Onset is abrupt: fever, chills, intense joint pain, and stiffness.

Joint involvement affects wrists, ankles, knees, phalanges, and feet; movement becomes extremely painful.

Synovitis, tenosynovitis, and periarticular swelling are common.

Rash: erythematous maculopapular or morbilliform, often pruritic; appears 2–5 days after fever onset.

Gastrointestinal: nausea, vomiting, abdominal pain in some patients.

Neurological: headache, photophobia, irritability; rare cases may show neuropathic pain.

Eye involvement: conjunctival injection; rare anterior uveitis.

Children: bullous lesions, oral ulcers, irritability, refusal to walk.

Elderly: prolonged fatigue, prolonged incapacity to walk, severe joint stiffness.

– Recurrent joint pain and stiffness, worse in mornings.

– Symmetric hand/foot swelling, reduced grip strength.

References

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Peri Patellar effusion • 2025-11-17 00:35:05

Acute complications:

– Hepatitis: mild to moderate elevation of liver enzymes.

– Hemorrhagic manifestations are rare compared to Dengue.

– Bullous skin lesions more common in children.

– Hypotension due to volume depletion (not plasma leakage like Dengue).

Neurological:

– Encephalitis, encephalopathy, seizures (rare but documented).

Cardiac:

– Myocarditis with elevated troponin and ECG changes.

– Sinus tachycardia, arrhythmias, rare cardiogenic shock.

Renal:

– Acute kidney injury in elderly or in those with comorbidities.

Ocular:

– Conjunctivitis, anterior uveitis, optic neuritis, retinitis.

Chronic complications:

– Mimics rheumatoid arthritis but seronegative.

*– Tenosynovitis and carpal tunnel-like symptoms*.

– Fatigue and depression (post-viral syndrome).

Dengue fever:

– Fever and myalgia prominent; joint pain milder compared to Chikungunya.

– Hemorrhagic manifestations more common.

– Platelets drop significantly; hemoconcentration typical.

Zika virus:

– Rash more pruritic; conjunctivitis common.

– Joint pain milder and shorter in duration.

– Associated with neurological complications (GBS, microcephaly in pregnancy).

Malaria (P. falciparum / vivax):

– Fever pattern cyclic (tertian/quartan).

– Anemia, splenomegaly, thrombocytopenia.

– No disabling arthralgia.

Rheumatoid arthritis:

– Chronic, symmetric small joint arthritis.

– RF and anti-CCP positive in RA (usually negative in Chikungunya).

– Erosive changes on imaging in long-standing RA.

Dengue–Chikungunya coinfection:

– Severe joint pain + thrombocytopenia + rash.

– Requires careful CBC/hematocrit monitoring.

Leptospirosis:

– Fever, myalgia, headache.

– Conjunctival suffusion + jaundice in severe cases.

– Arthralgia less severe.

Septic arthritis:

– Monoarticular severe joint pain, redness, warmth.

– High fever, elevated CRP/PCT.

– Requires urgent aspiration.

Parvovirus B19:

– “Slapped cheek” rash in children.

– Adults: arthralgia mimicking RA; IgM/IgG help diagnosis.

COVID-19 viral arthropathy:

– Polyarthralgia with fatigue.

– Associated respiratory or anosmia symptoms.

Chikungunya virus belongs to the Semliki Forest antigenic complex.

Morphology: Enveloped virus, ~60–70 nm diameter, icosahedral symmetry.

Genome: Linear, 11.8 kb RNA encodes non-structural (nsP1–nsP4) and structural proteins.

Environmental stability: Sensitive to heat, desiccation, UV; survives short time in environment.

Reservoirs: Primarily humans during outbreaks; primates in sylvatic cycles (Africa).

CBC: Mild leukopenia or normal WBC; lymphopenia common. Platelets generally preserved (unlike Dengue).

LFT: Mild elevation in AST/ALT may occur.

ESR/CRP: Often significantly elevated, correlating with joint inflammation.

Urinalysis: Usually normal.

