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Paragonimus
Epidemiology:
1) small snails serve as the 1st intermediate host
2) freshwater crabs or crayfish serve as 2nd intermediate host & harbor infectious metacercariae
3) infection may result from ingestion of raw, undercooked or marinated crustaceans
Pathology:
1) larvae are released into the stomach, migrate through the intestinal wall & into the peritoneal cavity
2) they reach the lungs by penetrating the diaphragm
3) maturation takes 5-6 weeks & the worms may live many years
4) adults measure 12 by 6 mm
5) they are often found in pairs in lung parenchyma of cats, dogs, other carnivores & humans within a fibrous capsule produced by the host
6) the capsule communicates with the bronchi through which eggs pass to be excreted in the sputum or feces
7) eggs remaining in the lung or other tissues may cause an extensive granulomatous reaction
8) worms may develop in ectopic sites, including the peritoneum, subcutaneous tissues & the brain
Clinical manifestations:
1) related to migration of larvae or by adults in tissue
2) onset of lung infection associated with fever/chills
3) chronic cough
4) abundant mucus production
5) episodes of hemoptysis
6) pleural effusion
Laboratory:
1) complet blood count: eosinophilia
2) isolation of eggs from
a) feces
b) sputum
c) tissues
3) unembryonated eggs
a) measure 80-120 by 45-70 um
b) operculated
c) moderately thick, yellow-brown shell
d) different species of Parogonimus cannot be distinguished on the basis of appearance of eggs
4) Paragonimus eggs may be distinguished from those of Diphyllobothrium, Fasciola & Fasciolopsis on the basis of size
4) Paragonimus serology
Radiology:
- Chest X-ray:
a) nodular shadows, calcifications, patchy infiltrates
b) pleural effusion may be present
Management:
-> praziquantel 25 mg/kg TID for 2 days
Specific
paragonimiasis
Paragonimus caliensis
Paragonimus ecuadoriensis
Paragonimus kellicotti
Paragonimus mexicanus
Paragonimus westermani
General
Troglotrematidae
Properties
KINGDOM: animal
PHYLUM: helminth
References
- Clinical Diagnosis & Management by Laboratory Methods,
19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia,
PA. 1996, pg 1291-92
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 772