Paragonimiasis, a food-borne zoonosis caused by Paragonimus spp., can cause severe pulmonary inflammation and fibrosis. However, relationships among the host, parasite and lung microbiome at defined infection stages remain poorly understood. We compared independent groups of rats sampled at 14, 28 and 42 days post-infection (dpi), together with a separate group sampled after triclabendazole (TCBZ) treatment. Histopathological and molecular analyses were combined with multi-region (5R) 16S rRNA gene sequencing and fluorescence in situ hybridization (FISH). Groups sampled at later post-infection time points showed greater pulmonary inflammation and collagen deposition, with the highest values in Pp-42d; both outcomes were lower in Pp-TCBZ than in Pp-42d. Th1-, eosinophil-, Th2- and Treg- associated markers differed among experimental groups. TLR4/NF-κB -related protein expression and pulmonary microbial profiles also differed among groups including enrichment of taxa such as Lactobacillus in infected animals. FISH detected bacterial signals within inflammatory lesions and Lactobacillus-associated signals spatially associated with parasite eggs. These repeated cross-sectional findings identify stage-associated differences in pulmonary pathology, immune markers and microbiota during P. proliferus infection, together with lower pathological measures in the Pp-TCBZ group than in the untreated Pp-42d group. The egg-associated bacterial signals warrant further investigation but do not establish a functional host-parasite-microbiome mechanism.

A study was conducted to identify and characterize trematode cercariae infecting freshwater snails in three paragonimiasis endemic areas namely, Luwangsangbam matai, Motbung, and Moreh of Manipur, India, from 2020 to 2024. A total of 9467 snails belonging to seven species namely Bortia costula (2404), Filopaludina bengalensis (1869), Paludomous pustulosa (1474), Racesina luteola (1147), Melanoid tuberculota (891), Radix rufescens (869) and Indoplanorbis exustus (814) were collected and examined for cercarial infection using the shedding and crushing methods. The overall prevalence of trematode infection in snails was 0.26%, with the highest infection rate observed in Moreh (0.41%), followed by Motbung (0.36%) and Luwangsangbam Matai (0.09%). Among the snail species, Melanoides tuberculata showed the highest infection rate (0.90%), whereas Indoplanorbis exustus and Paludomous pustulosa were not infected. Morphological examination revealed nine different morphological types of cercariae: Lophocercous (1), Apharyngeate ocellate furcocercariae (1), Gymnocephalous (2), Xiphidio (1), Furcocercous (2), and Echinostomous (2). Molecular analysis based on 18 S rDNA sequencing and phylogenetic analysis identified six trematode species: Euryhelmis costaricensis, Trichobilharzia stagnicolae, Haematoloechus sibiricus, Australapatemon burti, Echinostoma revolutum, and Hypoderaeum conoideum. Seasonal variations in cercarial infection were observed, with higher rates from late spring to summer and lower rates in winter and early spring. This study provides baseline data on trematode-snail dynamics in the freshwater ecosystems of Manipur, which can be used for future epidemiological research and targeted control strategies.

Paragonimiasis is a parasitic infection that can closely mimic lung malignancy on imaging, creating a significant diagnostic challenge. We report the case of a 60-year-old man from South Korea who presented with hemoptysis and was found to have a suspicious pulmonary nodule. Despite antibiotic therapy and serial imaging, the nodule persisted, and the patient subsequently developed a large pleural effusion. Radiologic findings raised concern for malignancy; however, noninvasive diagnostic evaluations were inconclusive. The patient ultimately underwent video-assisted thoracoscopic surgery, which revealed diffuse pleural thickening and numerous parasitic ova. Histopathologic and laboratory findings confirmed paragonimiasis. Following treatment with praziquantel, the patient achieved full clinical recovery. This case illustrates the potential for paragonimiasis to mimic malignancy and underscores the importance of including parasitic infections in the differential diagnosis, particularly in endemic regions. In selected cases, surgical intervention may be required to establish a definitive diagnosis.

