Flagellates: Organism Description and Disease

Locomotion and Sensation:
- Possess at least one flagellum during some stage of their life cycle, aiding in locomotion and sensation.
Outer Covering:
- Many flagellates have a thin, firm pellicle or a jelly-like substance as an outer covering.
Classification:
- Classified as anaerobic eukaryotes.
Reproduction:
- Can reproduce both sexually and asexually.
Life Cycle Stages:
- Life cycles typically consist of a trophozoite stage, while some species also have a cyst stage.
Major Orders:
- Two main orders of flagellates are Trichomonadida and Diplomonadida.
- Organisms within both orders are considered to be among the most primitive eukaryotic organisms.

Flagella:
- Typically possess 3 to 6 flagella (5 is the most common).
- One flagellum curves backward along the cell wall to form an undulating membrane.
Habitat:
- Live primarily in the digestive systems of animals.
Structural Features:
- Most are uninucleate and have a teardrop shape.
- Some species lack a cell wall.
- Characterized by a prominent median tube-like axostyle.
- Contain hydrogenosomes, which allow for ATP production; do not require oxygen but can produce ATP with hydrogen (H2) as a by-product.

Life Cycle Phase:
- Contains only the trophozoite stage, lacking a cyst stage, which complicates survival in external environments.

Prevalence:
- A common human parasite, infecting approximately 250 million people globally each year.
Habitat:
- Found primarily in the lower genitourinary tract of females and in the prostate and urethra of males.
- Males are often asymptomatic carriers.
Transmission:
- Typically acquired through direct sexual contact.
- Can survive for only a few hours in moist environments.
Microbial Interactions:
- Harbors two species of Mycoplasma and a virus (trichomonas vaginalis virus), which may enhance the fitness of T. vaginalis.

Common Symptoms:
- Foul-smelling yellow or green vaginal discharge, often with a frothy appearance.
- Dyspareunia (painful intercourse).
- Increased urinary frequency.
- Dysuria (painful urination).
- Vulvar pruritus or erythema (unpleasant sensation).

Cytotoxic Proteins:
- T. vaginalis releases cytotoxic proteins that destroy the epithelial lining of the urogenital tract.
Epithelial Cell Adherence:
- Relies on adherence to epithelial cells for survival against elimination through vaginal secretions.
Interactions with Microbiota:
- Can inhibit the growth of Lactobacillus, which is part of the normal vaginal microbiota, potentially leading to increased adherence of the parasite to host epithelial cells.
Influence of Microbial Dynamics:
- Pathogenesis may be exacerbated by the presence of Candida albicans.
Vaginal pH:
- Trichomonas vaginalis prefers a higher pH environment, which can enhance HIV transmission.
- Infection during pregnancy is linked to premature delivery and low birth weight.

Stages:
- Consists of both trophozoite and cyst stages.
Cyst Survival:
- Cysts can survive for months in cold water and soil.
Excystation:
- Cysts excyst into trophozoites after exposure to the acidic environment of the stomach.
Replication:
- Trophozoites replicate in the small intestine through a process known as longitudinal binary fission.
Cyst Formation:
- Following exposure to biliary fluids, some trophozoites form cysts in the jejunum, which are excreted in feces.

Cell Structure:
- Contains two nuclei, each associated with four basal bodies and four flagella, totaling eight flagella.
- Lacks a Golgi apparatus and mitochondria but contains mitosomes.
Motility:
- Movement is described as “falling leaf motility.”
Ecosystem:
- Can exist as either free-living or parasitic forms.

Symptoms List:
- Diarrhea.
- Gas.
- Foul-smelling, greasy stools that float.
- Stomach cramps/pain.
- Nausea and vomiting.
- Dehydration.

Chronic Giardiasis:
- Can result in long-term growth retardation in children due to damage to enterocytes and loss of the brush border of epithelial cells in the intestine.
- Leads to shortening of microvilli and altered epithelial barrier function.

Stages:
- Contains only the trophozoite stage; a pseudocyst stage may occur in adverse environmental conditions but is not common.
Reproduction:
- Asexual reproduction occurs via longitudinal binary fission.
Habitat:
- Can colonize genital or intestinal tracts.
- Direct transmission occurs in the genital tract, while fecal-oral transmission occurs in the intestinal tract.

Geographical Distribution:
- Found in Europe, Asia, North America, and Australia.
Size:
- Ranges from 10-25 μm in length.
Flagella:
- Contains three anterior flagella and one posterior flagellum.
- An axostyle that extends the length of the cell typically projects posteriorly and has an undulating membrane.
Nutritional Needs:
- Depends on endogenous bacteria and host secretion for nutrients.
- Can survive for short periods in water, urine, and feces.

Common Symptoms:
- Early fetal death and infertility.
- Vaginitis and endometritis.
- Macroscopic lesions and placental edema.
- Fetal pneumonia.

Common Symptoms:
- Can be asymptomatic in healthy or older individuals.
- Diarrhea with a very strong odor, containing mucus and blood.
- Normal appetite with no vomiting or noticeable weight loss.
- Symptoms may include flatulence, straining during defecation, incontinence, and inflamed anus.

Stages:
- Has both trophozoite and cyst stages.
- Trophozoites reproduce in the intestinal tract through binary fission.
- Cysts are primarily found in the mucous of the intestinal tract and are excreted during defecation.
Transmission:
- Transmission occurs through contaminated feces and water.

Order:
- Part of the Diplomonadida order.
Morphology:
- Possesses four anterior, two anterolateral, and two posterior flagella (total of eight flagella).
- Exists in both free-living and parasitic forms, measuring 6-10 µm in length.

Common Symptoms:
- Causes spironucleosis (hexamitosis), characterized by acute, infectious catarrhal enteritis primarily in turkeys, but also observed in other animals like fish.
- Symptoms include lethargy, weight loss, diarrhea, distention of duodenum and upper jejunum, increased mucus production in the duodenum and upper jejunum, and potential for death.