昆明市西山区2009年人群4种免疫抗体水平的监测分析

为了解昆明市西山区2009年健康人群中麻疹IgG、白喉IgG、乙肝表面抗原、乙肝表面抗体、乙脑IgG的免疫水平,评价预防接种效果,按卫生部《预防接种工作规范》(2005年版)人群免疫水平监测方法开展了调查。结果显示,白喉抗体总阳性率57.67%,1～4岁组白喉抗体阳性率为89.71%,白喉疫苗在计划免疫人群中实施效果较好,其它人群未能达到免疫成功率;麻疹抗体总阳性率69.71%,未能达到保护水平,而1～6岁组麻疹抗体阳性率为88.10%,达到计划免疫规程人群抗体阳性率85%的指标;乙肝表面抗原阳性率1.57%,乙肝抗体阳性率75.55%,但1～6岁组抗体阳性率较高,然后随年龄增加而降低;乙脑全人群抗体阳性率为70.53%,经过多次乙脑强化免疫,在人群中构建了较为有效的免疫屏障。西山区四种疫苗预防接种工作在国家免费所针对人群中实施效果较好,学龄前人群抗体阳性率较高,除乙脑疫苗接种人群外其它人群因未开展加强免疫工作,未能形成有效抗体免疫屏障,需定期开展重点人群强化免疫工作。     

百色市1～6岁儿童乙肝疫苗接种后免疫水平状况分析

掌握百色市乙型肝炎疫苗纳入儿童免疫规划后的免疫效果,客观评价免疫规划工作现状。方法按现况研究原理,全市12个县(区),每个县(区)各抽取150名儿童,每个县在东、西、南、北、中五个方位随机抽取5个行政村,每个行政村抽取6个年龄组(1～6岁儿童),每个年龄组抽取5名常住儿童(当地居住三个月以上),收集血清样本进行乙肝病毒感染相关标志表面抗原及抗体检测。结果全市共调查1～6岁儿童1 809名儿童,乙肝表面抗原携带率为0.66%,低于2006年全国调查的1～4岁人群乙肝表面抗原携带率(0.96%),达到中国《2006—2010年全国乙型病毒性肝炎防治规划》提出的5岁以下儿童乙肝表面抗原携带率<1%的控制目标要求;1～6岁儿童乙肝表面抗体阳性率为77.77%,高于2006年全国调查的1～4岁人群乙肝抗体阳性率(71.24%)。结论百色市自2003年将乙肝疫苗纳入免疫规划管理后,乙肝免疫效果显著,乙肝病毒表面抗原阳性率大幅度下降,婴幼儿体内保护性抗体水平也高于全国水平。加强对孕产妇住院分娩率和婴幼儿乙肝疫苗接种工作,尤其是乙肝疫苗首针及时接种是今后乙肝预防控制的重点。     

2007年重庆市流脑流行季节前健康人群抗体水平和带菌率调查

为了解重庆市流脑流行季节前健康人群免疫水平和带菌状况,预测发病趋势,提出新的免疫策略,提供有效的预防措施。按照全国流脑监测方案并结合重庆市2006年流脑疫情情况,选择重庆市北碚区、长寿区和万盛区为2007年流脑监测点,采集0~、5~、10~、15~、25~、35~及45岁以上共7个年龄组人群的静脉血和咽拭子,分别进行抗体水平和带菌率检测。结果显示,重庆市健康人群A群流脑IgG抗体的阳性率为76.02%(485/638),C群流脑IgG抗体的阳性率为47.65%(304/638),健康人群脑膜炎奈瑟菌(简称Nm)带菌率为0.47%(3/638)。重庆市健康人群A群流脑IgG抗体阳性率维持在较高水平,而C群流脑IgG抗体的阳性率较低,提示该市大部分人群对A群流脑有免疫作用,但C群抗体水平较低,有引起局部流脑爆发的风险。     

