Fungal and Protozoan Diseases of the Reproductive System

Vulvovaginal Candidiasis

Candidal vulvovaginitis is an infection of the vagina’s mucous membranes caused by Candida albicans.

Learning Objectives

Analyze the symptoms and factors involved in vulvovaginal candidiasis

Key Takeaways

Key Points

  • Up to 75% of women will have this infection at some point in their lives, and approximately 5% will have recurring episodes. It is the second most common cause of vaginal inflammation after bacterial vaginosis.
  • The Candida species of fungus is found naturally in the vagina, and is usually harmless.
  • It is not known exactly how changes in the vagina trigger thrush, but it may be due to a hormone (chemical) imbalance. In most cases, the cause of the hormonal changes is unknown. Some possible risk factors have been identified, such as taking antibiotics.

Key Terms

  • Candida albicans: a diploid asexual fungus (a form of yeast). An overgrowth results in candidiasis in immunocompromised patients.
  • vulvovaginal candidiasis: candidal vulvovaginitis or vaginal thrush is an infection of the vagina’s mucous membranes by Candida albicans.

Candidal vulvovaginitis or vaginal thrush is an infection of the vagina’s mucous membranes by Candida albicans. Up to 75% of women will have this infection at some point in their lives, and approximately 5% will have recurring episodes. It is the second most common cause of vaginal inflammation after bacterial vaginosis.

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Candida albicans: Tramsmission photomicrograph showing a number of Candida albicans chlamydospores.

It is most commonly caused by a type of fungus known as Candida albicans. The Candida species of fungus is found naturally in the vagina, and is usually harmless. However, if the conditions in the vagina change, Candida albicans can cause the symptoms of thrush. Symptoms of thrush can also be caused by Candida glabrata, Candida krusei, Candida parapsilosis, and Candida tropicalis. Non-albican Candida are commonly found in complicated cases of vaginal thrush such that first line treatment is ineffective. These cases are more likely in immunocompromised patients.

It is not known exactly how changes in the vagina trigger thrush, but it may be due to a hormone (chemical) imbalance. In most cases, the cause of the hormonal changes is unknown. Some possible risk factors have been identified, such as taking antibiotics.

The symptoms of vaginal thrush include vulval itching, vulval soreness and irritation, pain or discomfort during sexual intercourse (superficial dyspareunia), pain or discomfort during urination (dysuria) and vaginal discharge, which is usually odorless. The discharge can be thin and watery, or thick and white, like cottage cheese.

In addition to the above symptoms of thrush, vulvovaginal inflammation can also be present. The signs of vulvovaginal inflammation include erythema (redness) of the vagina and vulva, vagina fissuring (cracked skin), oedema (swelling from a build-up of fluid), also in severe cases, satellite lesions (sores in the surrounding area). This is rare, but may indicate the presence of another fungal condition, or the herpes simplex virus (the virus that causes genital herpes).

While vulvovaginal candidiasis is caused by a the yeast Candida there are many predisposing factors:

  • Infection occurs in about 30% of women who are taking a course of oral antibiotics. The evidence of the effect of oral contraceptives is controversial.
  • In pregnancy, changes in the levels of female sex hormones, such as estrogen, make a woman more likely to develop a yeast infection. During pregnancy, the Candida fungus is more prevalent (common), and recurrent infection is also more likely.
  • Frequency of sexual intercourse appears to be related to the frequency of infections, however infections often occur without sex. Tight-fitting clothing, such as tights and thong underwear, do not appear to increase the risk. Neither do personal hygiene methods.
  • Those with poorly controlled diabetes have increased rates of infection while those with well-controlled diabetes do not.
  • The risk of developing thrush is also increased in a immunodeficiency, for example, by an immunosuppressive condition, such as HIV or AIDS, or receiving chemotherapy. This is because in these circumstances the body’s immune system, which usually fights off infection, is unable to effectively control the spread of the Candida fungus.

Trichomoniasis

Trichomoniasis is primarily an infection of the urogenital tract; the most common site of infection is the urethra and the vagina in women.

Learning Objectives

Outline the causes and symptoms associated with trichomoniasis

Key Takeaways

Key Points

  • Trichomoniasis is a sexually transmitted disease, and is caused by the single-celled protozoan parasite Trichomonas vaginalis producing mechanical stress on host cells and then ingesting cell fragments after cell death.
  • Symptoms usually appear in women within 5 to 28 days of exposure. In many cases, men may hold the parasite for some years without any signs (dormant).
  • Trichomoniasis is diagnosed by visually observing the trichomonads via a microscope.

Key Terms

  • trichomoniasis: A common sexually transmitted disease caused by the parasite Trichomonas vaginalis and infecting the urinary tract or vagina.
  • vaginitis: Inflammation of the vagina.
  • trichomonads: flagellate protozoa of the genus Trichomonas.

