H

hantavirus pulmonary syndrome An illness
resulting from INFECTIONwith hantavirus. Certain
species of deer mice carry the hantavirus, which
they shed in their droppings, URINE, and saliva.
People who come into contact with these excre-
tions, which may be through direct touch or
inhalation, may then acquire infection with the
VIRUS. Deer mice live primarily in wooded areas.
Most often a person acquires the infection after
cleaning in barns and outbuildings where mouse
droppings can accumulate; the cleaning stirs up
dust that carries the virus into the respiratory
tract. People who go camping in areas where there
are large populations of deer mice also are at risk
for infection.
The INCUBATION PERIOD(time between exposure
and illness) is one to three weeks. Symptoms
emerge abruptly and include FEVER, severe MUSCLE
aches (particularly in the large muscles of the legs
and back), and shortness of breath (DYSPNEA) that
rapidly progresses to respiratory failure. A BLOOD
test can show the presence of antibodies to con-
firm the diagnosis. Treatment is hospitalization,
usually in an intensive care unit, to provide sup-
port for BREATHINGwhile the virus runs its course.
Hantavirus pulmonary syndrome is a very serious
infection with a high fatality rate. Early, aggressive
medical support offers the best potential for suc-
cessful recovery.
See also ANTIBODY; HEMORRHAGIC FEVERS; MECHANI-
CAL VENTILATION.

hemorrhagic fevers Life-threatening illness
resulting from INFECTION with various viruses,
spread by the bites of mosquitoes and ticks, the
hallmark of which is the collapse of multiple
organ systems because damage to the BLOODves-
sels impairs their ability to contain and transport

blood. The dozen or so viruses that cause hemor-

rhagic fevers belong to four viral families: are-

naviruses, bunyaviruses, filoviruses, and

flaviviruses. These viral families also contain

viruses that cause infection other than hemor-

rhagic FEVER. For example HANTAVIRUSbelongs to

the bunyavirus family and the yellow fever VIRUS

belongs to the flavivirus family. Viral hemorrhagic

fever infections occur in tropical regions, notably

Africa and South America.

HEMORRHAGIC FEVER VIRUSES

Arenaviruses

Guanarito VIRUS Junin virus

Lassa virus Machupo virus

Sabia virus

Bunyaviruses

Crimean-Congo virus Rift Valley virus

Filoviruses

Ebola virus Marburg virus

Flaviviruses

Dengue virus Omsk virus

Rodents, primarily certain species of rats and

mice, harbor the viruses. Mosquitoes and ticks

that feed on the rodents continue to spread the

virus among rodent populations. Rodent drop-

pings and other excretions, such as saliva and

URINE, contain the viruses. The viruses can then

infect people who come into contact with the

excretions. Contact with body fluids from an

infected person further spread the virus. Symp-

toms of illness arise suddenly and are severe, typi-

cally including high fever, fatigue, evidence of

internal bleeding, and weakness. Subsequent

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