Pulmonary paragonimiasis: diagnostic value of pleural fluid analysis

Distinguishing tuberculosis pleural effusion from parasitic pleural effusion using pleural fluid characteristics: A case control study

Tuberculosis pleural effusion (TPE) and parasitic pleural effusion (PPE) present with similar clinical manifestations. We evaluated the pleural fluid features of TPE and PPE.A total of 76 patients with pleuritis, including 25 patients with TPE and 51 patients with PPE were retrospectively studied. Pleural fluid was sent for analyses of protein, cytology, cell count, acid fast bacilli (AFB) staining, Gram stain, culture, sensitivity, and adenosine dehydrogenase (ADA).The proportion of eosinophilia present in the PPE group was significantly higher than that in the TPE group (P < .001). However, the proportion of lymphocytes found in the TPE group was significantly higher than that in the PPE group (P < .001). The mean level (SD) of ADA was 46.99 ± 22.09 U/L in the TPE group and 39.08 ± 23.03 U/L in the PPE group. No difference was detected between the study groups in terms of the ADA level of the pleural fluid (P > .05).When the results of pleural fluid testing reveal marked eosinophilia and a low proportion of lymphocytes, physicians should consider a diagnosis of PPE, especially for patients who live in or have traveled to endemic areas.

Paragonimiasis

Paragonimiasis is a zoonotic disease caused by lung flukes of the genus Paragonimus. Humans usually become infected by eating freshwater crabs or crayfish containing encysted metacercariae of these worms. However, an alternative route of infection exists: ingestion of raw meat from a mammalian paratenic host. Adult worms normally occur in pairs in cysts in the lungs from which they void their eggs via air passages. The pulmonary form is typical in cases of human infection due to P. westermani, P. heterotremus, and a few other species (Table 5.1). Worms may occupy other sites in the body, notably the brain, but lung flukes have made their presence felt in almost every organ. Ectopic paragonimiasis is particularly common when infection is due to members of the P. skrjabini complex (Table 5.1). Human paragonimiasis occurs primarily in the tropics and subtropics of Asia, Africa, and the Americas, with different species being responsible in different areas (Table 5.1).

Pleural fluid characteristics of pleuropulmonary paragonimiasis masquerading as pleural tuberculosis

BACKGROUND/AIMS

Pleuropulmonary paragonimiasis produces no specific symptoms or radiologic findings, allowing for the possibility of misdiagnosis. We evaluated the specific clinical and pleural fluid features of pleuropulmonary paragonimiasis masquerading as pleural tuberculosis.

METHODS

We retrospectively analyzed the clinical and radiologic characteristics of 20 patients diagnosed with pleuropulmonary paragonimiasis between 2001 and 2011.

RESULTS

In total, 17 patients presented with respiratory symptoms, including dyspnea (30%), hemoptysis (20%), cough (20%), and pleuritic chest pain (15%). Chest radiographs revealed intrapulmonary parenchymal lesions, including air-space consolidation (30%), nodular opacities (20%), cystic lesions (15%), ground-glass opacities (10%), and pneumothorax (5%). A pleural fluid examination revealed eosinophilia, low glucose levels, and high lactate dehydrogenase (LDH) levels in 87%, 76%, and 88% of the patients, respectively. These traits helped to distinguish pleuropulmonary paragonimiasis from other pleural diseases such as parapneumonic effusion, malignancy, and pleural tuberculosis.

CONCLUSIONS

Pleuropulmonary paragonimiasis is often initially misdiagnosed as other pleural diseases. Therefore, it is important to establish the correct diagnosis. In patients with unexplained pleural effusion living in paragonimiasis-endemic areas, pleural fluid obtained by thoracentesis should be examined to distinguish pleuropulmonary paragonimiasis. When marked eosinophilia, high LDH levels, and low glucose levels are identified in pleural fluid, physicians could consider a diagnosis of pleuropulmonary paragonimiasis.

Paragonimiasis

Paragonimiasis is a zoonotic disease caused by lung flukes of the genus Paragonimus. Humans usually become infected by eating freshwater crabs or crayfish containing encysted metacercariae of these worms. However, an alternative route of infection exists: ingestion of raw meat from a mammalian paratenic host. Adult worms normally occur in pairs in cysts in the lungs from which they void their eggs via air passages. The pulmonary form is typical in cases of human infection due to P. westermani, P. heterotremus, and a few other species (Table 5.1). Worms may occupy other sites in the body, notably the brain, but lung flukes have made their presence felt in almost every organ. Ectopic paragonimiasis is particularly common when infection is due to members of the P. skrjabini complex (Table 5.1). Human paragonimiasis occurs primarily in the tropics and subtropics of Asia, Africa, and the Americas, with different species being responsible in different areas (Table 5.1).

Clinical features of recently diagnosed pulmonary paragonimiasis in Korea

STUDY OBJECTIVE

Paragonimiasis is a typical food-borne parasitic disease that is common in Southeast Asia, the Far East, Latin American, and Africa. Recently, however, this disease has been seen in many parts of the world, largely due to increases in the numbers of immigrants and overseas travelers. The purpose of this study was to evaluate the clinical and radiologic features of recently diagnosed pulmonary paragonimiasis.

PATIENTS

We retrospectively analyzed the clinical and radiologic characteristics of 36 patients (21 men and 15 women; median age 48 years; range, 19 to 75) with pulmonary paragonimiasis whose conditions were diagnosed between October 1994 and September 2004.

RESULTS

Thirty-four patients (94%) presented with respiratory symptoms, including hemoptysis (n = 20, 56%) and cough (n = 17, 47%). However, chest pain (n = 5, 14%) and fever (n = 5, 14%) were less frequently reported. Chest radiography revealed intrapulmonary parenchymal lesions (n = 26, 72%), such as nodules (n = 14, 39%), linear opacity (n = 6, 17%), and airspace consolidations (n = 4, 11%), which occurred more commonly than did pleural lesions (n = 10, 28%). Most cases were initially suspected to be lung cancer or tuberculosis. In 13 patients with intrapulmonary parenchymal lesions who underwent bronchoscopy, bronchial luminal narrowing, coupled with congested or edematous mucosal changes, was seen in 7 patients (54%). Bronchial mucosal biopsy specimens exhibited chronic inflammation with eosinophilic infiltrations in three of these seven patients (43%).

CONCLUSIONS

Our findings indicate that patients with pulmonary paragonimiasis presented with a variety of clinical and radiologic findings that were different from the classic presentations reported earlier, frequently mimicking those of lung cancer or tuberculosis.

Paragonimiasis: a view from Columbia

Paragonimiasis is a zoonosis caused by adult trematodes of the Paragonimus genus. The infection in humans is a result of a complex transmission cycle that includes two obligate intermediate hosts, a snail and a crustacean or a crayfish, and a definitive mammalian host. It has been shown that 9 of the more than 40 species of Paragonimus described affect humans in over 39 countries in Asia, Africa and America. It is estimated that 20.7 million people have paragonimiasis and it is calculated that 195 million people are at risk of being infected. The illness usually is caused once the parasite has settled in the lung at the site of the main clinical symptoms: cough, thoracic pain and hemoptysis. The diagnosis of paragonimiasis is based on the patient's history, the parasitological findings (ova in sputum and in feces), and the result of radiological and immunological tests. In severe cases, the patient may suffer from life-threatening hemoptysis or pneumothorax. Currently, praziquantel is the drug of choice.