Tropical Pulmonary Eosinophilia (Occult Filariasis)
Epidemiology
History
Tropical Pulmonary Eosinophilia was First Described in 1940 Disease was Initially Called “Pseudotuberculosis with Eosinophilia” The Term “Tropical Pulmonary Esoinophilia” was First Used by Weingarten in 1943
Demographics
Most Common in Southeast Asia, India, South Pacific > Africa, South America However, Cases Have Occurred in North American and European Visitors to Endemic Areas Requires Exposure in and Endemic Area for at Least a Few Months Age Usually Occurs in Patients 20-40 y/o Sex Approximately 80% of Cases are Males Race Indians are Most Susceptible
Disease Associations
Possible Relationship to Tropical Myocardial Fibrosis : unclear though
Etiology
Brugia Malayi Mosquito-Borne Parasite Which Infests the Lymphatics Occurs in Human and Animal Hosts Brugia Timori Mosquito-Borne Parasite Which Infests the Lymphatics Occurs in Human and Animal Hosts Wuchereria Bancrofti Mosquito-Borne Parasite Which Infests the Lymphatics : larvae mate in lymphatics and lymph nodes, shedding microfilariae to complete the life cycleMan is the Only Reservoir Host Physiology
Transmission : mosquitoes transmit infected larvae into humansDisease Course: larvae migrate within human lymphatics and get trapped in pulmonary microvasculature -> hypersensitivity/allergic reaction to filariae with lung injuryEarly: histiocytic alveolitis and interstitial infiltration Later: eosinophilic alveolitis Late: granulomatous reaction and fibrosis (may cause pulmonary HTN when ILD is advanced) Diagnosis
Leukocytosis (see Leukocytosis )Peripheral Eosinophilia (see Peripheral Eosinophilia )Absolute Eosinophil Count is Usually 3,000-60,000/μL Higher than that Seen in Simple Pulmonary Eosinophilia Pericardial Effusion May Be Seen in Some Cases Markedly Elevated : serum IgE usually >10,000 ng/mL (4200 IU/mL)May Be Elevated in Advanced Disease Sputum Gram Stain and Culture (see Sputum Culture )
Anti-Filarial IgG Antibody
Markedly Elevated : diagnostically usefulHowever, Lower Titer Elevation May Be Seen in Helminthic Infections : due to cross-reactivity of the antibodyLiver Biopsy/Lymph Node Biopsy/Lung Biopsy
Rarely Necessary for Diagnosis : may demonstrate filaria, but speciation is usually difficultClinical Criteria (Respiration, 1996) [MEDLINE ] (Respir Med, 1998) [MEDLINE ]
Residence in an Endemic Filarial Region Insidious Onset and Prolonged Duration of Symptoms for >4 wks Nocturnal Paroxysmal Cough and Wheezing (see Cough and Wheezing Striking Peripheral Eosinophilia (see Peripheral Eosinophilia )Markedly Elevated Immunoglobulin E (IgE) Levels (see Serum Immunoglobulin E )Elevated Filarial Antibody Titer Clinical Manifestations
Allergic Manifestations
Elevated Immunoglobulin E (IgE) Levels (see Serum Immunoglobulin E )Serum IGE is Usually >10,000 ng/mL (4200 IU/mL) Cardiovascular Manifestations
Gastrointestinal Manifestations
Hematologic Manifestations
Neurologic Manifestations
Fatigue (see Fatigue ): 75% of casesPulmonary Manifestations
General Comments Approximately 20% of Cases Have a Normal Lung Exam Normal CXR May Be Seen in Some Cases Pulmonary Function Tests (PFT’s) (see Pulmonary Function Tests )Restrictive Defect: seen in all stages of disease Reversible Obstructive Defect: seen in 25-30% of cases (typically early in course, in first month of disease) Cough (see Cough )Epidemiology Cough: occurs in 90% of cases Paroxysmal Cough with Dyspnea (see Dyspnea ): occurs in 70% of cases Clinical May Be Nocturnal Mucoid Sputum: occurs in 55% of cases Exertional Dyspnea (see Dyspnea )Epidemiology : occurs in 45% of casesHypoxemia (see Hypoxemia )Epidemiology : occurs in 25% of casesInterstitial Lung Disease (ILD) (see Interstitial Lung Disease )Epidemiology : seen late in the coursePleural Effusion Pneumonia (see Community-Acquired Pneumonia )Diagnosis Pneumothorax (see Pneumothorax )Epidemiology : uncommonSmall Nodular Infiltrates (see Lung Nodule or Mass )Diagnosis Chest X-Ray/Chest CT (see Chest X-Ray and Chest Computed Tomography )Diffuse Miliary Pattern Mid-Lower Lung Zone-Predominant 1-3 mm Nodular Interstitial Infiltrates: nodules may cavitate Bronchoscopy (see Bronchoscopy )Bronchoalveolar Lavage (BAL): eosinophilia Wheezing (see Obstructive Lung Disease ): 28% of casesWheezing/Rales, or Diffuse Rhonchi Other Manifestations
Fever (see Fever ): 25% of casesTreatment
First-Line Agent Pharmacology Also Has Anti-Helminthic Activity : may produce some response in helminthic infectionAdministration : 6 mg/kg/day (usually 150 mg TID) x 3 wksTime Course of Response : symptoms usually improve within days (however, residual radiographic and PFT changes, BAL eosinophilia, and mild symptoms may persist for weeks to years after therapy)Response to Trial is a Diagnostic Maneuver Relapse May Occur : responds to repeat treatmentDelayed in Therapy : may have poor clinical response with pulmonary fibrosisAdverse Effects Allergic Mazzotti’s Reaction : edema and fever occurring within 16 hrs after the first doseDue to Lethal Effect on Coexistent Onchocerciasis (see Onchocerciasis ) Hypotension (see Hypotension )Urticaria (see Urticaria )Mebendazole with Levamisole (Ergamisol) (see Mebendazole and Levamisole )
Alternative Which May Be Used When Patient is Allergic to Diethylcarbamazine May Be Used as an Adjunct to Diethylcarbamazine for the Treatment of Bronchospasm Bronchodilators
May Be Used for the Treatment of Bronchospasm References
Tropical pulmonary eosinophilia masquerading as acute bronchial asthma. Respiration. 1996;63(1):55-8 [MEDLINE ] Pathogenesis of tropical pulmonary eosinophilia: parasitic alveolitis and parallels with asthma. Respir Med. 1998 Jan;92(1):1-3 [MEDLINE ] Tropical pulmonary eosinophilia – A review. Indian J Med Res. 2013 Sep; 138(3): 295–302 [MEDLINE ]
Property of Kenneth J. Serio, MD. Author is not responsible for errors in content, site is for information purposes only.