Trichomoniasis, sometimes referred to as “trich”, is a common cause of vaginitis. It is a sexually transmitted disease, and is caused by the single-celled protozoan parasite Trichomonas vaginalis producing mechanical stress on host cells and then ingesting cell fragments after cell deat. Trichomoniasis is primarily an infection of the urogenital tract; the most common site of infection is the urethra and the vagina in women. Typically, only women experience symptoms associated with Trichomonas infection.

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Trichomoniasis vaginalis: Trichomoniasis is primarily an infection of the urogenital tract; the most common site of infection is the urethra and the vagina in women.

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Micrograph showing Trichomoniasis: Micrograph showing a positive result for trichomoniasis. A trichomonas organism is seen on the top-right of the image.

Symptoms include inflammation of the cervix (cervicitis), urethra (urethritis), and vagina (vaginitis) which produces an itching or burning sensation. Discomfort may increase during intercourse and urination. There may also be a yellow-green, itchy, frothy, foul-smelling (“fishy” smell) vaginal discharge. In rare cases, lower abdominal pain can occur. Symptoms usually appear in women within 5 to 28 days of exposure. In many cases, men may hold the parasite for some years without any signs (dormant). Some sexual health specialists have stated that the condition can probably be carried in the vagina for years, despite standard tests being negative. While symptoms are most common in women, some men may temporarily exhibit symptoms such as an irritation inside the penis, mild discharge or slight burning after urination or ejaculation. Trichomoniasis is diagnosed by visually observing the trichomonads via a microscope. In women, the examiner collects the specimen during a pelvic examination by inserting a speculum into the vagina and then using a cotton-tipped applicator to collect the sample. The sample is then placed onto a microscopic slide and sent to a laboratory to be analyzed.

The TORCH Panel of Tests

TORCH infections are a group of viral, bacterial, and protozoan infections that gain access to the fetal bloodstream from the mother.

Learning Objectives

Summarize the importance of a TORCH panel of tests

Key Takeaways

Key Points

  • The TORCH complex acronym spells out: T – Toxoplasmosis / Toxoplasma gondii; O – Other infections; R – Rubella; C – Cytomegalovirus; H – Herpes simplex virus.
  • TORCH infections cause a syndrome characterized by microcephaly, sensorineural deafness, chorioretinitis, hepatosplenomegaly, and thrombocytopenia.
  • Symptoms of a TORCH infection may include fever and difficulty feeding, with the newborn often small for their gestational age.

Key Terms

  • haematogenous: Spread by blood.
  • petechial: Characterised by, pertaining to, or resembling petechiae (small, nonraised haemorrhages on the skin).
  • TORCH complex: TORCH complex is a medical acronym for a set of perinatal infections (which are infections that are passed from a pregnant woman to her fetus).

TORCH complex is a medical acronym for a set of perinatal infections (which are infections passed from a pregnant woman to her fetus). TORCH infections can lead to severe fetal anomalies or even fetal loss. They are a group of viral, bacterial, and protozoan infections that gain access to the fetal bloodstream through the placenta via the chorionic villi. Haematogenous transmission may occur at any time during gestation or occasionally at the time of delivery via maternal-to-fetal transfusion. The TORCH panel is used to screen for certain infectious diseases that can cause birth defects in a baby if the mother contracts them during the pregnancy. The TORCH panel of tests acronym spells out as follows:

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Herpes Simplex Virus: Micrograph of a pap test showing changes (upper-right of image) associated with Herpes Simplex Virus, a TORCH infection.

  • T – Toxoplasmosis / Toxoplasma gondii
  • O – Other infections
  • R – Rubella
  • C – Cytomegalovirus
  • H – Herpes simplex virus

The “other infections” included under the letter O include Coxsackievirus, Syphilis, Varicella-Zoster Virus, HIV, and Parvovirus B19. Hepatitis B is also sometimes included among “other infections,” but Hepatitis B is a large virus and does not cross the placenta, hence it cannot infect the fetus unless there have been breaks in the maternal-fetal barrier, such as can occur due to bleeding during childbirth or during amniocentesis.

TORCH infections cause a syndrome characterized by microcephaly, sensorineural deafness, chorioretinitis, hepatosplenomegaly, and thrombocytopenia. Symptoms of a TORCH infection may include fever and difficultly feeding. The newborn is often small for their gestational age. A petechial rash on the skin may be present, with small reddish or purplish spots due to bleeding from capillaries under the skin. An enlarged liver and spleen (hepatosplenomegaly) is common, as is jaundice. However, jaundice is less common in Hepatitis B because a newborn’s immune system is not developed well enough to mount a response against liver cells, as would normally be the cause of jaundice in an older child or adult. Hearing impairment, eye problems, mental retardation, autism, and death can be caused by TORCH infections. The TORCH panel is valuable for checking for infections because the mother often has a mild infection with few or no symptoms. It is also possible for genetic conditions (such as Aicardi-Goutieres syndrome) to present in a similar manner.

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Cytomegalovirus infection: Hematoxylin and Eosin stain showing cytomegalovirus (CMV) infection of the placenta (CMV placentitis), a TORCH infection. The characteristic large nucleus of a CMV infected cell is seen off-center at the bottom-right of the image.