Whenever we hear the word dangerous disease, the first and foremost term that comes to our mind is malaria or dengue. But there is one quiet risk frequently overlooked: yellow fever. Is it merely an old tropical disease? It is a viral infection that poses a potential major risk in some parts of Africa and South America. What is worse is that a lot of people do not know the severity of the disease- it is something that can be prevented with a simple vaccination.
CritiCare Hospital believes in creating awareness as the first line of defense. The more aware you are, the better protected you are. This blog will take you through everything you need to know about yellow fever-from causation, symptoms, and diagnosis to treatment and, most importantly, prevention. Let us make this step towards staying informed and staying safe.
What Is Yellow Fever?
Yellow Fever is a common misconception people have, associating it with jaundice or thinking that jaundice sets in. This was often thought to be so because one of the frequent symptoms of Yellow Fever is jaundice downward the yellowing of skin and the eyes. However, it must be clear that in these cases, yellow walls are symptomatic and not the cause.
In truth, Yellow Fever is a serious viral human disease that gets into the system through the bites of infected female mosquitoes, especially of the Aedes aegypti species. Hence, the yellow coloring does happen due to liver damage by the virus and not by jaundice as a variety of liver problems. Clearing up this misconception plays an important role in creating awareness and promoting timely prevention. Let’s take a deep dive into the transmission of yellow fever and what the cycle is going on after the transmission has already taken place.
How Is Yellow Fever Transmitted?
It is mainly seen that the main reason for this disease transmission is because of the bite of a mosquito that is infected with the virus causing yellow fever. This is how the cycle goes:
- A mosquito bites an infected human or primate.
- The virus replicates inside the mosquito.
- When the mosquito bites another person, the disease is transmitted.
There are three transmission modes:
- Sylvatic (jungle) cycle: Transmission is between mosquitoes and wild animals, mainly monkeys.
- Intermediate (savannah) cycle: In Africa, mosquitoes convey the infection to either monkeys or humans, mostly in rural areas.
- Urban cycle: In towns, infected humans transmit the virus to mosquitoes, which bite other people.
Symptoms of Yellow Fever
The incubation period, which is the time from when the mosquito bite transmits the pathogens to the appearance of the symptoms leading to yellow fever, is quite short, that is, mainly three to six days, and the symptoms are observed in two phases:
Phase 1: Initial Stage (Mild to Moderate Symptoms)
- Sudden fever
- Chills
- Headache
- Back pain
- Muscle pains, especially in the shoulders and back
- Loss of appetite
- Nausea and vomiting
- Fatigue
- Flushing of face
By 3 to 4 days, most patients recover; in 15-25% of cases, however, the disease advances to its severe form.
Phase 2: Toxic Stage (Severe Symptoms)
The first ones to arrive are hemorrhagic features:
- Jaundice (yellowing of skin and eyes)
- Dark urine
- Bleeding from the nose, mouth, eyes, or stomach
- Vomiting blood (black vomit)
- Liver-kidney failure
- Delirium, seizures, coma
- Shock
In this period, yellow fever may be fatal. The case-fatality rate for severe yellow fever is between 20 and 50%, depending on the availability of supportive care.
Diagnosis of Yellow Fever
Accurate diagnosis is vital, but most times very difficult, especially in the early phase when symptoms can resemble other illnesses such as malaria, dengue, or hepatitis. At CritiCare Hospital, we use a composite approach to diagnosis:
- Medical History & Travel Details
We begin by assessing
- Recent travel to endemic areas
- Vaccination history
- Mosquito exposure
- Any previous infections
- Physical Examination
Doctors look for clinical signs like
- Fever
- Jaundice
- Dehydration
- Bleeding
- Laboratory Tests
- Blood tests to detect liver enzymes (ALT/AST), kidney function, and platelet count
- Serologic tests to detect yellow fever-specific IgM antibodies
- RT-PCR (Reverse Transcription Polymerase Chain Reaction) to identify viral RNA, especially early in infection
- Liver biopsy (rare) in fatal cases to confirm
Yellow fever is a notifiable disease, so any suspected or confirmed case has to be reported to the public health authorities.
Treatment for Yellow Fever
There is currently no antiviral medication available for yellow fever. General supportive care is aimed at alleviating symptoms and preventing complications.
Supportive Treatment:
- Hospitalisation, especially in the toxic phase
- IV fluids to prevent dehydration
- Oxygen therapy, if required
- Pain relievers and fever reducers (e.g., paracetamol).
- Monitor the proper functioning of the liver and kidneyss
- Blood transfusions in cases of severe bleeding
Many patients, even with severe forms quite often can die without timely medical help and proper supportive care.
Complications of Yellow Fever
Promptly untreated, yellow fever leads to:
- Acute liver failure
- Kidney failure
- Multiple organ dysfunction
- Sepsis
- Shock
- Death
Survivors mostly complain of prolonged fatigue and weakness for weeks or even months post-recovery.
Prevention: The Best Defense Against Yellow Fever
- Vaccination: Your Strongest Shield
The yellow fever vaccine is a single-dose live-attenuated vaccine that confers life-long immunity to most people.
- Given to persons aged 9 months or older
- Provides immunity within 10 days; 99% effective within 30 days
- An International Certificate of Vaccination (Yellow Card) is generally required for entry into certain countries
We at CritiCare Hospital provide WHO-approved yellow fever vaccine services to international travelers.
- Mosquito Control
Since it is the vector, exposure is the key:
- Use insect repellents (DEET or picaridin contents)
- Wear long sleeves and long pants
- Sleep under a mosquito net, especially in endemic areas
- Stay indoors when mosquitoes are most active (dawn and dusk)
- Ensure your windows and door screens are intact
- Drain standing water (mosquito breeding sites)
- Travel Precautions
Before traveling to high-risk countries:
- Seek advice from a travel medicine clinic at least 10 days before leaving
- Get vaccinated and carry the International Certificate of Vaccination
- Get updated on yellow fever outbreaks through WHO or CDC updates
Who Should NOT Get the Vaccine?
Although it is generally considered safe, the vaccine may not be suitable for:
- Infants under 6 months
- Those with severe allergies to eggs
- People who have immune deficiencies
- Anyone receiving cancer treatments
- Pregnant or nursing mothers (should discuss with a doctor)
In such situations, travellers should carry medical exemption letters and take precautions.
Yellow Fever and Public Health
Owing to the risk of an instant outbreak, surveillance and vaccination campaigns double up as a primary method of prevention. While the WHO and GAVI are seeking to improve vaccine coverage in endemic areas. Though India is non-endemic, strict regulations exist for persons arriving from yellow fever risk zones.
Conclusion
To wrap up, while Yellow Fever still stands as a health threat worldwide, it is mostly preventable by taking precautions. Vaccinating on time, controlling mosquitoes, and promptly seeking medical attention make all the difference. At CritiCare Hospital, we intend to advise and guard you every step of the way. Keep yourself informed, stay protected-and this goes to show that your health matters wherever you live.
