Trichuriasis PDF - Gastrointestinal Infections

458 Section 5  Gastrointestinal (GI) Infections Trichuriasis Trichuriasis is also known as whipworm infection;...

458 Section 5  Gastrointestinal (GI) Infections Trichuriasis Trichuriasis is also known as whipworm infection; caused by the intestinal nematode Trichuris trichiura. It is a soil- transmitted helminth (see the highlight box, subsequently in this chapter). Trichuris has several other species, which rarely infect animals. Epidemiology Trichuriasis is worldwide in distribution, mainly in warm and moist climate similar to ascariasis. Fig. 46.16: Developmental stages of nematodes. ™™ Children are commonly affected ™™ Global prevalence in humans is about 604 million. Morphology Similar to other nematodes, T. trichiura exists in three forms: adult, larvae (four stages) and egg. The adult worm resembles to a handle of a whip, (therefore called as whipworm). Life Cycle (Fig. 46.18) https://t.me/docinmayking Humans are the only host. ™™ Mode of transmission: Men (usually children) acquire infection by ingestion of contaminated food and water containing embryonated egg (infective form) ™™ Human GIT: Eggs hatch out in the small intestine releasing the L2 larva, which migrate to large intestine and molt twice to transform into adult worms „„ The female worms following fertilization start laying unembryonated eggs, that are released in feces (diagnostic form) „„ Each female worm can lay 14,000–20,000 eggs per day for 1–3 years. ™™ Embryonation: The eggs passed in the feces become Fig. 46.17: Adult male and female nematode embryonated (i.e. molt twice to produce L2 larvae within (schematic diagram). ™™ Organs: Body is bilaterally symmetrical, surrounded by a body wall containing various organs such as alimentary canal, body cavity, nervous system, excretory system and reproductive organs ™™ They are diecious (bisexual), i.e. male and female worms are different (Fig. 46.17). Life Cycle Intestinal nematodes complete their life cycle in one host (man); discussed under the respective parasite subsequently in this chapter. ™™ Trichuris, Enterobius and Ascaris have considerable similarities in their life cycle such as mode of transmission (ingestion), infective form (embryonated eggs) and diagnostic form (eggs). In addition, Ascaris larvae have a migratory phase in the lungs ™™ The life cycles of Strongyloides and hookworm also have similarities such as mode of transmission (skin penetration) and infective form (L3 larva). Fig. 46.18: Life cycles of Trichuris and Enterobius.  Chapter 46  Intestinal Helminthic Infections 459 the eggshell) in warm (25°C) and moist environment. Embryonated eggs are infective to man and thus the Trichuris trichiura (eggs and adult worm) Eggs: Measure 50 × 22 µm, barrel-shaped, with mucus plugs life cycle continues. at the ends. Eggs are bile-stained and float in saturated salt Pathogenicity and Clinical Feature solution (Fig. 46.19A) Whip shaped adult worms of 3–5 cm long, are occasionally Incubation period varies from 70 to 90 days. Most infected seen on proctoscopy (Fig. 46.19B). Anterior three-fifth is thin, individuals are asymptomatic, with or without having hair like, coiled (like rope of a whip) and posterior two-fifth is eosinophilia. short and thick. In people with heavy infections: Adult female worms get buried in the large intestinal mucosa, that leads to: Other Findings ™™ Mechanical distortion: Leading to inflamed, edematous, ™™ Peripheral blood eosinophilia (