Detection Of Specific IgM Antibodies Research Articles

Application of a truncated ORF2 protein-based ELISA for diagnosis of hepatitis E in an endemic area.

Enterically transmitted waterborne hepatitis E (HE) caused due to hepatitis E virus (HEV) prevails as a significant public health problem endemic to India. Due to short-term viremia/fecal excretion and poor in vitro transmissibility of HEV, HE diagnosis depends on detection of specific IgM antibodies in serum. Present study evaluated performances of two in-house and six commercial IgM detection enzyme-linked immunosorbent assays (ELISAs) using sera collected from volunteers/acute hepatitis patients (n = 716). The in-house ELISAs were based on complete and truncated open reading frame 2 (ORF2) proteins containing neutralizing epitope/s region of genotype 1 HEV (ORF2p, 1-660 amino acid (a.a.) and T1NEp, 458-607 a.a., respectively). The commercial ELISAs included Wantai (China), MP Diagnostics (MPD) (Singapore), DIA.PRO Diagnostics (Italy), MBS (Italy), abia (Germany), and ImmunoVision (USA). T1NE ELISA showed 97.0% positive percent agreement (PPA), 99.4% negative percent agreement (NPA), and 98.6% concordance (κ = 0.97, P = 0.0000) with ORF2 ELISA. ORF2, T1NE, Wantai, and MPD ELISAs agreed on results for 88% of sera tested. Two percent sera showed reactivity in each combination of three and two of aforementioned four ELISAs. Remaining 8% sera were single ELISA reactive. PPA and NPA value ranges were 76.3-99.0% and 84.8-99.5%, respectively. Pairwise concordances between all the eight ELISAs ranged from 88.0 to 100% (κ: 0.74-1.00). Both the in-house ELISAs agreed better with Wantai over MPD ELISA. In conclusion, both ORF2 and T1NE ELISAs were equally efficient in diagnosing HEV infections. T1NEp proved to be an excellent tool in HE sero-diagnosis and is worth exploring in development of simple rapid tests. KEY POINTS: • In-house ELISA based on bacterially expressed neutralizing epitope/s region protein • In-house ELISA based on complete ORF2 protein expressed in insect cells • Comparison of two in-house and six commercial anti-HEV IgM antibody detection ELISAs.

Anti-Toxoplasma gondii IgM Long Persistence: What Are the Underlying Mechanisms?

Diagnosis of Toxoplasma gondii acute infection was first attempted by detection of specific IgM antibodies, as for other infectious diseases. However, it was noted that this immunoglobulin declines slowly and may last for months or even years. Apart from the diagnostic problem imposed on clinical management, this phenomenon called our attention due to the underlying phenomena that may be causing it. We performed a systematic comparison of reports studying IgM antibody kinetics, and the data from the papers were used to construct comparative plots and other graph types. It became clear that this phenomenon is quite generalized, and it may also occur in animals. Moreover, this is not a technical issue, although some tests make more evident the prolonged IgM decay than others. We further investigated biological reasons for its occurrence, i.e., infection dynamics (micro-reactivation–encystment, reinfection and reactivation), parasite strain relevance, as well as host innate, natural B cell responses and Ig class-switch problems inflicted by the parasite. The outcomes of these inquiries are presented and discussed herein.

Analysis of Factors Hindering the Measles Elimination among Children at a Tertiary Care Hospital in South India

