Yellow Fever - Clinicals, Diagnosis, and Management

Infectious diseases

Clinicals - History

Fact Explanation
During the first phase of the illness: fever with chills, nausea, vomiting, anorexia, headache and myalgia. This is followed by a toxic second phase: hepatitis, coagulopathy, renal failure, multiorgan failure, shock and even death. This disease has 2 phases in its course. Initially there is an acute phase with viraemia which consists of flu-like symptoms It starts 3–6 days after the mosquito bite. Then there will be a second phase with increasing fever and complications due to different organ involvement. During the first phase of the illness: fever with chills, nausea, vomiting, anorexia, headache and myalgia. This is followed by a toxic second phase: hepatitis, coagulopathy, renal failure, multiorgan failure, shock and even death.
This disease has 2 phases in its course. Initially there is an acute phase with viraemia which consists of flu-like symptoms It starts 3–6 days after the mosquito bite. Then there will be a second phase with increasing fever and complications due to different organ involvement.
Fever with chills Yellow fever is a zoonotic arboviral disease acquired from the vector: Aedes aeigypti. Person is infectious during the from the onset of fever upto first 3–4 days of fever. Fever is low grade in the initial phase and high grade in the toxic phase. Fever with chills
Yellow fever is a zoonotic arboviral disease acquired from the vector: Aedes aeigypti. Person is infectious during the from the onset of fever upto first 3–4 days of fever. Fever is low grade in the initial phase and high grade in the toxic phase.
Nausea, vomiting, anorexia, headache,myalgia, These are the constitutional symptoms associated with yellow fever. Nausea, vomiting, anorexia, headache,myalgia,
These are the constitutional symptoms associated with yellow fever.
History of travelling Yello fever is endemic in tropical South Central America and sub-Saharan Africa. Most of the patients are having a history of travelling to Africa and South America. Aedes aegypti mosquitoes are the primary mode of transmission. History of travelling
Yello fever is endemic in tropical South Central America and sub-Saharan Africa. Most of the patients are having a history of travelling to Africa and South America. Aedes aegypti mosquitoes are the primary mode of transmission.
If complicated with hepatitis: Right hypochondrial pain, yellowish discolouration of eyes, loss of appetite This is a complication occurring during the second phase of disease, which is called toxic phase. If complicated with hepatitis: Right hypochondrial pain, yellowish discolouration of eyes, loss of appetite
This is a complication occurring during the second phase of disease, which is called toxic phase.
If complicated with renal failure: oliguria, body swelling The second phase of the illness can become complicated with organ failure. If complicated with renal failure: oliguria, body swelling
The second phase of the illness can become complicated with organ failure.
If complicated with coagulopathy: gum bleeding, menorrhagia and haematuria can occur Yellow fever is an acute viral hemorrhagic disease. There will be gum bleeding, menorrhagia, haematuria occurring during the second phase of disease. If complicated with coagulopathy: gum bleeding, menorrhagia and haematuria can occur
Yellow fever is an acute viral hemorrhagic disease. There will be gum bleeding, menorrhagia, haematuria occurring during the second phase of disease.
History of vaccinaton Vaccination with yellow fever vaccine provides protective immunity for 10 years. History of vaccinaton
Vaccination with yellow fever vaccine provides protective immunity for 10 years.

Clinicals - Examination

Fact Explanation
Febrile Elevation of temperature may be low grade initially and will be high grade in the toxic stage. Febrile
Elevation of temperature may be low grade initially and will be high grade in the toxic stage.
Bleeding manifestations: petechial rash, purpura, gum bleeding Coagulopathy is a complication of yellow fever. Bleeding manifestations: petechial rash, purpura, gum bleeding
Coagulopathy is a complication of yellow fever.
Low blood pressure Shock can be a complication during the toxic second stage. Low blood pressure
Shock can be a complication during the toxic second stage.
Jaundice and icterus Hepatitis can develop as a complication. Jaundice and icterus
Hepatitis can develop as a complication.
Right hypochondrial tenderness As mentioned above due to hepatitis. Right hypochondrial tenderness
As mentioned above due to hepatitis.

