Enzyme-linked Immunoassay for Respiratory Syncytial Virus Is Not Predictive of Bronchiolitis in Sudden Infant Death Syndrome

Although respiratory syncytial virus (RSV)-infected infants may present with apnea, the role that RSV plays in sudden infant death syndrome (SIDS) is speculative. To determine whether RSV is associated with bronchiolitis in these patients, we examined histologic sections of lungs from 41 apparent SIDS cases and compared the results with those of enzyme-linked immunofluorescent assay (EIA) from nasal washings. Bronchiolitis was defined by a bronchiolar inflammatory cell infiltrate plus epithelial necrosis. A positive EIA was associated with bronchiolitis in 8 instances, compared with 6 having a positive EIA and negative histology, 14 having a negative EIA and positive histology, and 13 having EIA and histology both negative. These results yield a predictive value of a positive test of 57% and a predictive value of a negative test of 48% (P > .9 by chi square analysis). Although RSV of the upper respiratory tract may be related to SIDS, our results indicate that EIA of nasal washings is not predictive of bronchiolitis, and we recommend other means of verification of histologic results. Received July 18, 1997; accepted December 8, 1997.     

新生儿呼吸道合胞病毒肺炎182例临床及流行病学特点

目的 探讨新生儿呼吸道合胞病毒(RSV)肺炎的临床及流行病学特点.方法 收集本院2009年2月-2011年3月确诊为新生儿肺炎的患儿709例,应用直接免疫荧光法检测其RSV抗原,根据检测结果分为RSV阳性组和RSV阴性组,对2组患儿临床及流行病学资料进行分析.结果 1.RSV阳性182例,RSV检出高峰期为10月份一次年2月份.2.RSV阳性组:日龄≤7 d者占17.0％(31/182例),明显低于阴性组[26.0％(137/527例)](x2=6.011,P=0.014);母乳喂养占40.7％(74/182例),明显低于阴性组[49.1％(259/527例)](x2=3.912,P=0.048).3.RSV阳性组较RSV阴性组显著增多的临床表现:咳嗽(x2=86.957,P=0.000)、肺部中细湿啰音(x2=17.504,P=0.000)及哮鸣音(x2=25.293,P=0.000).4.RSV与细菌混合感染113例(62.1％),合并感染的常见细菌依次为大肠埃希菌28例(15.4％),肺炎克雷伯菌25例(13.7％),金黄色葡萄球菌23例(12.6％),与RSV阴性组病原菌构成相似.5.RSV阳性组需氧疗的患儿占22.0％(40/182例),明显高于阴性组[9.3％(49/527例)](x2=19.815,P=0.000);治愈好转出院的RSV阳性组患儿住院时间[(12.8±4.9)d,n=81]明显长于阴性组[(11.4±4.9)d,n=236](t =2.214,P =0.028).结论 RSV是重庆地区秋冬季新生儿感染性肺炎的重要病原之一.新生儿的RSV易感性与特应性体质可能存在关联,母乳喂养可减少新生儿感染RSV的风险.RSV肺炎常合并细菌感染,此类患儿宜给予抗生素治疗.     

白细胞介素-4基因C-589T多态性与呼吸道合胞病毒毛细支气管炎发病的相关性

目的 探讨白细胞介素-(IL-4)基因C-589T位点多态性与呼吸道合胞病毒(RSV)毛细支气管炎发病的相关性.方法 采用聚合酶链-限制性片段长度多态法(PCR-RFLP)检测RSV毛细支气管炎组(毛支组)和健康对照组儿童IL-4/C-589T位点多态性;用化学发光法和酶联免疫分析法(ELISA)分别检测RSV毛支组血清总IgE和鼻咽分泌物(NPS)中IL-4水平.结果 二组均发现IL-4/C-589T位点基因多态性,但仅见TT和CT 2种基因型,以TT纯合子基因型为主,其中RSV毛支组IL-4/C-589T位点TT、CT基因型频率分别为94.6%、5.4%,T、C等位基因频率分别为97.3%、2.7%;对照组TT、CT基因型频率分别为76.9%、23.1%,T、C等位基因频率分别为88.4%、11.6%.RSV毛支组TT基因型和T等位基因频率均显著高于对照组(χ2=15.995,14.842 Pa＜0.01),且T等位基因携带者患病的危险性为C等位基因携带者的4.73倍(OR=4.73 P=0).但2种基因型RSV毛支患儿间NPS中IL-4及血清总IgE水平均无显著性差异(Z=0.515,t=0.260 Pa＞0.05).IL-4/C-589T位点多态性在轻度和中重度患儿间无显著差异(χ2=0.024 P＞0.05).结论 温州地区儿童存在IL-4/C-589T位点的多态性.IL-4/C-589T 位点T等位基因可能是影响RSV毛细支气管炎发病的一个重要候选基因.     

