Phylum Nematodes (roundworms), phyla of Pseudocoelomates

Well known parasitic Nematodes are: Hookworms, Pinworms, Guinea Worms, and Intestinal Roundworms. Practicing good hygiene is the best way to prevent an infestation of Nematodes. Children are very susceptible to Nematodes since they like to handle pets and play in the dirt. "Dogs and cats infected with these worms contaminate their surroundings by passing eggs or larvae in their feces (waste). Because pets will pass feces anywhere, they may contaminate a large area quickly. These eggs and larvae are resilient and can survive in areas such as parks, playgrounds, and yards. Even inside homes." Center for Disease Control, A human can ingest the parasitic Nematode eggs by contaminated soil.

Phylum Nematodes (roundworms), phyla of Pseudocoelomates, have been characterized as a "tube within a tube," describing the fluid-filled cavity between the outer body wall and the digestive tube. Nematodes are very small, their size ranges from 400 micrometers to 5 mm. The majority of Nematodes feed on bacteria, fungi, and other soil organisms; the Nematodes that cause harm to humans, animals, and crops are parasitic in nature living off of its host.

Nematodes are free-living, colorless, unsegmented, lack appendages, and live almost everywhere on the face of the Earth. They have the ability to cryptobiosis, or suspend their life processes completely when conditions become bleak. It is no wonder that they have been around since before mankind.

Hymenolepis nana, The Dwarf Tapeworm

The Hymenolepis nana is also known as the Dwarf Tapeworm. There are 400 species of Hymenolepis. It is the Hymenolepis nana that is known as the Human Tapeworm. Beetles and fleas are the intermediate hosts (the tapeworm does not always need this host), and humans are both the primary and definitive hosts and can reinfect themselves. Once the eggs are ingested they hatch, go through their larval stage in the small intestine, and then move into the tissue in the gut and grow to adulthood. Hymenolepis nana infestations are prevalent in highly populated areas where hygiene and sanitary conditions are poor.

Symptoms of the Hymenolepis nana are:

• anorexia,
• abdominal pain, and
• diarrhea

However, symptoms often go unnoticed.

Diphyllobothrium Latum, The Fish Tapeworm.

Diphyllobothrium latum is the Human tapeworm that comes from fish. Fish and copepod's are the intermediate hosts, while humans and bears are the definitive hosts. The fish, often pike or salmon, (second host) usually come from arctic and sub-arctic waters. Many encounters occur when the fish migrate from salt water to fresh water for breeding. Humans become infested with the Diphyllobothrium latum tapeworm by ingesting raw or undercooked fish.

An infestation of Diphyllobothrium latum symptoms:

• abdominal distention,
• flatulence,
• intermittent abdominal cramping, and
• diarrhea

The disease resulting from the infestation is called, Diphyllobothriasis. An infestation of Diphyllobothrium latum may also cause an onset of anemia. The tapeworm competes for vitamin B12 and it is also thought to interfere with the absorption of the vitamin, leaving the host susceptible to both Pernicious anaemia and Megablastic anaemia.

The increased popularity of sushi increases the incidence of Diphyllobothrium latum infestations in the United States.