Parasitology Lecture Notes: Trichomoniasis PDF

LECTURE (2) Trichomoniasis ▶ It is caused by Trichomonas vaginalis. ▶ Worldwide in distribution. ▶ Trichomoniasis is a sexually transmitted disease. ▶ According to the World Health Organization (WHO):  Trichomonas vaginalis is the most common non-viral sexually-transmitted infection.  Ther...

LECTURE (2) Trichomoniasis ▶ It is caused by Trichomonas vaginalis. ▶ Worldwide in distribution. ▶ Trichomoniasis is a sexually transmitted disease. ▶ According to the World Health Organization (WHO):  Trichomonas vaginalis is the most common non-viral sexually-transmitted infection.  There were an estimated 156 million new cases of T. vaginalis infection among people aged 15–49 years old in 2020 globally. ▶ Urogenital flagellate, it exists as trophozoite stage & pseudocyst stage. ▶ No cyst stage.  pear-shaped  7x23 μ  Single vesicular anterior nucleus.  Five flagella:  Four flagella directed anteriorly  The fifth being incorporated within the undulating membrane (attach to 1/3 of parasite body).  To anchor the parasite to vaginal epithelial cells  Jerky and rapid.  Vaginal smears.  Urine (in both females and males).  Prostatic secretion  Round  No.  No true cyst wall  Pseudocyst wall with internalized flagellae.  Stress condition in the host (involved in resistance).  In culture  Isolated from cervical neoplasm.  Females: Vagina, cervix, and urethra.  Males: Urethra, epididymis, seminal vesicles and prostate.  Man.  Trophozoite.  Binary fusion ① Sexual transmission. ② Through contact with contaminated damp or moist objects such as towels or a toilet seat (less frequent). ③ Perinatal transmission from infected mothers to the newborns.   T. vaginalis is site specific & cannot survive outside the urogenital system.  After infection, proliferation begins, with resulting inflammation and large numbers of trophozoites in the tissues and the secretions.  As the infection becomes more chronic: The purulent discharge diminishes. The number of organisms decrease.  Pathology and virulence factors/properties: ① CYTOADHESION  Between T. vaginalis trophozoites and the target cells.  Contact-dependent cytotoxic effect (kill the cells without ② CYTOTOXIC phagocytosis). ③ CYTOLYTIC  Cytolytic activity and disruption of host tissues. ④ HAEMOLYSIS  via beta-hemolytic activity.  Cell-detaching factor, leads to exfoliation of epithelial cells and breakdown of the structural integrity and defense ⑤ CYSTEINE PROTEINASE barrier of the urogenital tract, making the host more vulnerable to other urogenital infections. ⑥ APOPTOSIS INDUCTION. -- ⑦ INTERACTION  Interaction with vaginal-associated microflora. ⑧ ENDOCYTOSIS AND  Of host cells, vaginal bacteria, viruses and fungi. PHAGOCYTOSIS  Endocytosis of host proteins  Degradation of immunoglobulins ⑨ IMMUNE EVASION  Surface molecular mimicry  Masking with host proteins.  Infection results in urethritis, vesiculitis,  Infection results in vaginitis, cervicitis, epididymitis and prostatitis. urethritis and cystitis. A relationship between trichomoniasis and urogenital carcinoma is suggested.  Predisposing factors for pathogenicity: ① Change of:  Normal vaginal bacterial flora  Acidic pH to be alkaline (↑ pH). ② Decrease in: secretory IgA.  Urethra, prostate, seminal  Vagina, cervix, urethra, urinary vesicles and epididymis. bladder & Bartholin glands.  Parasite attaches to mucosal surfaces of urogenital tract and uses flagella to move around vaginal and urethral tissues. 4-28 days. 95% of infected males 25-50% of infected females  May have persistent, or  Discharge: Vaginal offensive, recurring urethritis. profuse leucorrheic or yellowish  T. vaginalis detected in 10 to or purulent. 20% of men with nonspecific  Vulval or vaginal burning urethritis. sensation, soreness and pruritus.  Dysuria.  Dysuria (painful urination) and  Discharge (purulent to mucoid frequent urination. in character).  Dyspareunia (pain during sexual  Prostate may be enlarged and intercourse). tender.  Lower abdominal pain due to pelvic inflammatory disease.  Suggested role in infertility.  The vaginal mucosa is red, inflamed with petechial hemorrhages and erosion (strawberry appearance of mucosa).  Vaginal surface is covered by seropurulent, frothy creamy or yellowish discharge.  Vulval redness or erythema could be seen.  Untreated trichomoniasis during pregnancy is linked to adverse birth outcomes, including: ① Low birth weight. ② Preterm delivery ③ Premature rupture of membranes.  Also perinatal transmission of T. vaginalis can occur, leading to: ① Respiratory tract infections. ② Pneumonia ③ Urogenital infection in the newborns.  Concurrent infections with herpes simplex virus or human papillomavirus are seen.  There is association with increased human immunodeficiency virus transmission.  Urinary tract infections are the most common adult bacterial infections in outpatient setting.  Several studies have suggested that T. vaginalis may serve as a “vector” for the spread of other pathogens into genitourinary tract due to its ability to ingest Neisseria gonorrhoea, Mycoplasma, other bacteria, and viruses.  It is possible that T. vaginalis, in addition to its direct harm to the urogenital tract, also it makes the host more vulnerable to urogenital bacteria, thereby increasing the risk of recurrent bacterial urinary tract infections for patients with trichomoniasis.  The chronic inflammation induced by persistent Trichomonas vaginalis infection may increase the risk of developing genitourinary cancers.  Studies demonstrated that:  Had a a higher risk of:  Had a higher risk of: ① Benign prostate hyperplasia ① Cervical cancer, especially co-infected ② Prostate cancer. with human papilloma virus.   Detection of Trichomonas trophozoites by examination of wet preparations of  Vaginal discharge, urethral discharge, urine (in both ① DIRECT MICROSCOPY females and males) and prostatic secretions. OF WET MOUNT  This examination must be performed within 10 to 20 min of sample collection, or the organisms lose motility and may be difficult to see. Urine sample could appear cloudy.  Permanent stains as Giemsa and fluorescent stains, can be ② STAINED SMEARS used. ③ CULTURE  Using Diamond's media or InPouch culture. ④ DETECTION OF T.  in vaginal discharge: Using ELISA or rapid detection VAGINALIS ANTIGENS immunochromatographic dipstick test.  Nucleic acid (DNA) detection using: ⑤ MOLECULAR DIAGNOSIS ① Dot Blot hybridization ② PCR amplification. ③ DETECTION OF ANTIBODIES. ① Metronidazole: 500 mg orally 2 times/day for 7 days. ② Tinidazole: 2 g orally in a single dose. ③ Both partners must be treated at the same time. ④ Attention to personal hygiene and health education.