Rat lungworm

Angiostrongylus cantonensis

ORDER Strongylida

FAMILY

Angiostrongylidae TAXONOMY

Pulmonema catonesis (Chen, 1935), Dominican Republic, originally Pulmonema raltucnorvegicus, Canton, China.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Moderate sized, adult males measure 0.79-0.87 in (20-22 mm) in length by 0.0126-0.0165 in (320-420 pm) in width, and adult females measure 0.87-1.34 in (22-34 mm) in length by 0.0134-0.0221 in (340-560 pm) in width.

DISTRIBUTION

Distribution can only be identified by the disease caused by this species, which has been reported in Asia (Philippines, Indonesia, Malaisia, Thailand, Vietnam, Taiwan, Hong-Kong, Japan); Oceania (Pacific Islands [Tahiti, New Caledonia],

Papua New Guinea, Australia); Cuba, Puerto Rico, Hawaii; United States; and Africa (Madagascar). (Specific distribution map not available.)

HABITAT

They utilize a wide variety of invertebrate intermediate hosts where adults live primarily in the blood vessels of the lungs of the host.

BEHAVIOR

Adults live within the blood vessels of the lungs of the rodent host. Females produce eggs that hatch in the lungs and then attach to the terminal branches of the pulmonary arteries. First-stage juveniles enter the respiratory tract and, from there, the juveniles move up the trachea, where they are then swallowed and later passed in the host's feces; juveniles can be detected in feces 40-60 days after infection. Requires an intermediate host (usually snails, but it can be found in almost any invertebrate such as oysters, slugs, and crabs) to complete its lifecycle. The rodent or human host is infected when it ingests an intermediate host (such as snails and slugs) containing infective juveniles. The infective juveniles develop to adults through two stages in 2-3 weeks. Adults enter the pulmonary arteries and the lungs where they become mature; they eventually enter the rodent host's brain. Adults then migrate back to the host's lungs via the venous circulation. In human hosts, the parasites enter the brain, but do not develop further and die.

FEEDING ECOLOGY AND DIET

Live off nutrients of their hosts, specifically around the lungs (and pulmonary arteries) and brains of rodent hosts, and usually only around the lungs of human hosts, but also in the blood vessels between the lungs and brain.

REPRODUCTIVE BIOLOGY

After mating, oviposition takes place in the lungs. Eggs are then coughed up, swallowed, and are subsequently passed in the host's feces. Hatched larvae develop in about two weeks to the infective third stage.

CONSERVATION STATUS

Not listed by the IUCN.

SIGNIFICANCE TO HUMANS

Especially dangerous to humans because it ruptures vessels in the brain. The presence of juveniles in the blood vessels, meninges, or tissue of the human brain can result in symptoms such as headache, fever, paralysis, neurological disorders, and even coma and death. The appearance of worms is often associated with eosinophilia, and is the primary cause of eosinophilic meningoenciphalitis, a disease that occurs when humans eat infected, raw snails. ♦

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