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Pleural parasitic infection is an extremely rare disease of the pleura caused by a variety of parasites, with paragonimiasis infection being the most common. The lack of specific clinical symptoms for paragonimiasis makes it easy to misdiagnose as tuberculosis, causing unnecessary drug-related adverse effects and financial burdens from incorrect treatment. We report a case of a pediatric patient presenting with an isolated pleural effusion that was misdiagnosed as tuberculosis; the patient was eventually diagnosed with pleuropulmonary paragonimiasis infection after immunologic and serologic tests. The patient finally recovered after anti-parasitic treatment involving praziquantel administration. This report will help increase awareness of this disease among medical practitioners to avoid misdiagnosis and treatment delays which may lead to disease progression., Competing Interests: Declaration of competing interest The authors declared no potential conflicts of interest concerning the research, authorship, and/or publication of this article., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: To investigate the clinical features, diagnosis and treatment of paragonimiasis, so as to improve the prevention and treatment of it., Methods: The clinical data of paragonimiasis patients were collected and retrospectively analyzed., Results: Totally 17 patients were diagnosed as paragonimiasis and the main clinical features of 11 patients were cough, chest pain and fever, and the pleural effusion was found in 13 cases. Peripheral blood eosinophil percentages of all patients were significantly increased, and the detections of antibody IgG againstParagonimus parasite of ELISA method were positive in all patients. All the patients were cured after praziquantel treatment and no recurrence found in the follow-up visit., Conclusions: The clinical features of paragonimiasis patients are diverse, and pleural effusion is quite common in imaging examinations. The eosinophil percentages and antibody detections have important values for the diagnosis of paragonimiasis. Praziquantel is an effective medicine in the treatment.

A 38-year-old woman with sustained right chest pain was referred to our hospital. She showed pleural effusion and peripheral blood eosinophilia. Thoracentesis revealed eosinophilic pleural effusion in which the smear, culture and cytological examinations were all negative. Although she had no notable dietary history, chest CT revealed linear opacities, which suggested the migration tracks of paragonimiasis. The diagnosis was confirmed using enzyme-linked immunosorbent assays, which showed elevated Paragonimus westermani and Paragonimus miyazakii antibody levels. After the initiation of praziquantel therapy, all clinical findings were promptly improved. The detection of a migration track may therefore be useful in the diagnosis of paragonimiasis.

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.

In Korea, many people enjoy eating raw or underkooked freshwater crayfish and crabs which unfortunately may cause paragonimiasis. Here, we describe a case of pulmonary and abdominal paragonimiasis in a 9-year-old girl, who presented with a 1-month history of abdominal pain, especially in the right flank and the right inguinal area, with anorexia. A chest radiograph revealed pleural effusion in both lungs, and her abdominal sonography indicated an inflammatory lesion in the right psoas muscle. Peripheral blood analysis of the patient showed hypereosinophilia (66.0%) and an elevated total serum IgE level (>2,500 IU/ml). The pleural effusion tested by ELISA were also positive for antibodies against paragonimiasis. Her dietary history stated that she had ingested raw freshwater crab, 4 months previously. The diagnosis was pulmonary paragonimiasis accompanied by abdominal muscle involvement. She was improved after 5 cycles of praziquantel treatment and 2 times of pleural effusion drainage. In conclusion, herein, we report a case of pulmonary and abdominal paragonimiasis in a girl who presented with abdominal pain and tenderness in the inguinal area.

Paragonimiasis is a parasitic infection endemic in Asia but uncommon in the United States. It presents most frequently with cough and hemoptysis. Pleural effusions are common and can manifest occasionally as a pseudochylothorax, but a true chylothorax has, to our knowledge, never been reported. We report a case of a chylothorax from infection with Paragonimus westermani. The case is also unique because it occurred in a native Californian who had not traveled to Asia and was infected by eating raw crabs at a local sushi restaurant. The freshwater crabs had been imported from Asia.

Purpose: Most patients with pleuropulmonary paragonimiasis can be cured by the initial single set of Praziquantel (PZQ) treatment. However, several cases have been reported to have unsatisfactory responses to the initial PZQ treatment. The objective of this study was to evaluate the clinical findings of patients with pleuropulmonary paragonimiasis who needed additional PZQ treatment after the 1st set chemotherapy., Patients and Methods: Thirty-two patients who were diagnosed with pleuropulmonary paragonimiasis at our institution between 2003 and 2008 were retrospectively reviewed., Results: All patients were treated initially with PZQ for 3 days (1st set chemotherapy). Twenty-four patients (75.0%) showed improvement in respiratory symptoms and pulmonary involvements. However, eight patients (25.0%) suffered from relapsed respiratory symptoms and pleural effusion. For these patients, an additional 2nd set PZQ treatment resulted in the resolution of the symptoms and pulmonary involvements. The characteristics of patients who needed multi-set treatments were as follows; longer duration of respiratory symptoms (single vs multi-set treatment group; 6.67 ± 8.08 vs 17.86 ± 11.84 weeks, p=0.009), higher IgG titer (optical density, O.D.) for Pargonimus westermani (ELISA O.D. for PW, 0.54 ± 0.19 vs 0.88 ± 0.16 O.D., p=0.001) and higher frequency of multiple pulmonary lesions (% of patients with multiple lesions; 16.7% vs 50.0%, p=0.059)., Conclusion: The patients who had a longer duration of respiratory symptoms, higher ELISA titer for PW and/or multiple pulmonary lesions needed an additional PZQ treatment after the 1st set of chemotherapy. Close follow-up after the initial treatment is necessary especially for such patients.

