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Abstract：
BACKGROUND: The frequency and magnitude of dengue epidemics continue to increase exponentially in Malaysia, with a shift in the age range predominance toward adults and an expansion to rural areas. Despite this, information pertaining to the extent of transmission of dengue virus (DENV) in the rural community is lacking. This community-based pilot study was conducted to establish DENV seroprevalence amongst healthy adults in a rural district in Southern Malaysia, and to identify influencing factors.
METHODS: In this study undertaken between April and May 2015, a total of 277 adult participants were recruited from households across three localities in the Sungai Segamat subdistrict in Segamat district. Sera were tested for immunoglobulin G (IgG) (Panbio® Dengue Indirect IgG ELISA/high-titer capture) and immunoglobulin M (IgM) (Panbio®) antibodies. The plaque reduction neutralization test (PRNT) was conducted on random samples of IgG-positive sera for further confirmation. Medical history and a recall of previous history of dengue were collected through interviews, whereas sociodemographic information was obtained from an existing database.
RESULTS: The overall seroprevalence for DENV infection was 86.6% (240/277) (95% CI: 83-91%). Serological evidence of recent infection (IgM/high-titer capture IgG) was noted in 11.2% (31/277) of participants, whereas there was evidence of past infection in 75.5% (209/277) of participants (indirect IgG minus recent infections). The PRNT assay showed that the detected antibodies were indeed specific to DENV. The multivariate analysis showed that the older age group was significantly associated with past DENV infections. Seropositivity increased with age; 48.5% in the age group of <25 years to more than 85% in age group of >45 years (P < 0.001). No associations with occupation, study site, housing type, comorbidity, educational level, and marital status were observed, although the latter two were statistically significant in the univariate analysis. None of the studied factors were significantly associated with recent DENV infections in the multivariate analysis, although there was a pattern suggestive of recent outbreak in two study sites populated predominately by Chinese people. The majority of infections did not give rise to recognizable disease (either asymptomatic or nonspecific symptoms) as only 12.9% of participants (31/240) recalled having dengue in the past.
CONCLUSIONS: The predominantly rural community under study had a very high previous exposure to dengue. The finding of a high proportion of unreported cases possibly due to subclinical infections underscores the need for enhanced surveillance and control methods. This finding also has implications for measuring disease burden, understanding transmission dynamics, and hypothesizing effects on DENV vaccine efficacy and uptake.
METHODS: In this study undertaken between April and May 2015, a total of 277 adult participants were recruited from households across three localities in the Sungai Segamat subdistrict in Segamat district. Sera were tested for immunoglobulin G (IgG) (Panbio® Dengue Indirect IgG ELISA/high-titer capture) and immunoglobulin M (IgM) (Panbio®) antibodies. The plaque reduction neutralization test (PRNT) was conducted on random samples of IgG-positive sera for further confirmation. Medical history and a recall of previous history of dengue were collected through interviews, whereas sociodemographic information was obtained from an existing database.
RESULTS: The overall seroprevalence for DENV infection was 86.6% (240/277) (95% CI: 83-91%). Serological evidence of recent infection (IgM/high-titer capture IgG) was noted in 11.2% (31/277) of participants, whereas there was evidence of past infection in 75.5% (209/277) of participants (indirect IgG minus recent infections). The PRNT assay showed that the detected antibodies were indeed specific to DENV. The multivariate analysis showed that the older age group was significantly associated with past DENV infections. Seropositivity increased with age; 48.5% in the age group of <25 years to more than 85% in age group of >45 years (P < 0.001). No associations with occupation, study site, housing type, comorbidity, educational level, and marital status were observed, although the latter two were statistically significant in the univariate analysis. None of the studied factors were significantly associated with recent DENV infections in the multivariate analysis, although there was a pattern suggestive of recent outbreak in two study sites populated predominately by Chinese people. The majority of infections did not give rise to recognizable disease (either asymptomatic or nonspecific symptoms) as only 12.9% of participants (31/240) recalled having dengue in the past.
CONCLUSIONS: The predominantly rural community under study had a very high previous exposure to dengue. The finding of a high proportion of unreported cases possibly due to subclinical infections underscores the need for enhanced surveillance and control methods. This finding also has implications for measuring disease burden, understanding transmission dynamics, and hypothesizing effects on DENV vaccine efficacy and uptake.
