This document provides information on microbiology and parasitology. It discusses microorganisms like bacteria, parasites, fungi and viruses. It also describes different types of parasites including protozoa and helminths. Specifically, it summarizes the life cycle, symptoms, diagnosis and treatment of Entamoeba histolytica, which causes amoebiasis. It notes that amoebiasis is common in developing countries where sanitation is poor and transmission occurs through the fecal-oral route by ingesting cysts from contaminated food or water. Stool examination is used to diagnose by identifying trophozoites or cysts of E. histolytica.

2. By
DR: MUHAMMED NAJEEB
Faculty Of
Community Medicine &
Public Health Sciences LUMHS,
Jamshoro,Sind, PAKISTAN
mnajeeb80@gmail.com

3. Microbiology
• Branch of Biology
dealing especially
with Microscopic forms of life

4. • Micro organism
• An organism too tiny to be seen by naked
eye.

5. Parasitology
science that deals with organisms that seek shelter
and nourishment on or within other living organisms.

6. ENTOMOLOGY – science that deals with
arthropods of medical importance
• Helmintology: – helminths / worms

7. Microorganism
Prokaryotes Euokaryotes Non –cellular
Bacteria Parasite Viruses
Fungi Prion
Proteins

8. • A. PROTOZOA (Unicellular organism)
4 types according types of organs for locomotion
Amoebae - pseudopodia;
Flagellates - flagella;
Ciliates - cilia and
Sporozoa – absence of locomototion
B. METOZOA ( Multicellular organism )

9. A. PROTOZOA (Unicellular organism)
AMOEBA SPOROZOA FLAGELLETS
Plasmodium
Entamoeba Histolytica 1. Leishmenia
Plasmodium vivax
(Eat tissue) L .Donovani
Plasmodium ovale L. Tropica
L. Mexicana
Plasmodium malariae
L. Brasiliensis
Plasmodium falciparum
2. Intest: Flagellets
Giardia Lamblia
3. Ciliate:
Balantadium coli

10. B. METOZOA ( Multicellular organism )
Platyhelminths Nemathelminths
Plate helminthes
Tap worm R.Worm Skin worm
Cestodes Trematodes
Trematodes Intes: Nematodes Somatic
/ Flukes Nematodes
T. saginata
(Beef) Schist soma Ancylostoma
Hook.w
T. solium mansoni duodenale
-W.Bancrofti
(Pork) Schist soma
Hymenolepis nana japonicum -Loa Loa
R. worm Ascaris
lumbricoids -Dranculus
E. Granulosus Schist soma
haematobium Enterobius medinesis
Pin /
Diphylobothrium
Thread .w Vermiculus (Guinia .W)
latum
(Fish) (Anal irritation)
-Strangloides
Stercoralis

12. STAGES IN LIFE CYCLE OF PROTOZOA
Infective stage: –
Cysts, Oocysts, Sporozoites, Spores-
dormant stages and Resistant
Vegetative stage: –
Trophozoites – take nourishment
from the hosts; invasive causing pathology;
most are motile.

13. LUMINAL PROTOZOA
- COLONIZE THE LUMINAL ORGANS-
intestinal tract and the urogenital tract
- TWO STAGES – I ) Trophozoite (vegetatative / invasive)
II) Cyst (infective)

14. Entamoeba histolytica
(AMOEBIASIS)
AMEBIC DYSENTRY;
AMOEBIC LIVER ABSCESS

15. Life cycle:
inhabit the large intestine; the cyst is the
infective stage. On ingestion – excyst into
amoebulae –
trophozoites which is the vegitative stage –
invade the mucosa to absorb nourishment
from tissues dissolved by its cytolytic enzymes
and also ingest RBCs.

16. Helminthes Eggs / Ova
• Ancylostoma duodenale
Hymenolopis Nana
• Ascaris lumbricoids Trichus Trichuria
• Enterobius Vermiculus
• T. saginata
• T. solium
• Cysticercosis
• E. Granulosus
•
Diphylobothrium latum

17. Cysts
• Entamoeba histolytica ( single cell)
• Giardia lamblia
• Giardia Intestinals
• Entameba Coli ( Non pathogenic )
• Endolimax Nana ( = = )
• Chilomastix Mesnili
• Iodamoeba Butschli ( non pathog )

18. AMOEBIASIS

19. • Amebic Dysentery Amebic hepatitis
• ( Amoebic Liver Abscess )

20. AMOEBIASIS

21. The Organism
4 species of Entamoeba:
Nonpathogenic: Pathogenic:
- E. dispar, -
E.histolytica
– E. coli,
– E. hartmanni

22. Amoebiasis
Parasitic infection caused by the protozoan
Entamoeba histolytica
2nd to Malaria as protozoan cause of death
worldwide
1

23. Epidemiology
Helminthes, or parasitic worms, including
• Nematodes,
• Flukes and
• Tapeworms,
collectively infect approximately 2 billion people worldwide,
or about a third of the world population.
The majority of infected people reside in developing countries in
tropical & temperate climate zones,
where helminthes constitute a significant public health concern

24. Epidemiology
. Increased prevalence in developing countries (up to
25%)
• Principal frequency in countries with a deficiency
in sanitary conditions
• Poorest areasMost infected people.
• perhaps 90%, are asymptomatic, but this disease
has the potential to make the sufferer dangerously
ill.

