Paragonimiasis B66.4

Main species: East Asia: P. westermani; Japan: P. miyazakii; Tropical Africa: P. africanus, P. uterobilateralis; Central and South America: P. kelicotii, P. mexicanus.

Life span of adult worms: up to 20 years.

The oval eggs are golden brown, capped and contain one oocyte and 5-10 yolk cells; the eggshell is thickened at the posterior pole.

Occurs in freshwater snails in running waters (1st intermediate host) and crabs, shrimps and crayfish (2nd intermediate host). Final hosts are humans and carnivores.

• in running waters, the eggs develop mirazidia, which penetrate gill slug; in the slug, the eggs mature into cercaria, which leave the slug and enter the 2nd intermediate host (crabs, crayfish, lobsters).
• Humans and carnivores become infected by eating raw crustaceans (e.g. crab meat).
• The metacercaria decystify in the duodenum, penetrate the intestinal wall and mature in the liver or abdominal wall into mature adult worms, which then penetrate the diaphragm and enter the lungs. The worms cause an inflammatory, eosinophilic reaction. A thin-walled cyst forms around the worms, which ruptures at the beginning of egg excretion. The eggs then enter the bronchial system and thus reach the outside. If they are not coughed up, a granulomatous inflammatory reaction is formed; the eggs can break into the pulmonary veins and be carried haematogenously to various organs.

Rare: Acute febrile course with pleuropneumonia.

More frequent: insidious course with chronic bronchitis with viscous-gelatinous sputum, often with a bloody tinge (rust-colored), subfebrile temperatures, cough, dyspnea, pleural pain, night sweats, chills, weight loss, constipation.

Infestation of ectopic localizations:

• Integument: Temporary occurrence of inflammatory subcutaneous swellings or soft tissue swellings. Furthermore, shifting, skin-colored or red, subcutaneous nodules (calabar-like) containing immature flukes (detectable by biopsy) appear. The abdominal and inguinal regions are preferentially affected. Infestation with P. szechuanensis is characterized by larva migrans (parasites do not mature into adult worms).
• Genital region: Scrotal infestation may be very painful and may simulate epididymitis or an incarcerated hernia.
• Abdominal organs: Diffuse or localized abdominal pain, tumorous masses, appendicitis and even concomitant peritonitis.
• Brain: Headache, vomiting, fever, dizziness, confusion, Jacksonian-type hereditary epilepsy, hemiplegia, visual disturbances.

• Detection of eggs in sputum and pleural punctates.
• Immunodiagnostics (note cross-reactions with other helminths), detection of antibodies also in pleural punctates.
• Imaging:
• X-ray thorax: in the course of cysts as roundish shadows of up to 40 mm diameter, often with annular central brightening, often in the lower and middle fields of the lung, accompanying pleural effusions are possible.
• CT or MRI of the skull: fulminant mengioencephalitites, chronic abscesses and granulomas, mostly occipital or parietal ("bubble-like", older foci calcify).

• Tuberculosis; lung abscesses; echinococcosis and other helminth infections (schistosomiasis, strongyloidiasis and others; mycosis; foreign bodies; tumours; lung infarction; haemorrhagic diathesis; pulmonary endometriosis; Goodpasture's syndrome; Kaposi's sarcoma; hypersensitivity reaction to drugs; hypereosinophilic syndrome; allergic aspergillosis; Churg-Strauss syndrome;
• in cerebral paragonimiasis: Angiostrongylus cantonensis infection and cysticercosis.
• in cutaneous paragonimiasis: filariasis; fascioliasis; gnathostomiasis.

• Lung abscess
• Epilepsy
• Activation of tuberculous processes.

• Agent of the 1st choice is triclabendazole: one-day therapy with 10 mg/kg bw/day as ED p.o.
• Alternatively: Praziquantel: 3 times/day 25 mg/kg bw p.o. for 3 days, longer therapy duration for cerebral paragonimiasis.
• Alternatively biothionol (lorothidol, bitin [available from international pharmacies]): 30-50 mg/kg bw/day in 3 doses every other day, alternating with a day without treatment. 5-15 treatment days.
• In case of cerebral infestation: additional corticosteroids, anticonvulsants if necessary and in case of hydrocephalus intraventricular shunt.

1. Blair D (20245) Paragonimiasis. Adv Exp Med Biol 1454:203-238.
2. Dainichi T et al. (2003) A case of cutaneous paragonimiasis with pleural effusion. Int J Dermatol 42:699-702.
3. Harinasuta T et al. (1993) Trematode infections. Opisthorchiasis, clonorchiasis, fascioliasis, and paragonimiasis [published erratum appears in Infect Dis Clin North Am 1994 Mar; 8(1):following table of contents]. Infect Dis Clin North Am 7: 699
4. Kusner DJ et al (1993) Cerebral paragonimiasis. Semin Neurol 13: 201
5. Keiser J et al. (2005) Triclabendazole for the treatment of fascioliasis and paragonimiasis. Expert Opin Investig Drugs 14: 1513
6. Shah P et al. (2023) Pulmonary Paragonimiasis: A Case Series. JNMA J Nepal Med Assoc 61:290-293.
7. Yatera K et al. (2015) A rare case of paragonimiasis miyazakii with lung involvement diagnosed 7 years after infection: A case report and literature review. Parasitol Int 64:274-80.
8. Ziegler K et al. (1996) Liver and pulmonary fluke infections. In: Knobloch J., Tropical and travel medicine. Gustav Fischer