摘要：
背景：马来西亚登革热流行的频率和程度继续呈指数级增长，随着年龄范围向成年人转移，并向农村地区扩展。尽管如此,缺乏有关农村社区登革热病毒（DENV）传播程度的信息。这项基于社区的试点研究旨在在马来西亚南部农村地区的健康成年人中建立DENV血清阳性率，并找出影响因素。
方法：在2015年4月至5月进行的这项研究中，从Segamat地区SungaiSegamat街道三个地区的家庭中招募了277名成年参与者。测试血清的免疫球蛋白G(IgG)(Panbio®登革热间接IgGELISA/高滴度捕获)和免疫球蛋白M(IgM)(Panbio®)抗体。对IgG阳性血清的随机样品进行斑块减少中和试验(PRNT)以进一步确认。通过访谈收集病史和以前的登革热病史，而社会人口统计信息是从现有数据库获得的。
结果：DENV感染的总血清阳性率为86.6％（240/277）（95％CI：83-91％）。最近感染的血清学证据（IgM/高滴度捕获IgG）在11.2%（31/277）的参与者中被注意到，而75.5%(209/277)的参与者有既往感染的证据(间接IgG减去近期感染).PRNT测定显示检测到的抗体确实对DENV具有特异性。多变量分析表明，年龄较大的人群与过去的DENV感染显着相关。血清阳性随着年龄增长而增加；<25岁年龄组为48.5%，>45岁年龄组为85%以上（P<0.001）。与职业无关，研究地点,住房类型,合并症，教育水平,观察婚姻状况，尽管后两者在单变量分析中具有统计学意义。在多变量分析中，没有一个研究的因素与最近的DENV感染显著相关，尽管有一种模式暗示最近在两个主要由中国人居住的研究地点爆发。大多数感染没有引起可识别的疾病（无症状或非特异性症状），因为只有12.9％的参与者（31/240）记得过去患有登革热。
结论：研究中主要是农村社区的登革热暴露率很高。发现可能由于亚临床感染而导致的未报告病例比例很高，这突显了加强监测和控制方法的必要性。这一发现对衡量疾病负担也有意义，了解变速器动力学，并假设对DENV疫苗效力和摄取的影响。
方法：在2015年4月至5月进行的这项研究中，从Segamat地区SungaiSegamat街道三个地区的家庭中招募了277名成年参与者。测试血清的免疫球蛋白G(IgG)(Panbio®登革热间接IgGELISA/高滴度捕获)和免疫球蛋白M(IgM)(Panbio®)抗体。对IgG阳性血清的随机样品进行斑块减少中和试验(PRNT)以进一步确认。通过访谈收集病史和以前的登革热病史，而社会人口统计信息是从现有数据库获得的。
结果：DENV感染的总血清阳性率为86.6％（240/277）（95％CI：83-91％）。最近感染的血清学证据（IgM/高滴度捕获IgG）在11.2%（31/277）的参与者中被注意到，而75.5%(209/277)的参与者有既往感染的证据(间接IgG减去近期感染).PRNT测定显示检测到的抗体确实对DENV具有特异性。多变量分析表明，年龄较大的人群与过去的DENV感染显着相关。血清阳性随着年龄增长而增加；<25岁年龄组为48.5%，>45岁年龄组为85%以上（P<0.001）。与职业无关，研究地点,住房类型,合并症，教育水平,观察婚姻状况，尽管后两者在单变量分析中具有统计学意义。在多变量分析中，没有一个研究的因素与最近的DENV感染显著相关，尽管有一种模式暗示最近在两个主要由中国人居住的研究地点爆发。大多数感染没有引起可识别的疾病（无症状或非特异性症状），因为只有12.9％的参与者（31/240）记得过去患有登革热。
结论：研究中主要是农村社区的登革热暴露率很高。发现可能由于亚临床感染而导致的未报告病例比例很高，这突显了加强监测和控制方法的必要性。这一发现对衡量疾病负担也有意义，了解变速器动力学，并假设对DENV疫苗效力和摄取的影响。
