| Background:Human papillomavirus (HPV) infection is an established etiologic factor of cervical cancer, and there is growing evidence of HPV being a relevant factor in anogenital, oropharyngeal, and other cancers. Two available prophylactic HPV vaccines, the bivalent (targeted at HPV16,18) and quadrivalent (targeted at HPV6,11,16, and18), have shown a prominently type-restricted prophylactic efficacy for genital lesions related to targeted HPV types in women who were naive to the respective types at enrollment. A randomized, placebo-controlled, double blind clinical trial to evaluate the quadrivalent HPV vaccine (targeted at types6,11,16, and18) has completed participant recruitment and is currently ongoing among Chinese women. Since limited cross-protection could be offered between HPV types, heterogeneity in HPV type-specific distribution from different populations should be taken into account when predicting the efficiency of current prophylactic vaccines and designing for the second-generation vaccines targeted to specific regions. Several studies have been conducted to investigate the HPV type distribution among Chinese women, but data of type-distribution in Chinese female sex workers (FSWs) are limited. There have been only three studies, with limited sample size, on HPV prevalence among FSWs in China, which indicated a higher prevalence among them than among the general women population in the same areas. Of the three studies, one had no information on HPV genotypes, another study provided only genotype distribution for HPV types6,11,16, and18, and the other study found only17HPV positive samples due to limited sample size.Objectives:The current study was aimed to estimate the prevalence of HPV infection and the distribution of HPV genotypes in female sex workers in two cities in Guangxi, China.Methods:A total of811FSWs were recruited from venues between July and September of2009. Data on socio-demographic and behavior characteristics were collected, and cervical swabs were collected to determine HPV infection and genotype distribution. HPV DNA was extracted by QIAamp DNA Mini Kit, HPV DNA was amplified and viral types detected using the HPV GenoArray test kit, which can detect21kinds of HPV genotypes. All the operations were done according to the manufacturer's instructions. Prevalence with95%confidence intervals (CI) of HPV infections were estimated for overall, high risk HPV (HR HPV), and multiple types HPV infections. The x2test or Fisher's exact test was applied to compare HPV genotype prevalence rates across different category subgroups and different age groups of FSWs.Results:In the study, one sample was negative for internal control, resulting in its impossibility for further analysis. Finally,810samples were subject to further analysis. A total of19individual HPV genotypes were identified. The prevalence of HPV (any type) infection was38.9%. In bivariate analysis, the prevalence was significantly associated with age group (x2=14.15, P=0.007), indicating the highest prevalence in the group of age <20years with a prevalence of50.7%(95%CI:42.7-58.6%). In our study, high risk (HR) was defined as having HR HPV regardless of the presence of low risk HPV types, and multiple infections was defined as having more than one type of HPV genotype. In contrast, the noncase of multiple infections was defined as having only one type or none of HPV genotype. The prevalence of HR HPV and multiple HPV infection rates were31.2%and12.2%, respectively. HR-HPV genotypes were the predominant genotypes across all age groups with the highest prevalence of44.1%among the group of FSWs with age≤20years old. HPV type52was the most prevalent type with prevalence of11%, followed by HPV types16,58,53, and CP8304, with prevalence of6.5%,5.7%,5.6%, and4.8%, respectively. The prevalence rates of HPV types52,16,58,53, and CP8304were not statistically different among different tier of FSWs. The five most prevalent types were HPV types52(12.9%),58(7.1%),53(5.7%),16(4.3%), and CP8304(4.3%) among the FSWs from the luxurious venues; types52(11.7%),16(7.0%), CP8304(5.7%),58(4.7%), and53(4.1%) among the FSWs from the modest venues; and types52(10.2%),16(6.6%),53(6.4%),58(6.1%), and68(4.7%) among the FSWs from low tier venues. The prevalence rates of HPV types6,11,16, and18were1.7%,2.0%,6.5%and2.8%, respectively. The prevalence of HPV type16was statistically different across age groups (x2=14.4, P=0.006), indicating the highest prevalence of10.14%in age group of21-25years while the prevalence of type18was not statistically different across age groups (x2=7.3, P=0.099). HPV type16or18was seen in23.2%(73/315) of HPV positive women while only three of them were positive for both HPV types16and18. The proportions of type16or18among the FSWs from the luxurious venues (13.7%) was significantly lower than those from the modest (25.4%) or low tier venues (22.4%)(x2=12.34, P=0.002). A higher prevalence of multiple HPV infection was observed among FSWs from the low tier venues (14.0%;95%CI,10.6%-17.3%).Conclusions:HPV infection was substantial among FSWs in Guangxi, China. The infection was most prevalent among the group of FSWs with age<20years old, and multiple type infection was most prevalent among FSWs from the low tier venues. The genotype distribution was similar across different tier of FSWs. Besides HPV16, which is prevailing genotype across the world, HPV52and58was also prevalent among FSWs in China. However, HPV18was much less prevalent than other parts of the world. |
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