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به نام خدا دکتراقازاده General aspect: o Worldwide more than 2 billion people are infected with helminthes. o Classification helminthes of : 1. Nematodes (roundworm) 2. Platy helminthes: • Tissue nematodes • Intestinal nematodes • Trematodes • Cstodes Intestinal Nematodes o Ascariasis (1) • Causal Agents: – Ascaris lumbricoides is the most common and the largest nematode ( giant roundworm ) parasitizing the human intestine. (Adult females: 20 to 35 cm; adult male: 15 to 30 cm.) Ascaris lumbricoides Life Cycle: Geographic Distribution: Worldwide distribution. Highest prevalence in tropical and subtropical regions, and areas with inadequate sanitation. Clinical Features: adult worms usually cause no acute symptoms. High worm burdens may cause abdominal pain and intestinal obstruction. Migrating adult worms may cause symptomatic occlusion of the biliary tract or oral expulsion. During the lung phase of larval migration, pulmonary symptoms can occur (cough, dyspnea, hemoptysis, eosinophilic pneumonitis Loeffler’s syndrome). Laboratory Diagnosis: – Microscopic identification of eggs in the stool is the most common method for diagnosing intestinal ascariasis. Where concentration procedures are not available, a direct wet mount examination of the specimen is adequate fore detecting moderate to heavy infections. – Larvae can be identified in sputum or gastric aspirate during the pulmonary migration phase. – Adult worms are occasionally passed in the stool or through the mouth or nose and are recognizable by their macroscopic characteristics. Below are several Ascaris eggs seen in wet mounts. Diagnostic characteristics: •Fertilized eggs are rounded, thick shell, external mammillated layer Size: 60 µm in diameter when spherical, and up to 75 µm when ovoid. •Unfertilized eggs are elongated and larger (up to 90 µm in length); their shell is thinner; and their mammillated layer is more variable Unfertilized and fertilized eggs (left and right, respectively). Fertilized Ascaris egg, still at the unicellular stage.Eggs are normally at this stage when passed in the stool.Complete Egg containing a development of larva, which will be the larva infective if requires 18 days ingested. under favorabl Larva hatching from an egg Diagnostic characteristics: tapered ends; length 15 to 35 cm. This worm is a female(size and genital girdle ) Treatment: • The drugs of choice for treatment of ascariasis are: • • • - Albendazole (400mg once), - Mebendazole (500 mg once or 100mg BID for 3 days), - pyrantel pamoate(11mg/kg once; maximum 1g – safe in pregnancy). Hookworms • Causal Agent: • - The human hookworms include two nematodes : • • Ancylostoma duodenale Necator americanus • - A smaller group of hookworms infecting animals can invade and parasitize humans (A. ceylanicum) or can penetrate the human skin (causing cutaneous larva migrans), but do not develop any further (A. braziliense, Uncinaria stenocephala). hookworms Life Cycle: Geographic Distribution: o o - The second most common human helminthic infection - Worldwide distribution, mostly in areas with moist, warm climate. Both N. americanus and A. duodenale are found in Africa, Asia and the Americas. Necator americanus predominates in the Americas and Australia, while only A. duodenale is found in the Middle East, North Africa and southern Europe. Clinical Features: o o o o - Iron deficiency anemia (caused by blood loss at the site of intestinal attachment of the adult worms) is the most common symptom of hookworm infection, and can be accompanied by cardiac complications. - Gastrointestinal and nutritional/metabolic symptoms can also occur. - In addition, local skin manifestations ("ground itch") can occur during penetration by the filariform (L3) larvae, - and respiratory symptoms can be observed during pulmonary migration of the larvae. Laboratory Diagnosis: - Microscopic identification of eggs in the stool is the most common method for diagnosing hookworm infection. Treatment: o - In countries where hookworm is common and reinfection is likely, light infections are often not treated. o Albendazole (400mg once). Mebendazole (500mg once). or pyrantel pamoate(11mg/kg for 3 days) Strongyloidiasis • Causal Agent: • • Strongyloid Stercolaris Other Strongyloides include S. fülleborni, which infects chimpanzees and baboons and may produce limited infections in humans. Strongyloidiasis Life Cycle: Geographic Distribution: o