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Ascaris lumbricoides is a large parasitic roundworm of the genus Ascaris. It is the most common parasitic worm in humans. [1] An estimated 807 million–1.2 billion people are infected with A. lumbricoides worldwide. [2] People living in tropical and subtropical countries are at greater risk of infection.
There is a large variation in the number of eggs produced by different species of worm at one time; it varies in the range of 3,000 to 700,000. The frequency of egg deposition from an adult helminth is generally daily, and can occur up to six times per day for some Taenia species. Adult trematodes lay smaller numbers of eggs compared to ...
About 130 species of pentastomids are known; all are obligate parasites with correspondingly degenerate anatomy. Adult tongue worms vary from about 1 to 14 cm (0.4 to 5.5 in) in length, and parasitise the respiratory tracts of vertebrates. They have five anterior appendages. One is the mouth; the others are two pairs of hooks, which they use to ...
As part of the parasite defense strategy, Ascaris roundworms secrete a series of inhibitors to target digestive and immune-related host proteases, which include pepsin, trypsin, chymotrypsin/elastase, cathepsins, and metallocarboxypeptidases (MCPs). Ascaris species inhibit MCPs by releasing an enzyme known as Ascaris carboxypeptidase inhibitor ...
Dioctophyme renale, commonly referred to as the giant kidney worm, [1] [2] [3] is a parasitic nematode (roundworm) whose mature form is found in the kidneys of mammals. D. renale is distributed worldwide, but is less common in Africa and Oceania. [4] It affects fish-eating mammals, particularly mink [1] and dogs. [4]
A plate from Francesco Redi's Osservazioni intorno agli animali viventi che si trovano negli animali viventi (Observations on living animals found inside living animals), 1684. In his Canon of Medicine, completed in 1025, the Persian physician Avicenna recorded human and animal parasites including roundworms, threadworms, the Guinea worm and ...
A couple of weeks later, S. erinaceieuropaei mature into adult tapeworms and the life cycle continues. Adult tapeworms can survive up to 30 years in their definitive host (typically dogs and cats). [1] The secondary intermediate host can also be eaten by other animals such as primates, pigs, mice, birds, and even humans.
Trematoda is a class of flatworms known as flukes or trematodes.They are obligate internal parasites with a complex life cycle requiring at least two hosts.The intermediate host, in which asexual reproduction occurs, is usually a snail.