Newborn screening for congenital infectious diseases

To estimate the prevalence of congenital toxoplasmosis, Chagas disease, cytomegalovirus, and rubella, blood samples on dried blood spot (DBS) from neonates (day 3-20 of life) were screened for immunoglobulin (Ig) M against Toxoplasma gondii, cytomegalovirus, rubella virus, and IgG against Trypanosoma cruzi by methods used for serum and adapted for use with DBS. Positive samples were further analyzed for IgM and IgG in serum from neonates and mothers. DBS samples from 364,130 neonates were tested for Toxoplasma gondii-specific IgM, and 15,873 neonates were also tested for IgM against cytomegalovirus and rubella virus and for Trypanosoma cruzi-specific IgG. A total of 195 were diagnosed with congenital toxoplasmosis, 16 with cytomegalovirus, and 11 with congenital rubella. One newborn had a confirmed result for Chagas disease, and 21 mothers had positive serum antibodies. These results suggest that infectious diseases should be considered for future inclusion in programs for newborn screening of metabolic diseases in disease-endemic areas.     

Trypanosoma cruzi in persons without serologic evidence of disease, Argentina

Current diagnosis of chronic Chagas disease relies on serologic detection of specific immunoglobulin G against Trypanosoma cruzi. However, the presence of parasites detected by polymerase chain reaction (PCR) in patients without positive conventional serologic testing has been observed. We determined the prevalence and clinical characteristics of persons with seronegative results and T. cruzi DNA detected by PCR in a population at high risk for chronic American trypanosomiasis. We studied a total of 194 persons from two different populations: 110 patients were recruited from an urban cardiology clinic, and 84 persons were citizens from a highly disease-endemic area. Eighty (41%) of persons had negative serologic findings; 12 (15%) had a positive PCR. Three patients with negative serologic findings and positive PCR results had clinical signs and symptoms that suggested Chagas cardiomyopathy. This finding challenges the current recommendations for Chagas disease diagnosis, therapy, and blood transfusion policies.     

巴楚县2001年新疆出血热疫情的血清学证实

目的：以血清流行病学方法调查新闻出血热（XHF）病人，易感人群和主要宿主动物中疾病的感染情况。方法：分别收集2001年4－6月新疆巴县临床诊断为XHF的病人血清，易感人群血清和主要宿主动物的血清，用研制的诊断试剂以酶联免疫吸附试验（ELISA）检测XHF特异性IgG和IgM抗体；用抗原捕获ELISA检测XHF病毒抗原。结果：病人血清IgG抗体阳性率为39．62％（21／53）。IgM抗体阳性率为20．75％（11／53），抗原获ELISA有1份血清为XHF抗原阳性；易感人群血清IgG抗体阳性主为21．05％（4／19），IgM抗体检测和抗原捕获ELISA全部为阴性；羊血清IgG抗体阳性率为70％（56／80）。结论：血清流行病学研究证实该次疫情确系XHF、流行地区人畜均有较高水平的隐性感染。     

EV71抗原检测方法的建立及初步临床应用

目的建立EV71抗原双抗体夹心检测方法,并初步探讨其在临床血清样品检测中的应用。方法用抗EV71病毒单克隆抗体包被酶联反应板,加入待检标本反应后,用HRP标记的抗EV71病毒单克隆抗体进行检测,建立EV71抗原双抗体夹心检测方法;采用抗人IgM单克隆抗体包被96孔酶联板,辣根酶标记的EV71抗原,建立ELISA捕获方法检测抗EV71-IgM。2种方法同时检测230份体检人员血清,确定方法的cut-off(CO)值,并检测140份手足口病患者血清,采用Graraph Pad Prism 4软件作图并绘制ROC曲线。结果EV71抗原检测方法的CO值为0.168,抗EV71-IgM ELISA检测方法的CO值为0.173。在140例手足口病患者血清中,EV71抗原检测方法的阳性检出率为45.00%,抗EV71-IgM ELISA检测方法的阳性检出率为42.86%,其中共同阳性患者45例,单独EV71抗原阳性患者18例,单独抗EV71-IgM抗体阳性患者15例,如果2种方法联合检测,其阳性检出率可提高到55.71%。结论ELISA检测EV71抗原诊断HFMD具有很好的准确性,结合EV71-IgM抗体捕获检测技术,可进一步提高灵敏度,具有很好的临床应用前景。     

Antibody response to OspC-I synthetic peptide derived from outer surface protein C of Borrelia burgdorferi in sera from Japanese forestry workers.

