Yellow fever is an acute viral infection caused by a specific type of mosquito. It is a hemorrhagic condition that mostly occurs in countries like Africa and South America in the permanent residents of these countries as well as travelers who come for visiting purposes.
In mild cases, it develops with symptoms like fever, nausea, vomiting, and headache. However, in the acute condition, it can lead to high fever, bleeding into the skin as well as healthy cells death in liver and kidney organs that can lead to liver damages if enough cells died. If this happens the risk of developing Jaundice remains too high which is a health condition in which the affected person’s eyes and overall body skin turns yellowish.
This is the reason it crucial to identify the symptoms of this disease, as early-stage recognition and treatment of yellow fever can protect the patient’s health from major health hazard risks.
Yellow fever is better defined as an acute, systemic disease because it occurs suddenly and affects the whole body of the patient. Flavivirus causes this fever which particularly transmitted by mosquitoes belonging to Aedes and Haemogogus species.
As per the World Health Organization record in the year 2013, there were approximately 84,000 severe cases of yellow fever whereas the fatalities cases were between 29,000 and 60,000. Out of all these yellow fever cases, 90 percent of cases have solely occurred in Africa. A recent outbreak is identified in Brazil for which CDC has imposed level 2 alert for traveler’s safety.
What Is Yellow Fever?
Yellow fever is a severe flu-like disease, potentially deadly that is spread by mosquitoes. More precisely it is defined as high fever and Jaundice, a disease in which skin and eyes colors turn to yellowish. This characteristic of yellow fever gives it the name of this disease. The disease is very common in some parts of Africa, South America and certain parts of the Caribbean. Though it is not a curable condition but one can prevent its growth risk by taking a yellow fever vaccine.
Flavivirus causes yellow fever which then is transmitted through the mosquitoes bite, generally the Aedes aegypti mosquito. This particular mosquito gets infected whenever it bites an infected person or a monkey. Once a mosquito gets infected it remains infectious for the rest of its life.
Other than mosquitoes the other well-known host of Flavivirus includes primates and humans. If a mosquito bites a monkey that is affected with fever then it can pass the fever to humans by biting them. Resulting in an outbreaks situation may occur.
The Flavivirus is endemic among monkeys living on tree-tops known as the canopy, in the jungle of different parts of Africa and the Americas. That means an infected mosquito can easily transmit this virus to any traveler or who resides around the jungles of these countries making them infected. Hence the infected person bears the risk of spreading it to many other people when they return back to their community.
Anyone traveling to the yellow fever outbreak areas contains the risk of contracting this infectious disease. However, one positive thing about this disease is that once someone gets infected with this disease they become immune to it which means their future risk of developing this health issue decreases to a great extent with their natural immune power boost.
Settlements near the jungle areas where infected monkeys and mosquitoes live mostly are highly infected regions and the disease spreads from there to other areas. These regions include Sub-Saharan Africa, Tropical South America and some parts of the Caribbean.
So people who are planning to visits these areas of the world should ensure before their visits whether they need to get a vaccination or not. A vaccine for yellow fever needed to be taken before 10 to 14 days time period before the actual visits to these places in order to have complete protection from this disease risk.
Symptoms of Yellow Fever
After the exposures to yellow fever causing flavivirus the affected person starts developing the symptoms of this disease within 3 to 6 days of their exposure. The initials days symptoms of yellow fever are very much similar to the influenza virus symptoms including-
- Muscle aches
- Joint aches
During the acute phase of this disease which generally lasts for 3 to 4 days the symptoms include-
- Muscle aches
- Joint aches
- Loss of appetite
At the end of the acute phase of yellow fever, the symptoms of this disease start reducing and vanishing. In many cases, people recover from the disease at the end of this phase. However, in certain cases, people develop more serious symptoms after the acute phase.
The symptoms of acute-phase may disappear for 24 hours and then the symptoms return back along with new and more severe symptoms including-
- Abdominal pain
- Reduced urination
- Vomiting may be with blood
- Unusual heart rhythm
- Bleeding from nose, mouth ad eyes
This is the fatal phase of this disease however only 15% of total Yellow fever cases encounter this state as per the Trusted Source.
Causes of Yellow Fever
Flavivirus is a virus that causes Yellow fever disease. It is transmitted to a healthy person's body when an infected mosquito bites them. The mosquito gets this virus while it bites an infected person or monkey. However, just like many other infectious diseases, it cannot be spread from one person to another person's body.
The mosquitoes who bear this virus usually breed in humid, semi-humid and tropical rainforests regions. Also, they can breed in areas surrounding to still water bodies. The risk of creating small scale epidemics remains high in areas where human contacts with the infected mosquitoes are high and people over there have never got vaccinated for yellow fever.
The risk of developing yellow fever remains too high for people who are living in areas where infected mosquitoes population is very high and residents over there have never been vaccinated for the Yellow fever.
As per the World Health Organization approx. 200000 people get infected with this viral disease every year and Africa with its 32 affected countries ranks first in this list including Sierra Leone and Rwanda. In Latin America, 13 countries are highly infected places of this disease including Brazil, Bolivia, Colombia, Peru, and Ecuador.