Introduction: Measles is a highly infectious acute viral disease that can lead to serious complications and death. Effective immunisation coverage for measles will play a pivotal role in its elimination strategy. So, the global commitment, strengthening of health infrastructure and effective vaccine coverage are essential to achieve a world that will be free of measles. Aim: To assess the factors associated with the occurrence of measles and to determine the factors responsible for non compliance to measles vaccination. Materials and Methods: A cross-sectional study was conducted in the Department of Paediatrics at Niloufer Hospital, Hyderabad, India, during the period from October 2019 to March 2020 among the children clinical diagnosed with measles. The patients were evaluated for fever, rash, respiratory and other clinical symptoms associated with measles. History of measles vaccination and vitamin A administration were taken. Blood samples of patients were collected and measles specific IgM antibody detection test was done by Enzyme-linked Immunosorbent Assay (ELISA). Data was statistically analysed and presented as numbers and percentages were calculated. Results: Among 129 children, clinically diagnosed of measles, the predominant age group children effected was 1-6 years 68 (52.71%). Overall, 38 (29.5%) were vaccinated and 85 (65.9%) were unvaccinated during routine immunisation schedule. Measles-Containing Vaccine (MCV) coverage during Supplementary Immunisation Activities (SIAs) was also very limited (19.3%). Out of 129 cases, 121 (93.7%) were confirmed positive by measles IgM ELISA, 5 (3.8%) samples gave equivocal results and 3 (2.3%) were negative for the test. Conclusion: Inspite of the availability of effective and inexpensive measles vaccine for decades, vaccination coverage remains inadequate across the globe. So, effective implementation of vaccine services and monitoring of its surveillance system are needed for eradication of measles.

Hemorrhagic fever with renal syndrome in a child early age

In Russia, Hemorrhagic Fever with Renal Syndrome (HFRS) takes the leading place among all natural focal infections, the incidence rate in 2018 was 3,99 per 100 thousand population. In the Northwestern Federal District of the Russian Federation, HFRS occurs much less frequently – 1,46 cases per 100 thousand population. The disease is more susceptible to men aged 16–50 years, children rarely get sick. In 2019, 73 cases of HFRS (1,36 per 100 thousand population) were registered in St. Petersburg, among them only 2 episodes – in children under 18 years of age. A clinical case of HFRS in a child aged 1 year and 8 months is presented. The diagnosis was established on the basis of clinical and epidemiological data (acute onset of the disease, the presence of fever, thrombohemorrhagic syndrome, oliguria, anuria, information on cases of HFRS at the place of residence of the child) and laboratory data (detection of specific IgM antibodies to the Hantaan virus) in the later stages of the disease. The described case should alert pediatricians regarding possible natural focal diseases, including HFRS. A thorough analysis of the anamnestic, epidemiological and clinical data of the patient will help in the early stages of the disease to suggest a diagnosis, conduct laboratory diagnostics and prescribe appropriate therapy.

Evaluation of West Nile Virus Diagnostic Capacities in Veterinary Laboratories of the Mediterranean and Black Sea Regions.

The increasing incidence of West Nile virus (WNV) in the Euro-Mediterranean area warrants the implementation of effective surveillance programs in animals. A crucial step in the fight against the disease is the evaluation of the capacity of the veterinary labs to accurately detect the infection in animal populations. In this context, the animal virology network of the MediLabSecure project organized an external quality assessment (EQA) to evaluate the WNV molecular and serological diagnostic capacities of beneficiary veterinary labs. Laboratories from 17 Mediterranean and Black Sea countries participated. The results of the triplex real time RT-PCR for simultaneous detection and differentiation of WNV lineage 1 (L1), lineage 2 (L2) and Usutu virus (USUV) were highly satisfactory, especially for L1 and L2, with detection rates of 97.9% and 100%, respectively. For USUV, 75% of the labs reported correct results. More limitations were observed for the generic detection of flaviviruses using conventional reverse-transcription polymerase chain reaction (RT-PCR), since only 46.1% reported correct results in the whole panel. As regards the serological panel, the results were excellent for the generic detection of WNV antibodies. More variability was observed for the specific detection of IgM antibodies with a higher percentage of incorrect results mainly in samples with low titers. This EQA provides a good overview of the WNV (and USUV) diagnostic performance of the involved veterinary labs and demonstrates that the implemented training program was successful in upgrading their diagnostic capacities.

