How To Diagnose, Treat And Prevent Yellow Fever

Diagnosing Yellow Fever; Treating Yellow Fever; Preventing Yellow Fever; Is yellow fever preventable and treatable?
Medical Tutors Limited
November 1, 2019

03:09 PM

Summary
Yellow fever is one of the dangerous fevers ever known to men. It is transferable from one human to another through the mosquito. Although not fully treatable, yet it's preventable if all measures are succinctly followed.

Diagnosing yellow fever based on signs and symptoms can be difficult because early in its course, the infection can be easily confused with malaria, typhoid, viral hepatitis, dengue fever (and other viral hemorrhagic fevers) and poisoning.

Diagnosis of yellow fever is based on the clinical history of exposure to a mosquito bite in an endemic region, as well as a history of symptoms. Blood sample(s) will be analyzed for the presence of the virus or for the antibodies meant to fight the virus.

Polymerase chain reaction (PCR) testing in blood and urine can sometimes detect the virus in early stages of the disease. In later stages, testing to identify antibodies is needed (ELISA and PRNT).

There are a few tests that can support or confirm the diagnosis of yellow fever. They include:

  • Antibody Test: This test is the most well-established diagnostic test for yellow fever. It looks for the presence of immune proteins to yellow fever in your blood, which indicates that you are either fighting off or have effectively have fought the infection. It may take several days for your body to produce enough antibodies to be able to be detected, however. You may need to wait up to two weeks to get your results.
  • Viral PCR Test: PCR tests can detect the genetic material of the virus in your blood. A positive PCR test indicates that you have the virus in your body, so it is considered a stronger indicator of current infection than an antibody test. An important limitation: The viral RNA is detectable early after infection, but is not easily detectable after several days of infection. This means that you can get a negative PCR test result even if you have the infection. 
  • Urine Test: A relatively new test can detect the viral PCR in the urine, making the diagnosis more practical. However, this test, while promising, is not yet used widely.

Treatment of Yellow Fever

Presently, there is no specific antiviral in treating yellow fever. However, the illness can become quite severe, and related complications can require medical care, where good and early supportive treatment can help to improve survival rates As a result, treatment consists primarily of supportive care in a hospital.

People should understand that treating Yellow fever can only be supervised at the hospital and not at home. And these supervisions include:

  • Prevention of bleeding:Because of the risk of bleeding, medications that induce it, such as aspirin, ibuprofen, and naproxen, should generally be avoided.
  • Hydration:Maintaining hydration throughout the illness with oral or IV fluids may be necessary, particularly if you experience vomiting or low blood pressure.
  • Fever control: Generally, yellow fever is associated with low-grade fevers. But if your fevers become higher than expected, you may need medication to lower your temperature.
  • Pain:If you experience muscle pain or generalized discomfort, it may be managed with oral or injected pain relievers.
  • Blood pressure support:For those who are in shock, which occurs when blood pressure is extremely low, blood pressure can be raised with medications that constrict the blood vessels, often referred to as pressors.
  • Management of organ failure:When yellow fever causes organ failure, those organs need to be supported while the infection improves. For example, a ventilator may be needed to assist with breathing; dialysis may be required to do the work of the kidneys.

Prevention of Yellow Fever

How Yellow Fever is Spread (Transmission)

Yellow fever virus is a ribonucleic acid (RNA) virus that belongs to the genus Flavivirus. Yellow fever virus is transmitted to people primarily through the bite of infected Aedes or Haemogogus species mosquitoes. Mosquitoes acquire the virus by feeding on infected primates (human or non - human) and then can transmit the virus to other primates (human or non - human). People infected with yellow fever virus are infectious to mosquitoes (referred to as being “viremic”) shortly before the onset of fever and up to 5 days after onset.

Yellow fever virus has three transmission cycles: jungle (sylvatic), inter­mediate (savannah), and urban.

  • Sylvatic Cycle (Jungle Yellow Fever): This is when yellow fever spreads in the jungle, largely spreading without humans; thereby, spreading from non - human primate (like a monkey) to non-human primate by mosquitoes. When humans visit such jungle area where yellow fever is spread among these primates (i.e. for mining, hunting, or tourism), they can also be bitten by a mosquito and become ill, thus becoming infected with the yellow fever virus.
  • Intermediate or Savannah Cycle (Intermediate Yellow Fever): In this type of transmission, yellow fever spreads regularly between monkeys and humans through semi – domestic mosquitoes in areas (i.e. mosquitoes on the edge of jungle areas). It is spread from monkey to human, monkey to monkey, human to human, or human to monkey. Increased contact between people and infected mosquitoes leads to increased transmission and many separate villages in an area can develop outbreaks at the same time. This is the most common type of outbreak in Africa.
  • Urban Cycle (Urban Yellow Fever): In the urban cycle, yellow fever spreads primarily between people through mosquitoes living in urban areas (high populated areas) where people have little or no immunity, due to lack of vaccination. It usually starts when someone who has been infected with the virus returns from a jungle area. In these conditions, infected mosquitoes transmit the virus from person to person, therefore leading to sudden and large outbreaks in those areas.

How to Prevent Yellow Fever

In preventing yellow fever from becoming epidemic or spreading from one human to another, it is imperative for people to understand the various ways to prevent yellow fever. Here are some ways in preventing yellow fever.

  1. Vaccination: Vaccination is the most important means of preventing yellow fever. The yellow fever vaccine is safe, affordable and a single dose provides life-long protection against yellow fever disease. A booster dose of yellow fever vaccine is not needed.

Several vaccination strategies are used to prevent yellow fever disease and transmission: routine infant immunization; mass vaccination campaigns designed to increase coverage in countries at risk; and vaccination of travelers going to yellow fever endemic areas.

In high-risk areas where vaccination coverage is low, prompt recognition and control of outbreaks using mass immunization is critical. It is important to vaccinate most (80% or more) of the population at risk to prevent transmission in a region with a yellow fever outbreak.

Though being given the vaccine is quite recommended and important, yet there are certain individuals who can be exempted from the vaccination. They include:

  • Infants aged less than 9 months.
  • Pregnant women (except there is an outbreak and high rate of being infected).
  • People with severe allergies to egg protein.
  • People with severe immunodeficiency due to symptomatic HIV/AIDS or other causes, or who have a thymus disorder.
  1. Vector Control (Mosquitoes Precaution): The risk of yellow fever transmission in urban areas can be reduced by eliminating potential mosquito breeding sites, including by applying larvicides to water storage containers and other places where standing water collects.
    Although it isn’t always possible to completely avoid mosquito bites, people can wear layers, particularly when traveling in jungles and forests, and you can use insecticides. It is also recommended to sleep under protective nets while in an enclosed room.
  2. Protecting Others:Due to the fact that yellow fever virus can be spread from one human to another, it is highly recommended that one remain under a mosquito net to avoid epidemic of the virus..

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