Dr. RAAFAT MOHAMED

*How to classify parasites taxonomically? All parasites belonging to the Animal Kingdom are classified under: Phylumشعبة Classفصيلة Order رتبة Family عائلة جنس Genus (written in italics) نوع Species (written in italics) e.g. Entamoeba histolytica is a protozoon that belongs to phylum protozoa and class Rhizopoda. Entamoeba is the genus and histolytica is the species and they have to be written in italics or underlined. Dr. RAAFAT MOHAMED

MEDICAL PROTOZOOLOGY General Characters: ❶ Unicellular ❷ Capable of performing all functions. ❸ consists of a mass of protoplasm differentiated into outer Ectoplasm & inner Endoplasm. ❸ Ectoplasm is concerned with --- Locomotion / Nutrition / Excretion & Cyst formation . ❹ Endoplasm is concerned with --- Metabolism & Reproduction. Includes the following structures: nucleus / food vacuoles / contractile vacuoles . ❺ Locomotion --- by pseudopodia / flagella or cilia . ❻ Nutrition --- by diffusion of soluble particles / pseudopodia or cytostome ❼ Excretion --- by diffusion or contractile vacuoles . ❽ Secretion --- digestive enzymes / toxins / antigenic substance & material for cyst wall formation . Dr. RAAFAT MOHAMED

Dr. RAAFAT MOHAMED

cytoplasm forming MANY DAUGHTER CELLS (Schizogony). • Sexual: ❾ Reproduction: • Asexual: *Simple binary fission: The nucleus & cytoplasm divide into two equal parts forming TWO NEW CELLS.   *Multiple fission: The nucleus divides into several parts followed by division of the cytoplasm forming MANY DAUGHTER CELLS (Schizogony). • Sexual: *Syngamy: Formation & union of male & female gametes to produce Zygote (Gametogony & Sporogony). *(Conjugation: Exchange of nuclear material between two organisms . Dr. RAAFAT MOHAMED

Liver Schizogony Blood Schizogony Gametogony Sporogony (Schizont containing merozoites) Blood Schizogony Gametogony (formation of ♂ & ♀ gametes) Sporogony Dr. RAAFAT MOHAMED

CLASSIFICATION OF PROTOZOA RHIZOPODA CLASS CILIATA CLASS ZOOMASTIGOPHORA CLASS SPOROZOA (Flagellates) Plasmodium spp. Toxoplasma gondii Cryptosporidium parvum. Isospora. Cyclospora Entamoeba histolytica E. Hartmani E. Dispar E.coli Balantidium coli Giardia lamblia Trichomonas vaginalis Leishmania spp. Trypanosoma spp. General characters: General characters: General characters General characters 1- move by flagella. 2- multiply by simple binary fission. 1- move by pseudopodia. 2- inhabit the colon of man 3- multiply asexually by binary fission. 4-Encyst in the large intestine forming cyst. 5- E. histolytica is the only pathogenic member. 1- move by cilia. 2- inhabit the colon of man 3- multiply by binary fission & conjugation. 4-Encyst in the large intestine forming cyst. 1- No organs for locomotion. 2- Alternate generations (sexual & Asexual) in the same or diff. hosts. Intestinal flagellates Urogenital flagellates Uncertain Classification Free-living amoeba: Naeglaria fowleri & Acanthamoeba are potentially pathogenic amoeba Haemoflagellates Pneumocystis carnii Microsprodia . Dr. RAAFAT MOHAMED

Unicellular organisms Protozoa Unicellular organisms Pathogenic protozoa: Protozoa that exist in human body and cause harm to infected human. Commensal protozoa: Protozoa that exist human body but does not cause harm to infected human. Opportunistic protozoa: weak protozoa that cause minimal effect to infected healthy man but has severe effect on infected immunocompromized man. Potentially pathogenic free-living protozoa: free-living in nature away from man but some of them may cause disease if they enter the human body by certain route. Dr. RAAFAT MOHAMED

Opportunistic protozoa Intestinal Protozoa Entamoeba histolytica (large intestine). Balantidium coli (large intestine). Giardia lamblia (small intestine). Cryptosporidium parvum (small intestine). Cyclospora cayetanensis (small intestine). Isospora belli (small intestine). Microsporidia (small intestine). In large intestine: dysentery. In small intestine: diarrhoea. Pathogenic protozoa Opportunistic protozoa Dr. RAAFAT MOHAMED

INTRODUCTION TO DIARRHOEA & DYSENTRY Increase in frequency / fluidity / volume of bowel motions. May be defined in a clinical sense as change in bowl habits • Results from excessive fluid secretion - diminished absorption (fluids / solutes / electrolytes) - hypermotility (propulsive activity) secondary to intestinal irritation. Decreased intestinal motility may also produce diarrhea as it promotes stasis & bacterial growth. DYSENTRY Painful - frequent evacuation of small quantities of stool largely composed of blood & mucus. Large volume diarrhea implies hypersecretion common for small intestine. Small volume diarrhea implies hypermotility common for large bowel. Character of stool predicts the site involved: Small bowl involvement (enteritis) the stool is of large volume / watery / devoid of pus or blood (Cryptosporidium etc). *Large bowel involvement (colitis) the stool is often of small volume / contains blood / mucus / may be associated with tenesmus (E.histolytica). » Traveler's diarrhea 'new arrivals to foreign countries' is acquired by ingestion of contaminated food or water. Dr. RAAFAT MOHAMED

Dr. RAAFAT MOHAMED