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  • Fig. 14.21
  • Echinococcus+hydatid

    1. 1. Patient History <ul><li>31 year-old man with a 10-day history of mild diarrhea, anorexia, fatigue, and low grade fever </li></ul><ul><li>A radiograph of the chest revealed a lesion in the upper lobe of the left lung and a small nodule in the right lung </li></ul><ul><li>MTX test was negative </li></ul><ul><li>Laboratory tests showed eosinophilia (30%) </li></ul><ul><li>Stool and blood cultures were negative </li></ul><ul><li>A test for antibodies against Entamoeba histolytica was negative </li></ul><ul><li>A CT scan of the thorax revealed the presence of multiple nodules / cysts in both lungs </li></ul>
    2. 2. Questions to Consider <ul><li>What caused the cysts? </li></ul><ul><li>How is this parasite transmitted to humans? </li></ul><ul><li>How does the lab help in the diagnosis of this parasite? </li></ul><ul><li>What is the treatment for this parasite? </li></ul>
    3. 3. -Tapeworms- Echinococcus species Dr Kamran Afzal Classified Microbiologist
    4. 4. Classification - Tapeworms
    5. 5. Taxonomic Classification of Helminths Fasciolopsis (liver fluke) Schistosoma (not leaf shaped!) Tapeworms Taenia Diphyllobothrium Echinococcus Hymenolopis Ascaris (roundworm) Trichuris (whipworm) Ancylostoma (hookworm) Necator (hookworm) Enterobius (pinworm or threadworm) Strongyloides Genus – examples Trematodes Non-segmented, usually leaf-shaped, with two suckers but no distinct head They have an alimentary canal and are usually hermaphrodite and leaf shaped Schistosomes are the exception. They are thread-like, and have separate sexes Cestodes Adult tapeworms are found in the intestine of their host They have a head (scolex) with sucking organs, a segmented body but no alimentary canal Each body segment is hermaphrodite Platyhelminthes Flat worms; dorsoventrally flattened, no body cavity and, if present, the alimentary canal is blind ending Nematodes Round worms; appear round in cross section, they have body cavities, a straight alimentary canal and an anus Metazoa Class Phylum Sub kingdom
    6. 6. Echinococcus Species <ul><li>3 known species of Echinococcus are medically important </li></ul><ul><ul><li>Echinococcus granulosus </li></ul></ul><ul><ul><li>Echinococcus multilocularis </li></ul></ul><ul><ul><li>Echinococcus vogeli </li></ul></ul><ul><li>Larval forms capable of developing in humans resulting in ‘hydatidosis’ </li></ul><ul><li>Echinococcus granulosus - has carnivores, especially dogs and other canines as definitive hosts </li></ul>
    7. 7. Epidemiology <ul><li>Endemic areas include Mediterranean countries, the Middle East, Iceland, Australia, New Zealand </li></ul><ul><li>Tribes in Kenya - relish dog intestine </li></ul><ul><li>Patients traveling from these countries to Pakistan </li></ul>
    8. 8. Echinococcosis <ul><li>A zoonotic infestation by a tapeworm causing hydatid disease </li></ul><ul><li>Echinococcus granulosus </li></ul><ul><ul><li>Cystic echinococcosis </li></ul></ul><ul><ul><li>Produces cystic lesions </li></ul></ul><ul><li>Echinococcus multilocularis </li></ul><ul><ul><li>Alveolar echinococcosis </li></ul></ul><ul><ul><li>Invasive solid lesions of firm consistency, </li></ul></ul><ul><li>full of connective tissue and a jelly-like material </li></ul>
    9. 9. Morphology - Egg <ul><li>Found in dog feces </li></ul><ul><li>Infective stage </li></ul><ul><li>These eggs are virtually indistinguishable from other closely related species of tapeworms such as Taenia </li></ul>
    10. 10. Morphology - Adult <ul><li>3-6 mm long when mature </li></ul><ul><li>Consists of </li></ul><ul><ul><li>Head - Scolex </li></ul></ul><ul><ul><li>Short neck - Strobila </li></ul></ul><ul><ul><li>Usually 3 proglottids: Immature, mature, gravid </li></ul></ul>