2020年广州市荔湾区健康人群麻疹、风疹和水痘的IgG抗体水平监测分析

目的了解广州市荔湾区2020年健康人群的麻疹、风疹和水痘IgG抗体水平,为本地制定免疫规划策略提供科学依据。方法采用分层随机抽样方法确定被调查对象,采集血液标本共238份,进行麻疹、风疹和水痘的IgG抗体水平监测并进行分析。结果 ELISA检测血清样本共238份,麻疹、风疹和水痘IgG抗体阳性率分别为97.06%、92.02%和79.41%,抗体几何平均浓度(geometric mean concentration, GMC)分别为1 204.65、43.38和290.38 mIU/mL。男女性别比为1.02∶1,麻疹、风疹和水痘IgG抗体阳性率差异无统计学意义(P0.05)。2～4岁组麻疹IgG阳性率最低,不同年龄组阳性率差异有统计学意义(χ~2=48.158,P0.05);0～1岁组的风疹IgG抗体阳性率最低,不同年龄组抗体阳性率差异有统计学意义(χ~2=36.980,P0.05);0～1岁组水痘IgG抗体阳性率非常低,不同年龄组抗体阳性率差异有统计学意义(χ~2=30.832,P0.05)。接种麻疹疫苗≥2剂次的人群IgG抗体阳性率为95.10%,不同免疫史差异无统计学意义(P=0.448,P0.05);接种风疹疫苗0剂次的人群IgG抗体阳性率最低,不同免疫史差异无统计学意义(P=0.020,P0.05);接种水痘减毒活疫苗0剂次的人群IgG抗体阳性率最低,接种2剂次的阳性率最高,不同免疫史差异有统计学意义(P=0.010,P0.05)。结论本区麻疹、风疹IgG抗体均维持在较高水平并有所提高;水痘IgG抗体水平较低,存在暴发、流行的可能。应加强麻疹、风疹免疫接种和查漏补种工作;有针对性地宣传水痘减毒活疫苗并推广接种;还须积极开展麻疹、风疹和水痘IgG抗体水平监测。     

儿童抗幽门螺杆菌IgG和IgA水平的酶联免疫吸附试验检测

目的：了解北京地区儿童幽门螺杆菌（Hp)的感染状况,探讨儿童幽门螺杆菌感染与年龄、性别的关系,比较分析HP感染后血清中抗体(IgG、IgA)水平。方法：采用ELISA方法对我院消化道门诊227例患儿同时检测血清抗Hp抗体IgG、IgA,任一项阳性者即诊断为Hp感染。结果：(1)227例门诊患儿Hp平均感染率53．7％,男孩感染率57．1％,女孩48．1％。(2)3岁以下就诊儿童Hp感染率57．1％,4—7岁组39．1％,8—12岁组60．5％,13岁以上47．1％;其中66．9％(81／120)的Hp阳性患儿在8—12岁之间;(3)HP感染总阳性率53．7％;若单独检测IgG,阳性率42．7％,假阴性率11％;单独检测IgA,阳性率22％,假阴性率31．7％;两项诊断符合率达57．3％。结论：北京地区儿童幽门螺杆菌感染率较高。有消化道症状伴HP感染的患儿以8—12岁居多,其感染率明显高于全国无症状儿童平均染率。儿童Hp感染性别差异无显著性,感染后血清抗体水平IgG显著高于IgA,同时检测IgG、IgA有助于提高ELISA方法Hp的感染检出率。     

潍坊市健康人群麻疹、风疹、流行性腮腺炎抗体水平调查

目的了解潍坊市健康人群麻疹、风疹、流行性腮腺炎血清抗体水平,为消除麻疹、控制风疹及腮腺炎疫情提供依据。方法 2011年8月,采集昌乐、潍城2个县区<2、2～5、5～8、8～11、11～15、15～20、20～40、>40岁健康人群血标本,应用酶联免疫吸附试验检测麻疹、风疹、腮腺炎IgG抗体。结果检测总数320人,其中昌乐县健康人群的麻疹抗体阳性率为98.75%、潍城为96.25%;风疹抗体阳性率昌乐县健康人群为89.38%、潍城区为91.88%。昌乐、潍城两地区健康人群麻疹、风疹的抗体阳性率差异均无统计学意义(χ2=1.15、0.59,P>0.05);昌乐县健康人群腮腺炎抗体阳性率为84.38%、潍城区健康人群为66.25%,两者差异有统计学意义(χ2=14.14,P<0.01);8组不同年龄健康人群的麻疹抗体阳性率为92.50%～100%,风疹抗体阳性率为87.50%～92.50%,腮腺炎抗体阳性率为67.50%～85.00%,各年龄组间均无统计学意义(χ2=13.49、1.58、5.23,P>0.05)。结论潍坊市麻疹抗体阳性率较高,风疹、腮腺炎抗体阳性率相对偏低,今后须要积极开展学龄儿童麻腮风三联疫苗的查漏补种工作。     