Investigations - Diagnosis

Fact Explanation
IgM antibodies After 3-4 days of onset of the disease, there will be specific IgM antibodies to the virus, which will be there for about 3 months. This is done by IgM-capture ELISA method or immunohistochemistry. IgM antibodies
After 3-4 days of onset of the disease, there will be specific IgM antibodies to the virus, which will be there for about 3 months. This is done by IgM-capture ELISA method or immunohistochemistry.
Viral antigen detection by ELISA (Enzyme-linked immunosorbent assay) Viral antigens can be detected in the blood immediately after the onset of the disease. Viral antigen detection by ELISA (Enzyme-linked immunosorbent assay)
Viral antigens can be detected in the blood immediately after the onset of the disease.
Reverse transcriptase PCR Used to detect the the yellow fever virus. Reverse transcriptase PCR
Used to detect the the yellow fever virus.

Investigations - Management

Fact Explanation
IgG antibody Necessary to detect the previous infection. IgG antibody
Necessary to detect the previous infection.
Full blood count Full blood count is important in excluding other conditions that can present with/as the fever. Bacterial infections causes leukocytosis (high white cell count), viral infections can cause lymphocytosis (elevated lymphocyte count) and low platelets. Platelets are also important as patients can develop coagulopathy. Full blood count
Full blood count is important in excluding other conditions that can present with/as the fever. Bacterial infections causes leukocytosis (high white cell count), viral infections can cause lymphocytosis (elevated lymphocyte count) and low platelets. Platelets are also important as patients can develop coagulopathy.
Renal function tests (Serum creatinine, blood urea and serum electrolytes) During the toxic phase patients can develop renal failure. Renal function tests (Serum creatinine, blood urea and serum electrolytes)
During the toxic phase patients can develop renal failure.
Liver Enzymes and Serum Bilirubin They can develop hepatitis as a complication. ALT and AST will be elevated, Serum direct and indirect Bilirubin is necessary to differentiate pre-hepatic, hepatocellular or obstructive jaundice. Liver Enzymes and Serum Bilirubin
They can develop hepatitis as a complication. ALT and AST will be elevated, Serum direct and indirect Bilirubin is necessary to differentiate pre-hepatic, hepatocellular or obstructive jaundice.
Clotting profile(PT/INR, APTT) During this acute viral hemorrhagic disease patients can go into coagulopathy leading to bleeding manifestations. Clotting profile(PT/INR, APTT)
During this acute viral hemorrhagic disease patients can go into coagulopathy leading to bleeding manifestations.

