What is the appropriate management for a patient presenting with fever and rash?

Management of Fever and Rash

All patients with fever and rash where meningococcal sepsis or meningitis cannot be immediately excluded must be referred to hospital via emergency ambulance for arrival within one hour, with empiric antibiotics administered immediately if any signs of shock, altered mental status, or rapidly progressing rash are present. 1, 2

Immediate Life-Threatening Conditions to Rule Out

The primary goal is to rapidly identify meningococcemia, Rocky Mountain spotted fever (RMSF), and other bacterial sepsis, as these conditions can progress to death within hours and require immediate empiric antibiotic therapy. 2, 3

Critical Red Flags Requiring Immediate Action

• Signs of shock: hypotension, prolonged capillary refill time >2 seconds, cold peripheries, altered mental status, oliguria 2
• Elevated lactate >4 mmol/L indicates cryptic shock even without hypotension 2
• Rapidly evolving rash progressing over hours rather than days strongly suggests meningococcemia 2
• Altered consciousness or GCS ≤12 indicates severe disease requiring immediate intervention 2
• Petechial or purpuric rash with fever mandates immediate evaluation for meningococcemia and RMSF 1, 3

Algorithmic Approach Based on Rash Characteristics

Petechial/Purpuric Rash with Fever

Meningococcemia is the primary concern and must be actively excluded. 2

Key distinguishing features:

• Rash typically begins as maculopapular and progresses to petechial/purpuric within hours 1, 2
• May become generalized and involve palms and soles in 50% of cases 1
• Critical pitfall: 37% of meningococcal meningitis patients have no rash 1, 2
• When rash is present with meningitis, Neisseria meningitidis is the causative organism in 92% of cases 1

Immediate management:

• Obtain blood cultures within 1 hour before antibiotics 2
• Administer IV or IM ceftriaxone immediately if meningococcemia cannot be ruled out 2
• Do not delay hospital transport to give pre-hospital antibiotics—give en route or upon arrival 2
• Perform lumbar puncture within 1 hour if safe (no signs of increased intracranial pressure) 2

Maculopapular Rash Starting on Extremities

RMSF is the primary concern, especially with tick exposure history. 1, 3

Key distinguishing features:

• Rash appears 2-4 days after fever onset as small pink macules on ankles, wrists, or forearms 1
• Evolves to maculopapules, then petechiae by day 5-6 1
• Palms and soles involvement occurs in only 50% of cases and typically late in disease 1
• Critical pitfall: Rash may be completely absent in up to 20% of RMSF cases 1

Immediate management:

• Do not delay treatment while awaiting laboratory confirmation 3
• Initiate doxycycline immediately, regardless of patient age 3
• Obtain CBC (expect normal WBC with bandemia), comprehensive metabolic panel (expect hyponatremia, mild transaminase elevation), and platelet count (expect thrombocytopenia) 1

Rash Confined to Superior Vena Cava Distribution

Meningococcal disease is unlikely in this distribution pattern. 4

• Petechiae limited to face, neck, and upper chest suggest benign causes (coughing, vomiting, trauma) 4
• If child appears well with normal capillary refill and no systemic signs, outpatient management may be appropriate 4
• Draw blood for culture and CRP; if CRP <6 mg/L, discharge with 24-hour follow-up 4

Essential Clinical Documentation

Document the following for every patient with fever and rash: 1, 3

• Timing: When rash appeared relative to fever onset 3
• Pattern of spread: Centrifugal (starting centrally, spreading outward) vs. centripetal (starting peripherally, spreading centrally) 3
• Distribution: Involvement of palms, soles, face, trunk, extremities 1, 3
• Neurologic status: Headache, altered mental status, neck stiffness, seizures 1
• Shock signs: Hypotension, capillary refill time, peripheral perfusion 1, 2
• Epidemiologic clues: Recent travel to endemic areas, tick exposures, animal contacts, sick contacts, new medications 3

Critical pitfall: Do not rely on Kernig's or Brudzinski's signs—they have sensitivity as low as 5% 1, 2

Differential Diagnosis by Rash Type

Most Common Causes Overall

In a prospective study of 100 adult patients with fever and rash, the five most common diagnoses were: measles, cutaneous drug reactions, varicella, adult-onset Still's disease, and rickettsial disease. 5 Viral diseases were the leading infectious cause, and drug reactions were the leading noninfectious cause. 5

Petechial Rash Differential

Infectious causes:

• Meningococcemia (progresses rapidly, signs of shock) 1
• Enteroviral infection 1
• RMSF (late presentation, extremity distribution) 1

Noninfectious causes:

• Drug hypersensitivity reactions (prominent itchiness, no fever, spares palms/soles) 6
• Immune thrombocytopenic purpura 1
• Thrombotic thrombocytopenic purpura 1

Maculopapular Rash Differential

Infectious causes:

• Viral exanthems: HHV-6 (roseola), parvovirus B19, enteroviruses, EBV 1, 3, 6
• RMSF (early presentation) 1
• Rickettsial diseases 5
• Secondary syphilis 1
• Disseminated gonococcal infection 1

Noninfectious causes:

• Drug reactions 1, 5
• Kawasaki disease 1

Laboratory Evaluation

Immediate testing for all patients with fever and rash: 1, 3

• Complete blood count with differential
• Comprehensive metabolic panel
• Peripheral blood smear
• Blood cultures (before antibiotics)
• Serum lactate (to assess for cryptic shock)
• ESR and CRP 3

RMSF-specific findings: 1

• Normal WBC with increased bands
• Thrombocytopenia (up to 94% in ehrlichiosis)
• Mild hepatic transaminase elevations
• Hyponatremia

Meningococcemia-specific findings: 2

• Low or normal WBC
• Thrombocytopenia
• Coagulopathy
• Low acute phase reactants

Special Population Considerations

Elderly Patients

• More likely to have altered consciousness than younger patients 1
• Less likely to have neck stiffness or fever 1
• Higher risk for Listeria or pneumococcal disease 1

Children

• Develop rash more frequently and earlier in RMSF course 3
• Rash occurs in up to 66% of children with ehrlichiosis (vs. 30% in adults) 1, 6
• Consider viral exanthems like roseola in infants and young children 3

Immunocompromised Patients

• May present with atypical or more severe manifestations 3
• Lower threshold for hospitalization and empiric antimicrobial therapy 3

Critical Pitfalls to Avoid

• Never delay antibiotics for meningococcemia or RMSF while awaiting diagnostic confirmation—mortality benefit of early treatment far outweighs risk of unnecessary antibiotics 2, 3
• Absence of rash does not exclude meningococcemia (37% have no rash) 1, 2
• Do not wait for hypotension to diagnose shock—look for cold peripheries, prolonged capillary refill, and elevated lactate 2
• Young healthy patients may appear alert despite severe shock because cerebral perfusion is maintained until late stages 2
• Palms and soles involvement in RMSF typically occurs late (day 5-6) and in only 50% of cases 1
• Drug history may be missed—up to 40% of patients may not recall or report new medications 6
• Petechial rashes are difficult to recognize in darker-skinned patients, increasing risk of delayed diagnosis 6