病毒性肺炎婴幼儿呼吸道合胞病毒免疫球蛋白M抗体检测的意义

目的探讨呼吸道合胞病毒(RSV)-IgM抗体对婴幼儿病毒性肺炎的诊断价值。方法婴幼儿病毒性肺炎108例(间质性肺炎76例,毛细支气管炎32例)和健康对照组40例,采用间接免疫荧光法(IIF)检测其血清RSV-IgM抗体。结果间质性肺炎患儿血清RSV-IgM抗体阳性率48.68%(37/76例);毛细支气管炎患儿RSV-IgM抗体阳性率为25.0%(8/32例),二组有显著性差异(χ2=5.20P<0.05)。间质性肺炎、毛细支气管炎组阳性率均明显高于健康对照组(χ2=28.59,11.25Pa<0.05)。病毒性肺炎婴幼儿RSV-IgM阳性率发热病例最高,占81.97%(50/61例),其次为呼吸困难占57.14%(12/21例),最低为气促,占26.87%(18/67例)。结论RSV-IgM抗体检测是婴幼儿病毒性肺炎诊断中重要参考指标之一,其检测对提高该疾病的诊断、指导治疗和估计预后均有重要意义。     

孟鲁司特钠对呼吸道合胞病毒毛细支气管炎的治疗作用

病毒是导致婴幼儿呼吸道感染最主要的病原体,其中呼吸道合胞病毒(RSV)占50%.RSV感染后呼吸道内半胱氨酰白三烯(CysLTs)除在急性期明显增高外,在急性期1个月内仍可维持在较高水平.呼吸道内CysLTs的持续高水平与患儿反复咳嗽、喘息,持续肺功能异常及哮喘发病率的增高密切相关.孟鲁司特钠为CysLTs特异性受体阻滞剂,可通过阻断CysLTs与其1型受体结合而发挥特异性抗炎作用.对于首次感染RSV的重症毛细支气管炎患儿,在急性期及4周内,每晚口服孟鲁司特钠4 mg,可有效改善急性期临床症状,防止肺功能下降,减轻持续性呼吸道高反应性,降低再次呼吸道RSV感染及反复咳嗽、喘息的发生率.     

Demonstration of Respiratory Syncytial Virus in an Autopsy Series

Respiratory syncytial virus (RSV) antigen was demonstrated in formalin-fixed, paraffin-embedded autopsy tissue using an immunoperoxidase technique. Eighteen autopsy cases were selected on the basis of one of the following criteria: a positive culture for RSV, antemortem or postmortem; positive ELISA test for RSV, antemortem or postmortem; or postmortem histology suggestive of paramyxovirus infection. Controls included three cases from which parainfluenza or influenza virus had been cultured and a case in which the clinical diagnosis of measles was firmly established. Sections of formalin-fixed, paraffin-embedded tissue were stained with a rabbit anti-RSV antibody (Dako) using an immunoperoxidase technique. Staining was achieved in 12 cases. This included 6 of 7 cases selected because of positive cultures or ELISA tests for RSV. The other 6 cases in which RSV was identified by the described technique lacked culture or ELISA confirmation. Granular and globular staining was seen in the cytoplasm of respiratory epithelial cells and syncytial giant cells. None of the control cases stained for RSV. The histology of RSV lungs was consistent with changes described in the literature for RSV infection, although pneumonic consolidation and syncytial giant cells were more prominent in this series.     

Neutralizing Activity in Human Milk Fractions against Respiratory Syncytial Virus

ABSTRACT. Neutralizing activity against respiratory syncytial virus (RSY) was measured in milk samples from 17 healthy women whose infants had an acute infection with respiratory syncytial virus (RSV) and from 27 women with healthy infants. All milk samples were obtained 2-8 months post partum. Neutralizing activity was detected in 36 samples. No major difference in neutralizing titers was observed between the two groups, and the titers were low. RSV-specific IgA was found in two samples, and RSV-specific IgG in one sample. RSV-specific IgM was not detected. In gel filtration studies, the neutralizing activity was eluted with an apparent molecular weight above 400 000. The neutralizing activity remained after removal of IgA by affinity chromatography. These findings suggest that both immunoglobulin and non-im-munoglobulin components in human milk can neutralize RSV.     