o Tropical and subtropical areas, but cases also occur in temperate areas More frequently found in rural areas, institutional settings, and lower socio-economic groups. Clinical Features: Frequently asymptomatic. Pulmonary symptoms (including Loeffler’s syndrome) can occur during pulmonary migration of the filariform larvae. • Dermatologic manifestations include urticarial rashes in the buttocks and wrist areas. o Disseminated strongyloidiasis occurs in immunosuppressed patients, can present with abdominal pain, distension, shock, pulmonary and neurologic complications and septicemia, and is potentially fatal. Blood eosinophilia is generally present during the acute and chronic stages, but may be absent with dissemination. Laboratory Diagnosis: Microscopic identification of larvae ( rhabditiform and occasionally filariform) in the stool or duodenal fluid. • Examination of serial samples may be necessary, and not always sufficient, because stool examination is relatively insensitive. The duodenal fluid can be examined using techniques such as the Enterotest string or duodenal aspiration. – Larvae may be detected in sputum from patients with disseminated strongyloidiasis. Treatment: The drug of choice for the treatment of uncomplicated strongyloidiasis is : Ivermectin(200μg/kg daily for 1 or 2 days), Thiabendazole (25 mg/Kg bid 2days) Albendazole (400mg daily for 3 days repeated at 2 weeks), All patients are at risk of disseminated strongyloidiasis and should be treated. Enterobiasis • Causal Agent: • • Enterobius vermicularis (previously Oxyuris vermicularis) also called human pinworm. (Adult females: 8 to 13 mm, adult male: 2 to 5 mm.) Humans are considered to be the only hosts of E. vermicularis. A second species , Enterobius gregorii, has been described and reported from Europe, Africa, and Asia. For all practical purposes, the morphology, life cycle, clinical presentation, and treatment of E. gregorii is identical to E. vermicularis. Enterobius vermicularis Life Cycle: Geographic Distribution : • Worldwide, with infections more frequent in school- or preschool- children and in crowded conditions. Enterobiasis appears to be more common in temperate than tropical countries. • Clinical Features: • • • Enterobiasis is frequently asymptomatic. The most typical symptom is perianal pruritus, especially at night, which may lead to excoriations and bacterial superinfection. Occasionally, invasion of the female genital tract with vulvovaginitis and pelvic or peritoneal granulomas can occur. Other symptoms include anorexia, irritability, and abdominal pain. Laboratory Diagnosis: – Scotch test", cellulose-tape slide test) on the perianal skin and then examining the tape placed on a slide. – Anal swabs or "Swube tubes" can also be used. Eggs can also be found, but less frequently, in the stool, and occasionally are encountered in the urine or vaginal smears. • Adult worms are also diagnostic, when found in the perianal area, or during ano-rectal or vaginal examinations. Laboratory Diagnosis: Eggs measure 50 to 60 µm by 20 to 3 µm. Anterior end of Enterobius vermicularis adult worm. Enterobius eggs on cellulose tape prep. • Treatment: • - Mebendazole 100 mg once daily(single dose) • Albendazole (400mg once) • pyrantel pamoate(11mg/kg once; maximum 1g -Susp . 250 mg/ 5 ml,Tab. 125 mg– safe in pregnancy) • PYRVINIUM PAMOATE (Coated Tab. 50 mg, Susp. 50 mg / 5 ml) • Measures to prevent reinfection, such as personal hygiene and laundering of bedding, should be discussed and implemented in cases where infection affects other household members. Tissue Nematodes Angiostrongylus Cantonensis Dracunculiasis Trichinella Spiralis Angiostrongyliasis Causal Agent: The nematode (roundworm) Angiostrongylus cantonensis, the rat lungworm, is the most common cause of human eosinophilic meningitis, Angiostrongylus cantonensis Life Cycle: Angiostrongyliasis Geographic Distribution: o Most cases of eosinophilic meningitis have been reported from Southeast Asia and the Pacific Basin, although the infection is spreading to many other areas of the world, including Africa and the Caribbean. Abdominal angiostrongyliasis has been reported from Costa Rica, and occurs most commonly in young children. Clinical Manifestations • - eosinophilic meningitis Symptoms include severe headaches, • Abdominal angiostrongyliasis mimics appendicitis, with eosinophilia. nausea, vomiting, neck stiffness, seizures, and neurologic abnormalities. Occasionally, ocular