The transmission of yellow fever is via the Aedes aegypti or Haemagogus mosquito species. The responsible microbe is an RNA virus which is a member of the genus Flavivirus. It is endemic in 45 African and Latin American countries. More than 900 million people in these regions are at risk for acquisition of this medical condition (World Health Organization, 2011).
Yellow fever is uncommon in the United States. Worldwide, there may be 200,000 new cases of it each year. There were, however, outbreaks of the infection in Europe and North America from the 17th to 19th centuries. Like malaria and other mosquito-borne illnesses, yellow fever may occur in countries where the disease is not endemic because of people who travel between endemic and non-endemic regions in the world.
Avoid Mosquito Bites
Preventive measures are similar to those for malaria and other mosquito-borne diseases. Specifically, individuals who visit or reside in parts of the world where yellow fever is common must wear protective clothing. This includes long-sleeved shirts, long pants, and socks when outdoors. They should tuck in their shirts too as this lessens the possibility of mosquito bites.
They should stay in facilities with either screens or air-conditioning in order to keep mosquitoes outside the home. Moreover, the use of insect repellents will lower the risk of mosquito bites. Unlike the female Anopheles mosquito which bites between dusk and dawn, the Aedes aegypti mosquito bites between dawn and dusk.
Yellow Fever Vaccine
The best preventive measure for yellow fever is vaccination. It is a safe, effective, and inexpensive method to establish long-term immunity for humans. One injection of the yellow fever vaccine provides at least a decade of protection against yellow fever, and unless the individual plans to remain or return to an area where yellow fever occurs, no further shots or boosters are necessary.
The yellow fever vaccine is necessary for people who are at least nine months of age and who plan to travel or reside in endemic areas. The United States Food and Drug Administration has approved the yellow fever vaccine, and this immunization has a long record of success.
Patients who are allergic to any component of the yellow fever vaccine should not take it. This includes eggs, gelatin, and chicken proteins. A prior allergic reaction to the vaccine is also a contraindication to its subsequent use in that patient.
Infants less than nine months of age should not receive routine immunization against yellow fever. However, if there is an epidemic, the physician can administer the vaccine to infants who are at least six months of age. Babies in the first six months of life should never receive it.
Unless there is a community outbreak of yellow fever which would significantly increase the risk of transmission, pregnant women should not take it. If a pregnant woman takes the yellow fever vaccine, there is no evidence that harm to the fetus or birth defects will occur. The recommendation is that she take it two to four weeks after conception occurs.
Individuals who have immune system compromise, malignancy, disorder of the thymus gland, or organ transplantation should not receive the yellow fever vaccine. Elderly patients who are at least 60 years old need to discuss the matter with their physician before they take this immunization because these patients may be at risk for a reaction to it.
Some countries require a certificate of yellow fever immunization for visitors. This is especially the case for travelers from endemic regions of Africa or Latin America who visit Asia. If there is a reason for the traveler’s failure to obtain the immunization, he or she must produce medical waiver documentation upon arrival to the destination.
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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