All helminths are multicellular eukaryotic invertebrates with tube-like or flatt

Question

All helminths are multicellular eukaryotic invertebrates with tube-like or flattened bodies exhibiting bilateral symmetry. Helminths have three main life cycle stages: eggs, larvae, and adults. Adult worms infect hosts where sexual development occurs. Larval stages may be free living or parasitize hosts. Helminth eggs have tough resistant walls to protect the embryo while it develops. Mature eggs hatch to release larvae either within a host or into the external environment. Many helminths are free living organisms in aquatic and terrestrial environments whereas others occur as parasites in animals and some plants. Parasitic helminths are an almost universal feature of vertebrate animals; most species are host to worms. Unlike other pathogens such as viruses, bacteria, protozoa and fungi, helminths do not proliferate within their hosts. Worms grow, molt, mature and then produce offspring which are passed from the host to infect new hosts. The severity of worm infections are therefore dependent upon intake. Worms develop slowly compared to other infectious pathogens so diseases caused by the infestation are slow to develop and chronic in nature. Most helminth infections have little if any noticeable effect on their hosts and are often asymptomatic. Clinical signs of infection may vary considerably depending on the site and duration of infection. Larval and adult nematodes can lodge, migrate or encyst within tissues resulting in obstruction, inflammation, edema, anemia, lesions and granuloma formation.

Are there any helminths that are known to infect humans? How many different kinds can we find?

Tell us a bit about one of your choosing.

Explanation / Answer

Answer:

The following helminths are known to infect humans:

1. Roundworms: Can live and feed in the human intestine

2. Giant worms: such as Ascaris lumbricoides can be upto 35 cm in length and inhabits in the intestine

3. Whip worms: such as Trichuris trichiura (can extend upto 8cm in length)

4. Hook worms: such as Ancyclostoma duodenale and Necator americanus. Infection by hook worms may lead to nutritional deficiencies

5. Filarial worm: such as Wuchereria bancrofti inhabits the lymph nodes

6. Tapeworms: Flat worms that makes entry into the body through consumption of contaminates meat and fish

7. Flukes: can be Blood flukes (inhabits the blood) or tissue flukes (infect the bile ducts, liver and other tissues)

Wuchereria bancrofti: (Filarial worm)

Infection is caused by mosquito vectors and are most common in Asia, Africa and South America. It infects the lymph nodes in the host and causes painful swelling of the lymph nodes. It is characterized by fluid retention in the genitals and the lower limbs.

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