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Heterophyes Species
Metagonimus Species


Causal Agent

Metagonimus Yokogawa, a minute intestinal fluke (and the smallest human fluke).

Life Cycle:

Clonorchis LifeCycle

Adults release fully embryonated eggs, each with a fully-developed miracidium, and eggs are passed in the host’s feces—the number 1. After ingestion by a suitable snail (first intermediate host), the eggs hatch and release miracidia which penetrate the snail’s intestine The number 2. Snails of the genus Semisulcospira are the most frequent intermediate host for Metagonimus Yokogawa. The miracidia undergo several developmental stages in the snail, i.e., sporocysts The number 2a, rediae, The number 2b, and cercariae The number 2c. Many cercariae are produced from each redia. The cercariae are released from the snail. The number 3 and encyst as metacercariae in the tissues of a suitable fresh/brackish water fish (second intermediate host) The number 4. The definitive host becomes infected by ingesting undercooked or salted fish containing metacercariae The number 5. After ingestion, the metacercariae excyst attach to the mucosa of the small intestine The number 6 and mature into adults (measuring 1.0 mm to 2.5 mm by 0.4 mm to 0.75 mm) The number 7. In addition to humans, fish-eating mammals (e.g., cats and dogs) and birds can also be infected by M. Yokogawa The number 8.

Geographic Distribution

Mostly the Far East and Siberia, Manchuria, the Balkan states, Israel, and Spain.

Clinical Presentation

The main symptoms are diarrhea and colicky abdominal pain. Migration of the eggs to the heart, resulting in potentially fatal myocardial and valvular damage, has been reported from the Philippines. Migration to other organs (e.g., brain) has also been reported.

Laboratory Diagnosis

The diagnosis is based on the microscopic identification of eggs in the stool. However, the eggs are indistinguishable from those of Metagonimus Yokogawa and resemble those of Clonorchis and Opisthorchis.

For more information, view the source: Center for Disease Control

Recommended Test: Full GI Panel

Recommended Product: Freedom Cleanse Restore Parasite Cleanse