Mammomonogamus - Life Cycle

Life Cycle

Although the complete life cycle of M. laryngeus is not fully known due to the rareness of the parasite in humans, some have postulated that the parasite adopts a life cycle similar to Syngamus trachea, the common gapeworm infection in birds that was initially thought to be Mammomonogamiasis. Currently, there are two existing hypotheses that will help aid medical diagnostics, especially in endemic areas such as the tropics, Caribbean, and Brazil.

Hypothesis #1: Infection initially begins by the ingestion of foods, water, or intermediate hosts contaminated by adult worms. The infective adults migrate to the larynx or trachea and attach to the mucosal walls. Sexual reproduction occurs here, and the females begin to lay eggs in the upper respiratory region. Eggs do not develop at body temperature and are expelled in sputum or re-swallowed and excreted in feces.

Hypothesis #2: The infective agent may be embryonated eggs or infective larvae, and infection is due to ingestion of contaminated food, water, or intermediate hosts. As larvae are released into the intestinal area, they can burrow through intestinal walls, travel into the mesenteric veins, and migrate to the alveoli. Here, they undergo a pulmonary cycle, where the larvae develop into adult worms in a process that may take 7 days. After reaching adulthood, M. laryngeus migrates upwards to the trachea, larynx, or bronchi, where sexual reproduction occurs. Egg production begins approximately 3 weeks later, and eggs are coughed up and expelled in sputum or feces. Larvae may hatch from embryonated eggs outside of the mammalian host.

More research is needed to fully elucidate the life cycle, but it may appear that both larvae and adults can be infective. One recent case reported finding adult worms in the duodenum, which is the first presentation of adult worms not in the upper respiratory region. It is possible that the adult worms might have been coughed up and re-swallowed before settling in the duodenum. The development from larvae to adult is about 3 weeks, but there is uncertainty regarding the existence of a larval pulmonary cycle. Intermediate hosts, although not fully known, may be earthworms (an intermediate host for the genus Syngamus, the parasite causing avian gapeworm), snails, or arthropods. Other than intermediate hosts, there has been no mention of other biological or mechanical vectors.