INFECTIOUS DISEASE
appearance of symptoms. This incubation
period, during which an infected person
is likely to pass the microorganism to
others, may vary from a few hours or
days to, in some cases, several months.
TREATMENT
A n t i b i o t i c d r u g s
and other antimicrobial
drugs are the mainstay of treatment for
bacterial infection. For viral infection,
however, drug treatment is restricted to
severe infections and often relies on
supportive measures alone.
OUTLOOK
Progress has been made in the fight
against infectious diseases, but many
problems remain. The spread of diseases
such as
s e x u a l l y t r a n s m i t t e d i n f e c t i o n s
is
difficult to control and, for many infec-
tions, no effective
v a c c i n e
exists.
Some bacteria have developed
r e s i s -
t a n c e
to the drugs available; this could
lead
to
a
rise
in
potentially
fatal
bacterial
infections
similar
to
those
common before the development of
INFECTIOUS DISEASES: VIRAL INFECTIONS
Disease
Infective agent
Transmission
Incubation
period
Symptoms
Treatment
AIDS/HIV
infection
Human
immunodeficiency
virus (HIV)
Sexual contact; sharing
hypodermic needles;
mother to fetus or to
breast-fed baby;
unscreened blood
transfusions
6-8 weeks
Flulike illness; fever; fatigue;
sore throat; muscle aches;
swollen lymph nodes; skin
disorders; fungal, viral, or
bacterial infections
Treatment given for
complicating infections;
antiviral drugs can
prolong life expectancy
Chickenpox
Varicella-zoster
virus (herpes
zoster virus)
Airborne droplets; direct
contact
7-21 days
Slight fever; malaise; crops of
itchy blisters
Relief of symptoms;
aciclovir beneficial
in adults
Common cold
Numerous
rhino- and
adenoviruses;
coronaviruses
Airborne droplets; hand-to-
hand contact
1-3 days
Sneezing; chills; muscle aches;
runny nose; cough
Relief of symptoms
Hepatitis, viral
Hepatitis virus
types A, B, C, D,
or E
A, E: infected food or water
B, C, D: sexual contact;
infected blood; sharing
needles
A, E: 3-6
weeks
B, C, D: a few
weeks to
several months
Flulike illness; jaundice; many
people are asymptomatic
Relief of symptoms;
interferon may be
beneficial in some cases
Influenza
Influenza virus
types A, B, or C
Airborne droplets
1-3 days
Fever; chills; aches; headache;
sore throat; cough; runny nose
Relief of symptoms;
fluids
Measles
Measles virus
(a paramyxovirus)
Airborne droplets
7-14 days
Fever; coldlike symptoms;
mottled red rash that fades to
leave staining; conjunctivitis
Relief of symptoms
Meningitis,
viral
Various viruses
Various methods, including
via rodents
Variable
Fever; headache; drowsiness;
confusion
Relief of symptoms
Mononucleosis,
infectious
(glandular
fever)
Epstein-Barr virus
Possibly via saliva
1-6 weeks
Swollen glands; fever; sore
throat; headache; malaise;
lethargy
Relief of symptoms; rest;
fluids
Poliomyelitis
3 polioviruses
From faeces to mouth via
hands; airborne droplets
3-21 days
Minor illness: headache; sore
throat; vomiting
Major illness: fever; stiffneckand
back; muscle aches; paralysis
Relief of symptoms
Rabies
Rabies virus
(a rhabdovirus)
Bite, or lick on broken skin,
from infected animal
Usually 2-8
weeks, but may
be over 1 year
Fever; malaise; irrationality;
throat spasms; hydrophobia
No effective treatment
Rubella
Rubella virus
Airborne droplets; mother
to fetus
14-21 days
Low fever; characteristic rash;
congenital abnormalities in
fetus, including ear, eye, and
heart defects
Relief of symptoms
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