Case report of severe seoul infection in peripartum period

Background: We present the case of severe Seoul orthohantavirus infection in 36 y old woman with onset of disease coincided with peripartum period. Case Description: The patient was admitted to the hospital for a period of 37–38 w of pregnancy with complaints for lower abdominal pain, backache, anuria, icterus, and fever 38.6 °C. Diagnosis at admission was: Pregnancy 37–38 w, first stage of labor. Severe preeclampsia, HELLP syndrome, multi-organ failure. Low level of platelets (40 x 109/l), a significant increase of serum aminotransferases, high serum levels of creatinine and urea, pathological findings of coagulation tests, slight neutrophilic leukocytosis and anemia partially supported preliminary diagnosis. Ultrasonic examination revealed diffuse changes in the liver and kidneys parenchyma, splenomegaly, effusion into the abdominal and pleural cavities and fluid in the lower pelvis. After spontaneous vaginal delivery the patient's condition worsened, anemia and thrombocytopenia persisted and due to indications of atonic postpartum hemorrhage the hysterectomy was performed. Discussion: Based on clinical symptoms and epidemiological data the orthohantavirus infection was supposed and confirmed by detection of specific IgM antibodies (titer 1:400) by ELISA. RNA isolated from patient blood was typing by reverse transcriptase PCR (RT-PCR) and subsequent sequencing of L-segment fragment (2969–3314 bp) and hantavirus Seoul (genotype Vladivostok) was identified as ethiological agent of this case. After 2 m of the patient's intensive care (including but not limited repetitive plasma exchanges and hemodialysis) her condition gradually improved. By the time of release, the coagulation system parameters were normal with moderate anemia (red blood cells 2.96 x 1012 g/l, hemoglobin 90 g/l, hematocrit 26.7%) and lymphocytosis. However, signs of renal failure (serum creatinine level 366 mmol / l, serum urea level 15.34 mmol / l, proteinuria 0.3 g /l) persisted. The final diagnosis: Severe hantavirus infection, renal-liver-failure. Acute renal damage stage 3 according to AKIN, class I by RIFLE. Symptomatic arterial hypertension. Secondary anemia with mixed causes. Conclusion: This case is a fascinating example of how difficult to recognize renal impairments associated with hantaviruses during past trimester of pregnancy in patient with different significant risks. The case also reinforces the fact that genotype Vladivostok of Seoul virus can cause severe, life threatening disease with multisystem failure.

LABORATORY COMPARATIVE ANALYSIS OF SEROLOGICAL AND MOLECULAR BIOLOGICAL METHODS FOR DETECTION OF MEASLES VIRUS IN BULGARIA

This study aimed to perform a comparative analysis between the frequency of detection of the measles virus in Bulgarian patients by using two types of laboratory methods - serological and molecular.
 Materials and Methods: The total 202 patients with two types of clinical material (serum samples and nasal swabs) were tested. The specimens were collected during the measles outbreak in Bulgaria in 2019. The serological - indirect EIA test for detection of specific IgM antibodies and molecular methods - extraction and detection of viral RNA were used.
 Results: In the present study, tested Bulgarian patients were divided into 11 age groups. The majority of patients were under 9 years of age (126/202, 62%), including children under 1 years of age (31/202, 15%). Acute measles infection was confirmed by ELISA-IgM in 136/202(67%) and by RT-PCR in 138/202 (68%) of cases. The positive patients detected only by PCR methods are mainly in younger tested. In 123/202 of the patients (60,89%) measles infection was confirmed by a combined serological and molecular-biological approach. The coincidence percentage rate of results obtained is 87%, including double positive (n=123) and double negative (n=52) tests. No significant differences in the results in terms of gender and age were found.
 Conclusion: The combined laboratory approach (immunoenzymatic and molecular assay of each suspected case) is a requisite for measles detection, especially before the onset of symptoms when specific Ig M antibodies could not be detected. Molecular biological techniques are basic and preferred approach in the field of modern biomedical sciences. They play an important role in the early and accurate etiological diagnosis and monitoring of viral infections, in particular the measles virus.