The prevalence of antibodies against Lyme disease spirochaetes in serum samples from 80 forestry workers at high occupational risk of Lyme disease was surveyed by enzyme-linked immunosorbent assay (ELISA) with the OspC-I synthetic peptide. The peptide is part of the outer surface protein C (OspC) amino acid sequence located in the region conserved among Borrelia burgdorferi sensu stricto or sensu lato. Positivity for antibodies against OspC-I was observed in 25 (313%) of the forestry workers. Of these positive cases, 12 (15.0%) and 19 (23.8%) were positive for immunoglobulin M (IgM) and IgG antibody, respectively. Among 62 workers who were negative for IgG antibody against B. garinii or B. japonica in our previous study, 9 (14.5%) and 4 (6.5%) were positive for IgM and IgG antibody, respectively, in OspC-I ELISA. These results demonstrate for the first time that Lyme disease in forestry workers can be revealed using OspC-I ELISA. We conclude that forestry workers who show positive results for antibodies against OspC-I have very likely been exposed to Lyme disease spirochaetes, and that those who show positivity for IgM antibody against OspC-I may be in the early stage of Lyme disease.     

Serodiagnostic assay for visceral leishmaniasis employing monoclonal antibodies

A highly specific and sensitive competitive serodiagnostic assay for visceral leishmaniasis (VL) was developed using species specific Leishmania donovani monoclonal antibodies. This assay, either RIA or ELISA, is based on the specific inhibition of monoclonal antibody binding to a crude parasite homogenate by serum from patients with VL. 15 monoclonal antibodies were examined. The binding of 13 antibodies was significantly inhibited by VL serum and unaffected by normal serum. 3 species-specific monoclonal antibodies, D-2, D-13 and D-14, which recognize different parasite antigens, were chosen for use in the competitive serodiagnostic assay. In 90% of the positive cases, regardless of geographic origin, VL sera inhibited monoclonal antibody binding to the parasite antigen by more than 30%. No false positive was obtained with sera from Chagas disease, lepromatous leprosy, schistosomiasis, malaria, systemic lupus erythematosus, cutaneous or mucocutaneous leishmaniasis, even at serum dilutions (1:100) which cross-react strongly with Leishmania antigen in direct binding assays. Inhibition by negative control sera from areas endemic for VL and from non-endemic areas was negligible. The assay takes less than 24 h, requires minimum amounts of sera or antigen, and is easily standardized allowing interlaboratory comparison of test data. The competitive serodiagnostic assay will be especially useful in areas where Chagas disease is coendemic and the rapid diagnosis of VL by direct binding serodiagnostic assays presents a problem.     

套式逆转录PCR检测戊型肝炎病毒RNA的临床应用

目的 评价套式逆转录PCR检测血清戊肝病毒(HEV) RNA的临床意义.方法 对GenBank数据库中的戊型肝炎病毒全基因组序列进行分析比对,并针对国内流行的HEV株序列,选择位于ORF2的保守区域设计引物,建立套式逆转录聚合酶链式反应(nRT-PCR)方法,并检测126例急性戊型肝炎患者,并与检测抗-HEV IgM的方法进行比较.结果 126例急性戊型肝炎患者血清中有67例HEV-RNA阳性,对照组血清HEV-RNA检测均为阴性;与血清抗HEV IgM检测结果比较,HEV RNA检测的总符合率为80.91％,两种方法的检测结果具有良好的一致性;nRT-PCR方法检测HEV-RNA与血清抗-HEV IgM检测方法存在明显的差异,不能相互替代,而有一定的互补性;3例患者的首份血清检测为HEV-RNA阳性,但抗-HEV IgM为阴性,系列追踪检测,均相继出现抗HEV IgM,急性戊型肝炎患者血清HEV-RNA的检出多在发病的1～12 d.结论 应用nRT-PCR方法能对急性散发戊型肝炎患者血清中的HEV RNA进行定性检测,且有较高的特异性和敏感性,临床使用可以提高对HEV早期诊断的水平,具有一定的临床应用价值.     

