This document discusses amoebiasis, an intestinal infection caused by the protozoan Entamoeba histolytica. About 90% of infections are asymptomatic, while the remaining 10% can cause a spectrum of clinical syndromes from asymptomatic to severe dysentery or liver abscesses. The life cycle and virulence factors of E. histolytica are described. Amoebiasis is typically acquired through ingestion of contaminated food or water and has a 1-4 week incubation period. Clinical manifestations range from intestinal symptoms to extra-intestinal infections of the liver or other organs. Diagnosis involves microscopic identification of cysts or trophozoites in stool samples. Treatment focuses on luminal and systemic amebicides depending
2. AMOEBIASIS
AMOEBIASIS IS AN INFECTION WITH THE INTESTINAL
PROTOZOA ENTAMOEBA HISTOLYTICA.
ABOUT 90% OF INFECTIONS ARE ASYMPTOMATIC
REMAINING 10% PRODUCE A SPECTRUM OF CLINICAL
SYNDROMES
RANGING FROM -
ASYMPTOMATIC DYSENTERY TO ABSCESSES OF LIVER
OR OTHER ORGANS
3. AGENTS
• ENTAMOEBA HISTOLYTICA
TROPHOZOITES
• 10 - 60 ΜM IN D
• CYTOPLASM – # OUTER CLEAR ECTOPLASM
# INNER GRANULAR ENDOPLASM
# FOOD VACUOLES WITH RBCS, LEUKOCYTES
& TISSUE
DEBRIS
• MOTILE BY PSEUDOPODIAL EXTENSIONS
• NUCLEUS WITH CENTRAL KARYOSOME, SURROUNDED BY
DELICATE MEMBRANE LINED WITH CHROMATIN GRANULES
7. CLINICAL FEATURES
Symptoms
stomach Pain,Abdominal cramping
Diarrhoea and / or Dysentery
Weight Loss
Cough
Dyspnoea
Physical findings
Localized tenderness
Enlarged Liver
Fever
Rales,rhonchi
Localized intercostal tenderness
Epigastric tenderness
Jaundice
8. INCUBATION PERIOD
• 1- 4 WEEKS
Faeco -oral route
• contaminated water and food
• direct hand to mouth
Agency of flies, cockroaches, rats, etc.
Sexual contact via oro -rectal route
9. RISK FACTORS
• PEOPLE WHO HAVE TRAVELLED TO TROPICAL LOCATIONS WITH POOR
SANITATION
• IMMIGRANTS FROM TROPICAL COUNTRIES
• TRAVELLERS TO DEVELOPING COUNTRIES
• PEOPLE WHO LIVE IN INSTITUTIONS THAT HAVE POOR SANITARY
CONDITIONS(PRISON)
• PEOPLE WITH COMPROMISED IMMUNE SYSTEM OR HIV-POSITIVE PATIENTS
• MEN WHO HAVE SEX WITH MEN
10. HOST FACTOR CONTRIBUTIONS
• SEVERAL FACTORS CONTRIBUTE TO INFLUENCE INFECTION
1 STRESS
2 MALNUTRITION
3 ALCOHOLISM
4 CORTICOSTERIOD THERAPY
5 IMMUNODEFICIENCY
6 ALTERNATION OF BACTERIAL FLORA
11. VIRULENCE FACTORS
• TROPHOZOITES OF E.HISTOLYTICA INTERACT WITH HOST
THROUGH A SERIES OF STEPS
1 ADHESION OF TARGET CELL, PHAGOCYTOSIS AND CYTOPATHIC
EFFECT
2 E.HISTOLYTICA INDUCES BOTH HUMORAL AND CELL MEDIATED
IMMUNE RESPONSES.
3 VIRULENCE FACTORS – IN MANY CIRCUMSTANCES LUMEN
DWELLING AMOEBA MAY BE ASYMPTOMATIC
4 CAUSES DISEASE ONLY WHEN INVADE THE INTESTINE
5 VIRULENCE IS ASSOCIATED WITH SECRETION OF CYSTEINE
PROTENIASE WHICH ASSISTS THE ORGANISM IN DIGESTING THE
13. CLINICAL SPECTRUM
• MOST COMMON TYPE OF AMOEBIC INFECTION IS
ASYMPTOMATIC CYST PASSAGE
• INTESTINAL AMOEBIASIS – ABDOMINAL CRAMPS WITH
MILD DIARRHOEA TO COLITIS AND DYSENTRY
• EXTRA-INTESTINAL AMOEBIASIS – AMOEBIC LIVER
ABCESS, RARELY LUNGS, SKIN, GENITALIA AND CNS ARE
AFFECTED
• AMOEBOMA – INFLAMMATORY AND EDEMATOUS
REACTION AROUND TROPHOZOITES
14. ASYMPTOMATIC CARRIERS
• 90% WITHOUT SYMPTOMS
• DOES NOT DAMAGE LUMEN
flask shaped ulcers superficial or deep
abd pain (tenesmus)
diarrhoea, dysentery, fever
peri-anal ulcers
<0.5%
severely ill with high fever
intestinal bleeding, perforation
paralytic ileus
CFR-40%
16. AMOEBOMA
• PSEUDOTUMORAL LESION
• NECROSIS, EDEMA AND INFLAMMATORY THICKENING OF MUCOSA
AND SUBMUCOSA OF INTESTINAL WALL
• 1% OF CASES
• PALPABLE MASS WITH TROPHOZOITES
• ALWAYS COEXISTS WITH ULCERATION
• SINGLE, RARELY MULTIPLE IN DIFFERENT PARTS OF COLON, ON
SKIN AT SITE OF ALA ASPIRATION
17.
18. This is the most common extra intestinal
form of invasive amoebiasis.
Adults > children ( 10 : 1 )
Male > female
20 % with past history of dysentery
19. PATHOGENESIS
Journey of E. Histolytica to the Liver
1. Direct Extension from the Gut to the Liver
2. Via the Lymphatics
3. Along the portal stream
Infarction – Enzymatic Dissolution
22. LABORATORY FINDINGS
Normocytic Normochromic anaemia
Leucocytosis -> 10×10 9 / L
ESR
Stool Cyst or Vegetative form of E . Histolytica
LFT Bilirubin
Transaminases more than 50 %
Alkaline phosphatase more than 75 %
24. According to the site where the
drug is effective, the amebicidal
drugs are classified as:
• Luminal amebicides (Act on
parasite in the lumen of bowel)-
diloxanidefuroate,
Iodoquinol,paromomycin
• Systemic amebicides (Against
amebas in intestinal wall & liver)
-chloroquine,emetine,dehydro
emetine
• Mixed amebicides ( Against
Classification of amebicidal drugs
25. PREVENTION
Health Education
Improved water supply
Chlorination – not effective
Amoebic cysts
Destroyed by
200 parts / 106 of Iodine 5 – 10 acetic acid.
Heating > 680C
Removed by
sand filtration
Boling for 10 minutes kill the cysts
