Zoo – Mastigophora Trichomonas vaginalis

Trichomonas vaginalis 

It is the most common parasitic cause of sexually transmitted diseases (STDs).

A. Females are commonly affected than males

B. It was first observed by Donne in 1836 from the purulent genital discharge of a female

C. Though it is an eukaryote, its metabolism is similar to a primitive anaerobic bacteria

D.  Carbohydrate is utilized ferment actively. It is unable to synthesize fatty acid, sterols, purines and pyrimidines and hence depends on exogenous sources.

Geographical Distribution:

 It is encountered in all climates and all social groups.

 Habitat:

 In female it is found mainly in vagina and in male it is in urethra.   Morphology:

1. It is found only in trophozoite form which bears following characters, pear shaped measuring 10 to 30 µ × 5 to 10 µ

2. It has short undulating membrane which comes up to the middle of the body

3. Possesses 4 anterior flagellates , a prominent axostyle which bifurcates the body into two and projects posteriorly.

4.  There is a costa, para-basal body.

5. Rounded nucleus (anteriorly)

6.  Chromatin granules are present all over, more densely near costa and axostyle

7.  flagella give characteristic webbing or rotatory motility.

8. It multiplies by binary fission in longitudinal axis.

Mode of Transmission

 It is primarily a venereal disease in which transmission can also be from person-to-person contact.

 However, newborns may get infected during birth. Fomites (such as clothes, utensils, and furniture) also form another way of transmission of infection. 

Incubation Time: It varies from 4 to 30 days.

 

Pathogenesis and Pathology

1. Within a few days following the introduction of viable Trichomonas vaginalisinto the vagina.

2.  the proliferating colonies of this flagellate cause degeneration and desquamation of the vaginal epithelium.

3.  It is followed by leukocytic inflammation of the tissue layer.

4.  Very large numbers of trichomonads and leukocytes are now present in the vaginal secretion, which is liquid, greenish, or yellow, and covers the mucosa down to the urethral orifice, vestibular glands, and clitoris.

5.  As the acute condition changes to the chronic stage, the secretion loses its purulent appearance due to a decrease in the number of trichomonads and leukocytes.

6. Trichomonas vaginalis in male genitalia may be symptomless or may be responsible for an irritating, persistent, or recurring urethritis.

Clinical Picture                                  

1. The vaginal secretion is extremely irritating, almost unbearable and is constantly flowing. 

2. The symptoms may continue from a few days to many months.

3.  After each menstruation there is a tendency for acute stage to recur.

4.  The chronic condition transforms into latent one and secretions become normal with no manifestation although trichomonas are still present.

5.  Difference in the intensity of symptoms may be due to differences in virulence of strains of this organism. 

6. In male patients it may be symptomless or may cause urethritis and prostatitis.

 

Laboratory Diagnosis 

1. In female patient, Trichomonas vaginalis may be demonstrated in sedimented urine, vaginal secretion, or from vaginal scraping.

2.  In male patient Trichomonas vaginalis may be found in the centrifuged urine and prostatic secretions following massage of the prostatic gland.

However, care should be taken to prevent contamination of the specimen with feces, since Trichomonas hominis maybe has seen and thus misdiagnosed as Trichomonas vaginalis. 

1. The smear is stained using Giemsa, PAS, Papanicolaou, Leishman, Diff Quick and acridine orange.

 

Antibody detection

ELISA is available using whole cell antigen preparation and aqueous antigenic extract to detect anti-trichomonial antibodies in serum and vaginal secretion of the patients. However, antibodies persist for longer time, hence cannot differentiate between current infection and past infection. Moreover, its sensitivity is variable with variable antibody response.

Antigen detection in Vaginal Secretion

Antigen detection methods are more sensitive than microscopy, easy to perform and indicates recent infection.

1.  A rapid immune-chromatographic test (ICT) (dipstick) is available which shows result within 10 minutes, requires no sophisticated instruments. Compared to culture, it is 83% sensitive and 99% specific

2.  ELISA using monoclonal antibodies has been developed; which shows sensitivity of 89% and specificity of 97%.

Treatment

1. Trichomoniasis is usually treated quickly and easily with antibiotics. 

2. Most people are prescribed an antibiotic called metronidazole which is very effective if taken correctly. You'll usually have to take metronidazole twice a day, for 5 to 7 days.

3.  Sometimes this antibiotic can be prescribed in a single, larger dose.

 

Trichomonas tenax 

1. Harmless commensal of the oral cavity, periodontal area, carious cavities of the tooth, tonsillary crypts, etc. 

2. Measures 5 to 10 µ, i.e. smaller in size as compared to Trichomonas vaginalis.

3. Transmission is through fomites, salivary droplets, and kissing.

Pentatrichomonas hominis

It is worldwide in distribution found both in warm and temperate climates.

1.  It is a harmless commensal present in large intestine

B.  Trophozoite is pyriform shaped, measures 5–15 μm long and 7–10 μm wide, similar to that of T. vaginalis, except that the undulating membrane is extended throughout the body.