How can I differentiate the arthralgia of dengue from that of chikungunya, and what are the appropriate management strategies for each?

Differentiating Dengue from Chikungunya Arthralgia

Chikungunya arthralgia is characterized by acute arthritis (joint swelling) affecting multiple joints that can persist for months to years, whereas dengue arthralgia presents as joint pain without true arthritis and resolves within days to weeks. 1

Key Clinical Distinguishing Features

Arthralgia Characteristics

Joint involvement pattern:

• Chikungunya: 57% of patients develop acute arthritis (true joint swelling and inflammation) compared to 0% in dengue, making arthritis the pathognomonic sign of chikungunya 1
• Dengue: Presents with arthralgia (joint pain) particularly affecting the back, but without objective joint swelling or inflammation 2

Duration and chronicity:

• Chikungunya: Median duration of arthralgia is 3 months (range 0-24 months), with 45% experiencing persistent arthralgia beyond 4 months and 22.5% still symptomatic at 1 year 3
• Chikungunya: Acute arthritis lasts mean 6 days (range 1-14 days) but can progress to chronic arthritic disability lasting 1-6 months or longer 1
• Dengue: Joint pain typically resolves during the acute febrile phase without chronic sequelae 2

Joint distribution:

• Chikungunya: Commonly presents as polyarthritis affecting small joints of hands and feet in a pseudorheumatoid arthritis-like pattern, with tenosynovitis and enthesopathy also frequent 4
• Chikungunya: Talocalcanean (ankle) joints are frequently involved with painful swelling 5

Associated Clinical Features

Demographics:

• Chikungunya: Mean age 45 years (range 21-74), with 70% female predominance 1
• Dengue: Mean age 30 years (range 15-63), with 71% male predominance 1

Rash timing:

• Chikungunya: Skin rash appears during the febrile period and is independently associated with chikungunya diagnosis 6
• Chikungunya: Maculopapular rash on trunk and limbs typically appears after 2-3 days as fever subsides 5
• Dengue: Rash occurs but timing is less specific 2

Other symptoms:

• Dengue: Headache, retro-orbital pain, and bleeding tendency are more pronounced 1
• Dengue: Myalgia is independently associated with dengue infection 3

Laboratory Differentiation

Platelet count:

• Dengue: Mean platelet count 75 × 10⁹/L with more pronounced thrombocytopenia 1
• Dengue: Negative correlation between illness duration and platelet count (r = -0.309, p<0.001) 1
• Chikungunya: Mean platelet count 117 × 10⁹/L with less severe thrombocytopenia 1
• Chikungunya: Positive correlation between illness duration and platelet count (r = 0.181) 1

White blood cell count:

• Chikungunya: WBC count ≥5000 cells/mm³ is independently associated with chikungunya (RR 13.7-18.3) 6
• Dengue: Leucopenia is independently associated with dengue infection (positive likelihood ratio 3.3-6) 7

Liver enzymes:

• Dengue: Raised aspartate transaminase is independently associated with dengue 3

Incubation Period

• Chikungunya: 2-3 days (range 1-12 days) 2
• Dengue: 4-8 days (range 3-14 days) 2

Diagnostic Confirmation

Chikungunya:

• PCR during the first 5 days of symptoms 8
• IgM antibodies from day 6 onwards 8

Dengue:

• PCR or nucleic acid amplification test on serum collected ≤7 days after symptom onset 8, 7
• IgM capture ELISA if symptoms >5-7 days 2, 8

Management Strategies

Dengue Management

Pain control:

• Use acetaminophen at standard doses exclusively for pain and fever relief 8
• Never use aspirin or NSAIDs due to increased bleeding risk and platelet dysfunction 8

Hydration:

• Ensure adequate oral hydration with oral rehydration solutions for moderate dehydration 8
• Target fluid intake exceeding 2500ml daily for non-severe cases 8

Monitoring:

• Daily complete blood count to track platelet counts and hematocrit 8, 7
• Monitor continuously for warning signs: persistent vomiting, abdominal pain, lethargy, restlessness, mucosal bleeding, rising hematocrit with falling platelet count 8, 9

Shock management:

• Administer initial fluid bolus of 20 mL/kg with careful reassessment for dengue shock syndrome 8
• Consider colloid solutions for severe shock when available 8
• Use vasopressors (dopamine or epinephrine) if fluid resuscitation inadequate 8

Chikungunya Management

Acute phase:

• Symptomatic treatment with analgesics and antipyretics 5
• Acetaminophen remains the safest analgesic option 8

Chronic arthritis (>4 months):

• Glucocorticoids may be required for persistent inflammatory arthritis 4
• Hydroxychloroquine can be used for chronic polyarthritis 4
• Course leads to slow clinical improvement, though complete resolution may not occur in all patients 4

Risk Factors for Chronic Chikungunya Arthralgia

• Age >40 years is an independent predictor of persistent arthralgia beyond 4 months 3

Common Pitfalls

• Overdiagnosis of chikungunya during outbreaks: The clinical triad of fever, arthralgia, and rash has only 70.6% specificity and 83.3% positive predictive value 6
• Relying on arthralgia alone: Fever with arthralgia together has only 47.1% specificity for chikungunya 6
• Missing dengue complications: Absence of thrombocytopenia significantly reduces dengue probability (negative likelihood ratio 0.2) 7
• Assuming early antibody positivity: Antibody tests may be negative in early stages of chikungunya when PCR is required for diagnosis 5