18～60岁健康人群肺炎链球菌IgG抗体水平调查

目的了解18~60岁健康人群肺炎链球菌IgG抗体水平,为肺炎链球菌性疾病的预防与控制提供参考依据。方法选取甘肃、宁夏健康献浆员为调查对象,分为18~30、31~40、41~50、51~60岁4个年龄组,共调查347人。采用WHO推荐的标准化酶联免疫吸附试验检测12种肺炎链球菌血清型IgG抗体水平,并计算IgG抗体阳性率和几何平均浓度(Geometric mean concentration,GMC)。结果质控血清QC907的IgG抗体浓度均值与参考值之间的误差百分数均未超过±40%,测定值符合其参考值范围,各血清型抗体浓度检测结果的CV均30%。347份血清样品肺炎链球菌IgG抗体总阳性率为64.8%~96.0%,GMC为0.37~2.24μg/m L。不同血清型间IgG抗体GMC差异具有统计学意义(P0.05)。不同年龄组同种血清型IgG抗体阳性率及GMC均无统计学意义(P0.05)。除19F型外,不同地区同种血清型IgG抗体阳性率均有统计学意义(P0.05);除4、7F、14和18C型外,不同地区同种血清型IgG抗体GMC间差异均有统计学意义(P0.05)。结论 18~60岁健康人群肺炎链球菌IgG抗体水平普遍较高,对肺炎链球菌主要流行血清型均具有一定的保护力。     

2016年吉林省健康从业人员麻疹和风疹抗体水平调查分析

目的调查分析吉林省2016年健康从业人员的麻疹(measles)和风疹(rubella)的抗体水平。方法采用方便抽样的方法,采集吉林省2016年各地区18岁及以上健康从业人员1 419人的血清,检测其麻疹和风疹的IgG抗体,进行描述性分析。结果 2016年吉林省健康从业人员麻疹IgG抗体阳性率为91.26%,风疹IgG抗体阳性率为81.46%。麻疹和风疹报告病例的时间分布,主要流行季节均在春季。吉林省8个地市麻疹IgG抗体阳性率在82.00%～98.00%之间,差异有统计学意义(χ~2=35.59,P<0.05);风疹IgG抗体阳性率在63.75%～86.24%,差异有统计学意义(χ~2=37.49,P<0.05)。男性与女性麻疹IgG抗体阳性率分别为92.64%和90.70%,性别差异无统计学意义(χ~2=1.38、P=1.42,P>0.05);男性与女性的风疹IgG抗体阳性率分别为82.84%和80.91%,性别差异无统计学意义(χ~2=0.72,P=0.22,P>0.05)。各年龄组麻疹IgG抗体阳性率在88.73%～100.00%之间,年龄差异无统计学意义(χ~2=7.11、P=0.21,P>0.05);风疹IgG抗体阳性率在75.00%～88.89%之间,年龄差异无统计学意义(χ~2=11.24、P=0.47,P>0.05)。结论 2016年吉林省健康从业人员麻疹和风疹的IgG抗体阳性率未达到可形成免疫屏障的水平,建议对该人群开展麻疹和风疹疫苗加强免疫。     

黑龙江省乙型肝炎血清流行病学调查分析

为了掌握黑龙江省乙型肝炎(乙肝)病毒(HBV)流行现状和人群免疫水平,评价我省儿童乙肝疫苗预防接种效果,为制订乙肝预防控制策略提供依据。采用横断面调查方法,选择全省7个国家级疾病监测点,在每个监测点随机抽取2个乡级单位,1～59岁作为目标人群共调查3337名人群。黑龙江省1～59岁人群乙肝病毒表面抗原(HBsAg)阳性率、乙肝病毒表面抗体(抗-HBs)阳性率和乙肝病毒核心抗体(抗-HBc)阳性率经标化后为5.65%、55.45%、30.50%,1～3岁人群乙肝表面抗原阳性率明显低于15～59岁人群。1～3岁、4～10岁和11～14岁人群乙肝疫苗全程接种率为99.43%、89.40%和64.81%;首针及时接种率分别为86.64%、75.57%和49.87。城市和农村HbsAg阳性率分别为3.26%和5.04%。医院出生儿童乙肝疫苗首针及时接种率高于在家出生儿童。结果显示接种乙肝疫苗可明显提高抗-HBs阳性率,提高人群对HBV的免疫保护能力,降低HBsAg携带率。     

