Overview
Definition:
Eosinophilia in children is defined as an absolute eosinophil count (AEC) greater than 500 cells/µL in peripheral blood
It represents an elevation of eosinophils, a type of granulocyte, which play a role in immune responses, particularly against parasitic infections and in allergic inflammation
Persistent or markedly elevated eosinophilia warrants a thorough workup to determine the underlying cause.
Epidemiology:
The prevalence of eosinophilia in children varies widely based on geographic location, socioeconomic factors, and prevalence of specific infections and allergic diseases
Helminthic infections are a significant cause in endemic regions, while allergic disorders are more common in developed countries
Children with atopic dermatitis, asthma, and allergic rhinitis are at higher risk for allergic eosinophilia.
Clinical Significance:
Eosinophilia in children can range from a benign finding to a marker of severe systemic disease
Identifying the cause is crucial for appropriate management, preventing complications, and improving patient outcomes
Untreated parasitic infections can lead to significant morbidity, while uncontrolled allergic diseases impact quality of life and lung development
Differentiating these etiologies is a core skill for pediatricians preparing for board examinations.
Clinical Presentation
Symptoms:
Symptoms are highly variable and depend on the underlying cause
Parasitic infections may present with fever
Abdominal pain, diarrhea, or malabsorption
Cough, wheezing, or dyspnea, especially with tissue-migrating helminths
Rectal itching (pruritus ani) with pinworm infestation
Allergic disorders commonly manifest as pruritic rashes (eczema)
Recurrent wheezing or shortness of breath (asthma)
Nasal congestion, rhinorrhea, and sneezing (allergic rhinitis)
Sometimes, significant eosinophilia can be asymptomatic and detected incidentally.
Signs:
Physical examination may reveal pallor due to anemia
Eczematous changes in the skin
Wheezing or rhonchi on pulmonary auscultation
Abdominal tenderness
Lymphadenopathy may be present in some parasitic infections
Dermatographism or urticaria may indicate atopy
Vital signs may be normal or show signs of respiratory distress.
Diagnostic Criteria:
No specific diagnostic criteria exist for eosinophilia itself, as it is a laboratory finding
However, diagnostic evaluation is guided by established criteria for suspected parasitic infections (e.g., specific helminth diagnosis) and allergic disorders (e.g., GINA guidelines for asthma, ARIA guidelines for allergic rhinitis, and diagnostic criteria for atopic dermatitis).
Diagnostic Approach
History Taking:
Key history points include duration and nature of symptoms
Travel history, especially to endemic areas for parasitic infections
Exposure to pets or contaminated water/soil
Dietary habits, including consumption of raw or undercooked meat
Family history of atopy, asthma, or allergies
Previous diagnoses of parasitic or allergic conditions
Medications, particularly antiparasitic drugs or steroids
Red flags include persistent fever, severe abdominal pain, significant weight loss, respiratory symptoms unresponsive to standard treatment, and a history of PICA.
Physical Examination:
A systematic head-to-toe examination is essential
Assess general appearance for distress or ill health
Examine skin for rashes, excoriations, or dermatographism
Evaluate respiratory system for wheezing, crackles, or decreased breath sounds
Palpate abdomen for tenderness, organomegaly, or masses
Examine for lymphadenopathy
Assess for signs of malnutrition or anemia.
Investigations:
Initial investigations should include a complete blood count (CBC) with differential to determine the absolute eosinophil count (AEC)
Peripheral blood smear to assess morphology and look for eosinophils
Stool examination for ova and parasites (O&P) is crucial for suspected helminthic infections, requiring multiple samples
Serological tests for specific parasitic infections (e.g., Toxocara, Trichinella) can be useful when suspicion is high but stool O&P is negative
Total IgE levels can be elevated in allergic disorders but are non-specific
Specific IgE (RAST/ELISA) tests or skin prick tests (SPT) are used to identify specific allergens in suspected allergic conditions
Imaging may include chest X-ray to assess for pulmonary involvement or eosinophilic pneumonia
Imaging of the abdomen may be indicated for suspected visceral larva migrans or other organ involvement.
Differential Diagnosis:
The differential diagnosis for eosinophilia in children is broad and includes: **Parasitic Infections:** Ascariasis, Ancylostomiasis, Trichuriasis, Strongyloidiasis, Schistosomiasis, Enterobiasis, Toxocariasis, Trichinellosis, Filariasis
**Allergic Disorders:** Asthma, Atopic Dermatitis, Allergic Rhinitis, Food Allergies, Drug Hypersensitivity
**Other causes:** Eosinophilic gastroenteritis, Hypereosinophilic syndrome, Certain malignancies (rare in children), Kawasaki disease, Certain viral infections (e.g., HIV), Drug reactions (not primarily allergic)
Distinguishing features include geographic exposure, specific symptoms like pruritus ani for pinworms, and presence of other atopic stigmata for allergic conditions.