A 28-year-old man had a 1-year history of hemoptysis. Consequently, he underwent a medical examination. A right pleural effusion, left hydropneumothorax, and multiple pulmonary nodular shadows were found on chest radiography. During a detailed interview, he reported that the hemoptysis began after eating "kejang" (a raw crab preparation) with a friend a year previously. His peripheral blood eosinophil count and serum IgE level were elevated. In addition, ova were detected in the sputum and bilateral pleural effusion. Morphological examination of the ova and immunoserological examination led to the diagnosis of Paragonimus westermani infection. The pleural effusion could be partially drained, and his symptoms and radiographic results showed improvement after treatment with Praziquantel administered at a dose of 75 mg/(kg x day) for 3 days. After one month, he and his friend ate seasoned raw crabs, Paragonimus was diagnosed in his friend. This case suggests that on encountering a paragonimus infection, everyone who ate food prepared in the same kitchen should be contacted because of possible infection with paragonimus.

Southeast Asia is the major endemic area for paragonimiasis. Diagnosis relies on identification of ova in the sputum, pleural fluid or tissue specimen, or serology. Low awareness, however, frequently results in the disease being overlooked. We report nine cases presenting as primary, massive and protracted pleural effusions. All patients had evidence of Paragonimus spp. in the pleural fluid; one discharged an adult worm through a chest tube during treatment with praziquantel. In three cases, resolution of symptoms and pleural effusions could not be achieved, despite repeated fluid evacuation procedures and courses of praziquantel, which contradicts the widely accepted statement of paragonimiasis being self-limited and easy to cure. The disease should be considered in any case of elusive pleural effusion occurring in endemic areas.

Paragonimiasis is a zoonosis affecting wild and domestic animals and human beings, caused by species of trematodes of the genus Paragonimus. Humans become infected after ingestion of raw or poorly cooked fresh water crustaceans. The aim of the present work is the description of a case of a 3-years old child, coming from Guárico State in Venezuela with a year of residence in the seashore of the Provincia Manabí in Ecuador, where he ate crabs in "ceviche". During hospitalization, he presented respiratory distress, hepatomegaly and nodules in the back. The thorax cat scan showed heavy infiltrate in both pulmonary bases and pleural compromise. Based on clinic, radiological images, an eosinophilia of 47% (Eosinophils absolute count (EAC) 6.682/mm3) and the antecedent of raw crabs ingestion, pulmonary paragonimiasis was diagnosed. Paragonimus eggs were not found in sputum and feces. ELISA with crude Paragonimus antigen was positive and Western blot revealed recognition of specific molecules. After treatment for three days with Praziquantel at a daily dose of 25 mg/kg body weight divided into three intakes, the sintomatology disappeared and radiological images and number of eosinophils diminished considerably.

Objective: To investigate the serial CT findings of Paragonimus westermani infected dogs and the microscopic structures of the worm cysts using Micro-CT., Materials and Methods: This study was approved by the committee on animal research at our institution. Fifteen dogs infected with P. westermani underwent serial contrast-enhanced CT scans at pre-infection, after 10 days of infection, and monthly thereafter until six months for determining the radiologic-pathologic correlation. Three dogs (one dog each time) were sacrificed at 1, 3 and 6 months, respectively. After fixation of the lungs, both multi-detector CT and Micro-CT were performed for examining the worm cysts., Results: The initial findings were pleural effusion and/or subpleural ground-glass opacities or linear opacities at day 10. At day 30, subpleural and peribronchial nodules appeared with hydropneumothorax and abdominal or chest wall air bubbles. Cavitary change and bronchial dilatation began to be seen on CT scan at day 30 and this was mostly seen together with mediastinal lymphadenopathy at day 60. Thereafter, subpleural ground-glass opacities and nodules with or without cavitary changes were persistently observed until day 180. After cavitary change of the nodules, the migratory features of the subpleural or peribronchial nodules were seen on all the serial CT scans. Micro-CT showed that the cyst wall contained dilated interconnected tubular structures, which had communications with the cavity and the adjacent distal bronchus., Conclusion: The CT findings of paragonimiasis depend on the migratory stage of the worms. The worm cyst can have numerous interconnected tubular channels within its own wall and these channels have connections with the cavity and the adjacent distal bronchus.

