Ascaris lumbricoides Infections PDF

‫ﺟﺎﻣﻌﺔ ﻣﺻر ﻟﻠﻌﻠوم و اﻟﺗﻛﻧوﻟوﺟﯾﺎ‬ ‫ﻛﻠﯾﺔ اﻟطب اﻟﺑﺷري‬ ‫ﻗﺳم ﻋﻠم اﻟطﻔﯾﻠﯾﺎت‬ ‫‪DHB202‬‬ ‫‪PARASITIC INFECTIONS OF THE‬‬ ‫‪SMALL INTESTINE‬‬  NEMATODES OF SMALL INTESTINE Ascaris lumbricoides/Ascarias...

‫ﺟﺎﻣﻌﺔ ﻣﺻر ﻟﻠﻌﻠوم و اﻟﺗﻛﻧوﻟوﺟﯾﺎ‬ ‫ﻛﻠﯾﺔ اﻟطب اﻟﺑﺷري‬ ‫ﻗﺳم ﻋﻠم اﻟطﻔﯾﻠﯾﺎت‬ ‫‪DHB202‬‬ ‫‪PARASITIC INFECTIONS OF THE‬‬ ‫‪SMALL INTESTINE‬‬  NEMATODES OF SMALL INTESTINE Ascaris lumbricoides/Ascariasis (Giant intestinal roundworm) X 0.5 mm 1.5 Tuesday, February 11, 2025 2  LEARNING NEEDS ⚫ Classification of the parasite according to taxonomy and habitat ⚫ Geographical distribution and epidemiological data ⚫ Identification criteria of different stages of the parasite (Lab identification) ⚫ Life cycle of the parasite (Parasite host relationship): ◦ Habitat ◦ Hosts ◦ Modes of infection and infective stage (Description) ◦ and diagnostic stage (Description) ⚫ Pathogenicity and clinical picture of the disease ⚫ Diagnosis of infection (Clinical/ Laboratory/Imaging) ⚫ Treatment Management ⚫ Integrated prevention and control Intended learning outcomes By the end of this lesson the student should be able to: 1- Classify Ascaris lumbricoides taxonomically as “a nematode” 2- Recognize the geographical distribution of Ascaris lumbricoides with special emphasis on the situation in Egypt and WHO campaigns. 3- Determine its habitat as a small intestine parasite 4- Discuss the role of human hosts for completion of the life cycle 5- Recognize mode of infection as a soil transmitted nematode and describe the infective stage Intended learning outcomes By the end of this lesson the student should be able to: 6- Interpret the life cycle inside the human host into pathogenesis and clinical picture of different stages of ascariasis. 7- Discuss possible complications in relation to the parasite behavior. 8- Select proper laboratory sample and techniquesand describe the diagnostic stage. 9- Recommend other important investigations 10- Recognize the drug of choice and that of MDA 11- Outline main measures for integrated prevention and control based on WHO guidelines and target population  Ascaris lumbricoides/Ascariasis (Giant intestinal roundworm) Classification Ascaris lumbricoides is the largest and commonest intestinal (habitat) nematode (Taxonomy) infecting human. T.S. shows body cavity That is why a nematode  Ascaris lumbricoides Geographical distribution: It is cosmopolitan in areas where there is inadequate sanitation and where untreated human faeces are used as an organic fertilizer. Definitive host: human. Habitat: The adult worms live in the small intestine of man in-between the folds of mucosa. Soil-transmitted helminth (STH) infections are widely distributed in tropical and subtropical areas (WHO) Morphology of the adult worms (diagnostic stage): - It is the largest intestinal nematode affecting man. - They have a club shaped oesophagus. Male: is about 15-30 cm in length with its posterior end coiled ventrally and has two copulatory spicules. Female: is about 20-40 cm in length with a straight posterior end and has 2 sets of genital organs (parallel in position). Female Male  Life cycle/ Parasite host relationship Modes of infection Diagnostic stage Infective stage 2 w to be infective Eggs are laid immature and not infective  Modes of infection Human gets infected by swallowing the mature embryonated egg containing rhabditiform larva (infective stage) through: - Soil contaminated foods or drinks. - Soil contaminated hands -The contamination may be via the house fly carrying infective eggs to the food (mechanical transmission).  -No autoinfection in ascariasis as the egg needs a period of embryonation in the soil (2 weeks). -Eggs remain viable in soil for years resisting desiccation, low temperature and strong chemicals. Only sun rays are lethal to them. - Children are more commonly and more heavily infected than adults because of their habits (e.g. directly or indirectly consuming soil). Interpret Why there is no auto infection in ascariasis? ✔ MCQ: 1) Ascaris lumbricoides is a: a) Cestode b) Nematode c) Trematode 2)The normal habitat of Ascaris lumbricoides is: a) The bronchi b) The small intestine c) The large intestine ✔ Right (√ )Or Wrong (X) a) The embryonated egg is the diagnostic stage of ascariasis X infective b) Ascariasis can be mechanically transmitted by housefly √ ✔ Interpret: No autoinfection in ascariasis 14  Pathogenesis of different stages of ascariasis I- Prepatent period: Larval migration Loffler’s syndrome or eosinophilic pneumonitis II- Patent infection: (4-16 days after egg Adult worms/ III- Complications: ingestion) intestinal phase Aberrant adult worms 6-8 weeks after egg migration ingestion) stimulated by fever, some anaesthetics and/or improper dosages of antihelminthics  Pathogenesis I- Prepatent Period: Loffler’s Syndrome Loffler’s Syndrome (eosinophilic pneumonitis): In the lung, migrating larvae produce transient local inflammatory and hypersensitivity reactions due to: their presence as well as the release of allergic mediators. This results in: Local eosinophilic infiltration around larvae. Systemic hypereosinophilia Peticheal haemorrhages at the site of the larval track that may be superadded by bacterial infection.  Clinical picture I- Prepatent Period: Loffler’s Syndrome Clinically, this is presented as 1. Sudden rise of the body temperaturehttp://cid.oxfordjournals.org/content up to 39oC. /53/2/205/F3.large.jpg 2. Dyspnea of asthmatic type, sometimes with cough and expectoration of blood tinged sputum (haemoptysis). 3. Eosinophilia. 4. The pulmonary symptoms may be accompanied by urticaria. 5. It is transient and N.B. Asthmatic children who spontaneous recovery usually have a history of playing in occurs after two weeks soil should be investigated for ascariasis  Pathogenesis and clinical picture II- Adult Intestinal Phase: According to the worm burden, the intestinal phase may be asymptomatic or presented by: 1. Diffuse or epigastric abdominal pain. 2. Weight loss or retarded growth (the worm feeds on semidigested food in the host’s intestine). 3. Nausea and vomiting. Sometimes adult worms are seen in the vomitus. 4. Adult worms may be expelled from the nares or the anus (expulsion phenomenon).  Ascaris Expulsion Through the anus Through the nose or mouth  Pathogenesis and clinical picture II- Aberrant adult worms migration: Causes acute abdomen and complications A single migrating adult worm can cause a serious trouble. This is usually stimulated by fever, some anaesthetics and/or antihelminthic drugs like pyrental pamoate. Improper dosages of antihelminthic drugs may also lead to worm migration. Intestinal obstruction. Intestinal perforation and peritonitis Severe cholangitis obstructive jaundice. Severe pancreatitis Blockage of the appendix causing appendicitis is also possible.  Complications of ascariasis OBSTRUCTION OF THE INTESTINAL OBSTRUCTION APPENDIX APPENDICITIS ASCARIS IN THE BILE DUCT ASCARIS CHOLECYSTITIS  Quiz Complete: In ascariasis, - Larval migration in the lung Loffler’s syndrome causes……………………………… Eosinophillic pneumonitis OR which is a form of verminous pneumonia :…………………………………………………….. Acute abdomen - Aberrant adult migration cholangitis appendicitis causes…………………………….. pancreatitis Tuesday, February 11, 2025 22  Diagnosis of ascariasis A) Clinical diagnosis: - It is difficult as ascariasis may share endemicity with other soil transmitted nematodes infections that have more or less similar clinical picture. - However, some patients complain of vomiting of adult worms or their passage from the anus or the anterior nares which is then pathognomonic. Through the anus Through the nose or mouth  Investigations of a case of Ascariasis A- Larval migration phase B- Adult phase Loffler’s syndrome Intestinal phase I) Laboratory diagnosis II) Chest x- ray I)Laboratory II)Imaging diagnosis techniques 1) Direct 2) Indirect 1) CBC diagnosis diagnosis 2) Examination of sputum :Serodiagnosis Stool and duodenal OF NO USE aspirate examination  Diagnosis of ascariasis B)Laboratory diagnosis: I- Prepatent period (larval migration/ Loffler’s syndrome): - Complete blood count (CBC): shows marked transient eosinophilia. - Sputum analysis: may reveal larvae (diagnostic stage) and/or Charcot-Leyden crystals. Stool examination: shows no Ascaris eggs.  