Clinical Manifestations of Respiratory Tract Infections due to Respiratory Syncytial Virus and Rhinoviruses in Hospitalized Children

ABSTRACT. From September 1984 to May 1986, nasopharyngeal secretions were obtained from 519 children with some form of respiratory tract infection. The nasal secretions were screened for respiratory syncytial virus (RSV), rhinoviruses, adenoviruses, parainfluenza virus types 1, 2,3, influenza virus types A and B, and enteroviruses by tissue culture virus isolation technique and/or enzyme-linked immunosorbent assay. A uniform questionnaire gave information about age, sex, individual signs and symptoms, findings of the physical examination and clinical diagnosis of the patients. RSV was detected in 119 (23%) specimens and was thus the most frequent causative agent of respiratory infections. After RSV, rhinoviruses were the most frequently recovered pathogens accounting for 60 (12%) cases of acute respiratory disease. A comparison of the individual signs and symptoms, the findings of the physical examination and the clinical diagnosis of RSV and rhinovirus infected children revealed that there was no characteristic clinical pattern associated with either of the two viral respiratory pathogens. According to our results, rhinovirus infections were a major cause of lower respiratory tract infections in hospitalized children ≤3 years old.     

Increased levels of BAL cysteinyl leukotrienesinacute [corrected] RSV bronchiolitis

BACKGROUND: Cysteinyl leukotrienes (CysLTs), including LTC4, LTD4 and LTE4, are pivotal mediators in the pathophysiology of asthma. AIM: To determine whether CysLT levels are increased in the lower airways of children with respiratory syncytial virus (RSV) bronchiolitis, as they are in asthmatic children, and to investigate a possible heterogeneity in CysLT levels in children with RSV bronchiolitis. METHODS: Bronchoalveolar lavage (BAL) fluids were obtained from children with acute RSV bronchiolitis (n = 20), from children with acute asthma who had no identifiable virus infection (n = 16) and from control subjects (n = 14). BAL cell counts and differentials were determined, and the concentrations of CysLTs were measured by ELISA. RESULTS: CysLT levels in the asthma (70.6 +/- 52.7 pg/ml, p < 0.001) and bronchiolitis groups (21.9 +/- 23.3 pg/ml, p < 0.05) were significantly higher than in the control group (8.7 +/- 5.2 pg/ml). Among bronchiolitis subjects, the eosinophil-positive subgroup (n = 6) showed significantly higher CysLT levels (49.0 +/- 26.7 pg/ml, p = 0.001) than the control group, but this was not observed in the eosinophil-negative subgroup (n = 14, 10.3 +/- 6.3 pg/ml, p = 0.47). CONCLUSION: CysLT levels are increased in the lower airways during RSV bronchiolitis, although their intensities are lower than those in acute asthma. Among bronchiolitis subjects, high CysLT producers could be distinguished from low CysLT producers by the presence of eosinophilia in BAL fluids, suggesting a pathophysiological heterogeneity in RSV bronchiolitis.     

呼吸道合胞病毒、副流感病毒3型毛细支气管炎患儿鼻咽分泌物趋化因子水平的比较

目的探讨趋化因子在呼吸道合胞病毒（RSV）及副流感病毒3型（PIV3）所致毛细支气管炎发病机制中的作用,比较两种病毒感染对其表达的影响。方法毛细支气管炎患儿40例,入院24 h内收集其鼻咽分泌物（NPS）,应用直接免疫荧光法检测RSV和PIV3抗原。对照组为行心导管检查术和腹部手术的患儿14例。应用酶联免疫吸附试验（ELISA）测定NPS中调节活化正常T细胞表达及分泌的趋化因子（RANTES）、巨噬细胞炎性蛋白1α（MIP-1α）、IL-8水平。结果RSV阳性26例,PIV3阳性14例。PIV3感染患儿RANTES、MIP-1α及IL-8水平均高于RSV感染组,但差异无显著性（Z=0.551,0.357,0.169 Pa〉0.05）。RSV及PIV3感染组RANTES、MIP-1α、IL-8水平均明显高于对照组（Z=3.65,4.10,4.22;Z=4.13,4.85,5.08 Pa〈0.001）。RSV感染组RANTES、MIP-1α、IL-8间均呈显著正相关（P〈0.01,0.05）;PIV3组IL-8与MIP-1α及RANTES均呈显著正相关（Pa〈0.01）,RANTES与MIP-1α无相关性。结论RSV与PIV3感染有相似的免疫发病机制。趋化因子可能在其发病机制和呼吸道炎症中起重要作用。     

