What is a Yeast Infection?
Vaginal infections caused by a specific kind of yeast (a fungus) called Candida are common and are technically called candidiasis. This yeast lives on the moist surfaces of many parts of the body, including your mouth, genitals, anus, and skin. Candida is a type of yeast, hence the term yeast infection. An infection may occur when the balance of yeast versus good bacteria in the body tips in favour of yeast. Surprisingly, some women who have Candida detected on their vaginal or cervical swabs have no symptoms at all [1, 2, 3].
Causes of a Yeast Infection
Candida can overgrow due to numerous factors that disrupt the vagina’s average balance of yeast. This includes fluctuating estrogen levels during pregnancy, while nursing, during the menstrual cycle, and after menopause; sexual intercourse; urinary tract infection; or prolonged antibiotic use, which changes bacteria levels in the vagina.
A spike in sugar in the vagina’s mucous membranes, caused by uncontrolled diabetes, for instance, can promote yeast growth. Antibiotics also wipe out many of the naturally occurring ‘good’ vaginal bacteria that keep yeast under control.
Other causes include flushing or washing the vagina with a douche or other vaginal sprays, which can recreate the bacterial imbalance in the vagina, and a poor immune system, such as those in HIV-positive individuals or with other autoimmune disorders, who might be more prone to vaginal yeast infections [4, 5].
In some cases, yeast infections can also be caused by exposure to exogenous sources of yeast, such as baker's yeast used in baking [6].
Risk Factors of Yeast Infections
Why do yeast infections develop in some individuals and not in others? The most critical risk factor for yeast infections is the overgrowth of yeast. There are some reasons why this can occur apart from infection.
Antibiotic use is a significant risk factor. The bacteria that antibiotics kill often keep Candida in check, thereby allowing yeast to multiply uncontrollably and allowing for infection. If you suffer from recurrent vaginal yeast infections, it’s essential to consider whether you are taking any antibiotics [7].
With that in mind, it’s worth considering that high-estrogen birth control pills can also promote yeast overgrowth, as can pregnancy, when estrogen levels naturally rise [7].
Environmental conditions, notably humidity and heat, add to the risk; candida yeasts thrive in a moist environment, so humidity in clothing, boots and other apparel can encourage fungal overgrowth [7].
Some conditions, like diabetes and a suppressed immune system, can increase one's chances of getting yeast infections, making it more challenging to control yeast growth [8, 7, 9, 10].
Sexual behaviours are also well-known risk factors for acquired yeast infections. Frequent sex, especially sex with a new partner, can raise the risk of yeast infection [11, 12].
Some other risk factors are hygiene habits and clothing, such as wearing tight or damp clothes, using soaps and skin products with harsh chemicals or irritants, and not washing your genitals or bathing often [9, 10].
In the end, though, certain demographic variables enhance the likelihood of yeast infections: not being circumcised, obese, and non-Australian-born [13, 10].
What is A False Positive Herpes Test?
False positives are incorrect herpes diagnoses, where a test shows a patient testing positive for herpes despite being herpes-free. One way false positives occur is through cross-reactivity, where the test picks up antibodies triggered by an infection other than herpes, yielding a positive result [14].
Of 121 patients diagnosed with herpes genitalis, four patients (4.1%) developed a biologically false positive reaction: that is, they tested positive for having the herpes virus when they did not [15].
False positives can result from any number of laboratory errors (for example, failure to properly label a test sample or mishandling it) [16, 17], the presence of certain medical conditions or inclusion in a study that influences markers in blood or saliva to undertake the exact chemical reaction they would when detecting a murder [16, 17].
This should go without saying, but it’s worth pointing out that a positive herpes test doesn’t mean you have herpes: you’ll probably have to repeat the test before you can trust the diagnosis [14].
Can a Yeast Infection Cause A False Positive Herpes Test?
While yeast infections and herpes are very different, they can sometimes present with similar symptoms, such as sores or blisters in the genitals [2]. Recognising that these symptoms don’t suggest that one condition can give rise to a false positive test for the other is essential.
With yeast infection, the diagnosis is frequently made presumptively based on clinical findings and direct microscopy, which can lead to false-positive and false-negative results [18]. That doesn’t mean a yeast infection can lead to a false positive herpes test.
Conversely, serological tests for syphilis, herpes and other conditions may result in false positives due to infection: one study found that 4.1% of patients with herpes genitalis developed biologically false positive serological tests for syphilis [15]. But these are irrelevant to the tests for yeast infection and herpes.
To conclude, even though yeast infections and herpes can sometimes present with similar symptoms, there is not yet clear proof to suggest that a yeast infection will result in a false positive for herpes. If you have symptoms of either infection, seek a healthcare provider for a proper diagnosis and treatment.