invasion occurs. Eosinophilia is present in most of cases. Most patients recover fully. Laboratory Diagnosis: o In eosinophilic meningitis the cerebrospinal fluid (CSF) is abnormal (elevated pressure, proteins, and leukocytes; eosinophilia). On rare occasions, larvae have been found in the CSF. o In abdominal angiostrongyliasis, eggs and larvae can be identified in the tissues removed at surgery. Treatment: o No drug has proven to be effective for the treatment of A. cantonensis or A. costaricensis infections. Relief of symptoms for A. cantonensis infections can be achieved by the use of analgesics, corticosteroids, and careful removal of the cerebral spinal fluid at frequent intervals. Trichinellosis Etiology Epidemiology Life cycle Clinical Manifestation Laboratory Finding Treatment trichinellosis Dracunculiasis Causal Agent: guinea worm disease is caused by the nematode (roundworm) Dracunculus medinensis Geographic Distribution: An ongoing eradication campaign has dramatically reduced the incidence of dracunculiasis, which is now restricted to rural, isolated areas in a narrow belt of African countries and Yemen. Dracunculus medinensis Life Cycle: Dracunculiasis Clinical Features: o The clinical manifestations are localized but incapacitating. The worm emerges as a whitish filament (duration of emergence: 1 to 3 weeks) in the center of a painful ulcer, accompanied by inflammation and frequently by secondary bacterial infection. Dracunculiasis Laboratory Diagnosis: The clinical presentation of dracunculiasis is so typical, and well known to the local population, that it does not need laboratory confirmation. In addition, the disease occurs in areas where such confirmation is unlikely to be available. Examination of the fluid discharged by the worm can show rhabditiform larvae. No serologic test is available. Treatment: Local cleansing of the lesion and local application of antibiotics, if indicated because of bacterial superinfection. Mechanical, progressive extraction of the worm over a period of several days. No curative antihelminthic treatment is available. Trematodes o Blood Flukes o Liver Flukes o Intestinal Flukes o Lung Flukes Blood Flukes (Schistosomiasis) S .Mansomi S .Intercalatum S .Hematubium S .Japonicum S .Mekongi Epidemiology S .Mansoni S .Japonicum West Africa S .Mekongi China .Philippines .Indonesia S .Intercalatum Africa .SousAmerica .Middle East Southeast Asia S .Haematobium Africa .Middle East Life cycle Clinical Manifestation Cercarial Dermatitis Acute Schistosomiasis- Katayama Fever Chronic Schistosomiasis Cercarial Dermatitis Dependent to species .Intensity of Infection and host factors Most often by S .mansoni &S .japonicum 2-3 days after invasion (swimmer itch) Self- limiting entity Acute Schistosomiasis (Katayama Fever) 4-8 wks after skin invasion Fever .lymphadenopathy . Hepato- splenomegaly . Eosinophilia . Generally benign Death occasionally reported in heavy exposure Chronic Schistosomiasis Intestinal & Hepatosplenic Diseases : S . japonicum .S.mansoni .S.intecalatum . S .mekonky – Intestinal diseases : Colicky abdominal pain .Bloody diarrhea .Colonic polyposis – Hepatosplenic Diseases : Urinary tract Diseases 15-20 % of infected patients Portal hypertension Cirrhosis S.haematobium Hemturia .Dysuria .Bladder granoloma .Hydronephrosis Bladder CA CNS Schistosomiasis Pulmonary Schistosomiasis Treatment Liver Flukes Fasciola Hepatica Clonorchis Sinensis Fascioliasis • Causal Agent: • The trematodes Fasciola hepatica (the sheep liver fluke) and Fasciola gigantica, parasites of herbivores that can infect humans accidentally. • Geographic Distribution: • Fascioliasis occurs worldwide. Human infections with F. hepatica are found in areas where sheep and cattle are raised, and where humans consume raw watercress, including Europe, the Middle East, and Asia. Infections with F. gigantica have been reported, more rarely, in Asia, Africa, and Hawaii. Fasciola hepatica Life cycle : Fascioliasis • Clinical Features: • During the acute phase (caused by the migration of the immature fluke through the hepatic parenchyma), manifestations include abdominal pain, hepatomegaly, fever, vomiting, diarrhea, urticaria and eosinophilia, and can last for months. In the chronic phase (caused by the adult fluke within the bile ducts), the symptoms are more discrete and reflect intermittent biliary obstruction and inflammation. Occasionally, ectopic locations of infection (such as intestinal