Medical Parasitology: Flagellates (Giardia lamblia & Trichomonas vaginalis)

Flashcards covering flagellates, giardiasis, and trichomoniasis from a medical parasitology course.

Flagellates

Organisms with one or more whip-like appendages called flagella. Used for motility.

Intestinal Flagellates

A category of flagellates that includes Giardia lamblia, Trichomonas vaginalis, Trichomonas tenax, Trichomonas hominis, Chilomastix mesnili, Enteromonas hominis, Retortamonas intestinalis, and Dientamoeba fragilis.

Urogenital Flagellates

A category of flagellates that includes Trichomonas vaginalis.

Haemoflagellates

A category of flagellates that includes Leishmania spp. and Trypanosoma sp. (Trypanosoma brucei, Trypanosoma cruzi), found in blood and tissue.

Giardia lamblia

A cosmopolitan flagellate prevalent in tropical and developing countries with low sanitation. Synonyms: Giardia duodenalis, Giardia intestinalis.

Giardia lamblia Habitat

Small intestine (duodenum, upper jejunum)

Giardiasis

Also known as lambliasis or 'Traveller’s disease,' is a disease caused by Giardia lamblia that leads to diarrhea.

Giardia lamblia Morphology

Exists in two stages: Trophozoite (pathogenic, diagnostic form) and Cyst (infective & diagnostic stage).

Giardia lamblia Transmission

Fecal-oral route through ingestion of cysts in contaminated water and food, oral-anal sex, and animal reservoirs.

Giardia lamblia Pathogenesis

Trophozoites adhere to enterocytes using their adhesive disk, disrupting the mucosal barrier, causing villus blunting, nutrient loss, diarrhea, and malnutrition.

Giardia lamblia Symptoms

Common symptoms include diarrhea, abdominal pain, bloating, flatulence, anorexia, nausea, and weight loss. Stools are loose, bulky, frothy, and/or greasy without blood or mucus.

Giardiasis Complications

Can lead to malabsorption and steatorrhea (excessive loss of fat in the feces).

Giardiasis Lab Diagnosis

Stool sample examination for cysts and trophozoites, duodenal contents by aspiration, upper small intestinal biopsies, serology tests (antibodies), and molecular diagnosis (PCR).

Giardiasis Treatment

Drugs used include Metronidazole (Flagyl), Tinidazole (Fasigyn), Nitazoxanide (Alinia), Quinacrine (Atabrine), Furazolidone (Furoxone), and Paramomycin (Humatin).

Giardiasis Prevention

Proper disposal of waste and fecal matter, personal hygiene, prevention of food contamination, and boiling and filtration of water.

Trichomonas vaginalis

A pathogenic Trichomonas species found worldwide that is associated with multiple sexual partners.

Trichomonas vaginalis Transmission

Primarily transmitted sexually, with rare vertical transmission.

Trichomonas vaginalis Disease

Causes Trichomoniasis, primarily affecting the urogenital tract in both females (vagina and urethra) and males (urethra and prostate).

Trichomonas vaginalis Morphology

Exists only as a Trophozoite stage (no cyst stage), which is the infective and replication form, surviving outside the body for 15-48 hours.

Trichomonas vaginalis Pathogenesis

Adheres to the epithelial cells lining the urogenital tract, causing inflammation and micro-abrasions/micro-ulceration.

Trichomonas vaginalis Female Symptoms

Vaginal discharge (often frothy yellow-green & malodorous), vaginitis, cervicitis, vaginal itching, dyspareunia. Can also be asymptomatic.

Trichomonas vaginalis Male Symptoms

Urethritis, epididymitis, prostatitis, discharge, burning after ejaculation or urination.

Trichomonas vaginalis Lab Diagnosis

In females: High vaginal swab (HVS) or urine. In males: Urethral swab or urine. Includes microscopy for trophozoite detection, culture, molecular tests (PCR), and serology tests.

Trichomonas vaginalis Treatment

Metronidazole (Flagyl) and Tinidazole (Tindamax).

Trichomonas vaginalis Prevention

Limiting the number of sexual partners, using condoms, and treating infected partners.

Trichomoniasis Complications in Women

Pelvic Inflammatory Disease (PID), increased susceptibility to other STIs including HIV, and an increased risk of cervical cancer.

Trichomoniasis Complications in Men

Prostatitis, epididymitis, urethritis, pain during urination/sexual intercourse, and potential infertility issues.

Trichomoniasis Additional Complications in Males

Balanoposthitis (inflammation of the foreskin and glans) and Balanitis (inflammation of the glans or the head of the penis).