How should I evaluate and manage a patient presenting with fever and headache but no other symptoms?

Evaluation of Fever and Headache Without Other Symptoms

Immediate Red-Flag Assessment

Any patient presenting with fever and headache must be urgently evaluated for meningitis, as this combination represents a classic presentation for CNS infection that can rapidly progress to life-threatening disease. 1, 2

Critical Red Flags Requiring Emergency Referral

Document the presence or absence of these features immediately:

• Altered mental status or confusion – strongly suggests meningitis or encephalitis and mandates urgent hospital transport 1, 2
• Neck stiffness – however, its absence does not exclude meningitis, as only 41-51% of bacterial meningitis cases present with the classic triad of fever, neck stiffness, and altered consciousness 1, 3
• Any rash, particularly petechial or purpuric – suggests meningococcemia 1
• Seizures or focal neurological deficits (weakness, sensory changes, visual disturbances) – indicate possible intracranial pathology 1, 2
• Severe or "worst ever" headache – may indicate serious CNS infection 2, 4
• Progressively worsening symptoms over hours to days 2

Important caveat: Kernig's and Brudzinski's signs have poor sensitivity (as low as 5%) and should not be relied upon for diagnosis – their absence does not rule out meningitis 1, 3, 5

Immediate Action for Red Flags

• Arrange emergency ambulance transport to ensure hospital arrival within 1 hour of assessment 1, 2
• Do not delay – patients with meningitis can deteriorate rapidly even if initially appearing stable 5

Travel and Exposure History

Obtain detailed epidemiological information, as this dramatically changes the differential diagnosis:

• Recent travel to malaria-endemic areas (especially sub-Saharan Africa, Asia, South America) – any febrile traveler returning from endemic areas should undergo laboratory testing for malaria 1
• Tick exposure or outdoor activities – consider ehrlichiosis, rickettsial diseases (fever + headache in 72-96% of cases) 1, 3
• Fresh-water exposure 4-8 weeks prior – consider Katayama syndrome (acute schistosomiasis), especially with eosinophilia 1
• Mosquito-endemic regions in Asia – consider dengue (most common arbovirus in travelers) or Japanese encephalitis 1, 6
• Time between return and symptom onset – malaria typically presents within weeks, dengue 4-8 days, chikungunya 2-3 days 1

Critical point: Absence of rash does not exclude tick-borne or arboviral diseases, as rash appears late or is absent in many cases 1, 3

Hospital Diagnostic Work-Up (When Red Flags Present)

Immediate Laboratory Studies

• Blood cultures (at least 2-3 sets) before antibiotics, but do not delay treatment beyond a few minutes 3, 5
• Complete blood count with differential – thrombocytopenia (<150,000/μL) is present in 70-79% of malaria cases and is a key screening finding 1
• Inflammatory markers (CRP, procalcitonin) to assess severity 5
• Metabolic panel to evaluate for hyponatremia (present in ~60% of autoimmune encephalitis), renal dysfunction 1, 5
• Lactate level – >4 mmol/L indicates high risk for fatal outcome in sepsis 5
• Malaria thick and thin blood films if any travel to endemic areas 1

Neuroimaging

• CT head without contrast is mandatory before lumbar puncture if altered mental status, focal neurological deficits, or signs of increased intracranial pressure are present 2, 3, 5
• Neuroimaging is NOT indicated for typical primary headache when no red flags are present 1, 2

Lumbar Puncture

• Perform urgently once CT clears the patient, ideally within 4 hours of starting antibiotics to maximize culture yield 5
• CSF analysis should include: cell count with differential, glucose, protein, Gram stain, bacterial culture, viral PCR panel, and cryptococcal antigen if immunocompromised 1, 5
• Opening pressure should be measured (elevated >32 cm H₂O suggests increased intracranial pressure) 1

Empiric Antibiotic Therapy

Administer immediately after obtaining blood cultures if bacterial meningitis is suspected – never delay antibiotics waiting for lumbar puncture or imaging, as this significantly increases mortality: 3, 5

• Ceftriaxone 2g IV every 12 hours PLUS vancomycin 15-20 mg/kg IV to cover S. pneumoniae (including resistant strains) and N. meningitidis 3, 5
• Add ampicillin 2g IV every 4 hours if age >50 years, immunocompromised, or risk factors for Listeria monocytogenes 5
• Add dexamethasone 10mg IV before or with first antibiotic dose to reduce neurological complications 5

Management When No Red Flags Present

Differential Diagnosis for Isolated Fever + Headache

The most common cause in otherwise healthy adults is a self-limited viral syndrome:

• Viral syndrome – typically resolves over 2-7 days with mild myalgias or malaise 2
• Aseptic (viral) meningitis – all patients have headache (typically severe and bilateral), with prodromal symptoms (malaise, myalgia, GI symptoms) in 46% of cases 4
• Influenza – but be cautious: symptoms lasting >5-7 days or appearing severely ill should prompt investigation for complications like sinusitis with intracranial extension 7
• Primary headache disorders (migraine, tension-type headache) with concurrent febrile illness 1, 2

Physical Examination Priorities

• Neurological examination – assess mental status, cranial nerves, motor/sensory function, reflexes, gait 1, 2
• Skin inspection – look for any rash, particularly petechiae or purpura 1
• Neck examination – assess for stiffness (but remember low sensitivity) 1
• Vital signs – document temperature, blood pressure, heart rate, respiratory rate, oxygen saturation 3

Symptomatic Treatment

• NSAIDs (naproxen 500-825 mg) or acetaminophen for fever and headache 1, 2, 8
• Paracetamol 1000 mg is first-line for fever in acute settings; paracetamol/ibuprofen combination (500/150 mg) may be more effective for bacterial fever at 1 hour 8
• Ensure adequate hydration and rest 2

Safety-Net Instructions

Advise patients to seek urgent care if they develop:

• Altered mental status or confusion 2
• Neck stiffness 2
• Any rash 2
• Worsening or "worst ever" headache 2
• New neurological symptoms (weakness, vision changes, seizures) 2
• Symptoms persisting or worsening beyond 5-7 days 7

Follow-Up

• Arrange urgent outpatient follow-up within 24-48 hours if symptoms are not improving or new concerning features appear 2
• Re-evaluate immediately if the clinical picture changes or red flags develop 2

Common Pitfalls to Avoid

• Never rely on absence of neck stiffness to rule out meningitis – elderly patients and those with early disease frequently lack this finding 1, 3
• Do not underestimate severity based on initial vital signs – patients with sepsis or meningitis can deteriorate rapidly 5
• Do not assume all fever + headache is viral or influenza – maintain high vigilance for meningitis when uncertainty exists 2, 7
• Do not delay antibiotics for imaging or LP in suspected bacterial meningitis – this is the single most important factor affecting mortality 3, 5
• Do not exclude malaria or tick-borne diseases based solely on absence of rash – these are frequently absent early in disease 1, 3