A viral infection spread by mosquitoes,Yellow Fever has gained popularity following the need for vaccination certificate for travellers to endemic areas.Most commonly seen in parts of Africa and South America,yellow fever has the potential to create serious life-threatening complications in severe cases.
Why is the fever "Yellow"?
The yellow in the name refers to the presence of jaundice in some infected individuals. It must be kept in mind that Yellow fever is a haemorrhagic fever meaning it can have bleeding manifestations.
How is Yellow Fever transmitted?
Aedes aegypti mosquitoes are the bearers of the virus.The interesting fact is that these mosquitoes breed in clean water also.Apart from humans,monkeys are also at risk of getting infected.As the mosquito bites humans or monkeys having yellow fever,the virus enters the mosquito's bloodstream and multiplicates there before transmitting the infection to another susceptible individual.
When am I at risk?
Since the disease is endemic to regions of Sub-Saharan Africa and tropical South America,travel to these areas must alert one to the possibility of contracting the disease.
What is the clinical picture like?
Once a person gets the infection,he/she might be asymptomatic for the first week(incubation period).Once symptomatic,in mild cases,the manifestations improve in another week's time.The commonest symptoms of Yellow Fever in the acute phase are:
Fever
Muscle pain and bodyaches
Severe backache
Nausea and/or vomiting
Fatigue
Loss of appetite.
A small proportion of patients might progress onto the more toxic,second stage eventually after this period.However,this period is characterised by High grade fever and involvement of multiple organ systems notably the liver and the kidneys. It is at this phase that jaundice develops which might be associated with decreased urine output,high coloured urine and abdominal pain.Bleeding manifestations develop in a majority and the mortality is as high as around 50%.
What are the diagnostic dilemmas faced by the clinicians?
Yellow Fever being not a common diagnosis can be difficult to diagnose but might be confused with other illnesses which resemble it.These include:
Malaria
Dengue fever
Leptospirosis
Viral hepatitis
Other viral haemorrhagic fevers,etc.
Specific tests such as Urine PCR and antibody detection by ELISA can aid in the diagnosis.
Treatment
There is currently no specific antiviral medication to treat Yellow fever.Having said that,the key to prompt recovery is adequate supportive treatment and hydration.Attempts must be made to ensure adequate control of fever and anticipation of system failure by taking note of parameters that might be manifested in such cases of organ involvement.
Preventive measures against Yellow Fever
Vaccination: Vaccination is undoubtedly the strongest weapon to ward off Yellow fever.A safe,affordable,single dose vaccine,it provides lifelong protection against the disease without any need for a booster dose.Before planning your travel to an endemic area,talk with your doctor regarding vaccination,preferable 10-14 days prior to travel.Some nations require its visiting travellers top produce a valid vaccination certificate also.The vaccine can have its own share of mild side effects and is considered to be safe for administration to individuals aged between 1 and 60 years. It is reported that the vaccine confers immunity to 99% of people within 30 days.
Vaccination is not advisable for:
Infants
Pregnant women
Those allergic to egg proteins
Severely immunocompromised like HIV positive individuals.
Control of Mosquitoes: Yellow fever being a vector-borne disease,the control of vectors(mosquitoes in this case)and their breeding grounds is crucial to prevention of disease outbreaks.
How can you reduce exposure to mosquitoes?
Personal Protective measures-such as adequately covered clothing with long sleeves and using repellants.
Repellants which can be those that can be directly applied to skin and those to be applied over fabrics.
Avoiding unnecessary outdoor activities.
However,the good news is that once infected,you would be immune to the disease for life!
The EYE Global Strategy 2017-2026
In the year 2016,Angola witnessed a major outbreak of Yellow Fever which created an epidemic that raised an urgent need for more than 28 million doses of vaccine which hugely dented the available resources.As a response,WHO conceptualised a comprehensive global strategy to Eliminate Yellow Fever Epidemics(EYE) which aimed at 'building a global coalition of countries and partners to tackle the increased risk of yellow fever epidemics in a coordinated manner'.
It is expected that as a result of the EYE Strategy,by the year 2026,more than a billion people would stand immune to the disease.
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