CME Dermatology 22: Measles - Empidemiology and Clinical Manifestations

CME Dermatology 22: Measles - Empidemiology and Clinical Manifestations Abstract. Measles is a highly contagious, acute and febrile illness that results from infection with measles virus. The World Health Organization (WHO) estimates a worldwide prevalence of ten million patients per year, leading to approximately 142 000 deaths (case fatality rate 1.4 %). The illness begins with fever, malaise and typically with at least one of the following signs: cough, coryza and/or conjunctivitis. Three to four days later, the characteristical rash appears. The primary clinical diagnosis needs to be confirmed by detection of specific IgM antibodies in serum or viral RNA by a throat swap. The management mainly consists of supportive therapy, a specific antiviral treatment does not exist. Therefore, prevention by widespread measles vaccination has absolute priority.

Severe anemia caused by parvovirus B19 in a patient with functioning kidney transplant: case report

Parvovirus B19 (PV B19) infection can cause pure red cell aplasia (PRCA) and severe normochromic anemia resistant to treatment with erythropoietin in renal transplant recipients. Active parvovirus infection usually develops in the first months after kidney transplantation (KT), but is not always accompanied by clinical symptoms. The incidence of PV B19-associated anemia is low - not more than 1–1.5 %. A confirmation of the etiology of the disease, in addition to the characteristic histological picture of the bone marrow (a decrease in the number of erythrokaryocytes of less than 5% with preserved myelopoiesis and megakaryopoiesis, the appearance of single giant pronormoblasts), is the detection of PV B19 DNA in the blood and / or bone marrow. The detection of specific IgM antibodies to parvovirus plays a less significant role in the diagnosis of active PV B19 infection in patients after KT receiving immunosuppressive therapy and should not be used as the only diagnostic method. There is no specific antiviral treatment for PV B19 infection, therefore other approaches to therapy are used: reduction of immunosuppression, transfusion of red blood cells, administration of intravenous immunoglobulin (IVIG). The article describes the clinical observation of a 33-year-old patient with stage 5 CKD who developed severe normochromic anemia resistant to treatment with erythropoietin 4 weeks after a successful KT. A cytological examination of the bone marrow revealed PRCA, and a large number of copies of PV B19 DNA were detected in the patient’s blood, while antibodies to parvovirus IgG and IgM were not revealed. A decrease of immunosuppression (withdrawal of mycophenolic acid), repeated administration of IVIG in a total dose of 147 g resulted to lasting normalization of red blood cells number and hemoglobin level after five months of treatment. The function of the renal transplant remained normal throughout the observation period.

Cellular immune response in convalescents from Ixodes tick-borne borreliosis

Ixodes tick-borne borreliosis is a natural focal transmissive infectious multi-system disease featured with complex pathogenesis, which multiple aspects remain unclarified. The persistence stage during this infection associated with prolonged Borrelia presence in metastatic foci and repeated multiple dissemination is most complicated for clinical practice. It is assumed that the chronic process can be caused by an inadequate immune response associated with activated autoimmune mechanisms leading to emergence of permanent irreversible (degenerative and atrophic) changes in affected organs. Patients who experienced tick-borne borreliosis need dynamic observation for assessing disease prognosis providing a maintenance therapy. The purpose of the study was to evaluate an opportunity of using cellular immunity indices for predicting disease transition to a chronic course.Materials and methods. The study was carried out at the Medical Association of the Far East Branch of the Russian Academy of Sciences. Case report form data, serum and blood plasma samples collected from 22 patients aged 29–83 years old were examined. Immunological examination data from patients with ixodes tick-borne borreliosis (12–18 months after the onset of acute period) were analyzed. Specific IgM and IgG against Borrelia burgdorferi were determined by using the OMNICS diagnostic test system (St. Petersburg). Lymphocyte immunophenotyping was performed on BD FACSCalibur flow cytometer (Becton Dickinson, USA) by using doublelabeled monoclonal antibodies (Beckman Coulter, France).Results. A variability of activated peripheral blood lymphocytes was found in patients with tick-borne borreliosis evidencing about individual immune response. An imbalanced cellular immune response recorded in seronegative convalescents from tick-borne borreliosis, may be an indirect finding of ongoing Borrelia infection. Finding of specific serum IgG and IgM antibodies in convalescents at late stage coupled to impaired immune system is a warning sign presuming a risk to developing autoimmune reactions. Detection of specific IgM antibodies at late timepoint combined with increased immune cytotoxic potential may be referred to a marker of possible disease transition to chronic course.