HCMV-DNA定量检测和HCMV-IgG抗体AI检测在儿童HCMV感染诊断中的临床价值

摘要 目的：探讨人巨细胞病毒（HCMV）-DNA定量检测和HCMV-免疫球蛋白G（IgG）抗体亲和力指数（AI）检测在儿童HCMV感染诊断中的临床价值。方法：收集高度疑似HCMV活动性感染患儿血清样本103例作为研究组,健康体检儿童血清样本94例作为对照组。分析HCMV-DNA定量检测结果和HCMV-IgG抗体AI检测结果,并比较不同年龄、不同性别患儿HCMV-DNA阳性结果检出率和低HCMV-IgG抗体AI检出情况。结果：研究组血清HCMV-DNA阳性率为33.01%（34/103）,对照组血清HCMV-DNA均为阴性,研究组血清HCMV-DNA阳性率明显高于对照组,差异有统计学意义（P<0.05）。研究组血清低HCMV-IgG抗体AI检出率为13.59%（14/103）,对照组未检出低HCMV-IgG抗体AI,研究组血清低HCMV-IgG抗体AI检出率高于对照组,差异有统计学意义（P<0.05）。研究组不同性别之间患儿血清的HCMV-DNA阳性率、低HCMV-IgG抗体AI检测结果均无统计学差异（P>0.05）。研究组年龄1～5岁患儿血清HCMV-DNA阳性率明显低于年龄1 d～<6个月和年龄6个月～<1岁患儿（P<0.05）。三个年龄段患儿的血清低HCMV-IgG抗体AI检测结果均无统计学差异（P>0.05）。结论：1岁以下儿童更易受到HCMV感染,HCMV-DNA定量检测和HCMV-IgG抗体AI检测结果可以为临床早期诊断和治疗HCMV感染提供有效依据。     

Protective effect of colostrum in Mycoplasma pneumoniae infection induced in infant mice

The immunological responses and mechanism of maternal immunity in Mycoplasma pneumoniae infection of mice were investigated. ICR female mice, 4 weeks old, and infant mice, 2 to 4 days old, were infected with M. pneumoniae. Anti-M. pneumoniae antibodies in serum and colostrum were determined by enzyme-linked immunosorbent assay. The specific IgG antibody production persisted for 9 months or longer in both the young and infant mice. These infected mice were protected from rechallenge with M. pneumoniae. In addition, the infected dams conferred passive immunity on their offspring. The infant mice born to uninfected normal dams were protected from the challenge with M. pneumoniae when fed by infected foster dams. Conversely, the infant mice born to infected dams were not protected from the challenge with M. pneumoniae when the infants were fed by uninfected dams. The specific IgG antibody appeared in serum of infant mice inoculated orally with M. pneumoniae-infected mouse serum and the infants were protected from challenge with M. pneumoniae, while the infants given protein A-absorbed serum were not protected from the challenge. These results suggest that one of the factors involved in the resistance of infant mice to M. pneumoniae infection is the specific IgG antibody present in the colostrum rather than the result of transplacental transfer.     

241 例儿童社区获得性肺炎支原体感染的临床分析

目的：总结2011-2012 年黄岛地区儿童社区获得性肺炎(CAP)患儿中支原体的感染情况,以指导临床诊断和治疗。方法：选取 2011-2012 年间因CAP住院的患儿241 例,所有CAP 患儿均于住院第2 天采集空腹血行9 项呼吸道感染病原体IgM检查,包括 肺炎支原体、嗜肺军团菌、Q热立克次体、肺炎衣原体、腺病毒、呼吸道合胞病毒、甲型流感病毒、乙型流感病毒、副流感病毒。结 果：241 例社区获得性肺炎患儿中支原体感染阳性74 例(30.7%),其中132例男性CAP患儿中支原体感染38 例(28.8%),109 例女 性CAP 患儿中支原体感染36 例;＞3 岁患儿的感染率为41.2%,1-3 岁患儿感染率26.2%,＜1 岁婴幼儿感染率为5.4%;2011 年 CAP患儿支原体感染率为19.4%,而2012 年为34.6%;74 例支原体阳性患儿合并其他感染者6 例。结论：黄岛地区儿童社区获得 性肺炎中支原体感染占重要地位,且有升高趋势,应重视婴幼儿支原体感染及难治性支原体肺炎的诊治。     

