Viral
Diseases
of
Human
Viruses
pathogenic
on
humans
are
artificially
classified
into
four
groups
mainly
on
the
basis
of
organs
on
or
in
which
typical
symptoms
are
produced.
These
groups
are
as
follows:
1.
Pneumotropic
viral
diseases involving
respiratory
tract,
such
as
influenza
and
common
colds.
2.
Dermotropic
viral
diseases involving
mainly
skins,
as
measles,
chicken
pox,
small
pox
etc.
3.
Viscerotropic
viral
diseases involving
mainly
internal
organs,
as
yellow
fever,
dengue
fever,
hepatitis
etc.
4.
Neurotropic
viral
diseases
involving
mainly
central
nervous
system,
such
as
rabies,
polio,
encephalitis
etc.
In
each
of
the
above
four
groups,
other
organs
may
also
be
involved.
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