Background

Several arboviruses, including dengue virus (DENV), Zika virus (ZIKV) and chikungunya virus (CHIKV), transmitted by Aedes mosquitoes, circulate in northeast Brazil. Diseases caused by these viruses are of great public health relevance, however, their epidemiological features in areas where the three viruses co-circulate are scarce. Here, we present analyses of molecular and serological diagnostics in a prospective study of acute febrile patients recruited from May 2015 to May 2016 in Recife, Brazil.

Methods

Two hundred sixty-three acute febrile patients with symptoms suggestive of an arboviral disease who attended an urgent heath care clinic in the Recife Metropolitan Region in northeast Brazil were enrolled. Acute and convalescent blood samples were collected and tested using molecular and serological assays for infection with DENV, ZIKV and CHIKV.

Results

Quantitative real-time reverse-transcriptase polymerase chain reactions (qRTPCR) performed on acute phase sera detected no patients positive for DENV, but 26 (9.9%) positive for ZIKV and 132 (50.2%) positive for CHIKV. There were a few suspected and only one confirmed dengue case. Specific serological assays for ZIKV and CHIKV confirmed the qRTPCR data. Analyses of DENV IgM and IgG ELISAs in the context of qRTPCR results suggested high levels of cross reactive antibodies in ZIKV-positive samples. Results from neutralization assays highly corroborated those from qRTPCR and ZIKV ELISA, indicating very few positive DENV cases. ZIKV infections were temporally clustered in the first months of the study and started to decrease concomitantly with an increase in CHIKV infections in August 2015. The proportion of CHIKV infections increased significantly in September 2015 and remained high until the end of the study period, with an average of 84.7% of recruited patients being diagnosed from August 2015 to May 2016. ZIKV infections exhibited a female bias and the cases were spread over the study site, while CHIKV cases had a male bias and were spatially clustered in each month.

Conclusions

In 2015–2016 in the Recife Metropolitan Region, we detected the tail end of a Zika epidemic, which was displaced by a chikungunya epidemic. Few dengue cases were identified despite a high number of official dengue notifications in the area during this period. We show here important epidemiological features of these cases.

中文翻译：

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巴西累西腓基孔肯雅热爆发导致寨卡病毒感染

背景

伊蚊（Eedes mosquitoes）传播的几种虫媒病毒，包括登革热病毒（DENV），寨卡病毒（ZIKV）和基孔肯雅病毒（CHIKV），在巴西东北部传播。由这些病毒引起的疾病与公共卫生息息相关，但是，在这三种病毒共同传播的地区，它们的流行病学特征很少。在这里，我们介绍了2015年5月至2016年5月在巴西累西腓招募的急性发热患者的前瞻性研究中的分子和血清学诊断分析。

方法

纳入在巴西东北部累西腓大都会地区就诊的急诊健康保健诊所的263名急性发热患者，其症状表明存在虫媒病毒病。收集急性和恢复期的血液样本，并使用分子和血清学检测方法检测DENV，ZIKV和CHIKV感染。

结果

对急性期血清进行的实时定量逆转录聚合酶链反应（qRTPCR）未检测到DENV阳性的患者，但ZIKV阳性的患者26例（9.9％），CHIKV阳性的患者132例（50.2％）。有几例疑似登革热病例，只有一例确诊。ZIKV和CHIKV的特异性血清学测定证实了qRTPCR数据。在qRTPCR结果中对DENV IgM和IgG ELISA的分析表明ZIKV阳性样品中的交叉反应抗体水平高。中和分析的结果高度证实了qRTPCR和ZIKV ELISA的结果，表明DENV阳性病例很少。ZIKV感染在研究的最初几个月中呈暂时性聚集，并于2015年8月开始随CHIKV感染的增加而减少。

结论

在2015-2016年的累西腓大都会地区，我们检测到寨卡病流行的尾声，该疫情被基孔肯雅热流行所取代。尽管在此期间该地区有大量官方登革热通知，但仍未发现登革热病例。我们在这里展示了这些病例的重要流行病学特征。