Causal Agents:
The principle agents of acanthocephaliasis in humans are the thorny-headed worms, Macracanthorhynchus hirudinaceous and Moniliformis moniliformis.  Bolbosoma species have also been known to infect humans.

Life Cycle:

Eggs are shed in the feces of the definitive hosts , which are usually rats for M. moniliformis and swine for M. hirudinaceous, although carnivores and primates, including humans, may serve as accidental hosts. The eggs contain a fully-developed acanthor when shed in feces. The eggs are ingested by an intermediate host , which is an insect (usually scarabaeoid or hydrophilid beetles for M. hirudinaceous and beetles or cockroaches for M. moniliformis). Within the hemocoelom of the insect, the acanthor molts into a second larval stage, called an acanthella . After 6-12 weeks, the worm reaches the infective stage called a cystacanth . The definitive host becomes infected upon ingestion of intermediate hosts containing infective cystacanths . In the definitive host, liberated juveniles attach to the wall of the small intestine, where they mature and mate in about 8-12 weeks. In humans the worms seldom mature, or mature but will rarely produce eggs.

Geographic Distribution:
Acanthocephalans are widely distributed and cases of acanthocephaliasis generally occur in areas where insects are eaten for dietary or medicinal purposes.