Tropical eosinophilia (TE) occurs in patients who have filariasis, which is an infection caused by certain types of roundworm, exemplified by Wuchereria bancrofti and Brugia malayi [1]. The presence of these parasites in the body leads to an exaggerated immune response in some individuals characterized by markedly high levels of eosinophils in the blood and even higher concentrations in the lungs [2]. This immune response, in turn, provokes transient episodes of acute respiratory symptoms such as wheezing, coughing, shortness of breath and chest pain, often worse at night [3]. Systemic symptoms such as fever, loss of weight and appetite, lymphadenopathy, hepatomegaly, and splenomegaly may also occur, although, in a small percentage of patients, no pulmonary symptoms are present.

TE is most frequently seen in areas where filarial infections are endemic, however, cases in non-endemic areas have been reported, aided by travel and immigration, albeit some cases are misdiagnosed due to failure to recognize the syndrome [4] [5]. Males are four times more affected by the illness than females. More serious clinical manifestations include permanent widening of the airways, pneumothorax, consolidation of the lungs and granulomas. Cardiac activity can also be affected, and this is demonstrated by electrocardiogram (ECG) abnormalities [6]. Changes in the lung tissue that result in chronic disease have also been reported in a minority of cases, where symptoms do not resolve despite adequate treatment with diethylcarbamazine (DEC) [7].

• Ankle Edema

  Jugular venous pressure was raised and ankle edema was present. Cardiac impulse was right ventricular in type. Pulmonary second sound was loud and palpable. A soft, grade 2/6 pansystolic murmur was heard over the tricuspid area. [atmph.org]

• Intermittent Fever

  An 8-year-old boy from District Hardoi, Uttar Pradesh presented in the Cardiology Outpatient Department in our institute on 10 th July, 2010 with complains of cough with expectoration, intermittent fever, progressive breathlessness, generalized swelling [atmph.org]

• Painter

  Abstract A 21-year-old man from Sri Lanka came to Japan in August 1992 and worked as a painter. He had often complained of dyspnea on exertion before coming to Japan. [jstage.jst.go.jp]

• Pulmonary Disorder

  Eosinophilia in Pulmonary Disorders. Immunol Allergy Clin North Am. 2015 Aug. 35 (3):477-92. [Medline]. [emedicine.medscape.com]

• Nocturnal Wheezing

  It is characterized by episodic nocturnal wheezing and coughing, strikingly elevated eosinophilia, and diffuse reticulonodular infiltrations of the lung. Sometimes the lymph nodes and spleen are greatly enlarged. [medical-dictionary.thefreedictionary.com]

  It is characterized by cough, dyspnea, and nocturnal wheezing with diffuse reticulonodular infiltrates in chest radiographs and marked peripheral blood eosinophilia. [1] Long-term sequelae are pulmonary fibrosis with chronic respiratory failure. [2] Pulmonary [atmph.org]

• Orthopnea

  There was no history of orthopnea, paroxysmal nocturnal dyspnea, chest pain, abdominal distension, or decreased urine output. [atmph.org]

• Pansystolic Murmur

  A soft, grade 2/6 pansystolic murmur was heard over the tricuspid area. There were inspiratory fine crepitations and rhonchi all over the chest. The liver was palpable 2 cm below right costal margin. [atmph.org]

• Impulsivity

  Cardiac impulse was right ventricular in type. Pulmonary second sound was loud and palpable. A soft, grade 2/6 pansystolic murmur was heard over the tricuspid area. There were inspiratory fine crepitations and rhonchi all over the chest. [atmph.org]

Patient history is important, especially in non-endemic areas, as a recent travel history to tropical regions may give diagnostic clues. Laboratory investigations such as white cell count as well as measurement of antibody titers are performed. In individuals with TE, leukocytes are increased, with a predominance of eosinophils. Furthermore, there are high titers of specific as well as non-specific immunoglobulins (Ig), namely IgE, IgG, and IgM, in response to filarial antigens [8].

Pulmonary function tests are necessary, and reveal a mixed picture of obstructive and restrictive lung disease, with a decrease in parameters such as the forced expiratory volume (FEV) and the diffusing capacity for carbon monoxide (DLCO) [7] [9]. In some cases, a purely restrictive picture is seen.