    11. 11. <ul><li>Scolex has non-retractable rostellum armed with double crown of 28-50 hooks </li></ul>
    12. 12. Life Cycle <ul><li>Dogs are the definitive hosts </li></ul><ul><ul><li>Adult worm develops in the small intestine </li></ul></ul><ul><ul><li>Eggs are voided in the feces of the dogs </li></ul></ul><ul><li>Sheep and other herbivores are intermediate hosts </li></ul><ul><li>Humans are accidental intermediate hosts </li></ul><ul><ul><li>Larval form develops mainly in the liver and lungs </li></ul></ul><ul><li>The cycle is completed when a dog eats a cyst-infested liver or lungs </li></ul>
    13. 13. Life Cycle
    14. 14. Life Cycle
    15. 15. Human Host <ul><li>Each egg contains an embryo (oncosphere) </li></ul><ul><li>Eggs hatch in the human stomach and release the oncosphere </li></ul><ul><li>The oncosphere penetrate the intestinal lining and enter the blood stream </li></ul><ul><li>Travel to any organ, usually lung and liver, and a cyst develops </li></ul>
    16. 16. Hydatid Cysts
    17. 17. The Hydatid Cyst <ul><li>The cyst is lined by a multilayer parasite tissue with the innermost layer being the germinal layer </li></ul><ul><li>GL can spawn the formation of “brood capsules” which are themselves lined by GL </li></ul><ul><li>The daughter cysts (the encircled body) &quot;bud&quot; into the center of the fluid-filled cyst </li></ul><ul><li>They will develop into tapeworms should this be eaten by a definitive or final host such as a canine </li></ul>
    18. 18. <ul><li>Thousands of protoscolices can fill the hydatid (hydatid sand) </li></ul><ul><li>Protoscolices are the infective stage for dogs </li></ul><ul><li>Hydatid cysts usually grow slowly but steadily (1-5 cm per year) </li></ul><ul><li>They are usually well tolerated until their size becomes a problem or they rupture </li></ul><ul><li>Cyst rupture or leakage can result in allergic reactions and metastasis </li></ul>
    19. 21. <ul><li>Hydatid sand </li></ul><ul><ul><li>Cystic fluid, brood capsules, protoscolices, daughter and grand daughter cyst </li></ul></ul>
    20. 22. <ul><li>The hydatid cysts are mainly located in the liver and lungs </li></ul><ul><ul><li>Rarely, the cysts may be found in the brain, eye, kidney, muscles and bones </li></ul></ul><ul><li>The early stage of infection is generally asymptomatic </li></ul><ul><li>As the cyst enlarges, symptoms of a space-occupying lesion develop </li></ul><ul><li>Allergic reactions and sometimes anaphylactic shock may occur if the cyst ruptures </li></ul><ul><li>Ruptures of the cyst may also lead to the escape of protoscolices into the surrounding tissues, these can then develop into further cysts </li></ul>Pathogenesis
    21. 24. Hydatid cyst (Hydatid disease) <ul><li>Mother cyst (left) daughter cyst (right) </li></ul>
    22. 25. Hydatid Cysts in Human Heart
    23. 26. Hydatid Cysts in Human Brain
    24. 27. Hydatid Cysts in Human Liver
    25. 28. Hydatid Cysts in Human Lung
    26. 29. Symptoms <ul><li>Vary by size and site of cyst </li></ul><ul><li>Usually no symptoms until cyst becomes enlarged </li></ul><ul><li>Liver: biliary duct obstruction - jaundice, portal hypertension and pain </li></ul><ul><li>Lung: coughing, shortness of breath, chest pain and hemoptysis </li></ul><ul><li>Brain: seizures, paralysis </li></ul><ul><li>Rupture of cyst: anaphylactic shock, spread of scolices, death </li></ul>
    27. 30. Morbidity <ul><li>Free rupture of echinococcal cyst (with or without anaphylaxis) </li></ul><ul><li>Infection of the cyst </li></ul><ul><li>Dysfunction of the affected organs </li></ul><ul><ul><li>Biliary obstruction </li></ul></ul><ul><ul><li>Cirrhosis </li></ul></ul><ul><ul><li>Bronchial obstruction </li></ul></ul><ul><ul><li>Renal outflow obstruction </li></ul></ul>
