More than 95% of KS cases in China, including all epidemiological forms, were observed in minority groups in Xinjiang, particularly in the Uygur group . Previous studies have shown a high seroprevalence of KSHV in the range of 12.5% to 48.0% in different study populations in this region, that correlated well with a high incidence of KS [18, 21–23]. However, these studies were mainly restricted to Uygur patients with diseases other than KS, and the study populations were mainly from the northern part of Xinjiang [18, 21]. Thus the discrepancy between the socio-economic status in these two geographical areas and the absence of behavior-associated data, mean that these studies did not take other variables into account. In the current cross-sectional study, the seroprevalence of KSHV among the general Uygur population in the southern and northern parts of Xinjiang was 23.1% and 25.9%, respectively, which is in agreement with previous findings from Xinjiang [21–24]. There was no significant difference in KSHV infection between the two regions of Xinjiang, indicating that minority group background is still the most important factor in KSHV infection. Although as expected, titers were higher in KS cases than in the general population, titers in the general population did not differ by geography, unlike the incidence of KS which is much higher in the South. Combined with the distribution pattern of KSHV antibody titers among seropositive individuals and KS patients, our findings suggested that other unknown factors may exist in South Xinjiang which potentially promote the development from KSHV infecton during KS pathogenesis. To further confirm this hypothesis, a prospective study focused on geographical and ethnic parameters should be carried out.
The seroprevalence of KSHV in the general Uygur population in Xinjiang was significantly more prevalent in individuals aged ≥55 years compared to those aged < 55 years. These results are consistent with those of several other studies, which described an increase in seroprevalence of KSHV with age in different populations [25–29]. This correlation may be related to the natural aging process. Generally, the immunity of older people is weaker than that of younger people, and hypoimmunity maybe a promoting agent for KSHV infection. Moreover, it is notable that KSHV prevalence was similar in men and women which is consistent with many studies [18, 29]. and our previous researches [21, 23] that find the distribution of KSHV seroprevalence has no difference by sex.
Further analyses were then carried out to focus on the 1008 rural Uygur people from South Xinjiang. This is the first report regarding KSHV seroprevalence and risk factors in this area, a region endemic for KS. The seroprevalence of KSHV in this study population was independently associated with educational level. It was apparent that with improved educational level (from illiterate/semiliterate to Junior high school level education), KSHV seroprevalence decreased from 28.3% to 17.7%, suggesting that a higher education level is a protection factor for KSHV infection. Notably, the educational level of this study population was usually below the high school level, and among the older age group (≥55) the percentage of illiterate/semiliterate individuals was 43.7%. Therefore, knowledge about health issues is far more limited in the Uygur population in this region, especially in the elder Uygur population. Furthermore, the mobility of the population in this region is relatively low. The traditional life style and behavior of the Uygur people has remained unchanged over the past two decades , with the life quality and level of education reflecting their low socioeconomic status. Such conditions might facilitate the transmission of KSHV infection, in line with with previous reports linking KSHV to rural settings in Italy and Sicily [31–33]. Interestingly, we also identified drinking could increase the risk of KSHV infection, a result consistent with previous studies [34, 35]. Among 13 drinkers, six were KSHV positive (46.2%). Because of the small sample size, the relationship between drinking and KSHV infection requires further investigation in a larger sample population in Xinjiang.