Protozoa Characteristics and Reproduction

Characteristics of Protozoa

• Unicellular organisms
• Chemoheterotrophs: obtain energy by breaking down organic matter
• Possess structures specialized for food ingestion
• Reproduce through various modes

Types of Reproduction

• Asexual reproduction includes fission, budding, and schizogony (rapid production of trophozoites)
• Sexual reproduction occurs via conjugation

Trophozoites

• Refers to any stage where protozoa ingest food, primarily the motile form
• Motility achieved through structures like pseudopods, cilia, or flagella

Protozoa Cysts

• Non-motile stage, often the infective form, encased in a protective membrane
• Contain a thick cell wall for enhanced survival in harsh environments

Resistance of Protozoa Cysts

• Not as resilient as bacterial endospores

Excystation

• The process by which a trophozoite emerges from a cyst

Killing Cysts

• Cysts can be destroyed by boiling

Duration of Cyst Survival

• Protozoa cysts can survive for months in soil or water

Nutrient Absorption

• Protozoa cysts do not seek out or ingest food actively, but absorb nutrients

Lack of Organelles in Cysts

• Cysts lack organelles necessary for food digestion

Definitive Host

• The host in which a parasite completes its sexual life cycle, e.g., Anopheles mosquito for Plasmodium

Intermediate Host

• A temporary host where the organism lives but does not complete its sexual life cycle, humans often serve this role

Subphylums for Sarcomastigophora

• Sarcodina (amoebas) and Mastigophora (flagellates)

Examples of Ciliates

• Paramecium spp. and Balantidium (parasitic ciliate causing disease)

Sporozoa Classification

• Apicomplexa as a group of non-motile obligate parasites

Movement Mechanisms

• Amoebas move using pseudopods
• Flagellates utilize flagella for movement

Contents of Sarcomastigophora Phylum

• Includes amoebas and flagellates

Sarcodina Subphylum Contents

• Exclusively contains amoebas

Free-Living and Non-Parasitic Examples

• Species like Amoeba spp.

Structure of Amoebas

• Characterized by a nucleus and pseudopods (false feet)

Features of Entamoeba histolytica

• Contains a nucleus and food vacuoles

Amoebiasis Disease Overview

• A globally prevalent disease, risk increases upon entering regions like Mexico

RBC Consumption

• Entamoeba histolytica consumes red blood cells

Detection of RBCs

• Presence observed in fresh diarrheal specimens

Histolysis

• Refers to the destruction of tissue

Pathogenic Behavior of Entamoeba histolytica

• Invades intestinal walls and can spread to other vital organs (liver, lungs, brain, eyes)

Effects of Entamoeba histolytica Infection

• Can cause liver abscesses, potentially fatal if untreated

Complications from Entamoeba Histolytica Infection

• Results in amoebiasis or amoebic dysentery

Symptoms of Complications

• Symptoms include dysentery (diarrhea), weight loss, fatigue, and abdominal pain

Diagnosis of Infection

• Diagnosis through stool samples; fresh fecal smears show trophozoites and cysts in ordinary stool samples

Treatment for Entamoeba Histolytica

• Commonly treated with the antibiotic Metronidazole

Diagnostic Features of Entamoeba Histolytica

• Characterized by ingested red blood cells and bull's eye karyosome

Giardia lamblia Characteristics

• Intestinal parasite featuring nuclei and flagella

Trichomonas vaginalis Characteristics

• Urogenital parasite also featuring a nucleus and flagella