wall, lungs, subcutaneous tissue, and pharyngeal mucosa) can occur. Fascioliasis o Laboratory Diagnosis: o Microscopic identification of eggs is useful in the chronic (adult) stage. Eggs can be recovered in the stools or in material obtained by duodenal or biliary drainage. False fascioliasis (pseudofascioliasis) refers to the presence of eggs in the stool resulting not from an actual infection but from recent ingestion of infected livers containing eggs. This situation (with its potential for misdiagnosis) can be avoided by having the patient follow a liver-free diet several days before a repeat stool examination. Antibody detection tests are useful especially in the early invasive stages, when the eggs are not yet apparent in the stools, or in ectopic fascioliasis. Fascioliasis (4): Wet mounts with iodine. The eggs are ellipsoidal. They have a small, barely distinct operculum Size range: 120 to 150 µm by 63 to 90 µm. Treatment: Unlike infections with other flukes, Fasciola hepatica infections may not respond to praziquantel. The drug of choice is triclabendazole with bithionol as an alternative. Intestinal Flukes Fasciolopsis Buski Heterophyes Heterophyes Lung Flukes Paragonimus Westermani Paragonimus Africanus Cestods Teniasis Saginata Teniasis Solium &Cysticercosis Hymenolepiasis Nana Echinococcosis Taeniasis Causal Agent: The cestodes (tapeworms) Taenia saginata (beef tapeworm) and T. solium (pork tapeworm). Taenia solium can also cause cysticercosis. Geographic Distribution: Both species are worldwide in distribution. Taenia solium is more prevalent in poorer communities where humans live in close contact with pigs and eat undercooked pork, and in very rare in Muslim countries. Life cycle of Taenia saginata and Taenia solium : Taeniasis • Clinical Features: • - Taenia saginata taeniasis produces only mild abdominal symptoms. The most striking feature consists of the passage (active and passive) of proglottids. Occasionally, appendicitis or cholangitis can result from migrating proglottids. • - Taenia solium taeniasis is less frequently symptomatic than Taenia saginata taeniasis. The main symptom is often the passage (passive) of proglottids. The most important feature of Taenia solium taeniasis is the risk of development of cysticercosis. Taeniasis Laboratory Diagnosis: - Microscopic identification of eggs and proglottids in feces is diagnostic for taeniasis, but is not possible during the first 3 months following infection, prior to development of adult tapeworms. - Microscopic identification of gravid proglottids(or,more rarely,examination of the scolex)allows species determination. - Antibody detection may prove useful especially in the early invasive stages Taeniasis Treatment: Treatment is simple and very effective. Praziquantel (10mg /kg)is the drug of choice. NICLOSAMIDE (4 tab single dose) Cycticercosis echinococcosis Causal Agent: • Human echinococcosis (hydatidosis, or hydatid disease) is caused by the larval stages of cestodes (tapeworms) of the genus Echinococcus. • - Echinococcus granulosus causes cystic echinococcosis, the form most frequently encountered; • - E. multilocularis causes alveolar echinococcosis; E. vogeli causes polycystic echinococcosis; and E. oligarthrus is an extremely rare cause of human echinococcosis. Echinococcus Life Cycle: echinococcosis Geographic Distribution: • occurs practically worldwide, and more frequently in rural, grazing areas where dogs ingest organs from infected animals. E. multilocularis occurs in the northern hemisphere, including central Europe and the northern parts of Europe, Asia, and North America. E. vogeli and E. oligarthrus occur in Central and South America. Clinical Features: – Echinococcus granulosus infections remain silent for years before the enlarging cysts cause symptoms in the affected organs. • Hepatic involvement can result in abdominal pain, a mass in the hepatic area, and biliary duct obstruction. • Pulmonary involvement can produce chest pain, cough, and hemoptysis. . • Rupture of the cysts can produce fever, urticaria, eosinophilia, and anaphylactic shock, as well as cyst dissemination. • In addition to the liver and lungs, other organs (brain, bone, heart) can also be involved, with resulting symptoms. • Echinococcus multilocularis affects the liver as a slow growing, destructive tumor, with abdominal pain, biliary obstruction, and occasionally metastatic lesions into the lungs and brain. • Echinococcus vogeli