241例儿童社区获得性肺炎支原体感染的临床分析

目的：总结2011-2012年黄岛地区儿童社区获得性肺炎（CAP）患儿中支原体的感染情况,以指导临床诊断和治疗。方法：选取2011-2012年间因CAP住院的患儿241例,所有CAP患儿均于住院第2天采集空腹血行9项呼吸道感染病原体IgM检查,包括肺炎支原体、嗜肺军团菌、Q热立克次体、肺炎衣原体、腺病毒、呼吸道合胞病毒、甲型流感病毒、乙型流感病毒、副流感病毒。结果：241例社区获得性肺炎患儿中支原体感染阳性74例（30.7%）,其中132例男性CAP患儿中支原体感染38例（28.8%）,109例女性CAP患儿中支原体感染36例;〉3岁患儿的感染率为41.2%,1-3岁患儿感染率26.2%,〈1岁婴幼儿感染率为5.4%;2011年CAP患儿支原体感染率为19.4%,而2012年为34.6%;74例支原体阳性患儿合并其他感染者6例。结论：黄岛地区儿童社区获得性肺炎中支原体感染占重要地位,且有升高趋势,应重视婴幼儿支原体感染及难治性支原体肺炎的诊治。     

Comparison of the influenza virus-specific effector and memory B-cell responses to immunization of children and adults with live attenuated or inactivated influenza virus vaccines

Cellular immune responses to influenza virus infection and influenza virus vaccination have not been rigorously characterized. We quantified the effector and memory B-cell responses in children and adults after administration of either live attenuated (LAIV) or inactivated (TIV) influenza virus vaccines and compared these to antibody responses. Peripheral blood mononuclear cells were collected at days 0, 7 to 12, and 27 to 42 after immunization of younger children (6 months to 4 years old), older children (5 to 9 years old), and adults. Influenza virus-specific effector immunoglobulin A (IgA) and IgG circulating antibody-secreting cells (ASC) and stimulated memory B cells were detected using an enzyme-linked immunospot assay. Circulating influenza virus-specific IgG and IgA ASC were detected 7 to 12 days after TIV and after LAIV immunization. Seventy-nine percent or more of adults and older children had demonstrable IgG ASC responses, while IgA ASC responses were detected in 29 to 53% of the subjects. The IgG ASC response rate to LAIV immunization in adults was significantly higher than the response rate measured by standard serum antibody assays (26.3% and 15.8% by neutralization and hemagglutination inhibition assays, respectively). IgG ASC and serum antibody responses were relatively low in the younger children compared to older children and adults. TIV, but not LAIV, significantly increased the percentage of circulating influenza virus-specific memory B cells detected at 27 to 42 days after immunization in children and adults. In conclusion, although both influenza vaccines are effective, we found significant differences in the B-cell and antibody responses elicited after LAIV or TIV immunization in adults and older children and between young children and older age groups.     

流行性腮腺炎疫苗免后血清学效果及免疫方案探讨

选以往无流行性腮腺炎患病史和接种史的学龄及学龄前儿童２４３名,血清检测流腮ＨＩ抗体,阳性率为５５．６％,阳性率明显地随年龄增大而上升,而性别无差异。经用Ｓ生物所及Ｂ生物所生产的两种疫苗接种,免后ＨＩ抗体的跳高率及ＧＭＴ均较免前有明显上升。双份血清检测结果,免后ＨＩ抗体显著跳高率（≥４倍）为４４．８％;９８名免前阴性儿童免后ＨＩ阳转率５７．１％,ＧＭＴ为１１３．２９,两种疫苗均无显著差异,提示疫苗的质量和稳定性有待提高,笔者对当前免疫方案提出了改进意见。     

Allergen-specific IgE and IgG4 are markers of resistance and susceptibility in a human intestinal nematode infection

IgG4 has been proposed to act as a 'blocking antibody' due to its ability to compete for the same epitopes as IgE thus preventing IgE-dependent allergic responses. IgG4 and IgE are both elevated in helminth infections and strong anti-parasite IgE responses are associated with resistance to infection. We wished to determine the relationship between anti-parasite IgG4 and IgE and Ascaris lumbricoides infection status. We examined anti-parasite responses, including antibody levels to recombinant Ascaris allergen-1A (rABA-1A), a target of serum IgE in endemic populations. Worm burden was indirectly estimated by measuring parasite egg output in a cross-sectional human population (N = 105). Levels of anti-parasite IgG4 and IgE in patients' plasma were quantified by immunoassay. Global anti-parasite antibody responses did not bear any significant relationships with intensity of Ascaris infection. Individuals who had detectable levels of IgE but not IgG4 to rABA-1A (11%) had lower average levels of infection compared with individuals who produced anti-rABA-1A IgG4 (40%) and sero-negative individuals (49%) (P = 0.008). The ratio of IgG4/IgE in rABA-1A responders positively correlated with intensity of infection (P < 0.025). IgG4 levels positively correlated with infection level in younger children (age 4-11) where average levels of infection were increasing (P = 0.038), whereas allergen specific IgE emerged as a correlate of immunity in older children and adults (age 12-36) where infection levels were decreasing (P = 0.048). Therefore, in a gastrointestinal helminth infection, differential regulation of anti-allergen antibody isotypes relate to infection level. Our results are consistent with the concept that IgG4 antibody can block IgE-mediated immunity and therefore allergic processes in humans.     

