Parasitic Infections


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Parasitic Infections

  1. 1. Parasitic Infections
  2. 2. Amoebiasis <ul><li>Introduction </li></ul><ul><li>Pathogenesis </li></ul><ul><li>Clinical Features </li></ul><ul><li>Investigations </li></ul><ul><li>Imaging techniques </li></ul><ul><li>Treatment </li></ul>
  3. 3. Amoebiasis <ul><li>Introduction </li></ul><ul><li>Pathogenesis </li></ul><ul><li>Clinical Features </li></ul><ul><li>Investigations </li></ul><ul><li>Imaging techniques </li></ul><ul><li>Treatment </li></ul>
  4. 4. Introduction <ul><li>Caused by Entamoeba histolytica </li></ul><ul><li>Common in the Indian subcontinent, Africa, parts of South America (> 50% population affected) </li></ul><ul><li>Mode of infection: faeco – oral </li></ul><ul><li>Substandard hygiene and sanitation </li></ul><ul><li>Amoebic liver abscess (MC extra intestinal manifestation): 10% of infected population </li></ul><ul><li>Immunocompromised and alcoholic: susceptible </li></ul>
  5. 5. Amoebiasis <ul><li>Introduction </li></ul><ul><li>Pathogenesis </li></ul><ul><li>Clinical Features </li></ul><ul><li>Investigations </li></ul><ul><li>Imaging techniques </li></ul><ul><li>Treatment </li></ul>
  6. 6. Pathogenesis <ul><li>Organism  gut (through food/water contaminated with the cyst)  cysts hatch  trophozoites  carried to colon  FLASK SHAPED ULCERS (in the submucosa) </li></ul><ul><li>Trophozoites multiply  cysts </li></ul><ul><li>Portal circulation Passed in faeces </li></ul><ul><li>Infects others </li></ul>
  7. 7. Pathogenesis <ul><li>Portal circulation </li></ul><ul><li>Trophozoites are filtered and trapped in the interlobular veins of the liver </li></ul><ul><li>Multiply in the portal triads; local infarction & liquefactive necrosis (proteolytic enzymes) </li></ul><ul><li>Areas ofnecrosis – coalesce to form Amoebic Liver Abscess Cavity </li></ul>
  8. 8. Pathogenesis –Amoebic Liver Abscess <ul><li>Right lobe> Left lobe (80% > 10%); remaining 10% are multiple </li></ul><ul><li>Right lobe: blood from the superior mesenteric artery runs n a straighter course through the portal vein into the larger lobe </li></ul><ul><li>More common in the diaphragmatic surface  pulmonary complications </li></ul><ul><li>Abscess cavity  chocolate coloured, odourless, ‘anchovy – sauce’ like fluid (mixture of necrotic liver tissue and blood) </li></ul><ul><li>Secondary infection in the cavity may occur  pus </li></ul><ul><li>Untreated abscess  likely to rupture </li></ul>
  9. 9. Pathogenesis… <ul><li>Chronic infection in the large bowel </li></ul><ul><li>granulomatous lesion along the large bowel; most commonly seen in the caecum </li></ul><ul><li>Amoeboma </li></ul>
  10. 10. Amoebiasis <ul><li>Introduction </li></ul><ul><li>Pathogenesis </li></ul><ul><li>Clinical Features </li></ul><ul><li>Investigations </li></ul><ul><li>Imaging techniques </li></ul><ul><li>Treatment </li></ul>
  11. 11. Clinical Features: Symptoms <ul><li>Young adult male </li></ul><ul><li>h/o pain, fever, insidious onset of non specific symptoms (anorexia, night sweats, cough, weight loss)  gradually progresses to more specific symptoms: pain in the rt upper abdomen, shoulder tp pain, hiccoughs, non productive cough </li></ul><ul><li>Past h/o bloody diarrhoea and travel to an endemic area </li></ul>
  12. 12. Clinical Features: signs <ul><li>Toxic, Anemic patient </li></ul><ul><li>Upper abdomen rigidity </li></ul><ul><li>Tender hepatomealy </li></ul><ul><li>Tender and bulging intercostal spaces, overlying skin edema, pleural effusion and basal pneumonitis </li></ul><ul><li>Occasionally – trace of jaundice, ascites </li></ul><ul><li>Rarely – emergency due to rupture into the peritoneal, pleural or pericardial activiy </li></ul>
