Question

Which one of the following diseases is caused by a nematode?
A. Filariasis
B. Amoebiasis
C. Leprosy
D. Poliomyelitis

Answer 1

Nematodes are very small, slender worms. Commonly called roundworms. Kingdom they belong to is animalia. The smallest nematodes are microscopic, while free living species which live under soil are $5cm$ and parasitic species are somewhat larger comparatively.

Complete answer:
Nematodes are among the abundant animals on earth. As we know that they are parasitic in nature, also can be in free-living forms in soil. Also found inside of animals, plants. Some unusual places like- vinegar, beer malts, water-filled cracks.
Nematodes are bilaterally symmetrical, elongated and tapered at both ends. Some species have a fluid-filled body cavity with a pseudocoel. As we discussed earlier about the parasitic nature of nematodes. Is because it can live inside the host body and take nutrition from its host cells which causes many diseases as it sucks up the blood of host cells. It is present usually in the larger organs like stomach, intestine.
It also affects human beings by the disease called- skin penetration, it undergoes autoinfection of the human host, causing chronic infections lasting as long as $40$ years. Prolonged infection. Nematode infections in humans include- ascariasis, trichuriasis, hookworm, enterobiasis, strongyloidiasis, filariasis, rat lungworm disease.
Nematode disease in plants generally affects the plant parts. Usually, microscopic plants affect the plants, parasitic nematodes may attack the roots, stem, foliage and flowers of plants. Symptoms of attack by nematodes include gall or root knots, root injuries, excess branching of the root, injured tips of the root and stunted systems of the root.
Nematodes of the bulbs and stems generate stem floating and internodes shortened. Bud and leaf nematodes distort and kill the tissue of the bud and leaves. In some cases, like the SCN, there may be no visible symptoms of loss of yield.

Hence the correct answer is option A. Filariasis

Note:
As we discussed the diseases, like many parasitoid insects, insect-pathogenic nematodes also use insect larvae to multiply in. They are in numbers which reside in animal and human parasites. They can be spread through water, soil. Waste, blood. They are highly contaminated in nature. The black specks in your stool can be caused by eggs of parasites. The two nematode classes are- chromadorea and enoplea. They are slender and transparent and sometimes cannot be seen by naked eye. If you can see an organism, with naked eye it is not a plant parasitic nematode.