01Approach to the Critical Patient/attcp73

Immediate priorities

›Airway and circulation threats

›Hemodynamic instability

›SBP < 90 mmHg

›MAP < 65 mmHg

›Signs of shock physiology

›Altered mental status

›GCS < 13 as atypical/severe disease marker

›Meningismus or focal neurologic deficit

›Respiratory failure

›SpO2 < 90% on room air

›Tachypnea > 30 per minute

›If hemodynamically unstable, initiate IV access and fluid resuscitation immediately

›Isotonic crystalloid 500 mL bolus

›Reassess lactate and organ perfusion

›Red flag features demanding escalation

›Neonatal exposure intrapartum

›Risk of hemorrhagic manifestations

›Risk of myocardial and neurologic disease

›Age > 65 with comorbidities

›Mortality risk 79-fold higher versus 20-29-year-olds

›Diabetes, hypertension, cardiovascular disease as multipliers

›Cardiovascular decompensation

›Myocarditis with arrhythmia

›New gallop or murmur

›Hemorrhagic signs

›Rare in chikungunya; exclude dengue coinfection

›Tourniquet test positive favors dengue

02History/hx71

Presentation pattern

›Core syndrome

›Fever onset

›Abrupt onset typically > 39 C

›Incubation period 3 to 7 days (range 1 to 12 days)

›Arthralgia characterization

›Severe symmetric bilateral polyarthralgia

›Large and small joints (hands, feet, wrists, ankles)

