Moniliformis moniliformis
| Moniliformis moniliformis | |
|---|---|
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| Adult specimen | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Acanthocephala |
| Class: | Archiacanthocephala |
| Order: | Moniliformida |
| Family: | Moniliformidae |
| Genus: | Moniliformis |
| Species: | M. moniliformis |
| Binomial name | |
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Moniliformis moniliformis (Bremser, 1811) |
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Moniliformis moniliformis is a parasite of the Acanthocephala phylum in the family Moniliformidae. Along with Macracanthorhynchus hirudinaceous, M. moniliformis is an acanthocephalan worm species that can infect humans, though rare.
The earliest known human infection was found in Utah in the coprolite of a prehistoric man. Specimen analysis showed a significant amount of M. moniliformis eggs in the coprolite. In 1888 in Italy, Calandruccio infected himself by ingesting larvae, reported gastrointestinal disturbances, and then shed the eggs in two weeks. This was the first report of the clinical manifestations of an M. moniliformis infection in humans.
Infected rats have been found world-wide. Cases of human infection by Moniliformis moniliformis have been reported in the United States, Iran, Iraq, and Nigeria.
Acanthocephalans do not have digestive tracts and absorb nutrients through the tegument, the external layer. The scolex of this worm has a cylindrical proboscis and a multitude of curved hooks. The main parts of the worm body are the proboscis, neck, and trunk. Because of horizontal markings on the worm, there is the appearance of segmentation. Acanthocephalans are sexually dimorphic (dioecious) - adult males are generally 4 to 5 cm long while females are longer, ranging from lengths of 10 to 30 cm. Males also have copulatory bursas, used to hold on to the female during copulation and cement glands. Females have floating ovaries within a ligament sac where fertilization of the eggs occurs. The eggs of this parasite are 90-125 μm long and 65 μm wide. They are oval in shape with a thick, clear outer coat.
While acanthocephalans rarely infect humans, there have been several cases reported of M. moniliformis causing acanthocephaliasis in humans as their definitive hosts. Usually, the definitive hosts for M. moniliformis are rodents, cats, dogs and red foxes (in Poland). The intermediate hosts are usually beetles and cockroaches.
No known vectors
In the life cycle of M. moniliformis, the intermediate hosts ingest the eggs of the parasite. In the intermediate host, the acanthor, or the parasite in its first larval stage, morphs into the acanthella, the second larval stage. After 6–12 weeks in this stage, the acanthella becomes a cystacanth. The cystacanth, or infective acanthella, of M. moniliformis are cyst-shaped and encyst in the tissues of the intermediate hosts. However, most other acanthocephalans have infective larvae that more closely resemble underdeveloped adult worms. The definitive hosts consume the cystacanths upon feeding on infected intermediate hosts. These cystacanths mature and mate in the small intestine in 8–12 weeks. After this time, the eggs are excreted with the feces, to be ingested yet again by another intermediate host and renew this cycle.
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Wikipedia