Congenital toxoplasmosis – clinico-evolutive aspects

Introduction. Congenital toxoplasmosis represents an im­por­tant cause of infant morbidity and mortality. The etio­lo­gical agent is a largely spread parasite microorganism, To­xo­­plas­ma gondii. Fetal infection is possible only when the preg­nant patient contracts the disease during pregnancy. The to­po­graphy of fetal lesions involves especially the brain and the eyes. The most common form of the disease is re­pre­sen­ted by congenital encephalomyelitis, manifested by hy­dro­ce­phalus, microcephaly, microphthalmia, typical signs of cerebellar suffering and ocular impairment. The definitive diag­nosis involves the detection of specific IgM antibodies in the patient’s blood, the persistence of IgG antibodies after the age of 1 year old, or the detection by PCR of the parasite DNA in the blood and cerebrospinal fluid. Objective. The paper presents the medical evolution of a case of congenital toxoplasmosis. Materials and method. We present the case of a male baby, 12 months old, institutionalized after birth, who was diagnosed with congenital toxoplasmosis at the age of 6 months old. Results. The evolution was un­fa­vo­ra­ble, the patient developing hydrocephalus, which ne­ces­si­ta­ted the mounting of a ventriculoperitoneal shunt, and frequent meningitis episodes, of both viral and bacterial etiology. There­after, the patient developed spas­tic tetraparesis, ge­ne­ral­ized epilepsy, profound men­tal retardation and mul­ti­ple respiratory infections. Con­clu­sions. The clinical mani­festa­tions in congenital toxo­plas­mo­sis range from asymptomatic or mild-medium disease forms to severe forms (4%), with serious neurological sequelae or even death.

Clinical and epidemiological features of mycoplasma infection in children in Ryazan region

Background. Acute respiratory infections are an urgent problem of pediatrics due to the high incidence rate and high risk of bacterial complications.
 Aim. The aim of the study was to analyze the statistical indicators of the incidence of communityacquired pneumonia (CAP) in children of the Ryazan region, to determine the clinical and epidemiological features of mycoplasmal infection, and to assess its role in CAP morbidity in children.
 Materials and Меthods. The analysis of the incidence of CAP in children of the Ryazan region (20142016) and of medical documentation of 106 children (55 boys, 51 girls) (age from 9 months to 17 years) was conducted. All patients underwent oxigenometry, clinical and laboratory examination, radiography, detection of specific IgM antibodies to M. pneumoniae.
 Results. In the Ryazan region there is noted an increase in the incidence of CAP in children as compared to the stable level of the incidence of CAP in Russia: in children under 14 years of age the incidence is 1.5 times higher than in 2014 and 2.8 times higher than in 2015, and is 2 times higher than in 2014 in 1517 year old children. Most commonly mycoplasmosis was recorded in preschool age children, with the peak incidence in OctoberDecember. The disease began acutely without significant symptoms of intoxication and local changes. 77.3% of children had pneumonia, mostly rightsided (48.8%), and 33.1% had a mixed bacterial infection. Hematological indices indicated the presence of iron deficiency anemia in 12.3%, and moderate leukocytosis in 28% of children. Antibiotic therapy was carried out with the use of macrolides, and in case of mixed bacterial infection a combination of antibiotics with cephalosporins of the 3d generation was used.
 Conclusion. In recent years there has been an increase in the incidence of CAP in children. Seasonality of hospitalization of children with mycoplasmal infection was revealed, and a high incidence of the disease in preschool children with chronic pathology. In 77.3% of examined children mycoplasmosis took the form of CAP, which influenced the incidence rate of CAP in children.