Virological tests:

– RT-PCR: Best test during acute phase (day 1–7), detects viral RNA.

– Viral culture: Rarely done, specialized centers only.

Serology:

– IgM: Detectable from day 5; persists 1–3 months.

– IgG: Appears after week 2; persists for years.

– Cross-reactivity: CHIKV IgM may cross-react with other alphaviruses.

Chronic phase (>3 months):

– ESR/CRP may remain elevated.

– Autoimmune mimics: RF and anti-CCP usually negative.

Imaging:

– Joint ultrasound: synovial hypertrophy, joint effusion, tenosynovitis.

– MRI (rarely needed): soft tissue edema, chronic arthritis changes.

Differentiation from Dengue:

– Dengue: marked leukopenia + thrombocytopenia + hemoconcentration.

– Chikungunya: severe joint pain + mild thrombocytopenia + high ESR/CRP.

Key diagnostic clue:

– Pain severity is out of proportion to clinical findings.

– Patients often describe “I cannot move my joints at all.”

Differentiation from Dengue:

– Dengue: high fever + myalgia + thrombocytopenia + bleeding.

– Chikungunya: severe arthralgia + synovitis + rash; bleeding rare.

– Platelets remain near-normal in Chikungunya.

Chronology:

– Acute phase: 1–2 weeks.

– Subacute phase: 3–6 weeks.

– Chronic phase: >12 weeks; mimics rheumatoid arthritis.

High-risk groups for chronic arthritis:

– Older age.

– Prior joint disease.

– High initial viral load.

– Female sex.

Red flag features requiring evaluation:

– Monoarticular severe swelling → rule out septic arthritis.

– Altered consciousness → consider encephalitis (rare).

– Chest pain → myocarditis consideration.

Therapeutic pearls:

– NSAIDs only AFTER Dengue is excluded.

– Hydroxychloroquine effective for chronic CHIKV arthritis.

– Steroids used only for short course in chronic inflammatory phase.

Pregnancy & neonates:

– Vertical transmission risk highest when mother infected intrapartum.

– Neonates may develop severe illness (encephalopathy, skin lesions).

Public health notes:

– Day-biting mosquitoes → repellents required throughout the day.

– Elimination of breeding sites is the most effective community strategy.

Teaching aids:

– Compare with Dengue and Zika for differential diagnosis.

– Emphasize joint involvement patterns and chronic symptoms.

Exanthem:

An exanthem is a widespread rash caused by a systemic infection.

In viral illnesses like Chikungunya, it appears as red spots, blotches, or bumps.

It is often accompanied by fever, fatigue, and body aches.

Maculopapular rash:

A rash that consists of both:

– macules (flat colored spots)

– papules (small raised bumps)

Common in Chikungunya, Dengue, and viral exanthems.

Polyarthralgia:

“Poly” = many, “arthralgia” = joint pain.

Severe, symmetrical joint pain is the hallmark of Chikungunya.

Movement becomes difficult and extremely painful.

Tenosynovitis:

Inflammation of the fluid-filled sheath surrounding a tendon.

In Chikungunya, this occurs in wrists, ankles, and fingers — causing stiffness.

This distinguishes CHIKV arthritis from simple post-viral joint pain.

Synovial hypertrophy:

When the synovium (joint lining) becomes thick and inflamed.

Seen in ultrasound/MRI of chronic Chikungunya arthritis.

Unlike rheumatoid arthritis, erosions are usually absent.

Viral vs bacterial exanthem:

A viral exanthem is a rash caused by a virus (e.g., Chikungunya, measles, rubella).

A bacterial exanthem may occur in illnesses like scarlet fever or toxic shock.

Viral exanthems usually resolve on their own; bacterial ones often need antibiotics.

Post-viral fatigue:

Common after CHIKV infection — prolonged tiredness due to immune activation.

Post-viral arthritis:

Joint pain and stiffness lasting weeks to months after infection.

In Chikungunya, this chronic phase may resemble rheumatoid arthritis but is seronegative.

