Reactive and Postinfectious Arthritis in Children
Introduction to Reactive and Postinfectious Arthritis in Children
Reactive arthritis (ReA) and postinfectious arthritis are inflammatory joint conditions that occur in response to infections elsewhere in the body. While often grouped together, there are subtle differences:
- Reactive Arthritis: Typically follows gastrointestinal or genitourinary infections, often associated with HLA-B27.
- Postinfectious Arthritis: Can occur after various infections, including upper respiratory tract infections, and is not necessarily associated with HLA-B27.
In children, these conditions can present diagnostic challenges due to their varied presentations and potential overlap with other pediatric rheumatological disorders. Understanding their characteristics is crucial for proper diagnosis and management.
Epidemiology of Reactive and Postinfectious Arthritis in Children
Incidence and Prevalence:
- The exact incidence in children is unclear due to varying diagnostic criteria and potential underdiagnosis.
- Estimated incidence of reactive arthritis: 0.6-27 per 100,000 children per year.
- Postinfectious arthritis is more common but exact figures are not well established.
Demographic Factors:
- Age: Can occur at any age, but more common in school-age children and adolescents.
- Gender: In children, the gender distribution is more equal compared to adults, where there's a male predominance in ReA.
- Ethnicity: ReA is more common in populations with higher prevalence of HLA-B27, such as Northern European descent.
Associated Infections:
- Reactive Arthritis:
- Gastrointestinal: Salmonella, Shigella, Campylobacter, Yersinia
- Genitourinary: Chlamydia trachomatis (more in adolescents)
- Postinfectious Arthritis:
- Upper respiratory tract infections (viral or streptococcal)
- Viral infections: Parvovirus B19, rubella, hepatitis B
- Lyme disease (Borrelia burgdorferi)
Pathophysiology of Reactive and Postinfectious Arthritis in Children
The exact mechanisms are not fully understood, but several factors contribute to the development of these conditions:
- Genetic Predisposition:
- HLA-B27 association in reactive arthritis (30-50% of cases).
- Other genetic factors may play a role in susceptibility.
- Triggering Infection:
- Bacteria or their components persist in synovial tissue.
- Viral antigens may trigger immune response.
- Immune Response:
- Molecular mimicry between bacterial antigens and host tissues.
- T-cell mediated response against persisting antigens.
- Cytokine dysregulation (increased TNF-α, IL-17, IL-23).
- Synovial Inflammation:
- Infiltration of synovium by inflammatory cells.
- Increased synovial fluid production.
- Cartilage and bone damage in prolonged cases.
The interplay between these factors leads to an aberrant immune response directed against joint tissues, resulting in arthritis even after the triggering infection has been cleared.
Clinical Manifestations of Reactive and Postinfectious Arthritis in Children
The clinical presentation can vary widely, but typical features include:
- Joint Involvement:
- Asymmetric oligoarthritis (typically <6 joints)
- Predominantly affects lower limbs (knees, ankles)
- Can also involve small joints of hands and feet
- Enthesitis:
- Inflammation at tendon insertion sites
- Common in reactive arthritis, especially at Achilles tendon and plantar fascia
- Extra-articular Manifestations:
- Ocular: Conjunctivitis, uveitis
- Mucocutaneous: Rash, oral ulcers
- Urogenital: Urethritis (more common in adolescents)
- Systemic Symptoms:
- Fever (usually low-grade)
- Fatigue
- Weight loss
Specific Features:
- Reactive Arthritis:
- Classic triad of arthritis, conjunctivitis, and urethritis (less common in children)
- Symptoms typically appear 1-4 weeks after triggering infection
- Postinfectious Arthritis:
- Often follows upper respiratory infections
- May have more symmetric joint involvement
- Can occur simultaneously with or shortly after the infection
Diagnosis of Reactive and Postinfectious Arthritis in Children
Diagnosis is primarily clinical, based on history, physical examination, and supportive laboratory findings. There are no definitive diagnostic criteria for children.
Key Diagnostic Steps:
- Clinical History:
- Recent infections (gastrointestinal, genitourinary, respiratory)
- Pattern of joint involvement
- Associated symptoms (eye, skin, urogenital)
- Physical Examination:
- Joint assessment (swelling, tenderness, range of motion)
- Enthesitis
- Eye examination
- Skin and mucous membrane examination
- Laboratory Tests:
- Inflammatory markers: ESR, CRP (often elevated)
- Complete blood count
- HLA-B27 testing (if ReA suspected)
- Synovial fluid analysis (if effusion present)
- Cultures and serology for triggering infections
- Imaging:
- X-rays: Usually normal in early stages
- Ultrasound: Useful for detecting synovitis and enthesitis
- MRI: For complex cases or to rule out other conditions
Differential Diagnosis:
- Juvenile idiopathic arthritis
- Septic arthritis
- Lyme arthritis
- Rheumatic fever
- Inflammatory bowel disease-associated arthritis
Treatment of Reactive and Postinfectious Arthritis in Children
Treatment aims to control inflammation, alleviate symptoms, and prevent complications. The approach is usually stepwise, based on disease severity and response to initial therapies.