Clinical and epidemiological features of mycoplasma infection in children in Ryazan region

Background. Acute respiratory infections are an urgent problem of pediatrics due to the high incidence rate and high risk of bacterial complications.
 Aim. The aim of the study was to analyze the statistical indicators of the incidence of communityacquired pneumonia (CAP) in children of the Ryazan region, to determine the clinical and epidemiological features of mycoplasmal infection, and to assess its role in CAP morbidity in children.
 Materials and Меthods. The analysis of the incidence of CAP in children of the Ryazan region (20142016) and of medical documentation of 106 children (55 boys, 51 girls) (age from 9 months to 17 years) was conducted. All patients underwent oxigenometry, clinical and laboratory examination, radiography, detection of specific IgM antibodies to M. pneumoniae.
 Results. In the Ryazan region there is noted an increase in the incidence of CAP in children as compared to the stable level of the incidence of CAP in Russia: in children under 14 years of age the incidence is 1.5 times higher than in 2014 and 2.8 times higher than in 2015, and is 2 times higher than in 2014 in 1517 year old children. Most commonly mycoplasmosis was recorded in preschool age children, with the peak incidence in OctoberDecember. The disease began acutely without significant symptoms of intoxication and local changes. 77.3% of children had pneumonia, mostly rightsided (48.8%), and 33.1% had a mixed bacterial infection. Hematological indices indicated the presence of iron deficiency anemia in 12.3%, and moderate leukocytosis in 28% of children. Antibiotic therapy was carried out with the use of macrolides, and in case of mixed bacterial infection a combination of antibiotics with cephalosporins of the 3d generation was used.
 Conclusion. In recent years there has been an increase in the incidence of CAP in children. Seasonality of hospitalization of children with mycoplasmal infection was revealed, and a high incidence of the disease in preschool children with chronic pathology. In 77.3% of examined children mycoplasmosis took the form of CAP, which influenced the incidence rate of CAP in children.

Serodiagnostic evaluation of recombinant CdtB of S. Typhi as a potential candidate for acute typhoid

Typhoid fever caused by human restricted Salmonella typhi presents a considerable health burden on developing South-Asian nations like India. The suboptimal sensitivity and specificity associated with culture-based isolation of etiological agent and the extensively used surface antigen-based serological assays often lead to misdiagnosis and inappropriate antimicrobial treatment. The increasing reports of the emergence of resistant strains and undefined disease burden signify the critical need for an inexpensive, reliable, easy-to-use, and highly sensitive diagnostic test for typhoid fever. Utilizing S. typhi-specific and immunogenic antigens in sero-diagnostic assays could lead to precise diagnosis of acute typhoid and prompt treatment. In this study, we report cloning, expression, and purification of recombinant Cytolethal distending toxin subunit B (CdtB) of S. typhi, which is reported to be highly specific, immunogenic, and expressed only upon S. typhi infection. We further evaluated the purified recombinant CdtB for its diagnostic potential in an IgM-based indirect ELISA format using 33 human samples. Twenty-one serum samples from blood culture confirmed cases (n = 21) of typhoid and 12 samples from healthy controls (n = 12) were tested. The assay showed sensitivity of 100% and specificity of 83.3% respectively with positive and negative predictive values of 91.3 and 100% respectively. Efficient detection of specific IgM antibodies indicates that CdtB could be highly valuable in sero-diagnosis of acute typhoid and rapid screening of clinical samples.