Diagnosis of Yellow Fever
People who have had a recent visit in counties that are popular for this disease outbreak should immediately consult with a doctor if they notice flu-like symptoms. This is because an early-stage diagnosis helps in initiating necessary treatment procedures on time and will prevent the risk of this disease to be fatal.
On your visit to the doctor’s office, they will ask every minute detail of the symptoms that you are experiencing. In case the doctor suspects that you have developed yellow fever they will ask for a blood test that requires to be done immediately. On the basis of signs and symptoms and your blood test report, the doctor will confirm this disease.
A blood test is very crucial to be done because it helps to rule out whether your symptoms are developing as a result of Yellow fever or due to other diseases or infections such as malaria, typhoid, dengue fever, viral hepatitis, poisoning, leptospirosis or some other viral hemorrhagic fevers.
The blood test will determine the virus responsible for Yellow fever. Also, it will detect the antibodies that the patient’s body produces as an immune response to fight off with the virus when it enters inside the body.
Also, the blood test report reveals any drop in the white blood cell level or leucopenia which is another important sign of this infection. The blood tests that are used for diagnosis the Yellow fever includes-
- Enzyme-linked Immunosorbent Assay (ELISA)
- Polymerase Chain Reaction (PCR)
The test results may take several days to come in hand.
There is no definite cure such as antiviral medication etc for the treatment of yellow fever. So the purpose of the treatment measures lies around giving enough supportive care to the hospitalized patient for this disease. The supportive care helps in managing symptoms and in boosting the immune system to enable it to fight off the infections. Supportive cares that are offered in a hospital include-
- Providing enough fluids through veins
- Providing oxygen support
- Blood transfusions if necessary to replace lost blood
- Maintaining a healthy blood pressure level
- Treatment is given for other infections which may develop or has already developed
- In the case of kidney-failure dialysis is given
- In some cases, plasma transfusion is given to replace proteins that aid in blood clotting function
During the hospitalization period, the complete focus remains to give full protection against mosquitoes bite to patient. Otherwise, if a mosquito bites a patient they get infected and then pass on the disease to other healthy people nearby. The Yellow fever infected patient should not use Aspirin and Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) because these medications increase the risk of bleeding in the patient.
As per one study report published by the journal PLOS Neglected Tropical Diseases in the year 2014, any unusual changes in the white blood cells indicate for the early stage sign of fatal yellow fever disease. So this can help is early-stage diagnosis and treatment of this fatal condition.
Vaccination is the most ideal way to prevent your risk of developing yellow fever. The vaccine for this fever is given on a single shot that contains live and very weak versions of the virus that aid in creating immunity in your body.
The Centers for Disease Control (CDC) recommends every person to get this vaccine as an essential routine for their health protection. As per the CDC people aging between 9 months to 59 years are eligible to get this vaccination at any point in time of their life.
However, it is highly essential if someone is about to travel in an outbreak area or living in places where the risk of yellow fever is quite high. People who are planning for international traveling should check the CDC official website to have awareness regarding the new vaccinations that they need to have before traveling.
People who shouldn’t get this vaccination include-
- Children aging under 9 months in the U.S. unless the risk of getting a yellow fever is unavoidable
- Infants who are younger than 6 months
- Breastfeeding mothers
- Pregnant women unless the risk of yellow fever is unavoidable
- People who are allergic to eggs, gelatin, and chicken proteins
- People with special health conditions that compromise their immune system making it weaker to fight off with diseases such as HIV, AIDS, and people who are receiving chemotherapy and radiotherapy.
People aging 60 and above who are planning to travel an area that is known for this virus outbreak should consult with their doctor first regarding vaccination that can prevent their risk of yellow fever.
Also breastfeeding women or those who are planning to travel with their infants of 6 to 8 months old should either postpone their travel to the affected areas or should consult with their doctor about any vaccination program for their health protection. The vaccination for yellow fever is highly safe and it requires only one shot for getting a minimum of 10 years of protection from the yellow fever contraction risk.
After 30 days of this vaccination in 99% cases, people have complete protection. The side effects that may occur after getting vaccine include-
- Muscle pain
- Mild headache
- Low-grade fever
- Soreness around the injected area
- In very rare condition infants and older age people may develop a serious reaction known as Encephalitis
Apart from vaccination other methods for preventing yellow fever is protection from mosquito bites especially in highly affected areas where these mosquitoes breed in a very high quantity. One should use insect repellant, wear protective clothing that minimizes the mosquito bites, and should proactively stay inside the home during the peak seasons of this insect bite in a year.
In most of the cases, of yellow fever, people do not develop symptoms however those who develop symptoms usually experience fatigue for several months. People who develop severe symptoms under this health condition among them the fatality rate remains between 20 to 50 percent containing the risk of death, as per the WHO Trusted Source. This is the reason why it is important to get immediate treatment of yellow fever once this condition is diagnosed medically.