    28. 31. Diagnosis <ul><li>Microscopy </li></ul><ul><ul><li>Fluid aspirated from hydatid cyst will show many protoscolices </li></ul></ul><ul><li>Antibody detection by Serologic tests </li></ul><ul><ul><li>IHA, IFA and EIA tests are sensitive tests for detecting antibodies in serum of patients </li></ul></ul><ul><li>Casoni’s test – Dermatological reaction </li></ul><ul><ul><li>Generally less sensitive then imagery </li></ul></ul><ul><li>Radiographic images of lungs and liver </li></ul><ul><ul><li>Hydatids are found during radiography, ultrasonography, CT scans </li></ul></ul>
    29. 32. Treatment <ul><li>Surgery </li></ul><ul><ul><li>Surgery is the most common form of treatment for echinococcosis </li></ul></ul><ul><ul><li>Risks of operative morbidity, recurrence of cyst, anaphylaxis or dissemination of the infection </li></ul></ul><ul><li>Anti-parasitic drugs </li></ul><ul><ul><li>Albendazole </li></ul></ul><ul><ul><li>Mebendazole or praziquantal </li></ul></ul>
    30. 33. Prevention <ul><li>Children most likely to get infected </li></ul><ul><li>Proper hand washing </li></ul><ul><li>Care not to ingest eggs from dog </li></ul><ul><li>Sheep herders should not live closely with their dogs </li></ul><ul><li>Control of stray dogs </li></ul><ul><li>Limit access of dogs to sheep offal </li></ul><ul><li>Treatment of pet dogs regularly </li></ul>
    31. 34. Questions to Consider <ul><li>What caused the cysts that were removed? </li></ul><ul><ul><li>Patient has hydatid disease caused by Echinococcus granulosus </li></ul></ul><ul><li>How is this parasite transmitted to humans? </li></ul><ul><ul><li>Ingestion of embryonated eggs present in dog’s feces </li></ul></ul><ul><li>How does the lab help in the diagnosis of this parasite? </li></ul><ul><ul><li>Microscopy, antibody detection </li></ul></ul><ul><li>What is the treatment for this parasite? </li></ul><ul><ul><li>Oral treatments of albendazole </li></ul></ul><ul><ul><li>Careful surgical removal of cysts </li></ul></ul><ul><li>Humans are which type of hosts? </li></ul><ul><ul><li>Humans are accidental intermediate hosts </li></ul></ul>
    32. 35. Question <ul><li>Which of the following description about hydatid disease is wrong? </li></ul><ul><li>A Carnivores serve as final hosts </li></ul><ul><li>B Human is infected by the egg of Echinococcus </li></ul><ul><li>granulosus </li></ul><ul><li>C Human hydatid disease is caused by adult worm </li></ul><ul><li>D Herbivores serve as intermediate hosts </li></ul>
    33. 36. Echinococcus multilocularis <ul><li>Rare multilocular alveolar form </li></ul><ul><li>Endemic in much of the upper Midwest of the United States, Alaska, Canada, Japan, central Europe, and parts of Russia </li></ul><ul><li>Definitive hosts are foxes and, less commonly, cats and dogs </li></ul><ul><li>Intermediate hosts are wild rodents </li></ul><ul><li>Humans are infested either by direct contact with definitive hosts or indirectly by intake of contaminated water or contaminated plants such as wild berries </li></ul>
    34. 37. <ul><li>Liver and the lungs are the most common sites of hydatid disease </li></ul><ul><ul><li>Can travel to any part of the body </li></ul></ul><ul><li>E. multilocularis lesions can cause physicians to generate a long list of differential diagnoses, including malignant tumors </li></ul><ul><li>Diagnosis of E. multilocularis lesions is more difficult </li></ul><ul><ul><li>The alveolar cysts grow by exogenous proliferation and behave like a malignant neoplasm </li></ul></ul><ul><ul><li>Thin outer wall that grows and infiltrates processes into surrounding host tissues like a cancer </li></ul></ul>