North American paragonimiasis: epidemiology and diagnostic strategies

Abstract

Paragonimiasis is a zoonotic, food-borne trematode infection that affects around 23 million people in Asia, Africa and the Americas. North American paragonimiasis, caused by Paragonimus kellicotti, is a common infection of crustacean-feeding mammals in parts of the USA and Canada. Although infection rates in crayfish are very high in some areas, human infections are rare and depend on the consumption of raw or undercooked crayfish. Human infections can be easily prevented and treated, but proper diagnosis of paragonimiasis is a problem. Paragonimus lung flukes often cause serious disease symptoms before they produce eggs that may be detectable in sputum, bronchoalveolar lavage, stool or histological sections by microscopy or PCR. Antibodies against selected Paragonimus proteins are detectable as early as 2–3 weeks after infection. Therefore, antibody serology is the most promising diagnostic approach for paragonimiasis in North America and elsewhere.

Keywords:

• diagnosis
• lung disease
• Paragonimus infection
• serology
• zoonosis

Financial & competing interests disclosure

This work has been supported by a grant of the Barnes Jewish Hospital Foundation. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• While the infection risk of paragonimiasis for humans can be reduced or eliminated by avoiding exposure to metacercariae, infection rates in crustaceans in most areas of the world do not depend on humans.

• In addition to the clinical and parasitological diagnostic approaches, immunodiagnosis with crude Paragonimus antigens as performed at the US Centers for Disease Control or in our laboratory can be useful for confirming diagnoses.

• Further genomic and proteomic information will facilitate progress in the development of standardized serodiagnostic assays using recombinant Paragonimus antigens.

• Improved diagnosis of human paragonimiasis will also improve differential diagnosis of other lung diseases, since clinical features of paragonimiasis (cough, fever, weight loss, chest pain, hemoptysis) overlap with those in patients with tuberculosis and lung cancer.

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