呼吸道合胞病毒毛细支气管炎患儿鼻咽分泌物白细胞介素-2水平的变化

目的探讨呼吸道合胞病毒(RSV)毛细支气管炎(毛支)患儿急性期鼻咽分泌物(NS)IL-2水平的改变及其临床意义。方法采用ELISA双抗体夹心法检测58例RSV毛支患儿急性期NS中IL-2含量。并根据临床评分标准、血氧饱和度、供氧和住院时间等不同标准,对疾病严重程度进行分析。结果入院时77.6%患儿血氧饱和度<95%;吸氧时间(4.8±3.4)d。RSV毛支患儿急性期NS中IL-2含量变化很大(0~3417μg/L),中位数76μg/L。各疾病严重程度组间比较,IL-2水平无显著性差异(P>0.05);IL-2与各疾病严重因素无明显相关性(P均>0.05)。结论RSV毛支患儿急性期NS中IL-2水平与RSV毛支无关,其改变可能系其他原因所致。     

低分子肝素对呼吸道合胞病毒肾病大鼠模型的影响

目的研究呼吸道合胞病毒(RSV)感染对肾小球基底膜的损伤机制;低分子肝素(LMWH)对RSV致大鼠蛋白尿及肾小球结构改变的减轻及保护机制。方法以6×106空斑形成单位(PFU)RSV鼻腔滴注及腹腔注射,LMWH400IU/kg腹腔注射接种SD大鼠。实验组A先接种RSV3d,后予LMWH11d;实验组B先予RSV和LMWH的混合悬液3d,后予LMWH11d;实验组C连续予LMWH14d,期间于d4、d5、d6接种RSV;RSV组和对照组分别接种RSV和DMEM3d。观察肾组织形态学改变;分析24h尿蛋白定量及血生化学指标。原位杂交检测肾组织RSVRNA表达。结果1.实验组A、B、C与对照组比较尿蛋白无明显增高,RSV组接种后尿蛋白逐渐增高;2.实验组A、B、C与对照组比较血清蛋白、尿素氮、肌酐、胆固醇均无明显差异(Pa>0.05),而RSV组与实验组A和对照组比较,血清蛋白降低,同其余各组比较,尿素氮增高(P<0.05);3.光镜及电镜下实验组A、B、C与对照组比较,肾小球结构无明显改变,RSV组部分肾小球充血肿胀,足突肿胀、融合;4.原位杂交:实验组A、B、C肾组织原位杂交可见RSV阳性信号表达,但较RSV组弱。结论RSV感染细胞机制是通过阴阳电荷吸引作用与细胞表面硫酸乙酰肝素(HS)链结合。LMWH能与肾脏靶细胞HS竞争结合RSV,有效阻止RSV对大鼠肾细胞的感染,保护肾小球不被破坏,减轻蛋白尿。     

RNA干扰技术与利巴韦林体外抗呼吸道合胞病毒的效应

目的比较RNA干扰(RNAi)技术与利巴韦林抗呼吸道合胞病毒(RSV)效应,探讨RNAi技术体外抑制RSV的有效性。方法用成功构建的表达载体pshRNA7816及利巴韦林处理HEp-2细胞,利用四甲基偶氮唑蓝比色实验检测pshRNA7816、利巴韦林的细胞毒性和对RSV感染后细胞的保护作用;通过显微镜观察pshRNA7816及利巴韦林对RSV感染细胞病变的抑制效率。结果pshRNA7816对HEp-2细胞的正常生长无明显细胞毒性作用,而利巴韦林在1.0mmol/L以上作用浓度即会对细胞产生细胞毒性作用;pshRNA7816和利巴韦林均能抑制RSV所致的细胞病变,但pshRNA7816对细胞病变抑制作用较利巴韦林强,经过pshRNA7816处理过的RSV感染细胞的细胞存活率明显高于利巴韦林对RSV的最大抑制率(P<0.05)。结论根据RNAi技术所设计的重组质粒pshRNA7816在体外细胞培养系统中较利巴韦林抗RSV活性强。     

