Nematoda

Ascaris lumbricoides The longest intestinal nematoda of human, (Look like lumbricus) Male:15-30 cm Female: 25-35 cm

Adult worm of A. lumbricoides

Morphology Covered with cuticle Digestive system (3 lips in mouth) Reproductive system

Ascaris lips

Ascaris - female cross section diagram

Life cycle 200,000 egg/day Liver, heart, lung 2-3 weeks 4 molting 2-2.5 months to have oviposition worm

Ascaris Fully embryonated eggs are swallowed and L2 hatches in the stomach and penetrate stomach or duodenal mucosa Larvae enter blood stream and leave through alveoli into lung Larvae molt several times in the lungs L3/L4 move up and get swallowed 2-3 months after infection the adult worms start laying eggs (200,000 daily) Eggs are shed with the feces and embryonate within 2-3 weeks

Ascaris egg Fertile egg unfertile egg Can survive for 7-8 months in an ambient condition (21-30 oC) unfertile egg 1- albuminoidal layer 2- Thick hyaline layer, 3-thin lipoidal membrane

Unfertile egg Longer and narrower Thin shell Irregular coating of albumin Filled with an amorphous mass of protoplasm with refractile granules

Ascaris Infection depends on fecal contamination of food, water or soil Eggs are sensitive to sun light but otherwise extraordinarily resistant. (50 C kills egg in 1 hour, but eggs can survive at -8 to -12 C)

Sign and symptoms Ascariasis During the lung phase of larval migration: (4- 14 days after infection) Cough (Asthma attacks) dyspnea hemoptysis eosinophilic pneumonitis, edema of lips (Loeffler’s syndrome) last for 10-14 days.

Signs and symptoms Adult worm in intestine: adult worms usually cause no acute symptoms Vague abdominal pain Rebound tenderness Gnashing, Vomiting Obstruction of intestine (in children) Migrating adult worms may cause symptomatic occlusion of the biliary tract or oral expulsion (Biliary ascariasis, cholangitis, Appendicitis, Peritonitis). Maltose misdigestion and intolerance

Ascariasis Fever, anesthetic drugs, other drugs

Ascariasis

Epidemiology Highest prevalence in tropical and subtropical regions, and areas with inadequate sanitation 1.3 billion people infected worldwide, 500 million in China (18000 tons of Ascaris egg!!) One of the most prevalent helminthes in Iran In Iran 5-6%, in some area up to 49% of people (children, 5-9 ys) are infected Contaminated vegetables, but not water, and soils are the main source of infection. Ascaris suum can infect human

Ascariasis in Iran Ascaris محل سال محقق 0.7 مهد كودكهاي تهران 1371 بهمن رخ 17.8 لاهيجان-روستاها رضائيان 23.68 كنگاور 1373 اشرفي 3.4 كرمانشاه-كلينيك 1369-74 نظري 16.3 تنكابن- شهر و روستا 1375 0.9 كاشان-كاركنان مواد غذايي 1376 والي 2.7 زنجان-مراكز درماني عطائيان 49 همدان-مدارس 1378 طاهرخاني

Ascariasis in Iran 1.5 اراك 1378 اسلامي 2.5 شهريار 1379 شهابي 0.4 ساري-روستاها 1380 روحاني 39.6 همدان-روستايي سعيدي جم 0.18 اراك-مادران مراكز بهداشتي دوامي 0.7 اصفهان-كاركنان اشپزخانه كتابي 0.6 شهرري نائيني 0.3 اسلامشهر 1381 عسگري 39.2 همدان-كودكان عقب مانده طاهرخاني 1 ورامين-كاركنان مواد غذايي 1382 امين زاده 53995 نمونه از كل ايران سياري 3 دامغان-مهد كودكها حيدري

Treatment Albendazole (adult: 400 mg/kg, children 200 mg/kg; single dose) In all nematodes exp strongyloides (Bind irreversibly to tubulin, blocking microtubule assembly and inhibiting glucose uptake) Mebendazole: 100 mg/day, 2 times; 3 days) Pyrantel pamoate 11mg/kg (single dose) (no effect on strongyloides and Trichocephalus) (Depolarizesthe myoneural junction in worm, paralyzing them in a spastic condition)

Prevention and control

Entrobius vermicularis Pin worm, Oxyurus Worldwide distribution Humans are considered to be the only hosts of E. vermicularis

Morphology Thread like and white Male: 2-5 mm Female: 8-15 mm Cephalic ale Bulb of esophagus

Entrobius vermicularis Female

Enterobius vermicularis

Life cycle of E. vermicularis The time interval from ingestion of infective eggs to oviposition by the adult females is about one month. Adult worm in caecum, colon or rectum 4- 6 hours The life span of the adults is about two months.