Paragonimiasis, a foodborne parasitic disease caused by Paragonimus, typically presents with pleural effusion and is often misdiagnosed as tuberculous pleurisy, especially in endemic regions. The present study aimed to investigate the causes of misdiagnosis of pleural effusion (PE) caused by paragonimiasis as tuberculous pleurisy and to propose preventive strategies. The clinical diagnostic and treatment course of one patient with paragonimiasis misdiagnosed as tuberculous PE (TPE) was analyzed. A literature review of English-language case reports and series on paragonimiasis with PE misdiagnosed as TPE was performed using PubMed, Google Scholar, and Web of Science databases up to January 1, 2026. A 41-year-old male patient presented to Gucheng County People's Hospital (Shiyan, China) in October 2024 with a 10-day history of cough, sputum production, fever and shortness of breath. with cough, sputum, fever and dyspnea. Chest computed tomography (CT) showed left-sided PE. Tuberculosis antibody detection was positive and erythrocyte sedimentation rate was elevated. The patient was misdiagnosed with TPE and showed poor response to antituberculosis treatment. At 8 months later, readmission revealed markedly elevated eosinophils in peripheral blood (18%; normal range: 0.4-8.0%, absolute count, 2.61x10[9]/l; normal range: 0.02-0.5x10[9]/l), pleural fluid and pleural biopsy tissue. The patient had longterm occupational exposure to freshwater aquatic products without a history of raw seafood ingestion. Intradermal test for Paragonimus-specific antigen (IDTPA) and serum Paragonimus IgG antibody were both positive. Following four courses of praziquantel (25 mg/kg three times daily; 3 days/course), the patient achieved clinical cure with resolution of PE and normalization of eosinophil count (0.46x10[9]/l). The correct diagnosis of paragonimiasis was established by peripheral and pleural eosinophilia, positive IDTPA and serology and response to praziquantel. A literature review of 16 English language publications (51 cases) showed that 92.2% of patients had a history of raw or undercooked freshwater product ingestion, 94.1% had peripheral blood eosinophilia and 93.8% were seropositive by ELISA. By contrast, the present case involved long-term occupational exposure to freshwater aquatic products without raw seafood ingestion, an unusual but important route of infection. All reported patients responded to praziquantel. Elevated eosinophil levels in peripheral blood and pleural fluid and biopsy tissue are valuable clues for the diagnosis of paragonimiasis. Detailed inquiry into occupational and environmental exposure in addition to dietary history is essential. IDTPA and/or serum Paragonimus IgG antibody testing enables early diagnosis. Praziquantel remains the standard effective treatment.

Paragonimiasis is a parasitic disease that involves the lungs but can manifest in extrapulmonary sites, including the peritoneum or subcutaneous tissue. Diagnosis is limited by nonspecific clinical manifestations and overlapping features with other diseases, such as tuberculosis (TB). A 55-year-old Korean male presented with acute abdominal pain and a recurrent subcutaneous mass in the left thigh. Although TB peritonitis was initially suspected, further diagnostic tests were performed. To confirm the diagnosis, multiplex real-time polymerase chain reaction (PCR) targeting the 28S rRNA gene and conventional PCR targeting the ITS2 region were performed on the ascitic fluid. Sequence analysis and phylogenetic clustering confirmed Paragonimus westermani. The patient was treated with praziquantel and showed clinical improvement. This case highlights the importance of considering paragonimiasis in patients with unexplained eosinophilia and peritoneal symptoms, even in the absence of pulmonary involvement. Molecular diagnostic tools can help confirm extrapulmonary infections and prevent misdiagnosis, particularly in endemic regions.

Paragonimiasis is a zoonotic disease caused by lung flukes of the genus Paragonimus, which use freshwater snails and crustaceans as intermediate hosts and mammals as definitive hosts. Despite its public health importance, few studies have documented the distribution of this parasite in tropical regions of Mexico. In April 2024, a total of 180 freshwater crabs of the genus Pseudothelphusa were collected from five localities in Oaxaca State, Mexico. Metacercariae were observed in 47.2% of the crabs examined, with the highest mean intensity (18.46 cysts per crab) recorded in San Pedro Molinos locality. Morphologically, the metacercariae corresponded to Paragonimus mexicanus, although a distinct pink morphotype resembling P. caliensis was detected in San Juan Cacahuatepec locality. Molecular identification based on the 28S rRNA gene confirmed a 98.51% to 98.72% similarity with P. mexicanus (GenBank accession no. HM172619.1). This study provides new molecular records of P. mexicanus in freshwater crabs from previously unsampled localities in Oaxaca, expanding the known geographic distribution of the parasite in southern Mexico. Continuous surveillance and molecular characterization of Paragonimus species are essential to clarify their diversity and assess zoonotic risk in Neotropical freshwater systems.

Paragonimiasis is a foodborne zoonosis transmitted mostly by the consumption of inadequately cooked crabs and crayfish harboring Paragonimus metacercariae. We present the case of a 38-year-old male with a history of crab ingestion who developed severe eosinophilia, transaminitis, and serositis. Initial presentation included fever, epigastric pain, weight loss, and pleural effusion. He was managed empirically with albendazole and corticosteroids along with other supportive measures. Two months later, he re-presented with hemoptysis and hypoxemia. HRCT showed multiple cavitary pulmonary lesions, pleural nodules, and left-sided pneumothorax. Sputum wet mount demonstrated Paragonimus species ova, confirming pulmonary paragonimiasis. The patient was managed with intercostal tube drainage, tranexamic acid nebulization, and praziquantel with clinical improvement. This case highlights the importance of considering paragonimiasis in patients, even with pneumothorax, when the patient has hemoptysis and eosinophilia in the background of ingestion of raw or undercooked crustaceans in endemic regions.