›Pain so severe patients may be unable to move

›Rash

›Maculopapular rash on trunk and extremities

›May involve palms, soles, face

›Pruritic component common

›Associated features

›Myalgia and headache

›Conjunctivitis bilateral

›Nausea and vomiting

›Intense fatigue and anorexia

›Important negatives

›Hemorrhagic manifestations absent or minimal

›Significant bleeding favors dengue

›Absence of thrombocytopenia distinguishing feature

›Respiratory and GI symptoms less prominent

›Diarrhea more typical of dengue or enteric infection

›Pulmonary findings suggest alternative diagnosis

Risk factors and exposure

›Epidemiologic exposure

›Travel to endemic areas within prior 2 weeks

03Physical Exam/exam67

Vitals and general

›Stability assessment

›Temperature

›Typically > 39 C in acute phase

›Biphasic pattern possible with brief defervescence

›Heart rate

›Tachycardia expected with high fever

›Persistent at rest after defervescence is a red flag

›Blood pressure

›Hypotension is a red flag for severe/atypical disease

›SBP < 90 mmHg triggers escalation

›Respiratory rate

›Tachypnea warrants assessment for pneumonia or myocarditis

›Hydration status

›Dry mucosa

›Skin turgor

›General appearance

›Prostration and inability to mobilize

›Characteristic of severe polyarthralgia

›Functional impairment assessment

›Toxic appearance

›Suggests sepsis or organ dysfunction

›Escalate evaluation if present

Musculoskeletal exam

›Joint assessment

›Symmetric bilateral polyarthralgia

›Interphalangeal joints

›Wrists and ankles

04Differential Diagnosis/ddx56

Arboviral and tropical infections

›Dengue fever

›ICD-10 A90

›Prominent headache and retro-orbital pain

›Thrombocytopenia and leukopenia more severe

›Hemorrhagic manifestations more common

›Plasma leak warning signs

›Tourniquet test more often positive

›Zika virus

›ICD-10 A92.5

›Lower-grade or absent fever

›Prominent pruritic rash

›Conjunctivitis present

›Less prominent arthralgia than chikungunya

›Malaria

›ICD-10 B50 to B54

›Cyclical fevers and rigors

›Hepatosplenomegaly

›Thick and thin peripheral smear diagnostic

›Other alphaviruses

›Mayaro, O'nyong-nyong, Ross River, Sindbis

›Similar arthritogenic presentation

›Geographic distribution helps differentiate

›Leptospirosis

›Conjunctival suffusion

›Jaundice and renal failure

›Water or animal exposure history

05Laboratory Tests/lt61

Confirmatory virologic testing

›RT-PCR for CHIKV RNA

›Most useful in first 7 days of illness during viremia

›High sensitivity in acute viremic phase

›Gold standard for acute diagnosis

›Specimen: serum or plasma

›Whole blood also acceptable

›Saliva and urine investigational

›IgM serology

›Develops toward end of first week

›Paired acute and convalescent samples increase sensitivity

›Can persist months to years

›Cross-reactivity with other alphaviruses

›O'nyong-nyong and Mayaro false positives possible

›Plaque reduction neutralization test (PRNT) for confirmation

›IgG serology

›Appears 4 to 10 days after symptom onset

›Persists for years; indicates past infection

›Fourfold rise in paired samples confirms acute infection

›PRNT confirmatory test

›Gold standard for discriminating cross-reacting antibodies

›Reference laboratory submission

›Not available in point-of-care settings

Rule-out and exclusion labs

›Dengue coinfection exclusion

›Dengue NS1 antigen

›Positive in first 5 to 7 days of dengue illness

›High specificity for dengue

06Diagnostic Tests/dt82

Scoring Systems

›Chikungunya clinical prediction rule

›Validated in dengue-endemic settings

›Fever: 1 point

›Exanthema: 1 point

›Myalgia: 2 points

›Arthralgia or arthritis: 2 points

›Joint edema: 2 points

›Score >= 4 has sensitivity 74% and specificity 52%

›Positive predictive value > 80% for CHIKV viremia in endemic areas

›Combined with epidemiologic exposure history increases utility

›Limitation: not validated outside endemic settings

›Dengue warning signs (WHO 2009) for exclusion

›Abdominal pain or tenderness

›Persistent vomiting

›Clinical fluid accumulation

›Mucosal bleed

›Lethargy or restlessness

›Liver enlargement > 2 cm

›Rapid platelet decline

›Rising hematocrit with rapid platelet fall

›Guides dengue severity classification

MRI

›MRI brain and spine indications

›Neurologic atypical disease

›Meningoencephalitis evaluation

›Myelitis evaluation

›Guillain-Barre syndrome supporting workup

07Disposition/dispo63

Admission indications

›Criteria for hospitalization

›Hemodynamic instability

›SBP < 90 mmHg

›Lactate >= 2 mmol/l with organ dysfunction

›Neurologic involvement

›Altered mental status

›Seizures or focal deficits

›Cardiac involvement

›Myocarditis with arrhythmia

›New ECG changes

›Severe organ dysfunction

›Acute renal failure

›Acute hepatitis with significant transaminase elevation

›Respiratory compromise

›SpO2 < 92% on room air

›Pulmonary edema pattern

›Inability to maintain oral hydration

›Persistent vomiting

›Dehydration with hemodynamic effect

›High-risk populations with any moderate symptoms

›Neonates

›Adults > 65 years with comorbidities

ICU indications

›Critical care criteria

›Refractory hemodynamic instability

›Vasopressor requirement

›Septic shock physiology

08Treatment/t115

Supportive care fundamentals

›Hydration

›Oral rehydration for mild cases

›2 to 3 liters per day oral fluids encouraged

›Electrolyte replacement solutions if vomiting

›IV crystalloid for severe cases

›Unable to tolerate oral intake

›Hemodynamic compromise

›Normal saline or lactated Ringer's 500 mL bolus with reassessment

›Targeted hydration; avoid volume overload in myocarditis

›Rest and physical measures

›Rest during acute febrile phase

›Activity limitation reduces joint strain

›Cold compresses to affected joints

›Symptomatic relief of periarticular edema

›Elevation of swollen limbs

›Reduces periarticular edema

›Physical therapy during subacute and chronic phases

›Range-of-motion exercises

›Prevents contractures from prolonged immobility

Analgesic and antipyretic therapy

›First-line: acetaminophen (paracetamol)

