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STRONGYLOIDES ‘STRONGYLOIDOSIS’ SCHISTOSOMA ‘SCHISTOSOMIASIS’ Dr Kamran Afzal,  Asst Prof Microbiology
Strongyloides stercoralis   (Threadworm)
Epidemiology <ul><li>Found worldwide -  An estimated 50  - 100 million cases </li></ul><ul><li>Favors warmer tropical and ...
<ul><li>Worms can be free-living in the soil or live in a host </li></ul><ul><li>Only females are parasitic </li></ul><ul>...
Classification <ul><li>Phylum:  Nemathelminthes </li></ul><ul><li>Class: Nematoda </li></ul><ul><li>Family:   Strongyloidi...
Morphology <ul><li>It’s a nematode, so it has two larval forms </li></ul><ul><ul><li>Rhabditiform larvae Filariform larvae...
<ul><li>The size and shape of the adult female are dependent on whether it’s parasitic or free-living </li></ul><ul><ul><l...
Life Cycle
Strongyloidiasis <ul><li>Strongyloides stercoralis has a direct parasitic life cycle, meaning it can complete its entire l...
<ul><li>Symptoms and Signs of Hyperinfection </li></ul><ul><ul><li>Diarrhea </li></ul></ul><ul><ul><li>Pleuritic pain </li...
Symptoms <ul><li>Dependent on the stage in the worm’s life cycle </li></ul>Stage Site Symptoms egg intestine --- rhabditif...
<ul><li>1/3 of patients are asymptomatic </li></ul><ul><li>Ground itch </li></ul><ul><ul><li>Pruritic papulovesicular cuta...
Lab Diagnosis <ul><li>Direct microscopy </li></ul><ul><ul><li>Rhabditiform larvae in stool </li></ul></ul><ul><ul><ul><li>...
<ul><li>With hyperinfection </li></ul><ul><ul><li>Filariform larvae may also be recovered in stool if fixed rapidly </li><...
<ul><li>Features of Rhabditiform larvae </li></ul><ul><ul><ul><li>Actively motile </li></ul></ul></ul><ul><ul><ul><li>200-...
<ul><li>Microscopic (biopsy) findings </li></ul><ul><ul><li>Intestinal biopsy shows adult worms, eggs and larvae </li></ul...
Treatment <ul><li>Ivermectin (drug of choice) </li></ul><ul><ul><li>200 mcg/kg/d PO for 2 days </li></ul></ul><ul><ul><li>...
Prevention <ul><li>Properly dispose of human wastes </li></ul><ul><li>Wear Shoes </li></ul><ul><li>… Don’t eat dirt </li><...
Schistosoma  species ‘Bilharziasis’
Epidemiology <ul><li>Second most prevalent tropical parasitic disease in the world (behind Malaria only) </li></ul><ul><li...
<ul><li>The disease is often associated with water resource development projects, such as </li></ul><ul><ul><ul><li>dams a...
Etiology <ul><li>The Schistosomes are blood trematodes (blood flukes) belonging to the Phylum Platyhelmintha </li></ul><ul...
<ul><li>Transmission: direct penetration of skin by fork-tailed cercaria in water </li></ul><ul><li>Pathogenic potential: ...
 
Schistosomiasis <ul><li>S. haematobium  (urogenital) </li></ul><ul><li>In urinary schistosomiasis damage to the urinary tr...
<ul><li>S. mansoni, S. japonicum </li></ul><ul><li>In intestinal schistosomiasis disease is slower to develop </li></ul><u...
<ul><li>They differ from other trematodes in that they have separate sexes </li></ul><ul><li>The schistosomes remain in co...
Clinical presentation of severe schistosomiasis Portal hypertension Hepatosplenic shunt Esophageal varices Hemorrhages
Acute Schistosomiasis <ul><li>Katayama Fever </li></ul><ul><li>Fever, headache, generalized myalgias </li></ul><ul><li>Rig...
Lab Diagnosis <ul><li>Detection of eggs in stools or urine: Diagnostic </li></ul><ul><ul><li>3 specimens may be needed: In...
<ul><li>Biopsy </li></ul><ul><li>The most sensitive diagnostic test for schistosomiasis is  </li></ul><ul><li>rectal or bl...
