Facts on File Encyclopedia of Health and Medicine

Enteroviruses and Haemophilus influenzaetype B
(Hib) VIRUSare the common viral causes, though
many viruses can cause meningitis. Bacterial
meningitis may be life threatening and requires
immediate treatment with intravenous ANTIBIOTIC
MEDICATIONS. The contagiousness of bacterial
meningitis depends on the BACTERIA.

Symptoms and Diagnostic Path
Symptoms of meningitis tend to be milder with
viral meningitis. They may appear gradually and
include

• FEVER


• severe HEADACHE


• NAUSEAand VOMITING


• sore or stiff neck, or inability to touch the chin
  to the shoulder or chest


• agitation and confusion


• inability to remain alert or awake

LUMBAR PUNCTURE, which may reveal elevated
cerebrospinal pressure and evidence of infection
such as white BLOODcells or the presence of bacte-
ria, is the definitive diagnostic procedure.

Treatment Options and Outlook
Bacterial meningitis requires immediate treatment
with antibiotic medications. Viral meningitis is
self-limiting and usually improves on its own as
the illness runs its course. Supportive treatment
for viral meningitis may include intravenous fluids
to maintain adequate HYDRATION. Complications
that may occur with meningitis regardless of the
causative PATHOGENinclude swelling of the brain
tissue, seizures, and diminished CONSCIOUSNESS.
With appropriate treatment many people recover
fully; some people have residual complications
such as cognitive dysfunction, VISION IMPAIRMENT,
orHEARING LOSS.

Risk Factors and Preventive Measures

The primary risk for meningitis is infection with
any virus that can involve the meninges. Meningi-
tis sometimes occurs in clusters of cases in settings
where people live in close contact, such as college
dormitories. People who are IMMUNOCOMPROMISED
have increased risk for meningitis and many other

kinds of infections. The most effective prevention

measures are those that reduce the risk for acquir-

ing viral infections—frequent HAND WASHINGand

diligent PERSONAL HYGIENE—and early treatment for

symptoms of bacterial meningitis.

See also COGNITIVE FUNCTION AND DYSFUNCTION;

ENCEPHALITIS; FUNGUS; VIRUS.

microbe A living organism, also called a

microorganism, that is too small to see with the

unaided EYE. Most microbes are single-cell or sim-

ple multiple cell organisms. Common microbes

include BACTERIA, fungi (yeasts and molds),

viruses, PROTOZOA, and algae. Microbes are abun-

dant in the natural environment as well as the

environment of the human body. Many microbes

can cause INFECTIONand illness in humans. Dutch

scientist Antonie van Leeuwenhoek (1632–1723)

identified many microbes using microscopes he

constructed himself, paving the way for what

would become the foundation of understanding

for many disease processes.

See also FUNGUS; VIRUS.

mononucleosis, infectious An illness that results

from INFECTIONwith the EPSTEIN-BARR VIRUS. Infec-

tious mononucleosis is most prevalent among

adolescents and young adults though may occur at

any age. The infection spreads through contact

with saliva; among young people and within fami-

lies, sharing drinks and food are common means

of contracting the illness. The Epstein-Barr VIRUS

infects B-cell lymphocytes, also called mononu-

clear (single nucleus) lymphocytes, which is what

gives the illness its name.

Symptoms and Diagnostic Path

The symptoms of infectious mononucleosis are

flulike and generally mild to moderate in severity.

Many people do not realize they have the illness.

Symptoms include

• low-grade FEVER


• HEADACHE


• sore THROAT(PHARYNGITIS)


• fatigue


• cervical and axillary LYMPHADENOPATHY(swollen
  LY M P Hnodes in the neck and underarms)

344 Infectious Diseases