5-70
(see CBR: Viral Hemorrhagic Fever), supportive fluid management with hemostatic monitoring is critical to
recovery. The incubation period is typically 3-6 days, and 80-90% of cases recover completely. 10-20%
develop jaundice and hemorrhagic disease, leading to death (50% mortality in these patients) or a chronic
convalescent phase lasting for several weeks or months. Geographic Association: Yellow fever is uncommon
in the US but occurs in jungle environments in Africa, and in jungle and possibly urban areas in Central and
South America. Seasonal Variation: As with other arboviral illnesses, epidemics may follow the rainy season,
particularly in areas contiguous to rain forests where jungle yellow fever is enzootic (monkeys). Endemic
yellow fever occurs sporadically year-round. Risk Factors: Travel to yellow fever-endemic areas, especially
if unvaccinated before exposure, is the major risk factor, especially among travelers. Occupational exposure
among young adult males is responsible for much yellow fever in forest regions of tropical Latin America.
Subjective: Symptoms
Abrupt onset of fever, chills, headache, backache, vomiting for 2-3 days; some deteriorate over 3-10 days
with coffee-ground hematemesis (‘black vomit’), jaundice, and disorientation.
Focused History: Have you ever been vaccinated against yellow fever? (reduces chance of yellow fever
infection to <1%) When did you first feel sick? (Typically patient recalls exact time of onset of fever,
headache, and prostration, usually within past week) Have you traveled overseas in the past 3 weeks? If so,
where? (look for travel to endemic areas—see above)
Objective: Signs
Using Basic Tools: Vitals: Fever to 102-104°F; hypotension and relative bradycardia; occasional arrhythmias
Inspection: facial flushing with conjunctival injection, strawberry tongue (red edges with central prominent
papillae); Advanced disease: Bleeding from orifices (epistaxis, hematemesis, and melena), jaundice.
Palpation: Epigastric or RUQ abdominal tenderness
Using Advanced Tools Lab: Proteinuria on urinalysis (nephritis); CBC for neutropenia (typical), hematocrit
and platelet count (see Dengue); type and cross match if bleeding; blood smear to r/o malaria
Assessment: Sudden onset of high fever without prodromal symptoms or rash is characteristic, when
accompanied by the classical triad of albuminuria, jaundice and hematemesis.
Differential Diagnosis
Rickettsial fevers - maculopapular rash that begins at the wrists and ankles and spread to the trunk.
Leptospirosis (see topic) - aseptic meningitis, encephalitis
Other hemorrhagic fevers (Lassa, Marburg or Ebola) - acquired in focal geographic areas (see Viral
Hemorrhagic Fever Section) - pharyngitis and retrosternal chest pain.
Snake bite (viper) - bite and similar consumptive coagulopathy, but usually no jaundice or proteinuria.
Plan:
Treatment
- There is no specific treatment for yellow fever.
- Provide supportive care, including codeine for analgesia (see Procedure: Pain Assessment and
Control) and anti-emetics (dimenhydrinate 50 mg IM prn, or prochlorperazine 25 mg PR bid, 5-10 mg
IM q 3-4 or 5-10 po tid-qid). - Evacuate severe cases.
- If unable to evacuate and bleeding or shock occurs, begin fluid resuscitation with IV isotonic fluid bolus,
followed by intravenous colloids (see Shock: Fluid Resuscitation). Monitor vital signs, carefully insert
nasogastric tube and Foley catheter, monitor fluid I & O, and serially repeat hematocrit and platelet count.
Treat bleeding with calcium gluconate (1 g IV daily or bid) and transfusions as needed (see Procedures:
Blood Transfusion).
Patient Education
General: Use body fluid precautions in hemorrhagic patients to avoid disease transmission.
Activity: Bedrest
Diet: NPO if hemorrhagic, until stable
Medications: Avoid acetaminophen (liver damage) and aspirin (bleeding)