affects mainly the liver, where it acts as a slow growing tumor; secondary cystic development is common Laboratory Diagnosis: The diagnosis of echinococcosis relies mainly on findings by ultrasonography and/or other imaging techniques supported by positive serologic tests. . - In seronegative patients with hepatic image findings compatible with echinococcosis, ultrasound guided fine needle biopsy may be useful for confirmation of diagnosis; during such procedures precautions must be taken to control allergic reactions or prevent secondary recurrence in the event of leakage of hydatid fluid or protoscolices Treatment: - Surgery is the most common form of treatment for echinococcosis, although removal of the parasite mass is not usually 100% effective. After surgery, medication may be necessary to keep the cyst from recurring. - The drug of choice for treatment echinococcosis is albendazole (Echinococcus granulosus). Some reports have suggested the use of albendazole or mebendazole for Echinococcus multilocularis infections. Hymenolepiasis(1): Causal Agents: Hymenolepiasis is caused by two cestodes (tapeworm) species: - Hymenolepis nana (the dwarf tapeworm, adults measuring 15 to 40 mm in length) - Hymenolepis dimnuta (rat tapeworm, adults measuring 20 to 60 cm in length). Hymenolepis diminuta is a cestode of rodents infrequently seen in humans and frequently found in rodents. Hymenolepis nana Life Cycle: Hymenolepiasis(2): Geographic Distribution: Hymenolepis nana is the most common cause of all cestode infections, and is encountered worldwide. In temperate areas its incidence is higher in children and institutionalized groups. Hymenolepis diminuta, while less frequent, has been reported from various areas of the world. Hymenolepiasis(3): •Clinical Features: Hymenolepis nana and H. diminuta infections are most often asymptomatic. Heavy infections with H. nana can cause weakness, headaches, anorexia, abdominal pain, and diarrhea. •Laboratory Diagnosis: The diagnosis depends on the demonstration of eggs in stool specimens. Concentration techniques and repeated examinations will increase the likelihood of detecting light infections. Egg of Hymenolepis diminuta,round or slightly oval, size 70 to 86 µm X 60 to 80 µm, with a striated outer membrane and a thin inner membrane. The space between the membranes is smooth or faintly granular. The oncosphere has six hooks. Egg of Hymenolepis nana,oval or subspherical and smaller than those of H. diminuta, their size being 40 to 60 µm X 30 to 50 µm. On the inner membrane are two poles, from which 4 to 8 polar filaments spread out between the two membranes. The oncosphere has six hooks. Hymenolepiasis(4): Treatment: - Praziquantel (25mg/kg once, F.C. Tab. 600mg ) is the drug of choice. - NICLOSAMIDE (4 tab daily for 5-7 days,Chewable Tab 500 mg) Diphyllobothriasis(1): Causal Agent: The cestode Diphyllobothrium latum (the fish or broad tapeworm), the largest human tapeworm. Several other Diphyllobothrium species have been reported to infect humans, but less frequently; they include D. pacificum, D. cordatum, D. ursi, D. dendriticum, D. lanceolatum, D. dalliae, and D. yonagoensis. Diphyllobothrium latum Life Cycle: Diphyllobothriasis(2): Geographic Distribution: Diphyllobothriasis occurs in areas where lakes and rivers coexist with human consumption of raw or undercooked freshwater fish. Such areas are found in the Northern Hemisphere (Europe, newly independent states of the former Soviet Union (NIS), North America, Asia), and in Uganda and Chile. Clinical Features:Diphyllobothriasis can be a long- lasting infection(decades). - Most infections are asymptomatic. - Manifestations may include abdominal discomfort, diarrhea, vomiting, and weight loss. -Vitamin B12 deficiency with pernicious anemia may occur. - Massive infections may result in intestinal obstruction. - Migration of proglottids can cause cholecystitis or cholangitis. Diphyllobothriasis(3): Laboratory Diagnosis: - Microscopic identification of eggs in the stool is the basis of specific diagnosis.Eggs are usually numerous and can be demonstrated without concentration techniques. - Examination of proglottids passed in the stool is also of diagnostic value. Treatment: Praziquantel is the drug of choice. Alternatively, Niclosamide can also be used to treat diphyllobothriasis. oval or ellipsoidal, with at one end an operculum. The eggs are passed in the stool unembryonat ed. Size range: 58 to 76 µm by 40 to 51 µm