3 Entamoeba histolytica: a protozoan parasite, cause amebiasispeople worldwide suffer from E. histolytica infectionamebic dysentery and amebic liver abscess kill at leastindividuals yearlythe second leading cause of death among parasitic diseases
4 Giardia lambila: giardiasis or ‘‘traveler’s diarrhea’’ a major cause of diarrheal outbreaks from contaminatedwater suppliesresides small intestine ( duodenum), gallbladder, causinggiardiasis or ‘‘traveler’s diarrhea’’common in children with younger age, with a high incidenceamong tourists & homosexual male,opportunistic protozoa (parasite)
5 Case study I Physical Examination: A 36 year old man presented to the emergency department ofa general hospital with 10 day history of intermittent diarrheaand tenesmus, with blood and mucus visible in the stool.He had just returned from a working trip to India, where hehad visited a rural town in the last week of his trip.Physical Examination:VS: T 38.8 C, P96/min, R 16/min, BP 130/80 mmHgPE: Ill- appearing male in mild distress; abdominalexam revealed mild diffuse tenderness, and rectalexam was positive for blood
6 Microscopic exam as following Laboratory studiesWBC: /l Differential: 72% PMNs 20% lymphImagingSigmoidoscopic examination revealed multiple smallhemorrhagic areas with ulcersMicroscopic exam as following
7 Case study II Physical Examination: A 25 year old man presented to a hospital clinic with a 2 weekhistory of sustained diarrhea (three to five bowel movement per day),nausea, flatulence, and lack of appetite. He described his diarrheaas initially watery, and then greasy and foul smelling. He added thathe had a bloating sensation. He did not have fever or chills.The patient had been in good health. Four weeks previous to seeinghis physician, he had visited a rural town for several days.Physical Examination:VS: T 37C, P82/min, R 14min, BP 134/80 mmHgPE: abdomen was distened and mildly tender,no hepatosplenomegaly. Rectal exam was normal.
8 Laboratory studies:WBC: /l Differential: normalSerum chemistries: BUN 22 mg/dl creatinine 1.2 mg/dlMicroscopic exam and duodenal aspirate exam as following
9 Brain abscess Lung abscess Lung abscess Live abscess Large intestine Inhabits inlarge intestineLarge intestineulcers
10 trophozites trophozites cyst trophozites metastasis Cysts or QuadrinucleateCyststrophozitescysttrophozites
11 Pathogenesis & Symptoms ingestion of the quadrinucleate cyst of E. histolytica fromfecally contaminated food or water initiates infectioninfection also occurs through direct person-to- personcontactinhabits the large intestine, invade the mucosal crypts,feed RBCs & form ulcers
12 … Pathogenic factors: Lectin adherence to host cells, in signal, amoebapores form pores in host cell membranescysteine proteinases: cytopathic for host tissuecell killingphagocytosisinvasion…
14 amoebic invasion through the mucosa and into the submucosal tissues is the hallmark of amoebic colitisthe lateral extension through the submucosal tissuesgives rise to the classic flask-shaped ulcer of amoebiasisor amebomaamebic liver abscess is the most common manifestationof extrainintestinal diseasethe most serious complication of amoebic liver abscessare rupture
15 Symptoms asymptomatic/Carrier state: the amoebae may reproduce but the patient shows no clinical symptomssymptomatic intestinal amebiasis: may complain of morespecific symptoms, including diarrhea, abdominal painand chronic weight losssymptomatic extraintestinal amebiasis: the formation ofan abscess in the right lobe of the liver , trophozoitesextension through the diaphragm, causing amebic pneumonitis(abscess) brain abscess
17 Diagnosis Microscopic examination a direct saline wet mount------trophozoites, cystfrom pus trophozoites onlyiodine stain cystconcentration techniquespermanent stained
18 E.histolytica E. coli size 10-40 m 20-50 m Trophozoite pseudopodium more transparent less transparentmovement active sluggishinclusion RBC no RBCkaryosome centrol, small asymmetricalsize m mCyst No. of nucleichromatoid rounded ends splintered ends
19 Immunologic techniques monoclonal antibody detected antigen from stool or pusdetected specific antibodies by antigenELISA, IFA, IHA
20 PCR techniques 16S rRNA, Prx gene … differentiation of E.histolytica from thecommensals E. dispar is not possible bymorphology but requires the use of species-specific Mab or PCR techniques
