Creutzfeldt-Jakob Disease (cont.)
How is CJD Transmitted?
CJD cannot be transmitted through the air or through
touching or most other forms of casual contact. Spouses and other household
members of sporadic CJD patients have no higher risk of contracting the disease
than the general population. However, exposure to brain tissue and spinal cord
fluid from
infected patients should be avoided to prevent transmission of the disease
through these materials.
In some cases, CJD has spread to other people from grafts of dura mater (a tissue
that covers the brain), transplanted corneas, implantation of
inadequately sterilized electrodes in the brain, and injections of contaminated
pituitary growth hormone derived from human pituitary glands taken from
cadavers. Doctors call these cases that are linked to medical procedures
iatrogenic cases. Since
1985, all human growth hormone used in the United States has been synthesized by
recombinant DNA procedures, which eliminates the risk of
transmitting CJD by this route.
The appearance of the new variant of CJD (nv-CJD or v-CJD) in several younger
than average people in Great Britain and France has led to concern that BSE may
be transmitted to humans through consumption of contaminated beef. Although
laboratory tests have shown a strong similarity between the prions causing BSE
and v-CJD, there is no direct proof to support this theory.
Many people are concerned that it may be possible to transmit CJD through
blood and related blood products such as plasma. Some animal
studies suggest that contaminated blood and related products may transmit the
disease, although this has never been shown in humans. If there are infectious
agents in these fluids, they are probably in very low concentrations. Scientists
do not know how many abnormal prions a person must receive before he or she
develops CJD, so they do not know whether these fluids are potentially
infectious or not. They do know that, even though millions of people receive
blood transfusions each year, there are no reported cases of someone contracting
CJD from a transfusion. Even among people with hemophilia, who sometimes receive blood plasma concentrated
from thousands of donors, there are no reported cases of CJD.
While there is no evidence that blood from people with
sporadic CJD is infectious, studies have found that infectious prions from BSE
and vCJD may accumulate in the lymph nodes (which produce white blood cells), the spleen, and
the tonsils. These findings suggest that blood transfusions from people with
vCJD might transmit the disease. The possibility that blood from people with
vCJD may be infectious has led to a policy preventing people in the United
States from donating blood if they have resided for more than 3 months in a
country or countries where BSE is common.
Next: How can people avoid spreading Creutzfeldt-Jakob disease? »
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