Epidemiology
Although vaginitis is common, affecting millions of women every year, little information about the prevalence of mixed vaginitis is available. A literature review to assess the occurrence and frequency of mixed vaginitis revealed that most investigators reported coinfection rather than mixed vaginitis, and the proportion of mixed vaginitis infections ranged from 6.30% to 35.06%(6, 7). As noted above, one challenge is that studies have failed to correlate symptoms with microbe types. Therefore, most reports do not distinguish between mixed vaginitis and coinfection. The representative data are depicted in Table 1. The following factors are limitations that prevent the obtention of a clear picture of the actual prevalence of mixed vaginitis.
1. The types of vaginitis observed have not been concordant. Evaluations have traditionally focused on VVC, BV, and TV. Most studies have reported that VVC plus BV is the most prevalent form of vaginitis(2). Another condition, AV, was recently characterized by Donders in 2002(8). When AV is included, epidemiologic estimates shift considerably. Some studies indicated AV plus BV, VVC plus AV, and VVC plus BV were the most frequent coinfections(9). It is possible that some clinicians are unaware of AV, thus sometimes misdiagnosing it as BV, affecting the epidemiological data.
2. There is great variability in the rates of infection in different populations. One study found a relatively low rate of mixed vaginitis (6.30%) in Brazil(6), while another found a higher rate (35.06%) in Shanghai(7). Research is required to demonstrate prevalence and outcomes in various populations, such as pregnant women, hypoestrogenic women, asymptomatic women, and so on.
3. The diagnostic criteria and tools to determine the prevalence of mixed vaginitis differ. The classical standards for vaginal infection diagnosis are physical examination, microscopy, and culture methods, which are usually performed in hospitals. Recent research has shown that some new molecular assays (Affirm VPIII, Aptima) for the diagnosis of mixed vaginitis have performed well, identifying proportions ranging from 9.26 to 27.23%(10, 11). In addition, the skill level of technicians is also an influencing factor(12).
4. The vaginal and cervical microbiome is an intricate ecosystem containing various normal and dysbiotic microbes in different ratios. At present, in the mixed vaginitis-related literature, only 4 common types of vaginitis are included. If one includes the cervical, but not strictly vaginal, pathogens such as HSV-2 virus, CT, NG, mycoplasma, and HPV may be included, and higher frequencies of mixed infections may be reported(13).
5. There is a lack of physician understanding and implementation of current guidelines(12). This is likely due, in part, to the fact that the majority of these infections are diagnosed empirically without objective data. Moreover, mixed vaginitis symptoms can be nonspecific and vary by patient. Empirical evidence in this population has likely led to many misdiagnoses.