<ul><li>Serology </li></ul><ul><li>Useful in specific circumstances </li></ul><ul><li>Useful in pts with no eggs: Katayama...
Treatment <ul><li>The only way to reduce disease symptoms </li></ul><ul><li>Praziquantel: effective in a single dose again...
Prevention and control <ul><li>Educate people to not urinate or defecate in fresh water supplies  </li></ul><ul><li>Elimin...
Adult worm habitat
Identify..
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Strongyloides schistosoma

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Strongyloides schistosoma

  1. 1. STRONGYLOIDES ‘STRONGYLOIDOSIS’ SCHISTOSOMA ‘SCHISTOSOMIASIS’ Dr Kamran Afzal, Asst Prof Microbiology
  2. 2. Strongyloides stercoralis (Threadworm)
  3. 3. Epidemiology <ul><li>Found worldwide - An estimated 50 - 100 million cases </li></ul><ul><li>Favors warmer tropical and subtropical climates </li></ul><ul><ul><li>Endemic in sub-Saharan Africa, Latin America, southeast Asia, and the southeastern United States </li></ul></ul>
  4. 4. <ul><li>Worms can be free-living in the soil or live in a host </li></ul><ul><li>Only females are parasitic </li></ul><ul><li>The definitive host is human, but may also affect other primates and dogs </li></ul><ul><li>Habitat </li></ul><ul><ul><li>Parasitic adult in duodenum and jejunum of man </li></ul></ul><ul><ul><li>Larvae not eggs are passed in human faeces </li></ul></ul><ul><ul><li>Infective larvae found in soil, intestine and perianal skin </li></ul></ul><ul><li>Mode of Transmission </li></ul><ul><ul><li>Skin penetration by larva </li></ul></ul>
  5. 5. Classification <ul><li>Phylum: Nemathelminthes </li></ul><ul><li>Class: Nematoda </li></ul><ul><li>Family: Strongyloididae </li></ul><ul><li>Genus: Strongyloides </li></ul><ul><li>Strongyloides stercoralis </li></ul>
  6. 6. Morphology <ul><li>It’s a nematode, so it has two larval forms </li></ul><ul><ul><li>Rhabditiform larvae Filariform larvae </li></ul></ul><ul><ul><li>(pathogenic form) (infective form) </li></ul></ul>
  7. 7. <ul><li>The size and shape of the adult female are dependent on whether it’s parasitic or free-living </li></ul><ul><ul><li>Free-living females 1 mm by 60 µm </li></ul></ul><ul><ul><li>Parasitic females 2.2 mm by 45 µm </li></ul></ul><ul><ul><li>Eggs 55 µm by 30 µm </li></ul></ul><ul><li>Adult Male </li></ul><ul><ul><li>Reproduction parthenogenetic </li></ul></ul>
  8. 8. Life Cycle
  9. 9. Strongyloidiasis <ul><li>Strongyloides stercoralis has a direct parasitic life cycle, meaning it can complete its entire life cycle in the definitive host </li></ul><ul><li>This causes an autoinfection in the human, because the worm keeps infecting them without ever leaving </li></ul><ul><li>Disseminated strongyloidiasis, or hyperinfection </li></ul><ul><ul><li>Immunocomprised, when the worms spread throughout the body </li></ul></ul><ul><ul><li>Massive larval invasion in tissues e.g. lungs and serous cavities </li></ul></ul><ul><ul><li>Leading to sepsis and secondary bacterial infections </li></ul></ul><ul><ul><li>Hyperinfection has an 85% fatality rate </li></ul></ul>
  10. 10. <ul><li>Symptoms and Signs of Hyperinfection </li></ul><ul><ul><li>Diarrhea </li></ul></ul><ul><ul><li>Pleuritic pain </li></ul></ul><ul><ul><li>Peripheral eosinophilia </li></ul></ul><ul><ul><li>Severe generalized abdominal pain, diffuse pulmonary infiltrates, ileus, shock, sepsis may occur </li></ul></ul>
  11. 11. Symptoms <ul><li>Dependent on the stage in the worm’s life cycle </li></ul>Stage Site Symptoms egg intestine --- rhabditiform intestine, soil --- (“free living”) filariform soil ground itch larva currens lungs wheezing, cough hemoptysis! eosinophilia adult intestines abdominal pain ulcers diarrhea/constipation weight loss bowel obstruction malabsorption