›Adult dosing

›500 to 1000 mg PO every 4 to 6 hours

›Maximum 4 g per 24 hours in adults without hepatic disease

›Reduce to 2 g per 24 hours maximum in hepatic impairment

›Preferred over NSAIDs until dengue excluded

›Avoids hemorrhagic risk of NSAIDs in dengue coinfection

›ACEP Level C recommendation for dengue exclusion before NSAID use

›Pediatric dosing

›15 mg/kg per dose PO every 4 to 6 hours

›Maximum 75 mg/kg per day; not to exceed adult maximum

›NSAIDs: use after dengue exclusion

›Ibuprofen

›400 to 600 mg PO every 6 to 8 hours with food

›Maximum 2400 mg per day

›Avoid if creatinine elevated or renal disease present

›Naproxen

›250 to 500 mg PO every 8 to 12 hours

›Maximum 1000 mg per day

›Caution: acute kidney injury risk with NSAIDs in volume-depleted patients

›Assess hydration before initiating

›Avoid in CKD or significant renal impairment

›Avoid aspirin and salicylates in acute phase

›Hemorrhagic risk in dengue coinfection

›Reye syndrome risk in children

›Contraindicated until dengue excluded

›Escalation analgesia for refractory pain

›Tramadol

›50 to 100 mg PO every 4 to 6 hours

›Maximum 400 mg per day

›Serotonin syndrome risk with concurrent serotonergic agents

›Tramadol plus acetaminophen combination

›Fixed dose combinations available

›Monitor for sedation

›Opioid analgesics for severe refractory cases

›Short-course only; taper as inflammation resolves

›Codeine 30 to 60 mg PO every 4 to 6 hours as alternative

Antipruritic therapy

›Antihistamines for pruritic rash

›Cetirizine

›10 mg PO daily

›Non-sedating; preferred for daytime use

›Loratadine

›10 mg PO daily

›Non-sedating alternative

›Diphenhydramine

›25 to 50 mg PO every 6 hours

›Sedating; caution in elderly (Beers criteria concern)

›Recommended by approximately 39% of global guidelines for rash management

›Topical measures

›Calamine lotion for localized pruritus

›Cool compresses for rash discomfort

Subacute and chronic arthralgia management

›Corticosteroids (controversial in acute phase)

›Not recommended routinely in acute phase

›Risk of rebound symptoms

›Immunosuppression risk

›Subacute arthralgia (3 weeks to 3 months)

›Prednisolone 5 to 10 mg PO daily short course

›Taper over 2 to 4 weeks

›Evidence of pain reduction when added to NSAIDs (low quality evidence)