Serological and molecular diagnosis of human brucellosis in Najran, Southwestern Saudi Arabia

This study aimed to investigate the prevalence of human brucellosis in Najran, southwestern Saudi Arabia, and to assess the performances of ELISA and PCR as diagnostic tools for brucellosis with respect to conventional methods. The study included 340 patients with clinical characteristics of brucellosis. Blood samples from cases and controls were subjected to culture, standard tube agglutination test (SAT), ELISA for IgM and IgG, and brucella PCR. The diagnosis of brucellosis was confirmed in 54 (15.9%) of the 340 provisionally diagnosed brucellosis patients. Blood culture identified only 14 (25.9%) cases. The SAT was positive for 50 (92.6%) cases, whereas ELISA IgM, IgG and PCR were found positive in 46, 52 and 38 cases respectively. The sensitivities of ELISA IgM and IgG were 85.2% and 96.3% respectively and the specificity was 100% for each. For PCR, the sensitivity and specificity were 70.4% and 100% respectively. In conclusion, ELISA offers a significant advantage over conventional serological methods in the diagnosis of brucellosis in endemic areas. The PCR test results can be particularly important in patients with clinical signs and symptoms, and negative serological results, allowing the early and rapid confirmation of the brucellosis.     

问号钩端螺旋体属特异性LipL41s抗原膜定位及其患者血清抗体检测

目的确定问号钩端螺旋体（钩体）属特异性脂蛋白抗原LipL41s膜定位及其自然抗体应答情况和抗体类型。方法采用显微镜凝集试验（MAT）检测四川地区钩体病患者血清标本。IPTG诱导重组原核系统表达目的蛋白rLipL41／1和rLipL41／2，Ni—NTA亲和层析法提纯目的重组表达产物。采用Westernblot检测感染不同血清群问号钩体病患者血清与rLipL41s的免疫反应性。采用胶体金免疫电镜技术，对LipL41s进行膜定位。建立基于rLipL41s的ELISA，检测钩体病患者血清中特异性抗体水平及其类型。结果黄疸出血群是四川地区最主要的优势钩体血清群。不同血清群问号钩体病患者血清均能有效识别LipL41s。LipL41s是位于钩体外膜表面的蛋白分子。156例MAT阳性钩体病患者血清标本中，rLipL41／1和rLipL41／2特异性IgM阳性率分别为84．6％～87．8％和78．2％～83．3％，特异性IgG阳性率分别为69．2％～81．4％和75．0％～80．1％。结论LipL41s是钩体表面蛋白抗原。自然感染钩体时，LipL41／1和LipL41／2可诱导机体产生IgM和IgG两类血清抗体，且两者之间有广泛的抗原交叉反应。rLipL41／1和rLipL41／2可作为研制通用型钩体基因工程疫苗和检测试剂盒的候选抗原。     

Mass screening for Trypanosoma cruzi infections using the immunofluorescence, ELISA and haemagglutination tests on serum samples and on blood eluates from filter-paper.

Methods used to diagnose Trypanosoma cruzi infection differ in their ability to discriminate between sera from infected and uninfected individuals. We compared the results of an immunofluorescence (IF) test, a haemagglutination (HA) test, and an enzyme-linked immunosorbent assay (ELISA) for the diagnosis of T. cruzi infections in a large population-based survey in central Brazil using blood eluates from filter-paper and venous blood samples. The sensitivities of the tests on eluates, compared with results on serum samples, were low: ELISA (78.1%), IF (69.2%) and HA (64.6%). The level of agreement between the tests on eluates was very poor, with the best co-positivity for IF and ELISA. Both the positive and negative predictive values of the three tests on eluates were similar (around 96%) to those for sera. Higher co-positivity values were obtained for the three tests on sera. The implications of these results are discussed in relation to blood screening, routine medical practice, sero-epidemiological surveys, and the follow-up of patients admitted to therapeutic trials.     

四种试剂盒在SARS实验室早期诊断中的作用分析

目的 比较4种检测严重急性呼吸综合征冠状病毒(SARS-CoV)基因、抗原和抗体的试剂盒在SARS患者早期实验室诊断的可能作用。方法 用3种酶联免疫吸附试验(ELISA)分别检测SARS-CoV IgG、SARS-CoV IgM和SARS-CoV N蛋白，用荧光定量聚合酶链反应(F-PCR)检测SARS-CoV核酸。结果 根据162份血清的检测结果，发病15天，N抗原的阳性率可达90．2％(55／61)；发病后的第1518天IgG和IgM阳性率为92．8％(13／14)；根据82份咽拭子的检测结果，F-PCR法在发病后15天的阳性率可达56．3％(14／24)，69天可达71．4％(10／14)。结论 除了检测SARS-CoV病毒基因的F-PCR方法以外，对疑似患者血清标本进行N蛋白的检测，具有早期预报意义。     