A 73-year-old man was referred to our hospital because of left chest pain, left pleural effusion and peripheral blood eosinophilia. After three months, left pleural effusion resolved without treatment and the etiology remained unclarified. Three years later, he was admitted for evaluation of right pleural effusion. Peripheral blood eosinophil count and serum IgE value were elevated. Eosinophilia was also observed in the pleural effusion. The diagnosis of paragonimiasis westermani was confirmed by immunoserological examination of the serum and by detection of Paragonimius eggs in the pleural effusion. Two cycles of treatment with praziquantel were effective in this case. When a patient has repeated pleural effusion, paragonimiasis should be considered in the differential diagnosis.

Paragonimiasis is an important cause of pulmonary disease worldwide. Infection in humans mainly occurs by ingestion of raw or undercooked freshwater crabs or crayfish. The disease is well known in endemic regions of Asian countries, where culturally based methods of food preparation foster human transmission. Three patients with clinical and radiological features compatible with pulmonary tuberculosis had been treated for tuberculosis without remedy despite an inability to demonstrate acid fast bacilli in sputum smears. All patients had history of ingestion of raw crabs and crayfish. The confirmed diagnosis of pleuropulmonary paragonimiasis was made based on the demonstration of Paragonimus eggs in the sputum, and high absolute eosinophilia in their peripheral blood and pleural fluid. All the patients had been treated with praziquantel successfully.

To investigate the pathogenic mechanisms of eosinophilic pleural effusion in patients with paragonimiasis, we measured the levels of IL-5, granulocyte-macrophage colony-stimulating factor (GM-CSF) and interferon-gamma (IFN-gamma) in pleural effusions. Samples were obtained from 11 patients with Paragonimus westermani infection. In addition, samples from 12 patients with pleural transudates, 16 with tuberculous pleurisy, seven with empyema and 20 with lung cancer were also examined. Eosinophilia was remarkable in peripheral blood (range 4-34%, median 23.4%) and pleural fluid (range 0-95%, median 71%) of paragonimiasis patients. IL-5 concentrations in pleural effusions of paragonimiasis were markedly higher than those in other groups. Although marked elevation of GM-CSF and IFN-gamma levels was observed in pleural effusion of empyema and tuberculosis patients, it was marginal in the pleural effusion of paragonimiasis patients. In paragonimiasis patients, IL-5 levels in the pleural effusion correlated well with the percentage of eosinophils in peripheral blood and pleural fluid. Such a correlation was not observed between GM-CSF levels in pleural effusion and percentages of eosinophils in pleural fluid or peripheral blood. Our findings suggest that in paragonimiasis IL-5 in the local inflammatory site is particularly important in mediating eosinophilia in peripheral blood and pleural effusion.

In the pleural effusion of a 46-year-old man with pulmonary paragonimiasis, numerous floating particles containing parasitic ova and granulation tissue were observed. The floating particles appeared as diffuse hyperechoic foci in the anechoic pleural effusion on ultrasonography. We concluded that rupture of the intrapulmonary paragonimiasis lesion into the pleural cavity caused the formation of these floating particles.

Miyazaki Prefecture has long been known as one of the endemic areas of paragonimiasis westermani. The prevalence of this disease peaked around 1956 and then drastically decreased. A few sporadic cases are still occasionally found in Miyazaki Prefecture; however, the number of new cases has gradually increased during the last 5 years. One important point to be noted is the change of clinical manifestations in the patients. A classically known form of paragonimiasis westermani is characterized by persisting cough, bloody sputum, and nodular or ring shadows in the lung field by chest x-ray. However, the patients recently found in Miyazaki Prefecture rarely showed such typical symptoms. Only four of 13 cases were found to have pulmonary infiltration and nine cases showed massive pleural effusion without pulmonary infiltration. Such atypical cases may be caused by low intensity of infection or, alternatively, be due to the earlier diagnosis.

We report a Laotian patient with pleural paragonimiasis who did not have the usual diagnostic triad for this parasitic disease. He did not have chronic hemoptysis (considered by many to be an "invariable" finding), there were no pulmonary infiltrations, and stool and sputum examinations did not yield Paragonimus ova. The diagnosis was made on the basis of ova found in the pleural fluid. Paragonimiasis pleural effusion did not resolve with bithionol, the drug of choice for pulmonary paragonimiasis, and, as a result, chest tube drainage was required. The difference between pleural paragonimiasis and pulmonary paragonimiasis is that the classic clinical presentation of the latter (hemoptysis, ova in sputum and stools, lung infiltration, etc.) requires an intrapulmonary location on the parasite. A search for ova in the pleural fluid may be the only diagnostic tool for patients suspected of pleural paragonimiasis. With the influx of Southeast Asia refugees, this case report may be of relevance to U.S. physicians involved in the care of patients in whom not all chronic pleuropulmonary diseases are tuberculous.

Pleural fluid studies showing a glucose value of less than 10 mg/dl, an LDH level greater than 1,000 IU/L, eosinophilia, a high protein value, and low pH are characteristic of paragonimiasis. In a patient with a pleural effusion and compatible clinical, radiologic, and serologic findings, pleural fluid analysis will allow diagnosis with reasonable certainty even in the absence of positive ova studies, and is useful in distinguishing paragonimiasis from tuberculosis.