卵蛋白致敏小鼠对呼吸道合胞病毒感染的免疫应答

目的探讨卵蛋白（OVA）致敏小鼠感染呼吸道合胞病毒（RSV）后肺内炎症及T辅助细胞相关细胞因子变化的特点。方法将Balb／c小鼠随机分成正常未致敏和致敏（用OVA雾化吸入）2个系列。每个系列中又包括对照组、RSV感染组。以肺组织病理检测和IL-4、IFN-γ mRNA表达作为评价指标。结果病理检查证实小鼠感染RSV后发展为典型的间质性肺炎；致敏小鼠感染RSV后病变更明显，细支气管周围淋巴细胞浸润形成管套增厚，嗜酸细胞增多，炎性细胞浸润的细支气管比例显著增高。单纯RSV感染小鼠肺组织IFN-γ mRNA有显著表达，但无IL-4 mRNA表达；致敏小鼠感染RSV后IL-4 mRNA的表达显著，但IFN-γ mRNA几乎不表达。结论致敏小鼠感染RSV后肺组织病变较单纯RSV感染者严重；单纯RSV感染后小鼠肺组织T辅助细胞因子改变呈Th1反应，而致敏后再感染RSV后则呈Th2反应。     

几种呼吸道合胞病毒检测方法的比较

目的比较不同从临床样本中快速、敏感特异的检测呼吸道合胞病毒（RSV）的方法,以便早期诊断RSV感染。方法应用不同方法对45例急性下呼吸道感染患儿鼻咽分泌物RSV进行检测,包括病毒分离、直接涂片间接免疫荧光法（IFA）、快速细胞培养法、双抗体夹心酶联免疫吸附法（ELISA）及链亲和素-生物素法（LSAB）。结果鼻咽分泌物45例中,病毒分离阳性12例（26.7%）,直接涂片间接免疫荧光法检测出阳性14例（31.1%）,快速细胞培养法阳性20例（44.4%）。双抗体夹心ELISA及LSAB法均仅检出4例阳性,阳性率均为8.9%。结论将直接涂片间接免疫荧光法与快速细胞培养法同时应用于RSV感染的早期诊断,既能及时提供检测结果,又能提高诊断的敏感性,是最适合于RSV感染早期诊断的方法。     

经鼻重组腺相关病毒T-bet基因转染对呼吸道合胞病毒感染小鼠呼吸道炎症的影响

目的 观察携带T-bet基因的重组腺相关病毒(rAAV-T-bet)转染对呼吸道合胞病毒(RSV)感染模型小鼠呼吸道炎症的影响.方法 健康6～8周龄Balb/c小鼠40只.按随机数字表法分为4组:正常对照组(A组)、RSV感染模型组(B组)、模型/对照病毒rAAV载体介导的增强型绿色荧光蛋白(rAAV-eGFP)干预组(C组)及模型/rAAV-T-bet干预组(D组),每组10只.将B组、C组和D组小鼠用滴度为1.26×1010 PFU·L-1的RSV液滴鼻,每只100 μL;A组用等量人喉癌上皮细胞(Hep-2细胞)培养上清液代替RSV液.于RSV接种第5天,再次麻醉小鼠,A组和B组经鼻滴入293细胞培养上清液;C组经鼻滴入293细胞包装的rAAV-eGFP对照病毒液,D组经鼻滴入293细胞包装的rAAV-T-bet.7 d后处死小鼠,检测各组小鼠支气管肺泡灌洗液(BALF)中细胞成分及IL-4和γ干扰素(IFN-γ)水平,并观察其肺组织病理学变化.结果 1.B组小鼠BALF中细胞总数和淋巴细胞计数百分比分别为(43.91±10.41)×109L-1、(65.15±1.88)%,A组分别为(14.52±3.57)×109L-1、(25.79±1.07)%,A组与B组比较差异均有统计学意义(Pa<0.05);D 组小鼠BALF中细胞总数和淋巴细胞计数百分比分别为(24.84±4.35)×109L-1、(29.48±11.97)%,与B组、C组比较差异均有统计学意义(Pa<0.05).2.B组小鼠BALF中IL-4和IFN-γ水平分别为(74.32±10.06) ng·L-1、(89.36±20.38) ng·L-1,A组分别为(6.01±1.02) ng·L-1、(177.32±18.16) ng·L-1,A组与B组比较差异均有统计学意义(Pa<0.05);D组分别为(49.14±7.59) ng·L-1、(145.28±43.52) ng·L-1,与B组、C组比较差异均有统计学意义(Pa<0.05).3.A组小鼠呼吸道无明显炎症改变;B组和C组小鼠小支气管、血管黏膜下和周围肺组织有明显炎性细胞浸润,血管壁明显水肿;D组小鼠呼吸道炎症明显减轻.结论 T-bet基因转染能改善RSV感染模型小鼠呼吸道内细胞因子IL-4和IFN-γ异常表达,同时对淋巴细胞在肺内聚集、肺组织炎症有一定抑制作用.     

