Amoebiasis & Giardiasis PDF

A protozoal disease in which an individual infected with Entamoeba histolytica organisms.  The disease incidence is high in tropical countries & Mexico, south America and south east Asia and Africa.  The global incidence rate is 10%.  Crowded urban community are often affect...

A protozoal disease in which an individual infected with Entamoeba histolytica organisms.  The disease incidence is high in tropical countries & Mexico, south America and south east Asia and Africa.  The global incidence rate is 10%.  Crowded urban community are often affected  Two types of amoeba are found  1-Normal commensal → non pathogenic fed on bacteria. E.dispar and E.coli.  2-Invasive amoeba unlike commensal , large in size, actively moving and contains RBCs.( E.histolytica)  The disease is transmitted by ingestion of infective form of E.H cyst and not the trophozoite  Convalescents and asymptomatic carriers are the main source of infection since patients with acute dysentery pass only trophozoites and there for not infectious.  Excystation occurs in lower ileum and caecum→ cyst ( 4 nuclei ) hatches to give 4 organisms→ binary vision to give 8 trophozoites → invade tissue and cause tissue damage by necrosis.  The caecum, ascending colon and the sigmoid are affected in this order of frequency. Small intestine rarely involved.  Bowel involvement may be patchy or continuous.  The lesion begin as discrete small erosion→ micro abscesses→ extends into the mucosa and muscularis mucosa→ extends laterally to give the typical flask shape ulcers.  Blood vessels involved in the disease may thrombose or bleed into the lumen and in case of portal vein radicals→ amoebae to the liver.  Cysts of E.H are never seen in the tissues. Amoebic colitis with dysentery  IP 1-2 weeks  Variable from mild to severe dysentery.  Onset is gradual and the symptoms wax and wan over period of few weeks to months.  Typically constitional symptoms are absent and the patient looks well and ambulant (walking dysentery).  Mild →Onset is gradual, constipation rather than diarrhea and tender ceacum and colon with scanty trophozoites in the stool.  Moderate→ Patient looks unwell, passes 5-15 motions per day which is muciod blood stained ( walking dysentery and the patient doesn't looks toxic)  Severe→ patient ill and toxic with severe diarrhea > 15 motion/ day, dehydrated, with tenesmus and trophozoites are found in large number plus leucocytes. This patient may develop toxic mega colon with severe bowel ulceration and dilatation. Chronic amoebic dysentery  Characterized by vague bouts of abdominal pain, caecum and colon full of gases with periodic diarrhea and constipation.ΔΔ IBS. Amoeboma  Asymptomatic or tender abdominal mass, may present as intestinal obstruction or can be confused with cancer  Peritonitis  Bleeding  Intestinal obstruction  Intestinal intussusceptions  Stricture of colon  Brain or liver abscess  Definite Δ by demonstration of trophozoite in acute state and cyst in remission. ΔΔ of the trophozoite is E. coli.  Amoebic fluorescent antibody test is + ve in 96% of invasive amoebiasis and 100% in liver abscess  ΔΔ  Bacillary dysentery  Schiastosomiaisis  Ulcerative colitis  Diverticular disease.  Metronidazole*(Flagyl) 200 mg acting in the tissue after oral or parenteral route ( tissue ameobicidal) With only minimal luminicidal activity so cannot eradicate cysts.  Dose 800 mg TDS or 5 days.  Side effects→ dizziness, anorexia, nausea and unpleasant metallic test.  Tinidazole ( Fasigyn Protogyn )500 mg can be used as single dose 2 g.  Diloxanide furoate(Furamide) is a luminal amoebicide is helpful adjunct in clearing the cysts. For cysts passer treatment is debatable.  Result from infection of the liver by E.H trophozoite from the colon → liver by portal circulation leading to liver cell necrosis and pus formation which is very thick and chocolate brown in color.  