Summary about Disease
Yellow fever vaccine-associated viscerotropic disease (YEL-AVD) is a rare but severe and potentially fatal adverse reaction to the yellow fever vaccine. It mimics a severe form of yellow fever disease, involving multiple organs. It's important to note that the risk is very low, but awareness is crucial for rapid diagnosis and supportive care.
Symptoms
Symptoms are similar to yellow fever and include:
Fever
Fatigue
Headache
Muscle aches
Jaundice (yellowing of the skin and eyes)
Bleeding (from gums, nose, or injection site)
Vomiting
Liver and kidney failure
Multi-organ system failure.
Causes
YEL-AVD is caused by the yellow fever vaccine virus replicating excessively in the body after vaccination. The exact reason why some individuals develop YEL-AVD while others do not is not fully understood, but risk factors may include primary immunodeficiencies, thymus disorders, and older age at vaccination.
Medicine Used
There is no specific antiviral treatment for YEL-AVD. Treatment focuses on supportive care, including:
Managing fever
Maintaining fluid and electrolyte balance
Supporting failing organ systems (e.g., dialysis for kidney failure, blood transfusions for bleeding)
Treatment of any secondary infections.
Is Communicable
YEL-AVD is NOT communicable. It is a reaction to the vaccine, not an infection that can spread from person to person.
Precautions
Screening: Individuals with known risk factors (e.g., primary immunodeficiencies, thymus disorders, age >60 for first-time vaccination) should be carefully evaluated before receiving the yellow fever vaccine. The CDC and WHO provide guidelines on contraindications and precautions.
Alternative Vaccine: In some cases, an alternative vaccination strategy may be recommended.
Awareness: Healthcare providers and vaccine recipients should be aware of the signs and symptoms of YEL-AVD and seek prompt medical attention if they occur.
How long does an outbreak last?
YEL-AVD is not an outbreak in the traditional sense. It is an adverse reaction following vaccination. Each case is individual and not related to spread between people. Therefore, there is no "outbreak duration.
How is it diagnosed?
Diagnosis of YEL-AVD involves:
Clinical presentation (symptoms similar to yellow fever after vaccination)
Ruling out other possible causes of the illness
Laboratory tests:
Detection of yellow fever vaccine virus RNA or antigens in blood or tissues (e.g., liver biopsy) using PCR or immunohistochemistry.
Elevated liver enzymes, bilirubin, and creatinine (indicating liver and kidney damage)
Complete blood count to evaluate for bleeding abnormalities.
Timeline of Symptoms
Symptoms typically appear within 2-7 days after vaccination. The illness can progress rapidly to severe multi-organ failure within days of symptom onset.
Important Considerations
YEL-AVD is a rare but serious risk associated with yellow fever vaccination.
The benefits of vaccination usually outweigh the risks, especially for individuals traveling to or living in areas with a high risk of yellow fever.
Careful screening of vaccine candidates and awareness of potential adverse events are crucial.
Prompt diagnosis and aggressive supportive care are essential for improving outcomes.
Report any suspected cases of YEL-AVD to public health authorities.