Diagnostic value of neutrophil-lymphocyte ratio versus C-reactive protein in discrimination between different pathogens causing community-acquired pneumonia

Early discrimination of the causative organisms of community-acquired pneumonia (CAP) is important. The aim of the present study is to evaluate neutrophil–lymphocyte ratio (NLR) and derived NLR (dNLR) as adjunct tests to differentiate different types of CAP. NLR, dNLR, and C-reactive protein (CRP) were measured in 187 patients with CAP. Identification of causative organisms was done by direct smears, microbiological cultures, VITEK 2 compact system, and PCR of patient’s sputa together with detection of specific IgM antibodies against Chlamydia pneumoniae. There was a significant increase of NLR and CRP values in patients with bacterial pneumonia as compared to patients with TB and patients with atypical pneumonia. NLR and CRP were significantly higher in atypical than TB pneumonia. Although dNLR was significantly higher in both bacterial and atypical than TB pneumonia, it was insignificantly differ between bacterial and atypical pneumonia. For discriminating bacterial CAP from TB, the area under curve (AUC) for NLR was found to be significantly higher than that of CRP at cutoff values of 7.8 for NLR and 172.9 mg/l for CRP. Also, at cutoff values of 6.6 for NLR and 179.1 mg/l for CRP, NLR distinguished bacterial from atypical pneumonia more accurately than CRP (AUC = 0.92 versus 0.74). There was no significant difference in inflammatory marker levels between subcategories of atypical pneumonia except for CRP. There was a significant positive correlation between NLR and CRP in pneumonic patients (r = 0.71, p = 0.000). NLR is easy to be calculated from daily practice and might be used as a surrogate marker to differentiate bacterial CAP from atypical and TB pneumonia as well as atypical from TB pneumonia but could not discriminate the different pathogens causing atypical bacterial pneumonia. dNLR could discriminate TB from both bacterial and atypical pneumonia but could not differentiate bacterial from atypical pneumonia.

Evaluation of Imaging Methods in Tick-Borne Encephalitis.

SummaryTick-borne encephalitis (TBE) is caused by a virus that belongs to the Flaviviridae family and is transmitted by tick bites. The disease has a biphasic course. Diagnosis is based on laboratory examinations because of non-specific clinical features, which usually entails the detection of specific IgM antibodies in either blood or cerebrospinal fluid that appear in the second phase of the disease. Neurological symptoms, time course of the disease, and imaging findings are multifaceted. During the second phase of the disease, after the onset of neurological symptoms, magnetic resonance imaging (MRI) abnormalities are observed in a limited number of cases. However, imaging features may aid in predicting the prognosis of the disease.

Detection of Serotype-Specific Antibodies to the Four Dengue Viruses Using an Immune Complex Binding (ICB) ELISA

BackgroundDengue virus (DENV) infections are preferentially diagnosed by detection of specific IgM antibodies, DENV NS1 antigen assays or by amplification of viral RNA in serum samples of the patients. The type-specific immunity to the four worldwide circulating DENV serotypes can be determined by neutralization assays. An alternative to the complicated neutralization assays would be helpful to study the serotype-specific immune response in people in DENV hyperendemic areas but also in subjects upon DENV vaccination.MethodsIn consecutive samples of patients with DENV-1- 4 infection type-specific antibodies were detected using an immune complex binding (ICB) ELISA. During incubation of serum samples and enzyme- labeled recombinant envelope domain III (EDIII) antigens immune complexes (ICs) are formed, which are simultaneously bound to a solid phase coated with an Fc–receptor (CD32). After a single washing procedure the bound labeled ICs can be determined. To further improve type-specific reactions high concentrations of competing heterologous unlabeled ED III proteins were added to the labeled antigens.ResultsFollow-up serum samples of 64 patients with RT-PCR confirmed primary DENV-1, -2, -3 or -4 infections were tested against four enzyme-labeled recombinant DENV EDIII antigens. Antibodies to the EDIII antigens were found in 55 patients (sensitivity 86%). A complete agreement between the serotype detected by PCR in early samples and the serotype-specific antibody in later samples was found. Type-specific anti-EDIII antibodies were first detected 9–20 days after onset of the disease. In 21% of the samples collected from people in Vietnam secondary infections with antibodies to two serotypes could be identified.ConclusionsThe data obtained with the ICB-ELISA show that after primary DENV infection the corresponding type-specific antibodies are detected in almost all samples collected at least two weeks after onset of the disease. The method will be of value to determine the distribution of the various type-specific anti–DENV antibodies in DENV endemic areas.

