Roundworms and Human Health

by

Marisa Nicol, Cierra Patrick, Jada Clawson, Anna Gruska, and Taja Wright

General Phylogenetic and Lineage Information

Roundworms belong to the very general Superphylum Ecdysozoa, which is made up from the Ancient Greek words ‘ekdusis’- meaning ‘shedding’  and ‘zoion’-meaning animal! This is a large group of organisms that share the common characteristic of shedding their skins, with other members of this group being insects and crustaceans! Their more specific group, their phyla, is Nematoda! This stems from the latin roots ‘nemat’-meaning ‘thread’ and ‘odes’-meaning ‘of the nature of’! This name is very descriptive of the shape of these creatures, they look like living moving threads in some cases! Nematoda however is still a very broad term! Scientists have broken this group down into 5 more specific groups called clades:

  • Dorylaimida: This group includes a lot of soil and freshwater species
  • Enoplia: This group has oval shaped amphids, sensory structures near the front of the organism, and they generally have smooth bodies
  • Spirurina: This group holds a lot of the parasitic nematodes that we’ll be speaking about!
  • Tylenchina: Pin worms make up most of this group and they typically parasitize plants
  • Rhabditina: These roundworms are typically free-living, meaning they don’t have to be a parasite in order to survive!

Species & Anatomy

Nematoda is one of the most abundant animal phyla, with greater than 80,000 known species, Although, not all of them have been classified. They are found in aquatic and terrestrial environments as well as parasitically on or within a variety of plants and animals. They are known as parasites – organisms that need to live on or in another creature to survive. Often, the parasite causes problems for its host. For roundworms, they need the body of humans or other animals to mature into egg-laying adults. Roundworms have long, round bodies and can be of different sizes, depending on the type. Roundworms have excretory, nervous, and reproductive systems. They lack an enclosed circulatory and respiratory system. Roundworms possess a pseudocoelom, or partially developed body cavity, and a complete digestive tract with two openings, a mouth and an anus. The presence of a body cavity allows circulatory fluid to flow freely throughout the body of the organism. A complete digestive tract with separate openings for the mouth and anus allows the animals to simultaneously feed, digest, and eliminate waste.

Adaptations

Roundworms have physiological, anatomical, and morphological adaptations.

  • Physiological: The respiration is almost entirely anaerobic. Extremely low metabolic rate and anaerobic respiration enable the worm to live inside the host’s intestine, where the free oxygen is negligible.
  • Anatomical: The pharynx (throat) is muscular and facilitates ingestion of food by sucking action. There are no digestive glands.The digestive tract is simple without pro­vision for storage, as there is constant sup­ply of food.
  • Morphological: The mouth is bounded by three lips which help the parasite to attach with the mucous membrane of the host’s intestine.The parasite lacks locomotory organs as the parasite lives in the intestine where protection from enemies and food supply are ensured.

 Common Illnesses and Symptoms

While there are various different types of roundworms, most infections result in the same general symptoms: diarrhea, fever and abdominal pain. Normally, infection happens when people come into contact with infected feces (poop), contaminated soil, food or even from pets!  In order to be diagnosed with a roundworm infection, a blood test and stool sample are needed. If roundworms are found, you will be prescribed a medicine called Albendazole, which keeps larvae from multiplying, and the worms pass through the feces. This takes about 3 days to happen and there may be multiple treatments needed in coming weeks. To prevent a roundworm infection, you must practice good hygiene, wash and cook food thoroughly, clean up after pets and make sure that they are dewormed, and ensure that children are not playing in infected areas.

Specific Diseases

Trichinosis

Trichinosis is a roundworm disease caused by worms within the genus Trichinella. The most common species that infects humans is T. spiralis which is commonly found in pigs. This worm is commonly transmitted by eating infected pig meat. The worm causes typical gastrointestinal symptoms such as nausea within a few days of infection as well as swelling of the face, weakness, muscle pain, or rashes after a few weeks. Diagnosis is achieved through antibody testing and can be treated with Albendazole. Prevention can be achieved by washing your hands and thoroughly cooking your meat.

Life Cycle of Trichinella

Baylisascaris

Baylisascaris is caused by the raccoon roundworm, Baylisascaris procyonis. It is extremely rare with less than 25 confirmed cases. This disease is spread through a fecal-oral route. It causes symptoms such as nausea, blindness, loss of attention or muscle control and may result in a coma. It is typically diagnosed only after ruling out other potential causes or using spinal fluid. There are no known drugs to cure Balisascaris, but in some cases Albendazole may help. In order to prevent this disease, it’s important to avoid potentially contaminated soil and take proper steps to reduce raccoon activity such as keeping lids on trash cans.

Life Cycle of Baylisascaris

Control and prevention of roundworms:

  • Use good hygiene
  • Wash plant produce well and cook meat to the standard safe temperature
  • Know risks when traveling
  • Deworm pets on a regular basis (4 times a year for adults with additional treatment if infected)
  • Clean after you pet to prevent the spread to other pets
  • Get your pets fecal matter tested at the vet regularly

Medical Applications:

  • A protein was found in a common digestive tract inhabiting roundworm that has the ability to make the body aware of the amount of food consumed and to suppress unnecessary hunger.
  • This protein could be used by humans in the future to help treat eating disorders, obesity, and other food-related diseases.

Citations 

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