Conjunctival injection:

Redness of eyes due to dilated conjunctival vessels.

Common in Chikungunya and Zika; rare in Dengue.

Persistent arthropathy:

Chronic joint pain, swelling, and morning stiffness for >12 weeks.

Seen in up to 40% of Chikungunya cases, especially older adults.

After inoculation, CHIKV infects keratinocytes, endothelial cells, macrophages, and dendritic cells.

Peak viremia occurs during first 3–5 days and correlates with fever severity.

Entry + local replication:

– Virus enters via Aedes mosquito bite.

– Replicates initially in dermal fibroblasts, macrophages, and endothelial cells.

– Early lesions show perivascular inflammation.

Viremia phase:

– Virus disseminates via bloodstream to joints, muscles, liver, spleen.

Joint pathology:

– Synovial membrane becomes edematous and thickened.

– Lymphocytes, macrophages, and plasma cells infiltrate synovium.

– Synovial hypertrophy causes pain and stiffness.

– Tenosynovitis: inflammatory infiltration of tendon sheaths, causing severe movement restriction.

Chronic arthropathy (>12 weeks):

– Viral RNA persists in synovial macrophages.

– Chronic inflammation mimics rheumatoid arthritis but seronegative.

– Joint cartilage typically preserved (unlike RA).

– Persistent swelling due to synovial hyperplasia and chronic inflammation.

Muscle pathology:

– Myositis: inflammatory infiltrates in muscle fibers.

– Elevated CK is uncommon but muscle tenderness common.

Liver:

– Mild lobular hepatitis with lymphocytic infiltration.

– Occasional periportal inflammatory changes.

Neurological pathology (rare):

– Lymphocytic meningoencephalitis.

– Microglial activation.

Vascular:

– Endothelial activation → increased cytokine release (IL-6, IL-8, GM-CSF).

Individual preventive measures:

– Use EPA-approved repellents:

• DEET (20–30%)

• Picaridin

• IR3535

• PMD (para-menthane-3,8-diol)

– Apply repellents to exposed skin; reapply as recommended.

– Wear light-colored, long-sleeved clothing; Aedes bites during daytime.

– Use mosquito coils, vaporizers, window screens, and air-conditioning where possible.

– Sleeping under insecticide-treated nets, especially for infants and pregnant women.

Environmental and community-level control:

– Remove stagnant water: buckets, flowerpots, old tires, containers.

– Cover water storage tanks; clean weekly.

– Community campaigns to eliminate breeding sites.

– Larvicides (e.g., temephos) for water containers where draining is not possible.

– Fogging during outbreaks to reduce adult mosquito density.

Travel advice:

– Use repellents throughout day; risk highest at dawn and dusk.

– Avoid visiting outbreak zones if immunocompromised, elderly, or pregnant.

– Continue preventive measures for at least 7 days after symptom onset to avoid infecting mosquitoes.

Vaccine status:

– No licensed vaccine yet; candidates under clinical development.

Acute phase:

– Imaging is usually not required.

– Ultrasound may show:

• Mild joint effusion

• Synovial thickening

• Periarticular edema

– Tenosynovitis particularly common in wrists, ankles, and flexor tendons.

Chronic phase (>12 weeks):

– Ultrasound:

• Persistent synovial hypertrophy

• Tenosynovitis (flexor > extensor)

• Doppler signal indicating active synovitis

– No erosions — important differentiator from rheumatoid arthritis.

MRI findings (rarely required):

– Synovial enhancement.

– Soft tissue and periarticular edema.

– Tenosynovial fluid collections.

– Myositis or muscle edema in severe cases.

– No significant cartilage destruction.

Differentiation:

– Dengue: musculoskeletal imaging usually normal; no synovitis.

– Rheumatoid arthritis: erosions + pannus; not seen in Chikungunya.

– Septic arthritis: large effusion, bone marrow edema — rule out if monoarticular.

When to image:

– Severe persistent joint pain >6–12 weeks.

