We examined the incidence, prevalence, and potential risk factors for vulvovaginal candidiasis among a cohort of reproductive-age women in Mysore, India. Among this cohort, we found evidence that a presumptive diagnosis of vulvovaginal candidiasis based only on presence of signs or symptoms, in absence of laboratory confirmation, would be mostly incorrect. Consistent with previous research [24
], we could not identify behavioral risk factors for vulvovaginal candidiasis, which provides impetus for additional investigation into intrinsic factors such as the composition of vaginal flora, the presence or absence of genetic factors, and the features of the host and local immune response.
Vaginal discharge, itching, and erythema, while quite common, were insufficient to diagnose vulvovaginal candidiasis in the absence of laboratory confirmation. Had syndromic diagnosis been used to diagnose vulvovaginal candidiasis in this cohort, the positive predictive values would have been very low (15–41%). Our results are consistent with other studies detailing the overtreatment that results from the use of syndromic diagnosis based on vaginal discharge to diagnose vaginal conditions [25
]. Previous findings also demonstrate that a minority of women with vaginal discharge have vulvovaginal candidiasis [25
]. Thus, the diagnosis of vulvovaginal candidiasis based solely on signs or symptoms leads to overestimation of the prevalence of vulvovaginal candidiasis and its overtreatment, while leaving the actual cause of the vaginal symptoms untreated. This finding of misdiagnosis based on symptoms is also relevant for women who self-diagnose vulvovaginal candidiasis.
The prevalence of laboratory-confirmed vulvovaginal candidiasis we observed is consistent with the results of two other community-based studies in India [9
]. Given that reproductive tract conditions account for nearly half of the days of illness experienced among women in this region of India [32
], it is critical to understand the incidence and prevalence of individual conditions; to our knowledge, this is the first study from India to describe the incidence of and possible risk factors for vulvovaginal candidiasis.
The study visit-specific point prevalence of vulvovaginal candidiasis in this cohort decreased from 9% to 5%, and 72% of treated women were negative for vulvovaginal candidiasis at their next study visit, indicating successful provision of treatment. Only 20% of those infected with Candida
were diagnosed as having vulvovaginal candidiasis, much lower than the 53% found in a community-based study in Tamil Nadu, India [9
]. We were not able to determine whether the 28% of women with a diagnosis of vulvovaginal candidiasis on two consecutive visits were cases in which, despite treatment, vulvovaginal candidiasis had cleared and then recurred. More likely, the repeat diagnoses at consecutive visits represent instances in which the vulvovaginal candidiasis was caused by Candida
species not susceptible to fluconazole treatment. Previous research in India has found a high proportion of women infected by non-albicans Candida
], which are more resistant to treatment with azoles [34
Of the sociodemographic and behavioral characteristics we examined, only age at initiation of sexual activity appeared to be associated with the prevalence of vulvovaginal candidiasis, such that those with later initiation of sexual activity had a higher prevalence of vulvovaginal candidiasis. As the number of years women had been with their sex partners was not associated with vulvovaginal candidiasis, these two sociodemographic results appear discrepant and warrant additional investigation.
We found a positive association between having clinically diagnosed bacterial vaginosis and vulvovaginal candidiasis. As both diagnoses include vaginal discharge as a component of their respective diagnostic criteria, it is very likely there is misclassification between vulvovaginal candidiasis and clinically defined bacterial vaginosis. For example, women infected with Candida
may have discharge caused by bacterial vaginosis and could thus be misdiagnosed with vulvovaginal candidiasis [36
]. Our findings emphasize the problems inherent in making diagnoses of vaginal conditions based on clinical examination alone [34
We found some evidence that the prevalence of vulvovaginal candidiasis varied with the presence of Lactobacillus
morphotypes. The evidence for a relationship between the prevalence of vulvovaginal candidiasis and the presence of Lactobacillus
in the vagina is conflicting, including studies in which the H2
-production status of Lactobacillus
was considered [24
]. Recently, a prospective cohort study of female sex workers in Kenya found the presence of Lactobacillus
, regardless of H2
-production status, was positively associated with prevalent vulvovaginal candidiasis (adjusted odds ratio (aOR) 2.3, 95% CI 0.8, 6.4), a relationship that was strengthened after restricting the analysis to women without a diagnosis of bacterial vaginosis (aOR 3.8, 95% CI 1.3, 10.8) [39
The loss of vaginal Lactobacilli is the hypothesized mediator for the relationship between the receipt of antibiotics and the risk of vulvovaginal candidiasis [1
]. The mediation hypothesis also underpins the long-standing interest in use of probiotic interventions to reduce the risk of developing vulvovaginal candidiasis [1
]; the results here do not provide strong support for this hypothesis.
Strengths of this study include a large effective sample size derived from the use of participants' repeated observations, which allows for measurements of prevalence and incidence. Additionally, other studies of vulvovaginal candidiasis in India use samples of symptomatic women recruited from clinics or used syndromic diagnosis and as a result were not able to estimate the community-level prevalence of vulvovaginal candidiasis. Our study is one of the few to examine the prevalence of vulvovaginal candidiasis across a range in the number of Lactobacillus morphotypes detected in the vagina; examination of a dose-response provides better evidence, if any, of a biological relationship.
There are also important limitations of our study to consider. First, the women in this cohort were recruited by nonrandom sampling; unmeasured sampling bias can limit the generalizability of these results. Second, because of the cross-sectional nature of our analysis, we cannot make causal interpretations for the variations in the prevalence of vulvovaginal candidiasis observed here. Third, we were not able to speciate the Candida
organisms detected. The associations between sociodemographic characteristics and potential risk factors and the prevalence of vulvovaginal candidiasis may differ by the Candida
species which infect women, which are known to vary considerably by geographical location [1
]. Fourth, we could not verify whether participants were self-medicating between visits with antibiotics or antifungals, which would influence the incidence and prevalence measurements of vulvovaginal candidiasis. Further, we could not immediately followup with women treated for vulvovaginal candidiasis, and so could not verify whether treatment was successful. Finally, given the limited duration of the study, we could not identify a subset of women with recurrent vulvovaginal candidiasis, an important condition with epidemiologic features distinct from acute vulvovaginal candidiasis [49