2003-2008年我国实验猴BV抗体检测结果及抗体水平变化规律的分析

目的对近年来我国实验猴BV（猴疱疹病毒Ⅰ型）抗体检测结果进行比较分析,以了解我国实验猴BV感染情况及其抗体水平变化规律,为我国实验猴质量控制及标准化提供依据。方法根据国标中ELISA方法 ,对2003～2008年我国11个单位送检的2个品种猴血清进行BV抗体检测,并对检测结果进行统计分析。结果检测的4612份猴血清中,有1843份BV抗体呈阳性,阳性率为39.96%;6年中检测猴群BV抗体阳性率基本在30%～50%。幼年（≤2岁）、青年（2.1～4.0岁）、成年（4.1～6.5岁）、老年（≥6.5岁）4个不同年龄段猴BV感染率分别为26.28%、31.53%、53.74%、87.27%。不同年龄感染率差异显著（P〈0.01）。雌猴BV感染率（35.91%）高于雄猴（34.93%）,但两者差异不显著（P〉0.05）。结论不同年龄猴BV感染率不同,随着年龄的增长BV感染率升高。     

Detection of serum antibodies against Chlamydia pneumoniae by ELISA

Abstract Chlamydia pneumoniae causes pneumonia and other respiratory infections in children, adolescents and adults. We tried to evaluate the diagnostic value of detection of serum antibodies by ELISA for C. pneumoniae infections in Japanese children. Serum IgG, IgA and IgM antibodies to C. pneumoniae were determined by the microimmunofluorescence (MIF) test. Serum IgG and IgA antibodies were also determined by ELISA test kits. Results obtained by ELISA were compared with those obtained by MIF test. IgG antibody to C. pneumoniae was detected in 135 (39.5%) by ELISA and in 125 (36.5%) by MIF out of 342 sera from Japanese infants and children without respiratory infections (aged from 2 months old to 15 years old). IgA antibody to C. pneumoniae was detected in 129 (37.7%) by ELISA and in 117 (34.2%) by MIF out of 342 sera tested. Of 342 specimens 113 were IgG-positive by ELISA and MIF (sensitivity: 90.4%, specificity: 89.9%, r = 0.853). Of 342 sera 28 had IgG antibody titers of 1:256 and none had titers 1:512 or higher by MIF. Of 28 infants and children a total of nine were less than 4 years of age. On the other hand, of 342 specimens 99 were IgA-positive by ELISA and MIF (sensitivity: 84.6%, specificity: 86.7%, r = 0.769). Of 342 sera 16 had IgA antibody titers of 1:256 or higher by MIF. Of 16 infants and children, ten were less than 4 years of age. ELISA had excellent sensitivity and specificity relative to MIF test for detection of IgC and IgA antibodies to C. pneumoniae . It was suggested that C. pneumoniae infection in Japanese infants and children under 4 years of age was not infrequent.     

Age of appearance of IgG, IgM, and IgE antibodies specific for Loa loa in Gabonese children

IgG, IgM, and IgE antibodies against the filaria Loa loa were measured in umbilical cord blood and in blood from young Gabonese children by an ELISA technique using a homologous metabolic antigen. For children in eight consecutive age groups and adults the percentage of the population positive for each of the antibody classes was determined. The number of children with maternal IgG decreased until one year of age when new synthesis began to become apparent. IgM antibodies were detected only after six months, probably indicating an early infancy as opposed to a fetal infection. The percentage of individuals positive for IgM or IgE reached a peak between two and three years old, followed by a slight decline. Over half of the individuals over one year of age had IgM antibody against L. loa, indicating long-term synthesis of this class of immunoglobulin in many people. In the first two years of life, IgE antibodies were usually accompanied by L. loa-specific IgM. This specific IgE did not appear to trigger the synthesis of nonspecific IgE. By the age of two, 95% of the population had some antibodies against L. loa and by five the percentage of individuals positive for each antibody class had reached adult levels.