Management
Initial Management:
Management is directed at the underlying cause
For suspected parasitic infections, empiric treatment may be considered in high-risk areas or when diagnosis is difficult, but confirmation is preferred
For allergic disorders, trigger avoidance, pharmacotherapy, and allergen-specific immunotherapy are key
General supportive care including hydration and nutritional support is important for all patients.
Medical Management:
For parasitic infections: Albendazole (400 mg once daily for 1-3 days for most nematodes, 200 mg twice daily for 3 days for cystic hydatid disease)
Mebendazole (100 mg twice daily for 3 days or 500 mg single dose for Enterobius vermicularis)
Praziquantel (40 mg/kg single dose for Schistosomiasis)
Pyrantel pamoate (11 mg/kg, max 1g, single dose for Enterobius and Ascariasis)
For allergic disorders: **Asthma:** Inhaled corticosteroids (ICS) are first-line
Bronchodilators (SABA, LABA)
Leukotriene receptor antagonists (LTRA)
**Atopic Dermatitis:** Topical corticosteroids, calcineurin inhibitors, emollients, antihistamines
**Allergic Rhinitis:** Intranasal corticosteroids, oral antihistamines, leukotriene receptor antagonists
Consider allergen-specific immunotherapy (ASIT) for severe or refractory cases.
Surgical Management:
Surgery is rarely indicated for eosinophilia itself but may be required for complications of parasitic infections, such as intestinal obstruction or perforation from Ascaris migration, or for management of complications in severe allergic disorders like anaphylaxis requiring airway management.
Supportive Care:
Nutritional assessment and support are vital, especially for children with chronic parasitic infections or malabsorption
Monitoring for hydration status and electrolyte balance
Patient and family education regarding disease process, medication adherence, and allergen avoidance is crucial for long-term management and prevention of relapse
Psychosocial support may be needed for children with chronic conditions impacting their quality of life.
Complications
Early Complications:
For parasitic infections: intestinal obstruction, intussusception, perforation, appendicitis, cholangitis, liver abscess, pneumonia (during larval migration), encephalitis or meningitis (rare)
For allergic disorders: severe exacerbations of asthma, anaphylaxis, secondary bacterial infections of eczematous skin.
Late Complications:
For parasitic infections: malnutrition, chronic enteritis, anemia, rectal prolapse (Enterobius, Trichuris), liver fibrosis, pulmonary hypertension (Schistosomiasis), neurological sequelae (Toxocariasis)
For allergic disorders: persistent airway remodeling in asthma, chronic sinusitis, reduced quality of life, educational impact due to chronic symptoms.
Prevention Strategies:
Prevention of parasitic infections involves improved sanitation, safe drinking water, proper food hygiene (cooking meat thoroughly), and deworming programs
Prevention of allergic diseases focuses on early identification of atopic risk, allergen avoidance, and adherence to prophylactic medications
Genetic predisposition is a factor that cannot be altered.
Prognosis
Factors Affecting Prognosis:
The prognosis depends heavily on the specific etiology and promptness of diagnosis and treatment
Children with uncomplicated parasitic infections treated promptly have an excellent prognosis
Those with severe or chronic infections, or complications, may have a poorer prognosis
For allergic disorders, early and consistent management of asthma and eczema can significantly improve long-term outcomes and prevent irreversible changes.
Outcomes:
With effective treatment, most children with parasitic infections achieve complete recovery
For allergic disorders, the goal is symptom control, prevention of exacerbations, and maintenance of normal growth and development
Chronic allergic conditions may require lifelong management but can be well-controlled with appropriate therapies.
Follow Up:
Follow-up is essential to ensure eradication of parasites, assess response to treatment for allergic diseases, and monitor for recurrence
Post-treatment stool examinations may be required for parasitic infections
Regular review by a pediatrician or specialist is recommended for children with chronic allergic conditions, especially asthma, to adjust therapy based on disease control and pulmonary function.
Key Points
Exam Focus:
Always consider parasitic infections in eosinophilia, especially in endemic areas or with relevant travel history
Stool O&P is the cornerstone investigation for suspected helminthic infections
Differentiate allergic eosinophilia by looking for atopic history, eczema, asthma, or rhinitis
Remember drug choices and dosages for common pediatric parasitic infections
High eosinophil counts in children often point towards parasitic or allergic causes.
Clinical Pearls:
Multiple stool samples (at least three) increase the yield for ova and parasite detection
Eosinophilic gastroenteritis can mimic inflammatory bowel disease
Tropical eosinophilia can be caused by filarial worms and may respond to diethylcarbamazine
In endemic areas, assume helminthic infection until proven otherwise in a child with eosinophilia
Consider a "red book" for allergy avoidance in children with atopic dermatitis.
Common Mistakes:
Not performing a thorough travel or exposure history for parasitic infections
Over-reliance on IgE levels for diagnosing specific allergies without considering skin prick tests or clinical history
Inadequate stool sample collection for O&P
Failing to initiate appropriate treatment for common parasitic infections due to fear of side effects
Not considering non-allergic/non-parasitic causes in recalcitrant or very high eosinophilia.