ByDR: MUHAMMED NAJEEB Faculty OfCommunity Medicine & Public Health Sciences LUMHS,Jamshoro,Sind, PAKISTAN email@example.com
Microbiology• Branch of Biology dealing especially with Microscopic forms of life
• Micro organism• An organism too tiny to be seen by naked eye.
Parasitology science that deals with organisms that seek shelterand nourishment on or within other living organisms.
ENTOMOLOGY – science that deals witharthropods of medical importance• Helmintology: – helminths / worms
MicroorganismProkaryotes Euokaryotes Non –cellularBacteria Parasite Viruses Fungi Prion Proteins
• 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 )
A. PROTOZOA (Unicellular organism) AMOEBA SPOROZOA FLAGELLETS PlasmodiumEntamoeba 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
STAGES IN LIFE CYCLE OF PROTOZOAInfective stage: – Cysts, Oocysts, Sporozoites, Spores- dormant stages and ResistantVegetative stage: – Trophozoites – take nourishmentfrom the hosts; invasive causing pathology; most are motile.
LUMINAL PROTOZOA- COLONIZE THE LUMINAL ORGANS- intestinal tract and the urogenital tract- TWO STAGES – I ) Trophozoite (vegetatative / invasive) II) Cyst (infective)
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.
Helminthes Eggs / Ova• Ancylostoma duodenale Hymenolopis Nana• Ascaris lumbricoids Trichus Trichuria• Enterobius Vermiculus• T. saginata• T. solium• Cysticercosis• E. Granulosus• Diphylobothrium latum
Cysts• Entamoeba histolytica ( single cell)• Giardia lamblia• Giardia Intestinals• Entameba Coli ( Non pathogenic )• Endolimax Nana ( = = )• Chilomastix Mesnili• Iodamoeba Butschli ( non pathog )
The Organism4 species of Entamoeba: Nonpathogenic: Pathogenic: - E. dispar, - E.histolytica – E. coli, – E. hartmanni
Amoebiasis Parasitic infection caused by the protozoan Entamoeba histolytica2nd to Malaria as protozoan cause of death worldwide 1
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
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.
FrequencyRegion Infection Diasease DeathsAfrica 85 millions 10 millions 10-30 thousandsAsia 300 millions 20-30 25-50 millions thousandsEurope 20 millions 100 Minimum thousandsAmerica 95 millions 10 millions 10-30 thousandsTotals 650 millions 45-50 40-110 millions thousands
2. Causative AgentEntamoeba histolytica 2
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
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
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.
3. ReservoirInfected Person OR Carrier
4. Mode of TransmissionIngestion of mature cyst through contaminated food or water TRANSMISSION: Faecal ---- oral route Contaminated water Contaminated meals Street vendors of meal anal-oral contact
5. SUSCEPTIBILITY1. 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
6. Incubation Period -Variable-Probably varies from few days --- weeks.
7.Period of CommunicabilityVaries from several days or months to several years
CLINICAL FEATURESINTESTINAL AMOEBIASIS: AMOEBIC LIVER ABSCESS:Mild Abdominal discomfort Onset- InsidiousPain Pain & tenderness in Rt: hypochondriumIrregular bouts of diarrhoea (Withor without blood & mucus)Fever may be present Fever High grade (with Nausea, Anorexia & VomitingAbdomen tenderLiver slightly enlarged & tender Usually there is single abscess In case of Rupture going toIn Fulminant colitis- All features Peritoneum, Pleural cavity &are Sudden & severe pericardial cavity.
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.
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)
TREATMENT(A) Luminal Amoebic ides: Diloxanide Furoate 500 mg tid x 10 days Idoquinol & Paramomycin(B) Tissue Amoebic ides: Metronidazole Tinidazole Secnidazolefollowed by diloxanide furoate
Prevention & ControlA. HEALTH EDUCATION:-reduce fecal-oral transmissionB. 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
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