Infectious
diseases
are
caused
by
harmful
organisms
called
____________________
entering
our
body
.
The
most
common
pathogens
are
____________________
and
____________________
.
Other
microorganisms
,
such
as
some
kinds
of
____________________
and
____________________
,
can
also
cause
diseases
.
An
infectious
disease
is
considered
____________________
if
it
is
easily
____________________
from
one
person
to
another
.
Some
diseases
,
such
as
colds
,
spread
from
person
to
person
through
the
____________________
.
The
pathogens
usually
enter
the
body
through
the
____________________
or
____________________
.