›Intra-articular corticosteroid for monoarticular severe flare

›Triamcinolone acetonide 10 to 40 mg per joint

›Hydroxychloroquine

›Chronic arthralgia beyond 3 months

›200 to 400 mg PO daily

›Requires baseline ophthalmologic screening

›Benefit in CHIKV chronic arthralgia supported by case series and small trials

›Monitor for QT prolongation

›Methotrexate

›Refractory chronic arthralgia mimicking RA

›7.5 to 15 mg PO or SC weekly

›Folic acid supplementation 1 mg daily

›Monitor CBC and LFTs monthly

›Rheumatology guidance recommended before initiation

›Chloroquine alternative

›250 mg PO daily where hydroxychloroquine unavailable

›Retinal monitoring required

Antiviral therapy

›No approved antiviral for chikungunya

›Ribavirin: in vitro activity; no clinical benefit demonstrated

›Not recommended for routine use

›Favipiravir: in vitro activity; clinical evidence lacking

›Investigational only

›Interferon-alpha: in vitro activity; not clinically validated

›Supportive care remains standard of care

Neurologic complication management

›Meningoencephalitis

›Supportive ICU care

›Airway protection if GCS declining

›Seizure management with benzodiazepines

›Empirical antiviral coverage until HSV excluded

›Acyclovir 10 mg/kg IV every 8 hours pending CSF HSV PCR

›Lumbar puncture if no contraindication

›CSF for cell count, protein, glucose, culture, PCR panel

›Guillain-Barre syndrome

›Neurology consultation

›IVIG 2 g/kg IV over 2 to 5 days

›Or plasmapheresis if IVIG unavailable

›Respiratory monitoring for ventilatory compromise

09Special Populations/sp73

Pregnancy

›Pregnancy-specific considerations

›Intrapartum transmission risk

›Vertical transmission rate estimated 48.3% if maternal viremia at delivery

›Neonatal disease severe: encephalopathy, hemorrhage, myocarditis

›Delivery planning with neonatology if maternal viremia near term

›First-trimester infection

›Spontaneous abortion risk reported

›Fetal malformation data insufficient; monitor closely

›Imaging safety

›Avoid unnecessary radiation

›Ultrasound preferred for fetal monitoring

›CT only when clinical benefit outweighs risk with appropriate shielding

›Analgesia selection

›Acetaminophen preferred analgesic throughout pregnancy

›NSAIDs relatively contraindicated in third trimester

›Risk of premature closure of ductus arteriosus

›Reduced fetal renal perfusion

›Avoid tramadol and opioids where possible; neonatal withdrawal risk

›Corticosteroids

›Short-course use under obstetric guidance only

›Betamethasone if preterm delivery anticipated for lung maturity

›Notifiable disease; public health reporting for travel surveillance

Geriatric

›Older adult considerations

›Mortality risk elevation

›79-fold increased mortality risk in those >= 60 versus 20 to 29 year olds

›Comorbidities (diabetes, hypertension, cardiovascular disease) as multipliers

10Background/b89

Epidemiology

›Global burden and distribution

›First identified 1952 in Tanzania

›Named from Makonde language: "that which bends up" describing arthralgia posture

›Alphavirus, Togaviridae family

›Endemic regions

›Southeast Asia and Indian subcontinent

›Sub-Saharan Africa

›Caribbean and Latin America (introduced 2013)

›Pacific Islands

›Mediterranean Europe (Italy, France outbreaks in Aedes albopictus territory)

›Symptomatic attack rate

›> 85% of infected individuals are symptomatic

›Attack rates up to 75% in susceptible populations during outbreaks

›Transmission vectors

›Aedes aegypti: primary tropical vector

›Aedes albopictus: secondary vector; extends geographic range to temperate zones

›No human-to-human transmission except intrapartum

›Chronic arthralgia burden

›Persistent arthralgia in 30 to 40% of patients beyond 3 months

›Subacute phase: 3 weeks to 3 months

›Chronic phase: > 3 months

›Some patients have arthralgia persisting years after acute infection

›Significant economic burden from productivity loss in endemic areas

Pathophysiology

›Viral biology and infection cycle

›Single-stranded positive-sense RNA alphavirus

›Incubation period 3 to 7 days (range 1 to 12 days)