23 Epidemiologygenerally higher in the tropics, subtropics, and poor sanitation,poor nutrition (for example)a high-carbohydrate diet, alcoholism, genetic makeup, bacteriainfection of the intestine, local injury to the colonic mucosathe true prevalence of E. histolytica is perhaps closer to 1%to 5% worldwide
24 the realisation that E. histolytica & E.dispar are morphologically identical species with remarkable different physiological andpathogical characteristics has impacted on all aspects but notablyon the epidemiologyno sexual preference for intestinal amoebiasis, but amebic liverabscess is 3 to 10 times more common in menthe high-risk group for amebiasis include travelers,institutionalized mental patients, promiscuous homonsexual
25 a severe form of infection in neonates, pregnant women, women in the postpartum period, immunocompromised patients, patientswith malnutrition or malignancyingestion of the infective cyst, through hand – mouthcontamination & food /water contaminationflies & cockroaches may also serve as vectors of E. histolytica
26 Treatment & Prevention Whenever possible, a laboratory diagnosis of E.histolyticainfection, unless confirmed by visualization of ingested RBCsin the trophozoite, should be substantiated by (1) presence ofRBCs in stool (2) serum antibody titer (3) stool E.histolyticaantigen titerInfection Drug and DosageAsymptomatic intestinal paromomycin 25-30mg/kg/D in 3amoebiasis divided does for 7 daysmetronidazole 750 mg 3 time dailyfor 10 daysAmebic dysentery and liver abscess metronidazole 750 mg 3 time dailyAmeboma for 10 days follow by paromomycin
27 Metronidazole and tinidazole are first-line agents in the treatment of acute amebic colitis and amebic liver abscesstherapeutic aspiration of an amebic liver abscess is occasionallyrequired as an adjunct to antiparasitic therapythe prevention of amebic infection starts with avoidance offecally contaminated food and water.The high incidence of amebiasis in recent community-basedstudies suggests that an effective vaccine would improvepublic health.
28 Naegleria Free-living amoebae --- Naegleria, Acanthamoeba, Balamuthia Human beings usually acquire Naegleria infection from swimmingin the contaminated water or contaminated pipelineNaegleria fowleri caused primary amebic meningoencephalitis(PAM), an acute, suppurative infection of the brain and meninges.
35 a wet mount of cerebrospinal fluid (CSF) is usually more usefuldetection of motile organisms is a diagnostic finding, but theymust distinguished from motile leukocytesto detected of parasites a culture is in orderDNA-based or Mab-based technique may also help fordifference diagnosis
36 the drug of choice for the treatment of PAM is amphotericin B the treatment of GAE has not been standardizedthe treatment of AK includes systemic antifungal drugs,tropical antiamebic eye drops, and surgical debridementof the ocular lesions
37 Giardia lambliaTrophozoites of Giardia are fund in the upper part of thesmall intestine ( duodenum), gallbladder, causinggiardiasis or ‘tourist diarrheaGiardia is worldwide in distributionGiardia lamblia is considered to be one of the major cause ofparasitic diarrheaHuman infection mainly results from ingestion mature cyst-contaminated food or water
38 excystation occurs in the upper regions of the small intestine, where the trophozoite resides & multiplies by binary fissiontrophozoites pass through the digestive tract, encyst in thecolon & transformed into cysts, pass in the fecescysts with highly resistant
40 Infections with G. lamblia are often completely asymptomatic Extensive ulceration of mucosa may occur in heavy infectionsymptomatic infection may cause intestinal disorders, mostcommonly diarrhea------Vit A & soluble fat, nausea,flatulence, weight lossa direct saline wet mount------trophozoites, cystiodine stain cystconcentration techniques
41 duodenal aspiration entero test -----an alternative & more satisfactory technique for trophozoites detection
43 DNA-based or Mab-based technique may also help for difference diagnosiscommon in children 6-10 years of age,with a high incidence among tourists &homosexual male,opportunistic protozoa (parasite)Metronidazole is most common drugin treatment (Tinidazole Paromomycin)
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