96590 Health Library | Health and Wellness | Wellmont Health System
  • Yellow Fever

    Definition

    Yellow fever is a disease carried by female mosquitoes of two species ( Aedes and Haemogogus species). Mosquitoes pass yellow fever to humans through a small amount of saliva when they bite. The species of mosquito that carry yellow fever are native to sub-Saharan Africa and South America, but can also be found in other areas.
    Yellow fever can cause flu -like symptoms, yellowing of both the skin and the whites of the eyes, and can cause death. Yellow fever is a rare disease in travelers because many get the vaccine, but is endemic in impoverished areas because the people cannot afford to get vaccinated. If you live in or have recently visited sub-Saharan Africa or South America, and believe you may have yellow fever, see your doctor.

    Causes

    The yellow fever virus is the cause of yellow fever. Yellow fever virus is transmitted to humans when an infected mosquito bites a person. Yellow fever is not communicable, meaning it cannot be passed directly from one person to another.
    Mosquito Bite
    Mosquito bite
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    Risk Factors

    The following factors increase your chance of getting yellow fever:
    • Living, working, or traveling in jungle or urban areas with yellow fever, including: Sub-Saharan Africa
      • Many countries in Africa have constant cases of yellow fever
      South America
      • Bolivia, Brazil, Colombia, Ecuador, and Peru are among the highest risk in South America
    • Failure to take proper precautions. Precautions include the following:
      • Receiving the yellow fever vaccination
      • Reducing contact with mosquitoes (for example, using bed nets, long-sleeved clothing, and screens)
      • Using insect repellents

    Symptoms

    Yellow fever has two phases: acute and toxic. All individuals infected with yellow fever will experience the acute phase. Fifteen percent of people with yellow fever will progress into the toxic phase.
    If you experience any of the following symptoms, do not assume that it is due to yellow fever. Many of them also occur due to other less serious illnesses such as the flu. However, if you experience any of these symptoms, seek medical attention.
    Acute Phase
    • Fever
    • Headache
    • Muscle pain
    • Backache
    • Chills
    • Loss of appetite
    • Nausea and/or vomiting
    Toxic Phase
    • High fever
    • Abdominal pain
    • Bleeding from the gums, nose, eyes, and/or stomach
    • “Black” vomit (vomit that appears black due to blood content)
    • Low blood pressure
    • Liver failure, which may lead to jaundice (yellowing of the skin and whites of the eyes)
    • Kidney failure
    • Confusion
    • Seizure
    • Coma
    • Death (approximately 50% of toxic phase patients die)
    Yellow fever symptoms appear 3 to 6 days after a person is bitten by an infected mosquito. Typically, acute phase symptoms will persist for 3 to 4 days, and then disappear. If an infected person is going to progress into the toxic phase, toxic phase symptoms will begin within 24 hours of the end of the acute phase. When a person recovers from yellow fever, they are considered to have lifetime immunity from the disease.

    Diagnosis

    Your doctor will ask you about your symptoms, medical history, and when and where you traveled. Your doctor will then perform a physical exam, and order blood tests to screen for signs of yellow fever in your blood.

    Treatment

    Currently, medications or treatments specifically for yellow fever are not available. However, there are treatments that that can be given at a hospital to ease some symptoms of yellow fever.

    Hydration

    It is important to keep the body hydrated. Fluids containing electrolytes and salts may be given orally, or may be injected through a vein to prevent dehydration.

    Fever Reduction Methods

    Cool water or fever reducing medications (for example, Tylenol) may be given to reduce fever.

    Kidney Dialysis

    In toxic phase cases, dialysis may be needed to help the kidneys filter waste.
    Dialysis Mechanism
    Dialysis pump
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    Blood Transfusion

    In toxic phase cases, a transfusion may be needed to replace blood cells and clotting agents lost through bleeding.

    Antibiotics for Secondary Infections

    Fighting yellow fever may cause a person’s immune system to become temporarily weak. A weak immune system cannot guard against bacterial infections as it normally would, so infections occur more easily. Antibiotics may be given to fight bacterial infections if they occur. Antibiotics cannot be given to treat yellow fever because yellow fever is a virus, and viruses do not respond to antibiotics.

    Prevention

    Vaccination is the best way to prevent yellow fever. The yellow fever vaccine is recommended for people aged 9 months to 59 years who are traveling to or living in areas where the disease is present. Your doctor will help decide if the vaccine is right for you.
    Other ways to reduce your risk of being bitten by a mosquito include:
    • Staying in air-conditioned or well-screened areas
    • Wearing long-sleeved clothing and long pants
    • Using bed netting while sleeping
    • Removing or destroying mosquito-breeding areas—Mosquitoes lay their eggs in standing pools of water, such as the inside of old tires, flower pots, and small puddles.
    • Using insect repellents containing DEET and Permethrin on clothes, exposed skin, and on bed nets for extra protection

    RESOURCES

    US Centers for Disease Control and Prevention http://www.cdc.gov/

    World Health Organization http://www.who.int/en/

    CANADIAN RESOURCES

    BC Health Guide http://www.bchealthguide.org/

    Travel Medicine Program, Public Health Agency of Canada http://www.phac-aspc.gc.ca/tmp-pmv/index.html/

    References

    García-Rejón JE, Loroño-Pino MA, Farfán-Ale JA, et al. Mosquito infestation and dengue virus infection in Aedes aegypti females in schools in Merida, Mexico. Am J Trop Med Hyg. 2011;84(3):489-496.

    Global map. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/ncidod/dvbid/yellowfever/YF%5FGlobalMap.html . Accessed November 19, 2009.

    Walker KR, Joy TK, Ellers-Kirk C, Ramberg FB. Human and environmental factors affecting Aedes aegypti distribution in an arid urban environment. J Am Mosq Control Assoc. 2011;27(2):135-141.

    Yellow fever. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/ncidod/dvbid/yellowfever/YF%5FFactSheet.html . Accessed November 19, 2009.

    Yellow fever. Massachusetts Government website. Available at: http://www.mass.gov/dph/cdc/gsrman/yellow.pdf . Accessed on July 14, 2005.

    Yellow fever. World Health Organization website. Available at: http://www.who.int/mediacentre/factsheets/fs100/en/ . Accessed July 11, 2005.

    Yellow fever vaccine: what you need to know. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/vaccines/pubs/vis/downloads/vis-yf.pdf . Published March 30, 2012. Accessed February 24, 2012.

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