  12. 12. <ul><li>1/3 of patients are asymptomatic </li></ul><ul><li>Ground itch </li></ul><ul><ul><li>Pruritic papulovesicular cutaneous eruption </li></ul></ul><ul><li>Larva Currens (“racing larvae”) </li></ul><ul><ul><li>Pathognomonic rash </li></ul></ul><ul><ul><li>Pruritic wheal or linear urticaria </li></ul></ul><ul><ul><li>Creeps 5-15 cm/hr! </li></ul></ul>
  13. 13. Lab Diagnosis <ul><li>Direct microscopy </li></ul><ul><ul><li>Rhabditiform larvae in stool </li></ul></ul><ul><ul><ul><li>Larvae are seen in stool approximately 1 month after skin penetration </li></ul></ul></ul><ul><ul><ul><li>>90% sensitivity for stool samples if 7 or more samples are examined </li></ul></ul></ul><ul><ul><li>Eggs </li></ul></ul><ul><ul><li>Larvae in sputum sample </li></ul></ul><ul><li>Serology </li></ul>ovo
  14. 14. <ul><li>With hyperinfection </li></ul><ul><ul><li>Filariform larvae may also be recovered in stool if fixed rapidly </li></ul></ul><ul><ul><li>Sputum samples </li></ul></ul><ul><ul><li>Bronchioalveolar lavage </li></ul></ul><ul><ul><li>Urinalysis </li></ul></ul><ul><ul><li>Semen analysis </li></ul></ul><ul><ul><li>CSF analysis </li></ul></ul><ul><ul><li>NO eosinophilia! </li></ul></ul>
  15. 15. <ul><li>Features of Rhabditiform larvae </li></ul><ul><ul><ul><li>Actively motile </li></ul></ul></ul><ul><ul><ul><li>200-250µm x 16 µm in size </li></ul></ul></ul><ul><ul><ul><li>Short buccal cavity </li></ul></ul></ul><ul><ul><ul><li>Rhabditiform large bulbed esophagus </li></ul></ul></ul>
  16. 16. <ul><li>Microscopic (biopsy) findings </li></ul><ul><ul><li>Intestinal biopsy shows adult worms, eggs and larvae </li></ul></ul><ul><ul><li>Lungs and other organs show only larvae </li></ul></ul>
  17. 17. Treatment <ul><li>Ivermectin (drug of choice) </li></ul><ul><ul><li>200 mcg/kg/d PO for 2 days </li></ul></ul><ul><ul><li>Binds to chloride ion channels </li></ul></ul><ul><ul><li>Causes hyperpolarization -> paralysis </li></ul></ul><ul><ul><li>Affects adults only… </li></ul></ul><ul><ul><li>Cure rate of up to 97% </li></ul></ul><ul><li>Albendazole (2nd line drug) </li></ul><ul><ul><li>400 mg BID x 7 days </li></ul></ul><ul><li>Thiabendazole (2nd line drug before) </li></ul><ul><li>Hyperinfection - treatment for 2-3 weeks may be life saving but the mortality is very high </li></ul>
  18. 18. Prevention <ul><li>Properly dispose of human wastes </li></ul><ul><li>Wear Shoes </li></ul><ul><li>… Don’t eat dirt </li></ul>
  19. 19. Schistosoma species ‘Bilharziasis’
  20. 20. Epidemiology <ul><li>Second most prevalent tropical parasitic disease in the world (behind Malaria only) </li></ul><ul><li>200 M people in 74 countries </li></ul><ul><li>120 M have symptoms </li></ul><ul><li>20 M have severe illness </li></ul><ul><li>Between 200,000 and 800,000 deaths/year </li></ul><ul><li>Described by Theodore Bilharz in Cairo in 1851 </li></ul>
  21. 21. <ul><li>The disease is often associated with water resource development projects, such as </li></ul><ul><ul><ul><li>dams and irrigation schemes, </li></ul></ul></ul><ul><ul><ul><li>fresh water reservoirs, </li></ul></ul></ul><ul><ul><ul><li>artificial lakes, </li></ul></ul></ul><ul><ul><ul><li>cultivation of rice, </li></ul></ul></ul><ul><li>where the snail intermediate hosts of the parasite breed </li></ul>
  22. 22. Etiology <ul><li>The Schistosomes are blood trematodes (blood flukes) belonging to the Phylum Platyhelmintha </li></ul><ul><li>Human disease caused mainly by 3 species of flat worms </li></ul><ul><ul><li>S. haematobium : affects 54 countries in Africa and the Middle East, urinary disease </li></ul></ul><ul><ul><li>S. mansoni : most common (Africa), intestinal disease </li></ul></ul><ul><ul><li>S. japonicum : Asia-Pacific, intestinal disease </li></ul></ul>
