Many patients who acquire yellow fever have few if any clinical symptoms. However, when signs and symptoms develop, they occur three to six days after the initial infection. Since jaundice is one of them, the name of the disease alludes to the clinical appearance of yellow skin.
Clinical Signs and Symptoms
There may be high fever, bleeding, and eventual circulatory shock with failure of several organs of the body. Severe headache, chills, generalized muscular aches and pain, nausea, vomiting, dizziness, loss of appetite, and lumbosacral discomfort may also occur.
The massive bleeding in these patients can manifest as dark or tarry stools, vomiting blood, irregularities in menstruation in women, blood in the urine, nosebleeds, bleeding from the gums, and skin lesions such as petechiae or ecchymoses which indicate easy bruisability or bleeding into tissues from ruptured blood vessels. They may also bleed from needle-puncture sites (Centers for Disease Control, 2011).
Yellow fever has two clinical phases. The first phase corresponds to the initial signs and symptoms and lasts three to four days. The second phase is more serious than the first and begins one day after the first phase. The second phase is when high fever returns, and the patient experiences multisystem organ failure.
Half of patients who reach the second phase will die within 10 to 14 days.
Clinical Laboratory Evaluation
Laboratory abnormalities in patients with yellow fever may include elevation or depression of the white cell count, prolongation of prothrombin and partial thromboplastin times, decrease in the level of platelets, and elevation of liver transaminase enzymes. Elevation of the blood level of bilirubin may occur, and laboratory tests in some cases will detect the presence of fibrin split products.
Since many of these clinical laboratory examinations occur in several medical conditions, the clinician will need virus-specific tests to confirm that the patient has yellow fever. Laboratory assessment for immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies which are specific for this disease will accomplish that.
The physician has to keep in mind that persistent antibodies to IgM can also be present for several years in patients who have already taken the yellow fever vaccine. Moreover, there may be serologic cross-reactivity with other flaviviruses such as those responsible for dengue and West Nile virus infection.
Despite the deadly nature of yellow fever, those who recover from the illness will have lifetime immunity against it.
Sources
- Centers for Disease Control. (2011). Yellow fever. Retrieved February 11, 2012.
- World Health Organization. (2011). Yellow fever. Fact sheet. Retrieved February 11, 2012.
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact their physician for advice.
Michael Koger - Dr. Koger obtained his medical education at Meharry Medical College and specialized in Internal Medicine.
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