肝素阻断呼吸道合胞病毒与呼吸道上皮细胞黏附作用

目的探讨呼吸道合胞病毒（RSV）与呼吸道上皮细胞的黏附机制。方法采用流式细胞仪定量检测RSV A2原型株与来自囊性纤维化患者的呼吸道上皮细胞株（CFBE）间的黏附效率。观察肝素及多种RSV抗体对黏附效应的影响。结果RSV与CFBE的黏附效率不及人喉淋状细胞癌细胞株（HEp-2）细胞，多种RSV抗体与RSV预孵后未能阻断其与CFBE黏附，但肝素却以剂量-效应依赖模式有效阻断黏附反应。结论CFBE细胞表面糖胺聚糖分子可能介导RSV与呼吸道上皮的黏附。采用流式细胞仪可直接定量评估RSV与靶细胞的黏附效率，优于病毒在靶细胞内繁殖的检测手段。     

短发卡结构状RNA体外抑制呼吸道合胞病毒M2基因 mRNA水平和病毒蛋白表达的研究

目的观察针对人类呼吸道合胞病毒(RSV)M2基因mRNA构建的短发卡结构状RNA重组质粒在细胞水平对RSV复制的影响,为利用RNA干扰技术抑制RSV感染的研究奠定基础。方法将已成功构建的重组质粒pshRNA7816/8330转染HEp-2细胞,通过显微镜观察pshRNA7816/8330对RSV感染细胞病变(CPE)的抑制效率,利用四甲基偶氮唑盐比色实验检测pshRNA7816/8330的细胞毒性,经RT-PCR方法检测pshRNA7816对RSVM2mRNA表达的影响,免疫细胞化学染色法检测pshRNA7816对细胞内RSV蛋白的影响。结果pshRNA7816/8330对HEp-2细胞的正常生长没有明显的细胞毒性作用,2个重组质粒均能抑制RSV所致的CPE,但pshRNA7816对CPE抑制作用较pshRNA8330要强,RT-PCR和免疫细胞化学染色法结果显示pshRNA7816能明显降低RSVM2基因mRNA和RSV蛋白表达水平。结论针对RSVM2-1基因所构建的短发卡结构状RNA重组质粒pshRNA7816在细胞水平能有效抑制RSV的CPE形成降低RSVM2mRNA和病毒蛋白表达水平,从而干扰RSV的复制。     

Eleven consecutive years of respiratory syncytial virus outbreaks in Croatia

Background:  Respiratory syncytial virus (RSV) is the most common cause of severe lower respiratory tract infections (LRTI) in infants. The aim of the present study was to analyze the epidemiologic characteristics of RSV outbreaks in Croatian children.
Methods:  Over a period of 11 consecutive years (1994–2005), 3435 inpatients with acute respiratory infections (ARI) aged from birth to 10 years and were residing in Zagreb County were tested for infection with RSV and other respiratory viruses at the Virology Department, Croatian National Institute of Public Health. RSV was identified in nasopharyngeal secretions by isolation on cell culture and/or detection with monoclonal antibodies using a direct fluorescence assay.
Results:  RSV was the most common causative agent of ARI (42.2%; 658/1559) for the infants 0–6 months of age. It was also the etiologic agent of LRTI in 49% (495/1010) of infants of similar age. RSV was demonstrated in 56.5% (382/676) of infants with bronchiolitis, and in 36.5% (49/134) of those with pneumonia in this age group.
Conclusion:  The overall prevalence of RSV infection in Croatian children with acute respiratory illness, and its occurrence in various age groups, has remained stable over the past decade. RSV was found to be the most common cause of bronchiolitis occurring throughout childhood (52.7%; 482/913).