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- The adult stage of A. cantonensis is only found in
rodents. Infected rodents can pass larvae of the worm in their
feces.
- The infected feces are ingested by snails or slugs (intermediate
hosts); it is also possible that the larvae enter the snail by
penetrating the body wall or via the respiratory pore.
- The larvae develop to the third stage in the snails and remain at that
stage until either the snail is eaten or dies.
- When snails carrying
third stage larvae are eaten by a rat, they move through the rat gut to
the small intestine where they penetrate the walls of the intestine and
enter the blood stream.
In the blood stream they travel passively and some eventually enter the
central nervous system and the brain.
- In the brain, larvae develop to the sub-adult stage. Light infections
appear to cause little damage to the brain and no obvious behavioral or
other reaction, but heavy infections may cause more serious damage and
behavioral symptoms.
- In the sub-adult stage ,the worms leave the brain, amd pass into the
venous circulatory system, and thence to the right ventricle of the
heart and to the pulmonary arteries where they mature, mate, and the
females lay eggs.
- The eggs travel in the blood stream to the lungs (hence the name rat
lungworm disease). They hatch into first stage larvae in the tissue of
the lungs which may cause significant damage to the arteries, and to the
lungs.
- The first stage larvae break through the walls of the bronchioles
and alveoli, move up the trachea in respiratory secretions, and are
swallowed, to be released in the feces.
- The cycle then repeats when
snails ingest the infected feces.
- The cycle takes about 45 days.
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