Detection of antibodies against Trypanosoma cruzi in Somoto, Nicaragua, using indirect ELISA and IFI on blood samples on filter paper]

We standardized a solid-phase enzyme-linked immunosorbent assay (ELISA) in order to study the presence of Trypanosoma cruzi antibodies in asymptomatic persons who live in an area of Nicaragua endemic for Chagas' disease. The test was standardized to analyze filter-paper blood samples, which are easy to transport. In the first phase of our investigation, ELISA was used to study 18 samples of total serum and 18 eluates of blood from patients with chronic Chagas' disease; 30 samples of serum and 30 eluates of blood from healthy people, used as negative controls; and 14 samples of serum and 14 eluates of blood from patients with cutaneous or visceral leishmaniasis, which were used to study cross-reactions. Both with the total-serum and the blood-eluate samples, the ELISA test provided 100% sensitivity and 90% specificity. Cross-reactions in the patient samples were observed only with visceral leishmaniasis. The second phase of our investigation was a population study that included eight rural communities in the area of Somoto, Nicaragua. Through random sampling, filter-paper blood samples were collected from 2,434 people (1,335 men and 1,099 women) from the communities of Aguas Calientes, El Brocal, La Manzana, Las Playas, Los Canales, Santa Isabel, Santa Rosa, and Santa Teresa. Studied by ELISA and by indirect immunofluorescence (IIF), the samples included 260 found seropositive by ELISA (10.7%), of which 207 were positive according to IIF (8.5%). With both techniques, the majority of seropositives were among women, but the difference between men and women was not statistically significant. There was a high level of agreement between the results obtained with the two techniques. There was an upward trend with age, with 5.4% of those found seropositive by ELISA being persons 10 years of age or younger and 42.7% of those found seropositive being older than 50. The vast majority of the individuals analyzed were asymptomatic.     

Detection of Chagas infections using Trypanosoma evansi crude antigen demonstrates high cross-reactions with Trypanosoma cruzi.

Antigenic similarities between salivarian trypanosomes are known for a long time, but similarities between salivarian and stercorarian trypanosomes have been very little investigated. Phylogenetically, these genus and species appear to be far. However, in a preliminary work we had shown strong reactions of chagasic human sera using T. evansi antigens in Western-blotting and ELISA. In the current work an ELISA test using T. evansi crude antigens was probed with one hundred and two sera of chagasic Bolivian patients previously diagnosed which presented different pathologies. The sensitivity of the ELISA T. evansi was 92.6% similar to that of ELISA T. cruzi. The specificity evaluated using 20 sera of patients infected by Leishmania sp. reaches a comparable value of that obtained with the T. cruzi immunofluorescent assay. Finally, the sensitivity and the specificity of the ELISA T. evansi were not really different from conventional serology of Chagas. In spite of their taxonomic position in various sections and their old divergence, these observations prove a strong antigenic community between T. cruzi and T. evansi. Consequently, the common antigens which remain to be characterized, could be an alternative source of antigen for the detection of antibodies against T. cruzi. Given that T. evansi seems to have strong antigenic communities with the majority of the pathogenic current trypanosomoses of mammals, it is very attractive to identify and characterize these highly conserved antigens which could be suitable targets to develop tools for diagnosis, prophylaxy and chemotherapy against several human and animal trypanosomoses.     

Schistosome circulating anodic antigen in serum of individuals infected with Schistosoma japonicum from the Philippines before and after chemotherapy with praziquantel.

The presence of the schistosome circulating anodic antigen (CAA) in serum of patients infected with Schistosoma japonicum from The Philippines has been investigated using an enzyme-linked immunosorbent assay (ELISA). Serum samples were tested from 48 patients who excreted S. japonicum eggs, 9 individuals with a negative stool examination, and 20 controls with both a negative stool and a negative circumoval precipitin test. No false positive result was detected for the unequivocally negative controls. CAA could be demonstrated in 72.9% of the egg-excreting patients. A positive correlation between parasite burden (eggs per gram of faeces) and antigen level (CAA titre) was found (Spearman's rho = 0.48, P < 0.001, n = 48). Four of 18 sera from the egg-negative individuals were positive in the ELISA. In view of the fact that anti-worm antibodies were also detected in these 4 sera, those reactions suggest active infection not detected by stool examination. In serum from patients treated with praziquantel, a significant drop in CAA titre was seen within 5 d after treatment (Wilcoxon's chi T = -2.23, P = 0.0258, n = 21). In conclusion, the detection of CAA by ELISA in S. japonicum infection can give valuable information in both individual diagnosis and therapeutic drug monitoring, as well as in epidemiological studies or disease control programmes.     

