OBJECTIVE Orthohantaviruses are geographically widely distributed and present various clinical manifestations from mild symptoms to the severe form of haemorrhagic fever with renal syndrome (HFRS) in Eurasia. Official registration of HFRS in Kazakhstan started in the year 2000. However, the true prevalence of human infections by orthohantaviruses within Kazakhstan is unknown. The aim of this study was to investigate of the seroprevalence of orthohantavirus infections in patients with fever of unknown origin (FUO) in two regions, Almaty and Kyzylorda region. METHODS Paired serum samples from 802 patients with FUO were screened for the presence of orthohantavirus IgG and IgM antibodies by ELISA. Positive samples were further tested by immunoblotting and indirect immunofluorescence tests (IIFT) to determine the respective orthohantavirus serotypes. Suspected acute serum samples were additionally checked by a RT-PCR to identify viral RNA. RESULTS In total 178/802 (22.2%) serum samples reacted with orthohantavirus IgG antibodies and 4/802 (0.5%) with IgM antibodies. All positive samples were tested by immunoblotting which resulted in 2.9% positive samples with IgG antibodies against Puumala (PUUV), Hantaan (HTNV) and Dobrava (DOBV) virus serotypes in Almaty region and 5.4% to PUUV and DOBV serotypes in Kyzylorda region, respectively. In the IFFT, 1.9% positive samples from Almaty and 3.1% from Kyzylorda were confirmed for PUUV and DOBV serotypes. Out of four IgM ELISA positive samples only three were positive against PUUV in the immunoblot and showed weak positive reactivity for the Saaremaa (SAAV), PUUV and HTNV serotypes in the IFFT. CONCLUSIONS This study demonstrates the presence of orthohantavirus infections among patients with FUO in Kazakh regions that were so far considered as non-endemic. The healthcare system needs to be prepared accordingly in order to be capable of detecting cases and providing adequate management of patients.

中文翻译：

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哈萨克斯坦不明原因发热患者的正汉坦病毒的血清学调查。

目的正汉病毒在欧亚大陆上分布广泛，并且表现出从轻度症状到严重的肾综合征出血热（HFRS）的各种临床表现。HFRS在哈萨克斯坦的正式注册始于2000年。但是，在哈萨克斯坦境内人类感染正汉塔病毒的真正流行率尚不清楚。这项研究的目的是调查两个地区，阿拉木图和克孜勒达地区的原发性肝炎病毒感染患者的血清阳性率。方法通过ELISA法对802例FUO患者的配对血清样本中的正汉坦病毒IgG和IgM抗体进行筛选。阳性样品通过免疫印迹和间接免疫荧光测试（IIFT）进行进一步测试，以确定各自的正汉坦病毒的血清型。另外通过RT-PCR检查可疑的急性血清样品，以鉴定病毒RNA。结果总共178/802（22.2％）血清样品与正汉坦病毒IgG抗体反应，而4/802（0.5％）与IgM抗体反应。所有阳性样品均通过免疫印迹进行测试，结果产生了2.9％的阳性样品，其中阿拉木图地区的抗Puumala（PUUV），汉坦（HTNV）和Dobrava（DOBV）病毒血清型的IgG抗体和Kyzylorda地区的PUUV和DOBV血清型的5.4％ 。在IFFT中，确认了来自Almaty的1.9％阳性样本和来自Kyzylorda的3.1％的阳性样本为PUUV和DOBV血清型。在四个IgM ELISA阳性样品中，只有三个在免疫印迹中对PUUV呈阳性，并且在IFFT中对Saaremaa（SAAV），PUUV和HTNV血清型显示弱的阳性反应性。结论这项研究表明哈萨克斯坦地区的FUO患者中存在正汉坦病毒感染，迄今仍被认为是非地方性的。需要相应地准备医疗保健系统，以便能够发现病例并提供对患者的充分管理。