›Acute viremia peaks in first 5 to 7 days

›Viral clearance typically within 10 days

›Target tissues

›Fibroblasts and synovial cells primary targets

›Monocytes and macrophages serve as viral reservoirs

›Muscle satellite cells involved in myalgia

›Viral persistence hypothesis

›Viral RNA and antigen detected in joint tissue in chronic phase

›Macrophage reservoirs may explain chronic arthralgia

›Immunopathology

›Innate immune response

›Type I interferon response critical for viral clearance

›NK cell activation

›Monocyte-derived cytokine storm contributes to symptoms

›Acute phase inflammatory markers

›IL-6, IL-1beta, TNF-alpha elevated

›Correlate with fever and arthralgia severity

›Chronic phase mechanism

›T-cell mediated synovitis

›Persistence of antigen in joint tissue driving inflammation

›Resembles seronegative RA histologically

›Clinical disease phases

›Acute phase: 0 to 10 days

›Viremia and innate immune activation

›Subacute phase: 3 weeks to 3 months

›Post-viremic arthralgia; immune complex deposition

›Chronic phase: > 3 months

›Persistent synovitis; resembles RA

Therapeutic Considerations

›No disease-modifying antivirals

›Supportive care is the cornerstone of management

›Hydration, analgesia, rest

›Pain control guiding functional recovery

›Antiviral drug development ongoing

›Novel entry inhibitors and replication inhibitors in trials

›Monoclonal antibodies in early clinical investigation

›Vaccine development

›Virus-like particle vaccine in Phase 3 trials as of 2024

›Live attenuated and recombinant vaccines in earlier stages

›Analgesic strategy rationale

›Dengue exclusion before NSAID use critical

›Dengue co-circulation in chikungunya-endemic areas

›NSAID-induced platelet dysfunction dangerous in dengue thrombocytopenia

›Step-up analgesia aligned with WHO pain ladder

›Acetaminophen first; NSAIDs second; weak opioids third

›Corticosteroid use remains controversial

›Short-course benefit for refractory subacute arthralgia

›Rebound risk limits utility

›Chronic disease management principles

›Hydroxychloroquine evidence strongest for CHIKV chronic arthralgia

›Anti-inflammatory and immunomodulatory mechanisms

›Also used in lupus and RA for similar reasons

›Methotrexate for erosive disease mimicking RA

›Disease-modifying benefit; requires monitoring

›Physical therapy integral to long-term recovery

›Prevents contractures and muscle atrophy

›Improves functional outcomes in chronic phase

›Prevention and public health

›Vector control measures

›Eliminate standing water (mosquito breeding sites)

›Insect repellent (DEET, picaridin, IR3535)

›Long-sleeved clothing and bed nets

›No prophylactic antiviral available

›Travel advisory awareness in endemic zone travelers

11Patient Discharge Instructions/pdi45

copy discharge instructions

›Chikungunya home care instructions

›Rest during the fever phase

›Limit strenuous physical activity until fever resolves

›Gentle range-of-motion movements to prevent joint stiffness

›Hydration

›Drink 2 to 3 liters of fluids daily

›Water, oral rehydration solutions, clear broths

›Avoid alcohol which worsens dehydration

›Pain and fever relief

›Acetaminophen (paracetamol) as prescribed for fever and joint pain

›Do not take aspirin or ibuprofen until your doctor confirms it is safe

›Cold compresses on swollen joints for comfort

›Rash care

›Antihistamine tablet as prescribed for itching

›Avoid scratching to prevent skin infection

›Loose comfortable clothing over rash areas

›Mosquito precautions to prevent spreading to others

›You can pass the virus to mosquitoes while you have fever

›Use insect repellent on exposed skin

›Wear long sleeves and long pants indoors and outdoors

›Sleep under bed nets if available

›Eliminate standing water around your home

›Buckets, flower pots, tires, clogged gutters

›Change water in pet bowls and bird baths every few days

›Warning signs to return to emergency

›Difficulty breathing or chest pain

›Confusion, unusual drowsiness, or seizure

12References/r20

Guidelines and key sources

›International guidelines

›WHO Regional Office for South-East Asia: Guidelines for Prevention and Control of Chikungunya Fever

›Defines clinical phases, case definitions, and management principles

›CDC: Chikungunya Virus — Clinical Evaluation and Disease (2023)

›Travel medicine guidance and laboratory testing algorithm

›PAHO: Preparedness and Response for Chikungunya Virus Introduction in the Americas

›Differential diagnosis framework including dengue exclusion

›Evidence references

›Burt FJ et al. Chikungunya: a re-emerging virus. Lancet 2017

›Epidemiology, pathogenesis, clinical spectrum, and management review

›Simon F et al. Chikungunya infection: an emerging rheumatism among travelers. Medicine 2007

›Acute and chronic arthralgia characterization

›Javelle E et al. Specific rheumatological consequences of chikungunya fever: a prospective follow-up study. Arthritis Research and Therapy 2015

›Chronic arthropathy natural history and DMARD management

›Thein S et al. Clinical prediction rule for chikungunya. Validation study in dengue-endemic settings

›Scoring system sensitivity and specificity data

›Coding standards

›ICD-10 A92.0 chikungunya fever

›SNOMED CT chikungunya fever disorder concept

›Dengue comparator ICD-10 A90 and A91

Evidence & Review