25. Frequency
Region Infection Diasease Deaths
Africa 85 millions 10 millions 10-30
thousands
Asia 300 millions 20-30 25-50
millions thousands
Europe 20 millions 100 Minimum
thousands
America 95 millions 10 millions 10-30
thousands
Totals 650 millions 45-50 40-110
millions thousands

26. 2. Causative Agent
Entamoeba histolytica
2

28. The Life Cycle
• 1. Cyst Stage
• Infective stage
• Survive from –4 to 40 Celsius
• Size – 12mm
• Quadrinucleated
• Ingested by contact with fecally
contaminated food
• Passes through stomach, excysts in
lower small bowel.
• Metacystic amoeba with four cystic
nuclei from each cyst
• 8 Small trophozoites from each
metacystic amoeba
• Trophozoites carried to cecum

29. LIFE CYCLE
Amebiasis is an
infection of the intestine, liver, or other tissues
by pathogenic amebas
(protozoan parasites).
E. histolytica is found primarily in
the colon where it can live as a
non-pathogenic commensal or
invade the intestinal mucosa
(green).
The ameba can metastasize to
other organs via a
hematogenous route (purple);
primarily involving the portal
vein and liver. The ameba can
also spread via a direct
expansion (blue) causing a
pulmonary infection, cutaneous
lesions or perianal ulcers

32. The Pathogenesis
• Area most commonly • Flask-shaped ulcers
involved = Cecum, then
Recto-sigmoid area
• May invade blood vessels
causing thrombosis,
infarction and
dissemination via portal
circulation to liver and
• extra-intestinal sites eg.
brain, pleura, pericardium
and genito-urinary system.

33. 3. Reservoir
Infected Person OR
Carrier

34. 4. Mode of Transmission
Ingestion of mature cyst through
contaminated food or water
TRANSMISSION:
Faecal ---- oral route
Contaminated water
Contaminated meals
Street vendors of meal
anal-oral contact

35. 5. SUSCEPTIBILITY
1. Age: Any age (Young Adults, rarely below the age of 5 Years.)
2. Sex : Both
3. Immunity: An attack of the dis: does not confer
immunity. (Relapses are common)
4. Env: Factors:
– Poor education
– Poverty and overcrowding
– Unsanitary conditions
– HIV infection 5

36. 6. Incubation Period
-Variable
-Probably varies from few days --- weeks.

37. 7.Period of Communicability
Varies from several days or months to
several years

38. CLINICAL FEATURES
INTESTINAL AMOEBIASIS: AMOEBIC LIVER ABSCESS:
Mild Abdominal discomfort Onset- Insidious
Pain Pain & tenderness in Rt:
hypochondrium
Irregular bouts of diarrhoea (With
or without blood & mucus)
Fever may be present Fever High grade (with Nausea,
Anorexia & Vomiting
Abdomen tender
Liver slightly enlarged & tender Usually there is single abscess
In case of Rupture going to
In Fulminant colitis- All features Peritoneum, Pleural cavity &
are Sudden & severe pericardial cavity.

40. METHODS OF DIAGNOSIS
• fresh or suitably preserved faecal specimens
• smears of aspirates or scrapings obtained by proctoscopy
• aspirates of abscesses or other tissue specimens
1. Exam: of Stool: (confirmed by trophozoites or cysts)
• Macroscopic: offensive, dark brown semi fluid, mixed
• with blood & mucus
• Microscopic Exam: ( Fresh sample, 3 types of mounts)
• (Trophozoites & cyst)
• 1. With Normal saline- motile Trophozoites
• 2. With Iodine + saline – Helps to distinguish from other parasites
• 3. With Methylene blue – only stain leukocytes.

41. 2. Exam: of Blood: moderate Leukocytosis
Serological Tests: (often Negative)
(when stool exam: -ve)
(IHA indirect haemagglutination &
EIA enzyme immunoassays Positive in extra-intestinal disease
such as liver abscesses)
3. X-ray, ultrasound and CT scans
(also useful in the identification of amoebic abscesses)
4. Liver Aspirate:
• Chocolate color, thick in consistency Trophozoites from material from
wall of abscess (after 4-5 days)

42. TREATMENT
(A) Luminal Amoebic ides:
Diloxanide Furoate
500 mg tid x 10 days
Idoquinol &
Paramomycin
(B) Tissue Amoebic ides:
Metronidazole
Tinidazole
Secnidazole
followed by diloxanide furoate

43. Prevention & Control
A. HEALTH EDUCATION:-
reduce fecal-oral transmission
B. SANITATION:-
Clean measures in & around the houses.
Sate disposal of human excreta.
Hand washing after defecation and before meals.
Use of sanitary latrines.
C. WATER SUPPLY:-
Safe water supply.
Protection of water from faecal contamination.
Water filtration or boiling (more effective than chlorination)
D. FOOD HYGIENE:-
Protection of food against faecal contamination.
Thorough washing of raw vegetables. (By full strength of vinegar)
Vaccination:
– None available currently
– Prototype subunit vaccines based on the Gal/Gal Nac - lectin under
study

44. The Complications
• Complications of Intestinal amoebiasis:
– Fulminant Amoebic Colitis with Perforation
• May have a mortality rate of up to 50%
• Children less than 2 yrs at increased risk of
perforation
– Massive Haemorrhage
– amoeboma
– amoebic Stricture
• Resulting from fibrosis of intestinal wall

45. • END