Gout

Viral arthritis refers to joint inflammation occurring as a direct or immune-mediated consequence of viral infection, generally self-limiting and distinct from bacterial septic arthritis in both course and management.

Common causative viruses include parvovirus B19 (particularly in adult women, often coinciding with or shortly after the classic "slapped cheek" rash in children but frequently presenting with arthralgia alone in adults, without a preceding rash), rubella (both wild-type infection and, historically, live attenuated vaccine), hepatitis B and C (often accompanying an immune complex mediated prodromal phase, alongside urticaria), chikungunya (notable for often severe, debilitating, and sometimes persistent polyarthralgia that can last months to years), and, less commonly, mumps, HIV seroconversion, and alphaviruses more broadly (Ross River virus, Sindbis virus in endemic regions).

Typically a symmetric, small joint polyarthralgia or polyarthritis (hands, wrists, knees, ankles) developing acutely, often alongside or shortly after a viral prodrome (fever, malaise, rash, lymphadenopathy).

Unlike septic arthritis, joints are generally not markedly hot, and systemic toxicity is usually mild to moderate rather than severe.

Parvovirus B19 arthropathy in adults can mimic early rheumatoid arthritis clinically (symmetric small joint involvement, morning stiffness) but typically resolves within weeks, though a subset of patients have more prolonged symptoms.

Chikungunya arthralgia is often disproportionately severe relative to objective joint swelling, and can become chronic in a meaningful minority.

Primarily clinical, guided by the accompanying features and epidemiological context (recent viral illness, rash, relevant travel history, or exposure).

Specific serology (parvovirus B19 IgM, hepatitis B/C serology, chikungunya IgM/PCR depending on timing) confirms the likely causative virus where relevant to management or where the presentation is atypical.

Joint aspiration is reserved for cases where septic arthritis cannot be confidently excluded (monoarticular, markedly hot joint, or significant systemic toxicity), given the very different management urgency, following the principles in the Septic Arthritis entry.

• Management is predominantly supportive, since most viral arthritides are self-limiting: NSAIDs (e.g. ibuprofen 400 mg PO tds, or naproxen 500 mg PO bd) for symptomatic relief, with paracetamol as an adjunct or alternative
• Parvovirus B19: supportive care as above; specific concern arises in pregnancy (risk of fetal hydrops, see relevant obstetric entries for fetal anemia workup) and in patients with an underlying hemolytic disorder or immunosuppression, where parvovirus can cause a transient aplastic crisis (see Sickle Cell Disease entry) rather than simple arthropathy
• Chikungunya: NSAIDs and analgesia for the acute phase; persistent arthralgia beyond 3 months (chronic chikungunya arthropathy) may require a more structured approach akin to inflammatory arthritis management, including consideration of hydroxychloroquine or methotrexate in refractory cases under rheumatology guidance
• Hepatitis B or C associated arthritis: managed alongside treatment of the underlying viral hepatitis (see those entries), with the arthritis typically improving as viral load is controlled
• Treatment of the specific underlying viral infection follows its own dedicated pathway where one exists and disease-modifying treatment is available and indicated (see Hepatitis B, Hepatitis C, HIV entries)

Referral: rheumatology for persistent symptoms beyond the expected self-limiting course, or diagnostic uncertainty with inflammatory arthritis; obstetrics for parvovirus B19 exposure in pregnancy.