ASCARIASIS 蛔蟲症 About 1/4 of the world population is infected Ascaris lumbricoides 蛔蟲 Infection is world-wide distribution common in areas where human feaces are used as fertilizer Children are more often and mor heavily infected than adults

The largest Intestinal Nematode MaleFemale Male:15~31 cm x 2~4 mm Female: 22~35 cm x 3~6 mm Cylindrical and white to tan with tapered ends The mouth surrounded by 3 lips Cuticle has both annulations and striations

Females Didephic Ovaries, oviducts & uteri are in the posterior 2/3 Vulva is located 1/3 from the anterior ens Males Posterior end curved Reproductive tube in the posterior half of the body Has 2 copulatory spicule

Embryonated eggEggs in faeces Unfertilised Trachea Lungs (L3) Portal circulation Ingested Fertilised Larva hatches in intestine Swalowed Pharynx Adults in small intestine 2-cell stage Advanced cleavage Infective stage (L2) Diagnostic stages MAN EXTERNALENVIRNOMENT Life Cycle of Ascaris lumbricoides L4 200,000~250,000 eggs per day 3~4 wks

Pathogensis 致病機轉 Abdominal pain, nausea, diarrhoea and vomiting Impaired absorption ( 吸收不良 ) Malnutrition ( 營養不良 ) Amount of worms infected 感染蟲數 Effects of visceral larval migration (VLM) 內臟幼蟲移行 Mechanical effects due to adult worms 成蟲機械式傷害 Nutritional deficiencies

Larvae migration ( 幼蟲移行 ) Mechanical damage ( 機械式傷害 ) cause inflammatory ( 發炎 ), bacterial infection ( 細菌性感染 ) and hypersensitive reaction 過敏反應 In lung cause Loeffler's syndrome Coughing, bronchial asthma and pneumonia- like symptoms Infiltartion of eosinphils, macrophages, and epitheloid cells around the larvae Allergic reaction consisting of dyspena, a dry or productive cough, transient eosinophilia, wheezing ot coarse rales, fever, and a chest X-ray suggestive of viral pneumonia. Sputum contain eosinophils, Charcot-Leyden crystal and sometimes larvae

Heavy Infection 重度感染 Pass or vomit of worms 排出或吐出成蟲 Intestinal obstruction by worm bolus 腸阻塞 Intestinal perforation 腸穿孔 Bile duct and pancreatic duct obstruction 阻塞膽管及胰管 → cholangitis 化膿性膽道炎 multiple liver absceses 多發性肝膿腫 ascarid chronic pancreatitis 慢性胰臟炎 Can be fatal

Bile duct Pancreatic duct Liver Peritoneal cavity Kidney Appendix Pleural cavity Upper respiratory tract Atopic Ascariasis 蛔蟲異位感染 Adult in liver Adult in bile duct Liver egg granuloma

Fertilized egg 受精卵 Unfertilized egg 未受精卵 Decorticated egg 去蛋白膜卵 Finding A. lumbricoides eggs in faeces through the anus or mouth Identifying A. lumbricoides worms expelled Laboratory Diagnosis Fertilized females lay about 200,000 eggs per day

A. lumbricoides eggs Embryonated egg 胎蟲卵 (infective) pale yellow or colourless contains a larva (R-form, 1 st or 2 nd stage ) Fertilized egg 受精卵 oval or round, 60 x 40 mm, yellowish brown egg shell covered by an uneven albuminous coat contains a central grandular mass Unfertilized egg 未受精卵 elongated, 90 x 45 mm, darker and more albuminous contains a central mass of large refractile grandules Decorticated egg 去蛋白膜卵 pale yellow or colourless smooth egg shell no albuminous coat

Prevention and Control 預防及控制 Providing and using adequate latrines Avoding the use of human feaces as fertilizer Treating infected individuals as part of a control programme especially children Preventing soil becoming faecally polluted by Washing the hands before eating Avoid the eating of uncooked vegetables, green salads and fruits Preventing eggs being ingested by

Treatment Pyrantel pamoate single dose, 10 mg/kg, max. 750 mg/adult Levamisole single dose, children (5 mg/kg), adult (150 mg) Mebendazole single dose, twice a day, 100 mg/each Albendazole single dose, children from 2~12 yr. (200 mg), adult (400 mg)