  23. 23. <ul><li>Transmission: direct penetration of skin by fork-tailed cercaria in water </li></ul><ul><li>Pathogenic potential: high, based on worm populations and location in veins, capability of eggs to erode tissue </li></ul>
  24. 25. Schistosomiasis <ul><li>S. haematobium (urogenital) </li></ul><ul><li>In urinary schistosomiasis damage to the urinary tract is done by schistosome eggs in the urine </li></ul><ul><li>Bladder cancer is common in advanced cases </li></ul><ul><li>Macrohematuria </li></ul>
  25. 26. <ul><li>S. mansoni, S. japonicum </li></ul><ul><li>In intestinal schistosomiasis disease is slower to develop </li></ul><ul><li>Progressive enlargement of the liver and spleen </li></ul>
  26. 27. <ul><li>They differ from other trematodes in that they have separate sexes </li></ul><ul><li>The schistosomes remain in copula throughout their life span, the male surrounding and holding the female within its gynephoric canal </li></ul>
  27. 28. Clinical presentation of severe schistosomiasis Portal hypertension Hepatosplenic shunt Esophageal varices Hemorrhages
  28. 29. Acute Schistosomiasis <ul><li>Katayama Fever </li></ul><ul><li>Fever, headache, generalized myalgias </li></ul><ul><li>Right upper quadrant pain, tender hepatomegaly </li></ul><ul><li>Bloody diarrhea </li></ul><ul><li>Respiratory symptoms: 70% S. mansoni </li></ul><ul><li>Interstitial pneumonia (radiologic) </li></ul><ul><li>Splenomegaly: 30% </li></ul><ul><li>Aseptic meningitis </li></ul>
  29. 30. Lab Diagnosis <ul><li>Detection of eggs in stools or urine: Diagnostic </li></ul><ul><ul><li>3 specimens may be needed: Intermittent shedding </li></ul></ul><ul><li>CBC with eosinophilia </li></ul><ul><li>Anemia </li></ul><ul><ul><li>Fe-deficiency </li></ul></ul><ul><ul><li>Anemia of chronic disease </li></ul></ul><ul><ul><li>Marocytic </li></ul></ul>
  30. 31. <ul><li>Biopsy </li></ul><ul><li>The most sensitive diagnostic test for schistosomiasis is </li></ul><ul><li>rectal or bladder biopsy </li></ul><ul><li>Perform on patients with typical clinical findings but negative feces and urine samples </li></ul><ul><li>Eggs in the venules of the </li></ul><ul><li>intestinal mucosa </li></ul>
  31. 32. <ul><li>Serology </li></ul><ul><li>Useful in specific circumstances </li></ul><ul><li>Useful in pts with no eggs: Katayama fever </li></ul><ul><li>Commercially available assays: Less sensitive and specific than multiple stool sample exams </li></ul><ul><li>Immunoblot assays to detect circulating egg or worm Ag: highly sensitive and specific </li></ul>
  32. 33. Treatment <ul><li>The only way to reduce disease symptoms </li></ul><ul><li>Praziquantel: effective in a single dose against all species </li></ul><ul><li>Oxamniquine: effective in a single dose, but only against S. mansoni </li></ul>
  33. 34. Prevention and control <ul><li>Educate people to not urinate or defecate in fresh water supplies </li></ul><ul><li>Eliminate snail vectors by making the water habitat unsuitable (increase water flow, remove vegetation) </li></ul><ul><li>Provision of safe, adequate water supply and sanitation </li></ul><ul><li>Provide piped water to avoid direct contact with cercariae </li></ul><ul><li>Snail control through focal mollusciciding </li></ul><ul><li>Mass drug treatment of communities to reduce reservoir of infection </li></ul>
  34. 35. Adult worm habitat
  35. 36. Identify..

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