Epidemiology of Chagas disease in Andrés Eloy Blanco, Lara, Venezuela: triatomine infestation and human seroprevalence

A seroepidemiological survey and vector captures were performed in four rural communities in Andrés Eloy Blanco, Lara State, Venezuela. Systematic random sampling was based on family clusters, with samples drawn from 869 individuals to determine anti-Trypanosoma cruzi and anti-Leishmania sp. antibodies by indirect immunofluorescence. Positive individuals were defined as > or = 1:32 for anti-T. cruzi antibody and non-reactive to Leishmania sp. antigen, revealing an antibody frequency of 6.9% (n = 60), of whom 46.66% were females and 53.33% males and 60% were over 39 years of age. Some 5 (8.33%) seropositive individuals were under 10 years of age and 10 (16.66%) under 20 years. Rhodnius prolixus and Panstrongylus geniculatus were the triatomines captured, with infestation rates of 1.9% and 10.54%, colonization index of 0% and 18.18% in infested houses, and a T. cruzi infection index of 20% and 5.07%, respectively. The results suggest active Chagas disease transmission in Andrés Eloy Blanco in the last two decades and that P. geniculatus is replacing R. prolixus as the Chagas disease vector.     

江苏省传染性非典型肺炎病原学检测研究

目的:建立传染性非典型肺炎(SARS)实验室检测方法,为SARS病例诊断和现场防治提供依据。方法:用逆转录套式PCR、实时荧光定量PCR检测SARS病毒核酸;酶联免疫法检测血清标本SARS病毒IgM抗体;部分PCR检测阳性或SARS病毒IgM抗体阳性病例的标本进行直接电镜观察;简并引物PCR检测冠状病毒属病毒核酸;鉴别诊断IFA检测血清中肺炎支原体等9种常见呼吸道感染病原IgM抗体,PCR检测军团菌以及甲、乙型流感病毒核酸。结果:检测各类临床标本506份。2003年全省报告临床诊断病例7例,5例检测结果阳性;逆转录套式PCR检测各类标本132份,阳性8份;对其中4份PCR扩增产物(108bp)进行了序列分析,与SARS病毒序列100%同源;实时荧光定量PCR检测各类标本30份,阳性3份;酶联免疫法检测血清标本101份,SARS病毒IgM抗体阳性4份;3个诊断病例的各类标本电镜检查发现冠状病毒样颗粒;IFA检测血清标本75份,嗜肺军团菌IgM抗体阳性9份,乙型流感IgM抗体阳性11份,两者同时阳性3份,其他病原体IgM抗体均为阴性。不明发热病例的标本21份简并引物PCR检测冠状病毒,2份咽拭子标本阳性;漱口液、尿液标本各15份PCR检测军团菌、漱口液25份PCR检测甲、乙型流感病毒结果均为阴性。结论:本研究建立的检测方法与临床诊断有比较好的符合性,对于临床诊断和防治工作具有重要的参考价值。PCR检测SARS-CoV特异性较好,而敏感性有待提高。     

Assessment of Brucellosis Card test in screening patients for brucellosis

The Brucellosis Card test (Brewers' Diagnostic Kits, Hynson, Westcott and Dunning, Inc., Baltimore, Md.) was evaluated in relation to the Brucelloslide test (bioMérieux, France), the microagglutination test (MAT) and the demonstration of brucella-specific IgG, IgM and IgA in an enzyme-linked immunosorbent assay (ELISA). A total of 573 serum specimens was tested. These included sera from patients with acute brucellosis (159), chronic brucellosis (23) and patients who had been diagnosed previously as having had brucella infection (155). Control groups consisted of patients with diseases other than brucellosis (52), others with non-infectious diseases (20), and healthy individuals (164). The Card test detected 100% of the patients with acute and 61% of the patients with chronic brucellosis. The sera from the control groups were all negative. Similar results were obtained with the Brucelloslide test and the MAT. The ELISA test detected brucella-specific Ig of all classes in the serum of patients with acute brucellosis, and IgG and IgA in the serum of patients with chronic brucellosis. In the latter group, IgM was also detected in 32% of the sera. Twenty-three per cent of sera with titres of 20 by the MAT were positive on the Card test and had ELISA titres for IgM, IgG and IgA of 400. Characterization of the antibodies involved in the Card test showed that sera with IgM ELISA titres of 1600, or an IgM titres of 800 together with IgG and IgA titres greater than or equal to 200 were Card test positive. Higher IgG (greater than or equal to 1600] plus IgA (greater than or equal to 400) titres were required to produce a positive Card test in the absence of IgM or when the IgM titre was less than or equal to 200. The Card test has a potential value as a rapid screening test for humans with acute brucellosis and shows similar results to Brucelloslide and MAT tests. ELISA, however, remains the most reliable test for diagnosis of brucellosis especially in patients with chronic and complicated stages of the disease.     