Trophozoites are found in the pus or the wall of the abscess but cyst are never found.  50% of patients gave history of dysentery.  95% seen after 5 months of infection.  Single abscess is common but can be multiple  87% in Rt lobe, 8% in Lt lobe and 5% both.  Onset may be acute or gradual and the most important feature is fever (85%) which is typically remittent( swinging) with prominent evening rise in temperature associated with rigors and very heavy profuse sweating.  Rt hypochodrium pain in > 80% of cases sharp in nature and increase with respiration or movements.  Liver is enlarged in (90%) of cases with costal tenderness which is almost diagnostic of ALA.  Plugging of Rt chest with raised upper liver dullness.  Anemia is rare and jaundice is not characteristic feature.  Signs pleural effusion or rub. Investigations  Chest x-ray→ effusion or raised Rt dome of the diaphragm.  X-ray abdomen → calcifications.  TWBC ↑15.000-30.000.  ESR invariably raised and normal ESR against the diagnosis.  U/S and CT abdomen.  Aspiration and centrifugation→ looking or trophozoites 80% of cases is + ve.  Treatment→ admission and abscess aspiration if large.  Metronidazole 800 mg TDS for 10 days + Chloroquine tabs 4 tabs initially then 2 tabs after 6 hours then 2 tabs daily for 3 weeks  Tinidazole 2g daily for 3 days + chloroquine as above. Act on the followings  1-Amoebiasis  2-Giardia lambia  3-Trichomonous vaginalis  4-Anaerobic activity.  5-Partial effect against lieshmaniasis.  The drug given orally well absorped with high concentration in the seminal and vaginal secretion and cross the blood brain barrier.  70% of the drug excreted unchanged in the urine. Its inhibitor to hepatic enzymes.  Amoebiasis→ useful against tissue type and also amoeboma and also has good effects against luminal amoebiasis.  Tabs 200mg Flagyl & 250mg local production.  Amoebiasis 800mg 3 times daily for 7 days and for liver extended up to 10 days adding with it chloroquine.  Giardiasis 200 mg 3 times daily for 5 days.  Its best drug for anaerobes in very ill patients with sepsis.  Also given in Vincent gingivitis.  In patients with prehepatic encephalopathy to clear the bowel from bacteria.  Sites effects  Nausea and vomiting and may severe enough to stop the drug.  Sharp metallic test  Reversible agranulocytosis.  Epidemiology  It occurs worldwide in area of poor hygien and sanitation  Humans are main reservoir  Infections are acquered through drinking water contaminated with Giardia cysts or cntaminated food by directfeac-oral spread  Cysts can survive outside the body for weeks  Life cycle  Giardia lamblia is a flagellte protozoon ihabits upper small bowel  Trophozoite stage is flattened pear-shape,has 4 pairs of flagella for locomotion, multiplies by binary fission  Trophozoite adherence disrupts intestinal border---inflammatiom leading secretion of fluid and electrolytes and damage to enterocytes Trophozoites encyst as they pass distally Cyst –oval,contains4 small nuclei,infective as soon as passed ,when swallowed by new host-excyst in the upperGIT and liberate trophozoites  C\P  I P—7-10 ds but may extended to many months  A symtomatic  Diarrhoea,abdominal pain,bloating ass with malaise  D\ D  Wide range of acute or chronic diarrhoea  Coeliac disease  Intestinal TB  MalnutritionSmall bowel lymphoma  Ivestigations  stool ex-cysts ,trophozoites  ELIZA  FAT  Dudenai fluid aspiration and microscopy   Small bowel biopsy  Management  Oral metronidazole 400 mg 3 times daily for 5 ds or2 g\d for 3 ds,paediatric doses are 15mg\kg\d in 3 devided doses or 40 mg \kg\d for 3ds  Tinidazole sngle oral dose of 2g for adults and 50mg\kg (max 2g) for children  Albendazole 400mg\d for 5ds  Nitazoxanide(HIV pt)  Failure of response:poor compliance,reinfection,antmicrobial resistance or immunodificiency  Persisting symtoms: lactose intolerance  Prvention:improving hygiene,sanitation and access to safe water