Diagnosis of ascariasis II- Established infection (adult phase/ intestinal phase): 1- Direct diagnosis: Stool examination: shows Ascaris eggs and sometimes adults are expelled (diagnostic stages). -Eggs may be also recovered in duodenal aspirate during the intestinal phase. -A female Ascaris may produce approximately 200,000 eggs per day, so diagnosis by stool examination is very feasible even to the extent that worm burden can be easily calculated.  Diagnosis of ascariasis Stool examination: (GOLD STANDRD TEST) Ascaris egg; the diagnostic stage: Size: 60X 40 um. Shape: Oval Shell: thick with an outer coarse albuminoid mammillations. Colour: Yellowish brown Content: Large unsegmented embryo  Diagnosis of ascariasis 2- Indirect diagnosis (serological diagnosis): It is of little value because of sharing antigenic epitopes with other nematodes. 3- Complete blood count (CBC): shows low eosinophilia.  Diagnosis of ascariasis C- Imaging techniques: 1- Chest radiography: may reveal patchy infiltrates of eosinophilic pneumonia that disappear later on (during Loffler’s syndrome). 2- Abdominal radiography: may reveal adult worms (especially with contrast). 3-Ultrasonography: may detect worms in gallbladder. 4- Cholangiopancreatography by endoscopy (ERCP) or magnetic resonance imaging (MRI): may detect adult worms in bile or pancreatic ducts. http://cid.oxfordjournals.org/content /53/2/205/F3.large.jpg Loffler’s Syndrome ASCARIS CHOLECYSTITIS Imaging Techniques to diagnose ascariasis  Quiz Choose the right statements concerning Loffler’s Syndrome and correct the wrong ones: 1- It is due to permanent pulmonary lesion X transient 2- It represents 3rd stage filariform larva migration to liver X 3- It is diagnosed by stool examination for Ascaris eggs X sputum/ 4- Chest X- ray shows patchy infiltrations √ larva Right or Wrong: 1- Serodiagnosis is satisfactory to diagnose intestinal phase of ascariasis X stool examination 2- In intestinal phase of ascariasis embryonated eggs are the diagnostic stage X immature 3- Housefly is a mechanical vector of ascariasis √ Tuesday, February 11, 2025  Treatment of ascariasis The most commonly recommended agents are albendazole and mebendazole. 1- Albendazole (Vermizole): -It is the drug of choice. It is a systemic broad spectrum antihelminthic agent. It is used for MDA -Dose: 400 mg single oral dose to be repeated after 3 weeks if not cured. Children less than 4 years old administer half the adult dose.  Treatment of ascariasis 2- Mebendazole (Vermox): -It is contraindicated for children less than 2 years of age. -Dose: 100 mg orally twice a day for 3 consecutive days. A second course is administered if no cure within 3-4 weeks. 3- Levamisole (ketrax): - It is sometimes used for mass treatment in schools’ children. - Dose: 2.5 mg/kg (100- 150 mg) as a single oral dose. INTEGRATED PREVENTION AND CONTROL WHO strategy for soil transmitted helminthiases 1. Geotargeting and mass drug administration (MDA) for deworming based on surveys and WHO prevalence threshold (20% and above prevalence). 2. Diagnosis and treatment of patients especially school children if prevalence is less than 20%. INTEGRATED PREVENTION AND CONTROL 3. Prevention of faecal contamination of soil through: Good sanitation and safe water supply. Promiscuous defecation especially by children has to be prohibited. Stop using untreated human excreta (night soil) as fertilizer or it has to be at least exposed to direct sunlight (lethal to the eggs). 4. Health education: Proper washing of vegetables. Playing in soil has to be prohibited by children. Washing hands before meals and house-fly control.  Quiz Complete: - The vermicidal drug used for treatment and MDA of ascariasis Albendazole is…………………………………………………….. Geotargeting - WHO strategy for mass and % drug adminstration is prevelance depending upon…………………………………. Tuesday, February 11, 2025 PARASITOLOGY DEPARTMENT 36 Assignment Management of ascariasis ?