Management - Supportive

Fact Explanation
Supportive management As there is no specific management for yellow fever, supportive management plays a major role. Supportive management
As there is no specific management for yellow fever, supportive management plays a major role.
Prevention of acquiring the new disease Advice should be given to prevent mosquito bites in order to prevent new disease. The mosquito, Aedes aegypti, that transmits yellow fever virus, is an outdoor biter that feeds during the daytime. Therefore taking preventive measures during daytime, evening and early morning is important in preventing mosquito bites.
Using mosquito nets and other protective measures, using insect repellent that contain DEET, picaridin or IR3535, wearing proper clothing and avoiding jungle visits are some important steps in preventing mosquito bites.
Prevention of acquiring the new disease
Advice should be given to prevent mosquito bites in order to prevent new disease. The mosquito, Aedes aegypti, that transmits yellow fever virus, is an outdoor biter that feeds during the daytime. Therefore taking preventive measures during daytime, evening and early morning is important in preventing mosquito bites.
Using mosquito nets and other protective measures, using insect repellent that contain DEET, picaridin or IR3535, wearing proper clothing and avoiding jungle visits are some important steps in preventing mosquito bites.
Prevention of transmission Infected persons can transmit the disease to the others. They are advised to stay indoors or under mosquito nets. Prevention of transmission
Infected persons can transmit the disease to the others. They are advised to stay indoors or under mosquito nets.
Vaccination There is a live, attenuated (17D-204 strain) freeze dried vaccine available for people at high risk and who required under international regulations. It is given as intramuscular or subcutaneous routes. Immunity develops after 1-2 weeks and lasts for 10 years. Previous anaphylactic reactions, age 9 months or less than that, symptomatic HIV/AIDS, myasthenia gravis, thymoma, thymectomy and DiGeorge syndrome has been identified as contraindications for the vaccination. Minor side effects of vaccination are myalgia, headache and low grade fever. Uncommon major side effects are anaphylaxis, yellow fever vaccine-associated viscerotropic disease (YEL-AVD, disease affecting internal organs, may presents with multi organ failure and septic shock), and yellow fever vaccine-associated neurologic disease (YEL-AND, disease affecting the nervous system- encephalitis or acute disseminated encephalomyelitis) Vaccination
There is a live, attenuated (17D-204 strain) freeze dried vaccine available for people at high risk and who required under international regulations. It is given as intramuscular or subcutaneous routes. Immunity develops after 1-2 weeks and lasts for 10 years. Previous anaphylactic reactions, age 9 months or less than that, symptomatic HIV/AIDS, myasthenia gravis, thymoma, thymectomy and DiGeorge syndrome has been identified as contraindications for the vaccination. Minor side effects of vaccination are myalgia, headache and low grade fever. Uncommon major side effects are anaphylaxis, yellow fever vaccine-associated viscerotropic disease (YEL-AVD, disease affecting internal organs, may presents with multi organ failure and septic shock), and yellow fever vaccine-associated neurologic disease (YEL-AND, disease affecting the nervous system- encephalitis or acute disseminated encephalomyelitis)
Yellow fever surveillance Suspected cases, should be followed up for development of antibodies to yellow fever. As Yellow fever is a notifiable disease in many parts of the world. Yellow fever surveillance
Suspected cases, should be followed up for development of antibodies to yellow fever. As Yellow fever is a notifiable disease in many parts of the world.

Management - Specific

Fact Explanation
No specific treatment No specific treatment for yellow fever, rather than supportive management. Bed rest during this period is also important. No specific treatment
No specific treatment for yellow fever, rather than supportive management. Bed rest during this period is also important.
Antipyretics and analgesia Patient may be having fever and myalgia which can cause discomfort to the patient. Therefore analgesia for the relief of pain, and antipyretics for the management of fever are used. Acetaminophen can be used in these patients and non steroidal anti inflammatory drugs should be avoided. Antipyretics and analgesia
Patient may be having fever and myalgia which can cause discomfort to the patient. Therefore analgesia for the relief of pain, and antipyretics for the management of fever are used. Acetaminophen can be used in these patients and non steroidal anti inflammatory drugs should be avoided.
Fluids Proper hydration with attention to electrolyte balance. Person may have reduced fluid intake that can lead to dehydration. Fluids
Proper hydration with attention to electrolyte balance. Person may have reduced fluid intake that can lead to dehydration.
Management of the complications Complications would be renal failure, hepatitis, coagulopathy and shock. Identification and appropriate treatment where relevant is necessary. Management of the complications
Complications would be renal failure, hepatitis, coagulopathy and shock. Identification and appropriate treatment where relevant is necessary.
Experimental therapies for yellow fever ALThough there is a live, attenuated 17D vaccine, new cases are still seen with a fatality rate as high as 50% in severe disease. Therefore it is important to have a specific treatment method for the treatment of yellow fever. Interferon (IFN) therapy, in combination with ribavirin, broad-spectrum kinase inhibitor SFV785, compound 2′-C-methylcytidine which is an RNA polymerase inhibitor and development of therapeutic antibodies to target the antigens are some of these experimental modes of treatment for yellow fever. Experimental therapies for yellow fever
ALThough there is a live, attenuated 17D vaccine, new cases are still seen with a fatality rate as high as 50% in severe disease. Therefore it is important to have a specific treatment method for the treatment of yellow fever. Interferon (IFN) therapy, in combination with ribavirin, broad-spectrum kinase inhibitor SFV785, compound 2′-C-methylcytidine which is an RNA polymerase inhibitor and development of therapeutic antibodies to target the antigens are some of these experimental modes of treatment for yellow fever.

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