Case history
Case history #1
A 42-year-old man presents with fever, headaches, abdominal pain, and vomiting. He is treated symptomatically in the hospital emergency department and discharged. He returns 2 days later with intractable vomiting, headache, and a worsening fever. A travel history is obtained and reveals that the patient has just returned from an eco-trip to Cameroon. The patient did not receive pre-travel immunisations and admits to poor compliance with malaria prophylaxis. On physical examination he is jaundiced, acutely ill, and febrile. Laboratory testing reveals thrombocytopenia, anaemia, and leukopenia, as well as elevated prothrombin time and partial thromboplastin time, raised transaminases, and renal failure with elevated creatinine. He is started on empirical malaria treatment, despite initial negative smears and cultures. Progressive disseminated intravascular coagulation with shock and a bleeding diathesis develops on the third day. He dies after 4 days of being in hospital. Serum collected during the final day of his illness is reported positive for yellow fever IgM.
Case history #2
A 25-year-old Brazilian man is seen at a Rio de Janeiro University hospital 2 days after returning from the state of Amazon, where he worked as a logger. He presents with severe headache, fever, chills, malaise, and generalised myalgia. On physical examination, he appears ill, febrile, and mildly jaundiced. Conjunctival injection is noted. Laboratory testing reveals leukopenia and elevated transaminases, with an increased bilirubin. Malaria stains are negative. The initial diagnosis is dengue fever, as his history disclosed a past infection with dengue. On the third day, he defervesces and recovers fully. Initial testing is negative for yellow fever IgM and positive for dengue IgG. On subsequent investigations, yellow fever serology indicates rising titres, confirming the diagnosis of yellow fever.
Other presentations
Clinical presentation of yellow fever is characterised by 3 periods: infection, remission, and intoxication. After an incubation time of 3 to 6 days, an initial period of infection is seen with an abrupt onset of non-specific symptoms such as fever (average temperature of 39°C [102°F]), headache, myalgias, dizziness, and malaise lasting 2 to 6 days.[2] Conjunctival injection, relative bradycardia (Faget's sign), and leukopenia are characteristic of this period. Most infections do not progress from this initial phase and resolve spontaneously. After a period of remission characterised by defervescence lasting for 24 to 48 hours, 15% to 25% of patients develop a period of intoxication.[2] This period is characterised by a rebound of symptoms, often accompanied by abdominal pain, vomiting, and lethargy. Jaundice, transaminitis, and coagulopathy develop, culminating in shock, hepatorenal failure, and death between 7 and 10 days after onset.
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