Diagnosing Yellow Fever:
A presumptive diagnosis of yellow fever can often be made
based on the patient’s presenting symptoms, places and dates of travel, and
epidemiologic history of the location where the presumed infection occurred.
However, Yellow Fever is usually difficult to diagnose based
on the symptoms alone. This is due to
the similarity of its symptoms to those of other conditions also commonly found
in affected areas, such as malaria, typhoid fever, viral hepatitis,
leptospirosis, and dengue fever.
A formal diagnosis requires laboratory testing of blood
serum to detect virus-specific IgM and neutralizing antibodies. If blood
samples are taken early in the illness, sometimes the virus itself can be
found.
Immunoglobulin M (IgM) is a basic antibody that is produced
by B cells in the body. It is the first antibody to respond to initial exposure
to an antigen (such as the Yellow Fever Virus). It is also physically the
largest antibody in the human immune system.
Here are two short videos that 1) go over the overall
function of immunoglobulin (Ig) antibodies and 2) differentiate and breakdown
the 5 types of antibody immunoglobulin:
Important to note, is that the blood test may also show a
reduction in the number of infection-fighting white blood cells (leukocytes).
You may also hear this condition addressed as leukopenia in the medical
community and literature. This can occur
because the yellow fever virus suppresses the bone marrow, the spongy bone of
some bones that is responsible for blood cell production.
References:
Centers for Disease
Control and Prevention. (2011). Yellow fever. Retrieved from: http://www.cdc.gov/yellowfever/
Monath, T. P.
(2015). Yellow fever. UpToDate. Retrieved from http://www.uptodate.com/contents/yellow-fever
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