses. Some, including Ebola, Marburg and Lassa,
are contagious. Although the Ebola virus gained notoriety in various films
such as Outbreak and books, VHFs aren’t expected to be prime
bioweapon candidates since people die so quickly from them and often don’t
get a chance to infect others.
World War II, the Japanese army fed botulinum toxin to prisoners of war
in Manchuria, with lethal results.
Is It Spread?
naturally occur in humans only after contact with an infected insect,
rodent or larger mammal. Transmission can happen via touching fecal matter,
receiving an insect bite or handling contaminated meat. It’s possible
VHFs can be manufactured for aerosol dissemination but the bacterium generally
don’t fare well in this form.
Are the Symptoms of Exposure?
the overall vascular system is damaged, and the body’s ability to regulate
itself is impaired. These symptoms are often accompanied by hemorrhage
(bleeding); however, the bleeding is itself rarely life-threatening. While
some types of hemorrhagic fever viruses can cause relatively mild illnesses,
many of these viruses cause severe, life-threatening disease.
types in severe cases can cause hemorrhagic syndromes that cause severe
internal and external bleeding in places such as internal organs, under
the skin and from the eyes, nose, mouth and ears. Symptoms generally include
high fever, dizziness, muscle aches and exhaustion. The first symptoms
may be felt from two days to three weeks after exposure. Advanced symptoms
include shock, nervous system malfunction, seizures and coma. Fatality
rates range from 90 percent for Ebola to 1 percent for Lassa.
Is It Treated?
is available for some VHFs, but not all. In the event of an outbreak,
routine infection control procedures, isolation and decontamination are
usually enough to stop transmission. Treatments vary depending on which
virus a victim has. No treatments or vaccines exist for Ebola or Marburg,
but therapy can prevent shock and help organs function. Antiviral drug
ribavirin can treat some VHFs fairly well if given early on. A yellow
fever vaccine is available. Other treatments are under development.
Has It/Where Can It Be Found?
most worrisome VHFs, such as Marburg and Ebola, are hard to acquire from
the wild because their natural host is unknown and outbreaks are rare.
VHFs are studied in some labs, mainly high-security ones. Research on
Ebola and several others was done by the Soviet Union before its
biowarfare program was dismantled.
warn that because microbe collections in Russia, Kazakhstan, Georgia and
Uzbekistan are not adequately secured, terrorist groups or states might
be able to steal or otherwise obtain weaponized strains of plague, tularemia