人颚口线虫病两种免疫诊断方法的建立和应用

目的 建立敏感和特异的人颚口线虫病免疫诊断方法,并加以应用.方法 以颚口线虫Ⅲ期幼虫可溶性蛋白为抗原,采用Western印迹技术检测颚口线虫特异的相对分子质量为21 000和24 000抗原蛋白条带,用ELISA半定量检测抗颚口线虫IgG抗体.结果 Western印迹法检测8份颚口线虫患者血清,均可见相对分子质量为24 000的条带,7份可见相对分子质量为21 000的条带;30份疑似患者血清共有18份可见相对分子质量为17 000～26 000之间的特异性条带;检测25份健康人血清和25份曼氏裂头蚴病、广州管圆线虫病、肺吸虫病、囊虫病、血吸虫病等其他蠕虫病患者的血清样本,未见该条带反应.ELISA检测8例颚口线虫患者血清IgG抗体均为阳性,检测50例健康人血清,特异性为98.0％（49/50）,与曼氏裂头蚴病、广州管圆线虫病、肺吸虫病、囊虫病、血吸虫病等其它蠕虫病患者血清的交叉反应率分别为20.0％（6/30）、14.3％（3/21）、6.7％（2/30）、3.3％（1/30）和3.3％（1/30）.30例颚口线虫疑似患者,ELISA检测均阳性,Western印迹法检测18例阳性.结论 免疫印迹检测颚口线虫特异的相对分子质量为21 000和24000抗原条带特异性强,适用于疑似患者鉴别诊断,但操作复杂、费时,技术要求高;ELISA检测抗颚口线虫IgG抗体的敏感性高、操作流程半自动化,适合门诊患者筛检和人群流行病学调查,但其与曼氏裂头蚴病、广州管圆线虫病等其它蠕虫患者血清交叉反应率高.     

2009年池州市麻疹疑似病例麻疹IgM抗体检测结果分析

目的了解池州市2009年麻疹疑似病例的麻疹IgM抗体水平,为麻疹预防和临床诊断提供可靠依据。方法采用酶联免疫吸附试验（ELISA法）对2009年池州市的麻疹疑似病例血清进行IgM检测。结果共检测血清324份,其中麻疹IgM抗体阳性81份,阳性率25.00%。实验室病例年龄以20～30年龄段最多。发病时间主要集中在3月份到5月份。结论加强麻疹预防知识的健康教育,加强对重点人群麻疹疫苗的强化免疫。     

Evaluation of enzyme-linked immunosorbent assay for detection of Salmonella typhi antigen and antibodies.

Enteric fever is considered a major health problem in developing countries. The need for a rapid, accurate and conclusive method for diagnosis is important for adequate and proper treatment. The usefulness and reliability of the ELISA test in detection of S. typhi O antigen and specific IgG and IgM antibodies were assessed using sera obtained from 63 subjects clinically suspected to have enteric fever, 22 febrilenon-enteric subjects and 20 normal subjects. ELISA detection of S. typhi somatic antigen was positive in 75% of subjects with positive clot cultures. IgG and IgM antibodies to S. typhi lipopolysaccharide (LPS) were detected in sera from 83% and 88% of enteric fever subjects, respectively. While anti-LPS IgM was negative in all sera from febrile non-enteric subjects, 9% were positive for anti-LPS-IgG. The use of an ELISA for detection of anti-S. typhi LPS antibody in combination with the Widal test and/or the O antigen detection ELISA would provide a useful (95.8% sensitivity) adjunct to standard culture methods and allow for an earlier and more rapid diagnosis of enteric fever.