General Principles:
- Treat underlying infection if still present
- Rest and physical therapy to maintain joint function
- Patient and family education
Pharmacological Treatment:
- Nonsteroidal Anti-Inflammatory Drugs (NSAIDs):
- First-line treatment for mild to moderate cases
- Examples: Naproxen, Ibuprofen
- Intra-articular Corticosteroid Injections:
- For persistent monoarthritis or oligoarthritis
- Provides rapid symptom relief
- Systemic Corticosteroids:
- Short courses for severe symptoms or polyarthritis
- Used cautiously due to side effects
- Disease-Modifying Antirheumatic Drugs (DMARDs):
- For persistent or severe cases
- Sulfasalazine: Often used in ReA
- Methotrexate: For refractory cases
- Biologic Agents:
- Reserved for severe, refractory cases
- TNF inhibitors (e.g., Etanercept) may be considered
Management of Extra-articular Manifestations:
- Conjunctivitis: Topical antibiotics if bacterial
- Uveitis: Ophthalmology referral, topical corticosteroids
- Skin lesions: Topical treatments as needed
Non-pharmacological Interventions:
- Physical therapy to maintain joint function and muscle strength
- Occupational therapy if activities of daily living are affected
- Psychological support if needed
Prognosis of Reactive and Postinfectious Arthritis in Children
The prognosis for reactive and postinfectious arthritis in children is generally favorable, with most cases resolving within 3-12 months. However, the course can be variable, and some children may experience prolonged or recurrent symptoms.
Outcomes:
- Acute course (most common): Resolution within 3-6 months
- Prolonged course: Symptoms lasting 6-12 months
- Chronic course: Persistent symptoms beyond 12 months (less common in children than adults)
- Recurrent episodes: Can occur in a subset of patients
Prognostic Factors:
- Favorable prognostic factors:
- Early diagnosis and treatment
- Absence of HLA-B27
- Oligoarticular involvement
- Unfavorable prognostic factors:
- Presence of HLA-B27
- Polyarticular involvement
- Hip involvement
- Persistent elevated inflammatory markers
Long-term Considerations:
- Joint damage is rare in children but can occur in prolonged, untreated cases
- Risk of developing chronic arthritis or spondyloarthropathy in adulthood (especially in HLA-B27 positive individuals)
- Potential for recurrence with subsequent infections
Follow-up:
- Regular monitoring until complete resolution of symptoms
- Long-term follow-up may be necessary for patients with risk factors for chronic disease
- Patient and family education about potential recurrence and when to seek medical attention
Reactive and Postinfectious Arthritis in Children
- What is the definition of reactive arthritis?
Sterile inflammatory arthritis occurring after an infection at a distant site - Which infections are commonly associated with reactive arthritis in children?
Gastrointestinal infections (Salmonella, Shigella, Campylobacter) and genitourinary infections (Chlamydia) - What is the classic triad of symptoms in reactive arthritis?
Arthritis, urethritis, and conjunctivitis - How long after the initial infection does reactive arthritis typically develop?
1-4 weeks - Which genetic factor is associated with an increased risk of reactive arthritis?
HLA-B27 - What is the typical pattern of joint involvement in reactive arthritis?
Asymmetric oligoarthritis, predominantly affecting lower extremities - Which extra-articular manifestation is common in reactive arthritis?
Enthesitis - What is the difference between reactive arthritis and post-infectious arthritis?
Post-infectious arthritis involves direct invasion of the joint by microorganisms, while reactive arthritis is sterile - Which virus is commonly associated with post-infectious arthritis in children?
Parvovirus B19 - What is the most common causative organism in septic arthritis in children?
Staphylococcus aureus - Which laboratory test is useful in differentiating reactive arthritis from septic arthritis?
Synovial fluid culture (negative in reactive arthritis, positive in septic arthritis) - What is the role of antibiotics in treating reactive arthritis?
Not routinely recommended, except for treating ongoing infections - Which medication is commonly used as first-line treatment for reactive arthritis?
NSAIDs (Nonsteroidal anti-inflammatory drugs) - What is the typical duration of reactive arthritis in children?
3-6 months - Which imaging modality is most useful in evaluating reactive arthritis?
Ultrasound or MRI - What percentage of patients with reactive arthritis develop chronic arthritis?
Approximately 15-20% - Which autoantibody is associated with post-streptococcal reactive arthritis?
Anti-streptolysin O (ASO) - How is post-streptococcal reactive arthritis different from acute rheumatic fever?
It does not meet Jones criteria and does not involve the heart - What is the recommended duration of follow-up for children with reactive arthritis?
6-12 months - Which complication can occur in untreated Chlamydia-associated reactive arthritis?
Chronic anterior uveitis - What is the role of intra-articular corticosteroid injections in reactive arthritis?
May be used for persistent mono- or oligoarthritis - Which disease-modifying antirheumatic drug (DMARD) may be used in chronic reactive arthritis?
Sulfasalazine - What is the prognosis for most children with reactive arthritis?
Good, with complete resolution in the majority of cases - Which rheumatologic condition should be considered in the differential diagnosis of reactive arthritis?
Juvenile idiopathic arthritis - What is the role of HLA-B27 testing in reactive arthritis?
May help in predicting the risk of chronic disease or recurrence - Which skin manifestation is associated with reactive arthritis?
Keratoderma blennorrhagicum - What is the recommended approach for managing enthesitis in reactive arthritis?
Local measures (rest, physical therapy) and NSAIDs - Which gastrointestinal manifestation can occur in reactive arthritis?
Inflammatory bowel disease-like symptoms - What is the role of probiotics in preventing post-infectious reactive arthritis?
May have a potential protective effect, but more research is needed - Which complication can occur in severe, untreated reactive arthritis?
Ankylosis of affected joints
