Paragonimiasis B66.4

Author: Prof. Dr. med. Peter Altmeyer

Last updated on: 29.10.2020

Synonym(s)

lung fluke infection; Pulmonary fluke infection

Trematode infection by Paragonimus spp.

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 egg cell and 5-10 yolk cells; the egg shell is thickened at the rear pole.
Occurrence in freshwater snails in running waters (1st intermediate host) and crabs, shrimps and lobsters (2nd intermediate host). End hosts are humans and carnivores.

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Dermatology

Acute, generalized, mostly febrile, non-follicular, sterile, pustular (subcorneal pustule) exanthema, which...

About 20 million infected people worldwide. Prevalence in endemic areas: 0.1-24%.

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: Gradual course with chronic bronchitis with viscous-gelatinous sputum, often bloody tinged (rust coloured), subfebrile temperatures, cough, dyspnoea, pleural pain, night sweats, shivering, weight loss, constipation.
Infestation of ectopic localizations:

Integument: Temporary appearance of inflammatory subcutaneous swelling or soft tissue swelling. There are also shifting, skin-coloured or red subcutaneous nodules (similar to Calabar) containing immature flukes (detectable by biopsy). Preferably affected are the abdominal and inguinal regions. Infestation with P. szechuanensis results in larva migrans (parasites do not mature into adult worms).
Genital region: Scrotal infestation can be very painful and simulate epididymitis or incarcerated hernia.
Abdominal organs: Diffuse or localized abdominal pain, tumorous masses, appendicitis and peritonitis.
Brain: headache, vomiting, fever, dizziness, confusion, Jackson-type focal 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.

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.

The mortality of untreated cerebral paragonimiasis is 5%.

No consumption of raw shrimps, crabs and lobsters (traditional dishes!).

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
Kusner DJ et al (1993) Cerebral paragonimiasis. Semin Neurol 13: 201
Keiser J et al (2005) Triclabendazole for the treatment of fascioliasis and paragonimiasis. Expert Opinion Investig Drugs 14: 1513
Ziegler K et al (1996) Liver and lung fluke infections. In: Knobloch J., tropical and travel medicine. Gustav Fischer