Transmission Autoinfection/ Retroinfection Person-to-person transmission can occur through handling of contaminated clothes or bed linens.  Through surfaces in the environment that are contaminated with pinworm eggs (e.g., curtains, carpeting).  Some small number of eggs may become airborne and inhaled. 

Transmission Autoinfection Retroinfection Cross infection Inhalation

Clinical Features (Entrobiasis, oxyuriasis) Enterobiasis is frequently asymptomatic. The most typical symptom is perianal pruritis, especially at night. Occasionally, invasion of the female genital tract with vulvovaginitis and pelvic or peritoneal granulomas can occur. Other symptoms include anorexia, irritability, and abdominal pain (migration to appendice). Ectopic infection (liver, csf, eye)

Entrobious vermicularis فريدون كنارمازندران- شهر و روستا Epidemiology infections more frequent in school- or preschool- children and in crowded conditions. Entrobious vermicularis محل سال محقق 54.9 رامسر 1378 راستي 4.71 فريدون كنارمازندران- شهر و روستا رضويون 52 ايرانشهر داوودي 8.15 گناباد مهد كودك 1380 فاني

Laboratory Diagnosis Microscopic identification of eggs collected in the perianal area.  This must be done in the morning, by pressing transparent adhesive tape ("Scotch tape test", cellulose-tape slide test) on the perianal skin and then examining the tape placed on a slide (Graham Method). Anal swab Nail finger (in 1/3 of infected children)

Eggs Uterus of each female worm contain about 15000 eggs

Eggs

Treatment Albendazole (adult: 400 mg/kg, children 200 mg/kg; single dose) Pyrantel pamoate: 11mg/kg (single dose)

Trichuris trichiura (Trichocephalus, Whipworm) live in the cecum and ascending colon 3-4 cm Tail Head

Trichuris trichiura

Trichuris trichiura Stichocytes

Trichuris trichiura

Trichuris trichiura The adult worms are fixed in cecum and colon, with the anterior portions threaded into the mucosa.

Trichuris trichiura Female Male

Trichuris trichiura On of the most common round worm of humans. Human is the main host (Infection reported from monkey and pigs as well) It is estimated that 800 million people are infected worldwide.  Distribution is similar to Ascaris. Infections more frequent in areas with tropical weather and poor sanitation practices, and among children. 

Trichuriasis in Iran Trichuris trichiura محل سال محقق 0.1 مهد كودكهاي تهران 1371 بهمن رخ 26.8 لاهيجان-روستاها رضائيان 11.26 كنگاور 1373 اشرفي 0.9 كرمانشاه-كلينيك 1369-74 نظري 22.5 تنكابن- شهر و روستا 1375 0.4 زنجان-مراكز درماني 1376 عطائيان 1 همدان-مدارس 1378 طاهرخاني 5.6 رامسر راستي 1.1 ايرانشهر داوودي شهريار 1379 شهابي 0.5 بندپي بابل-ابتدائي 1380 قهرمانلو 0.7 اصفهان-كاركنان اشپزخانه كتابي شهرري نائيني اسلامشهر 1381 عسگري همدان-عقب مانده 4.8 دامغان-مهد كودكها 1382 حيدري

Life cycle Larva stay for 3-10 days in intestine and then migrate to cecum eggs become infective in 15 to 30 days The females begin to oviposit 60 to 90 days after infection. 3,000 to 20,000 eggs per day

Clinical Features of trichuriasis Most frequently asymptomatic.   Heavy infections, especially in small children, can cause: abdominal pain, (migration to appendice which induce bacterial infection) diarrhea, sometimes bloody or mucoid) Tenesmus rectal prolapse Weight loss, weakness, anemia growth retardation. Each worm waste 5 µl of blood each day, lifespan 4-6 ys Disease is similar to IBS

Trichuris trichiura

Diagnosis Concentration (flotation with zinc sulphate) is a useful method for diagnosis)

Treatment Albendazole (drug of choice; adult: 400 mg/kg, children 200 mg/kg; single dose) Mebendazole: 100 mg/day, 2 times; 3 days) or 500 mg single dose