Paragonimus Infections and Associated Zoonoses

Paragonimiasis is a neglected foodborne trematode infection caused by lung flukes of the genus Paragonimus. The life cycle of these parasites involves two intermediate hosts—freshwater snails and crustaceans—and a mammalian definitive host, including humans, in which adult flukes inhabit pulmonary tissue. Transmission occurs through consumption of undercooked or raw crustaceans harbouring infective metacercariae. Clinically, paragonimiasis often mimics tuberculosis or lung cancer, presenting with chronic cough, haemoptysis and eosinophilia, which contributes to frequent misdiagnosis. Although treatment with praziquantel or triclabendazole is generally effective, diagnostic challenges and limited access to reliable serological assays prolong patient morbidity. Geographically, Paragonimus species display a global distribution across Asia, Africa and the Americas, with species prevalence shaped by environmental factors such as altitude, temperature and precipitation. Ongoing changes in culinary practices, habitat encroachment and climate have sustained endemic foci and driven emergent cases in non-traditional regions. Integrative research in genomics, epidemiology and diagnostics is now enhancing our understanding of parasite biology, host interactions and control strategies.

Research from Nature Portfolio

A retrospective clinical study of paediatric paragonimiasis reviewed cases over an eight-year period, highlighting that children often present with pleural effusion, hepatomegaly and subcutaneous nodules rather than classic pulmonary symptoms. Misdiagnoses as tuberculosis, pneumonia and intracranial lesions were common before confirmation by anti-parasite serology. Comparative analysis of treatment regimens showed that a single course of triclabendazole achieved higher cure rates than the conventional three-day praziquantel protocol, emphasising the need to refine therapeutic guidelines for paediatric populations.

Paragonimus Infections and Associated Zoonoses publication trend

The graph below shows the total number of articles in paragonimus infections and associated zoonoses across all publications each year (not limited to Nature Index journals).

Technical terms

Paragonimiasis: A parasitic disease caused by lung flukes of the genus Paragonimus.

Zoonosis: An infectious disease that can be transmitted from animals to humans.

Definitive host: The species in which a parasite reaches sexual maturity and reproduces.

Intermediate host: A species that harbours the parasite during an immature or non-reproductive stage.

Metacercariae: The encysted, infective larval stage of trematode parasites found in intermediate hosts.

Eosinophilia: An elevated concentration of eosinophil white blood cells, often indicative of parasitic infection.

References

1. A retrospective clinical analysis of pediatric paragonimiasis in a Chinese children’s hospital from 2011 to 2019. Scientific Reports (2021).
2. The first case report of Paragonimus westermani infection diagnosed by transbronchial lung cryobiopsy. International Journal of Infectious Diseases (2023).
3. Infection and biogeographical characteristics of Paragonimus westermani and P. skrjabini in humans and animal hosts in China: A systematic review and meta-analysis. PLOS Neglected Tropical Diseases (2024).
4. Lung flukes of the genus Paragonimus: ancient and re-emerging pathogens. Parasitology (2022).