  13. 13. Amoeboma <ul><li>Chronic granuloma </li></ul><ul><li>Arising in the large bowel, most commonly seen in the caecum </li></ul><ul><li>Prone to occur in longstanding amoebic infection that has been treated intermittently with drugs without completion of a full course </li></ul><ul><li>Suspected when a patient from an endemic area with generalized ill health, pyrexia, mass in the rt iliac fossa with a h/o blood stained mucoid diarrhoea </li></ul>
  14. 14. Amoebiasis <ul><li>Introduction </li></ul><ul><li>Pathogenesis </li></ul><ul><li>Clinical Features </li></ul><ul><li>Investigations </li></ul><ul><li>Imaging techniques </li></ul><ul><li>Treatment </li></ul>
  15. 15. Investigations <ul><li>Haematological & Biochemical investigations: anemia, leucocytosis, raised ESR, raised CRP, hypoalbuminemia, deranged LFT (particularly raised ALP) </li></ul><ul><li>Serological tests: more specific; tests for complement fixation, indirect haemagglutination, indirect immunofluorescence and ELISA. </li></ul><ul><li>Especially useful in non endemic areas </li></ul>
  16. 16. Investigations <ul><li>Rigid sigmoidoscopy </li></ul><ul><ul><li>Most ulcers occur in the rectosigmoid & therefore within reach of the sigmoidoscope </li></ul></ul><ul><ul><li>Shallow, flask shaped or collar stud, undermined ulcers </li></ul></ul><ul><ul><li>Biopsy/ scrapings can be taken for microscopic examination </li></ul></ul>
  17. 17. Amoebiasis <ul><li>Introduction </li></ul><ul><li>Pathogenesis </li></ul><ul><li>Clinical Features </li></ul><ul><li>Investigations </li></ul><ul><li>Imaging techniques </li></ul><ul><li>Treatment </li></ul>
  18. 18. Imaging Techniques <ul><li>Ultrasound: abscess cavity in the liver is seen as a hypo/ anechoic leson with ill defined borders; accurate; used for aspiration (diagnostic and therapeutic) </li></ul><ul><li>CT may be helpful if doubt in diagnosis </li></ul><ul><li>Barium enema </li></ul><ul><li>Colonoscopy & biopsy (to differentiate from carcinoma) </li></ul>
  19. 19. Amoebiasis <ul><li>Introduction </li></ul><ul><li>Pathogenesis </li></ul><ul><li>Clinical Features </li></ul><ul><li>Investigations </li></ul><ul><li>Imaging techniques </li></ul><ul><li>Treatment </li></ul>
  20. 20. Treatment <ul><li>Medical </li></ul><ul><ul><li>Effective </li></ul></ul><ul><ul><li>First choice </li></ul></ul><ul><ul><li>Surgery reserved for complications </li></ul></ul><ul><ul><li>Metronidazole and tinidazole: effective drugs </li></ul></ul><ul><ul><li>After treatment with metro/tinidazole; diloxanide furoate which is not effective against hepatic infestation, is used for 10 days to destroy any intestinal infestation </li></ul></ul>
  21. 21. Management… <ul><li>Aspiration </li></ul><ul><ul><li>When imminent rupture of an abscess is expected </li></ul></ul><ul><ul><li>Helps in the penetration of metronidazole; hence reduces the morbidity </li></ul></ul><ul><ul><li>Theshold for aspirating an abscess in the left lobe is lower because of its predilection for rupturing into the pericardium </li></ul></ul>
  22. 22. Management… <ul><li>Surgical </li></ul><ul><ul><li>Reserved for complications of rupture into the pleural (usually the rt side), peritoneal or pericardial cavities </li></ul></ul><ul><ul><li>Resuscitation, drainage and appropriate lavage with vigorous medical treatment – key principles </li></ul></ul><ul><ul><li>Large bowel – severe h’age, toxic megacolon are rare complications </li></ul></ul><ul><ul><ul><li>General principles of a surgical emergency apply </li></ul></ul></ul><ul><ul><ul><li>Resuscitation followed by resection of the bowel with exteriorisation </li></ul></ul></ul><ul><ul><ul><li>Vigorous supportive therapy </li></ul></ul></ul><ul><ul><ul><li>ICU care </li></ul></ul></ul>