In addition, the following studies are also done:

• Arterial blood gas analysis: May reveal lower than normal concentrations of oxygen due to a ventilation-perfusion mismatch [3].
• Chest X-ray: This may be normal in up to one fifth of patients. Usually, widespread nodular opacities are visible, similar to those seen in miliary tuberculosis.
• Computerized tomography scan: Useful in showing structural lung damage such as bronchiectasis [10].
• Bronchoscopy and bronchoalveolar lavage: This allows the visualization of inflammation of the parenchyma as a direct consequence of the presence of a large number of eosinophils in the lungs [2]. Furthermore, anti-filarial antibodies, as well as, nonspecific antibodies can also be seen.
• Lung biopsy: Biopsy is usually done in the context of chronic disease which is first confirmed via spirometry, in the years following treatment.

• Right Axis Deviation

  Electrocardiogram recorded sinus rhythm with right axis deviation and right ventricular hypertrophy. 2D-echocardiography (ECHO) revealed massive dilated right ventricle and atrium with dysfunction with right ventricular systolic pressure (RVSP) of 72 [atmph.org]

  Echocardiography showed right axis deviation with right ventricular hypertrophy, and chest radiography revealed pulmonary edema. [doi.org]

• Wuchereria Bancrofti

  Abstract Reaginic antibodies to antigens from the human filarial parasites Wuchereria bancrofti and Brugia malayi and the animal parasite Dirofilaria immitis were studied by histamine release from basophils in 7 patients with tropical eosinophilia (T.E [ncbi.nlm.nih.gov]

  Tropical (pulmonary) eosinophilia, or TPE, is characterized by coughing, asthmatic attacks, and an enlarged spleen, and is caused by Wuchereria bancrofti, a filarial infection. It occurs most frequently in India and Southeast Asia. [en.wikipedia.org]

  Definition / general Due to microfilaria of Wuchereria bancrofti or Brugia malayi, which circulate in pulmonary capillaries and cause an immediate type of eosinophilic hypersensitivity reaction Patients have high levels of IgE and high titers of filarial [pathologyoutlines.com]

• Dirofilaria Immitis

  No significant difference was observed between this antigen and that prepared from Dirofilaria immitis. [ncbi.nlm.nih.gov]

  IgG enzyme-linked immunosorbent assay showed a high titer against Dirofilaria immitis. Microfilaria were not detected in blood sampled at night. He was given a diagnosis of tropical eosinophilia. We could not give diethyl-carbamazine. [jstage.jst.go.jp]

  Immitis antigen, etc.): elevated (diagnosticaly useful but may have lower titer elevation in helminthic infections, due to cross-reactivity) ESR: may be elevated in advanced disease Blood C/S and exam: negative EKG: may be abnormal Echo: may show pericardial [mdnxs.com]

  immitis Pulmonary lesion Tropical and subtropical, including Australia Serology None Hookworm disease Ancylostoma duodenale Loeffler’s-like syndrome Tropical and subtropical areas Stool Albendazole * Loeffler’s-like syndrome: transient pulmonary infiltrates [mja.com.au]

• Restrictive Pulmonary Function

  Ongoing chronic inflammatory process may lead to development of pulmonary fibrosis and chronic respiratory failure. [6] These restrictive pulmonary function deficits may result in pulmonary hypertension that subsequently contributes to cor-pulmonale. [atmph.org]

• Amyloid Plaque

  Read More Full Text HTML Download PDF Figure 1: Alzheimer's disease (AD) is characterized by neuronal death, which is usually correlated with the appearance of amyloid plaques and neurofibrillary tangles (NFTs). (a) The Aβ pathway leading... [doi.org]

• Neurofibrillary Tangle

  Read More Full Text HTML Download PDF Figure 1: Alzheimer's disease (AD) is characterized by neuronal death, which is usually correlated with the appearance of amyloid plaques and neurofibrillary tangles (NFTs). (a) The Aβ pathway leading... [doi.org]

• Ventricular Hypertrophy

  Electrocardiogram recorded sinus rhythm with right axis deviation and right ventricular hypertrophy. 2D-echocardiography (ECHO) revealed massive dilated right ventricle and atrium with dysfunction with right ventricular systolic pressure (RVSP) of 72 [atmph.org]

  Echocardiography showed right axis deviation with right ventricular hypertrophy, and chest radiography revealed pulmonary edema. [doi.org]

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8. Billa G, Thakkar K. A Case of Chronic Cough with Progressive Breathlessness in a 32 Year-old Male Health Worker -Tuberculosis?, Allergic Bronchitis?, Asthma?. Br J Med Med Res. 2014;4(35):5513-5518.
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10. Sandhu M, Mukhopadhyay S, Sharma SK. Tropical pulmonary eosinophilia: a comparative evaluation of plain chest radiography and computed tomography. Australas Radiol. 1996;40(1):32–37.