– To differentiate chronic CHIKV arthritis from RA.

– To evaluate tenosynovitis causing hand stiffness or carpal-tunnel–like symptoms.

Chikungunya virus (CHIKV) shows genetic variation classified into:

1. West African genotype — geographically restricted, lower outbreak frequency.

2. East/Central/South African (ECSA) genotype — caused the major Indian Ocean and South Asia epidemics.

3. Asian genotype — currently circulating widely in Southeast Asia, including Bangladesh, India, Thailand.

E1–A226V mutation:

– Mutation in the E1 envelope protein.

– Enhances replication and transmissibility in *Aedes albopictus*.

– Responsible for explosive outbreaks in India, Sri Lanka, and Indian Ocean islands.

Despite genetic variation:

– Clinical disease is very similar across genotypes.

– No clinically significant differences in severity.

– No known differences in vaccine or antiviral response (currently none in routine use).

Phylogenetics:

– Genomic sequencing used in outbreak tracking.

– Evolution and lineage replacement occur regionally depending on mosquito ecology.

Musculoskeletal: marked tenderness over affected joints, reduced range of motion, difficulty weight bearing.

Rash: erythematous maculopapular, trunk and extremities; may include face.

Occasional desquamation in recovery phase.

Lymphadenopathy: cervical or generalized, mild.

Hematology (clinically visible): mild bleeding manifestations are rare (petechiae uncommon compared to Dengue).

Children: blistering lesions, oral ulcers, higher irritability.

It is caused by Chikungunya virus (CHIKV), an RNA virus belonging to the genus Alphavirus, family Togaviridae.

The disease is characterized by:

– sudden onset high fever,

– severe incapacitating polyarthralgia,

– headache,

– myalgia,

– rash.

The hallmark is *persistent joint pain* which may last weeks to months due to immune-mediated inflammation.

Chikungunya does not usually cause life-threatening complications, but severe disease may occur in elderly, pregnant women, newborns, and patients with comorbidities.

Unlike dengue, hemorrhage and plasma leakage are uncommon.

Aedes mosquitoes bite mainly during daytime, making vector control essential.

There is no specific antiviral treatment; management is supportive with analgesics, hydration and rest.

Fever begins abruptly, often with chills and rigors.

Gastrointestinal symptoms: nausea, vomiting, abdominal discomfort.

Neurological: irritability, mood disturbance, occasional neuropathic pain.

In children: bullous skin lesions, oral ulcers, more irritability.

Chronic symptoms (>3 months): persistent arthralgia, morning stiffness, hand/foot swelling.

Acute phase (first 1–2 weeks):

– Hydration and rest are essential.

– Paracetamol (acetaminophen) preferred for fever/pain.

– Avoid NSAIDs initially until Dengue is ruled out (risk of bleeding).

– If Dengue is excluded: ibuprofen, naproxen, or diclofenac may be used.

Joint pain management:

– Cold or warm compresses.

– Gentle joint mobilization exercises as pain improves.

Steroids:

– Not recommended in acute phase.

– In chronic phase (>6 weeks), low-dose prednisolone (5–10 mg/day) may benefit severe synovitis.

– Taper slowly over 1–2 weeks; avoid prolonged steroid use.

Chronic chikungunya arthritis (3 months – years):

– NSAIDs for symptom control.

– Hydroxychloroquine (HCQ) may be used in persistent inflammatory arthritis.

– Methotrexate reserved for severe RA-like disease (rheumatology guidance recommended).

– Physiotherapy for hand/wrist stiffness and tenosynovitis.

Neurological or cardiac complications:

– Managed supportively in hospital.

– Myocarditis: ECG monitoring, supportive care.

– Encephalitis: ICU care, seizure control.

Special populations:

Pregnancy:

– Paracetamol only.

– NSAIDs avoided in 3rd trimester.

– No steroids unless life-threatening complication.

Children:

– Avoid NSAIDs until Dengue excluded.

– No aspirin (Reye syndrome risk).