From Wikipedia,
the free encyclopedia
An asymptomatic carrier
(or carrier), is a person
who is infected with an
infectious disease or carries
the abnormal gene of a
recessive
genetic disorder, but displays
no symptoms. Although unaffected
by the disease or the disorder
themselves, carriers can transmit
it to others.
Mary Mallon, known as "Typhoid
Mary", was an asymptomatic carrier
of
typhoid fever. She worked as a
cook for several families in New
York City approximately a century
ago. Several cases of typhoid
fever in members of those families
were traced to her by the Health
Department. It appeared that she
"carried" the infectious agent
without becoming sick. There was
no way of eradicating the disease
and an attempt was made to
restrict her from continuing to
work as a cook to avoid spreading
it to others.
The daughters of Queen
Victoria, the princesses Alice
and Beatrix, were asymptomatic
carriers of the X-linked
hemophilia gene (more
precisely, an abnormal allele of a
gene necessary to produce one of
the blood clotting factors). Both
had children who continued to pass
the gene to succeeding generations
of the royal houses of
Spain and
Russia, into which they
married. Males who carried the
gene had hemophilia, while females
simply passed it to about half of
their children. The
genetic term for this type of
"carrying" of a
recessive trait is
heterozygote.