Situación de la tos ferina en la Comunidad Valenciana: ¿asistimos a una reactivación epidémica?

IntroductionPertussis is a highly contagious vaccine-preventable disease. An increasing incidence has been reported in several countries around the world in the last few years. The aim of this study is to analyze the situation of pertussis in the Valencian Community (Spain), with the purpose of verifying the increased incidence of the illness. MethodsA descriptive analysis of probable and confirmed cases detected during 2011 was conducted. Methods used for Bordetella pertussis detection from clinical samples were: culture isolation, polymerase chain reaction (PCR)-based detection of bacterial DNA, and/or detection of specific IgM antibodies. The disease incidence and other epidemiological variables were estimated. These results were compared to data collected in previous years (2008-2010). The Epidemiological Surveillance Analysis and Microbiological Surveillance Network integrated systems of the regional Department of Health were used as sources of information. ResultsIn 2011, 249 cases of pertussis were detected (incidence rate of 4.89×105 inhabitants). This rate is statistically significantly higher than those reported in 2008 (0.73×105 inhabitants), 2009 (0.53×105 inhabitants), and 2010 (0.53×105 inhabitants). The highest incidence rate was observed in cases younger than one year old (252.97×105 inhabitants), with marked differences compared to the rest of age groups. More than two-thirds (69%) of reported cases were confirmed by a laboratory test. Detection of specific serum IgM antibodies was positive in 10% of cases, culture isolation was positive in 17%, and PCR-based detection of bacterial DNA in 35% of cases. ConclusionsThe results of this study show a clear increase of pertussis incidence in the Valencian Community during 2011.

Seroprevalance of rubella in women with bad obstetric history

Rubella is a common cause of rash and fever during childhood. However, its public health importance relates to the teratogenic effects of primary rubella infection occurring in pregnant women, which can lead to fetal death with spontaneous abortion or to congenital defects in surviving infants. Most of the cases are asymptomatic and difficult to diagnose on clinical grounds. Detection of specific IgM antibodies by the enzyme-linked immunosorbent assay (ELISA) technique is a useful method for diagnosis. The present study was conducted on 180 pregnant women attending antenatal clinics at Government Maternity Hospital, Tirupati. All the serum samples were tested for Rubella-specific IgM antibodies. A seropositivity of 12.67% was observed among cases with bad obstetric history and 6.67% in normal pregnant women. Within the test group, high sero-positivity (13.33%) was observed in women with repeated abortions followed by in cases of intrauterine death (12.73%). The results indicate high prevalence of rubella in our population. All antenatal cases should be routinely screened for rubella, so that early diagnosis will help in proper management and fetal outcome.

Evaluation of serum specific IgM detection in diagnosis of respiratory viral infections in children

The present study was designed to explore the practical application of the rapid etiological diagnosis by detecting specific IgM antibody against common respiratory viruses in children with acute lower respiratory infections (ALRI). Clinical specimens including nasopharyngeal aspirates and serum of acute phase from hospitalized children were collected from 207 infants and children with acute lower respiratory infections from March 2009 to September 2010. Seven common respiratory virus antigens were identified from the collected nasopharyngeal aspirates by direct immunofluorescence assay (DFA). ELISA was used to detect specific IgM antibody against RSV, ADV, IFVA, IFVB and PIV, while indirect immunofluorescence assay (IFA) was used to detect specific IgM antibody against RSV, ADV, IFVA, IFVB, PIV1, PIV2 and PIV3 in collected acute phase serum. The overall positive rates to detect viral antigen by using DFA, ELISA and IFA was 67.6%, 57.5% and 39.6%, respectively. The consistent rate of ELISA and IFA versus accepted DFA were 21.7% and 31.4%, respectively. The average days from onset of the symptoms to blood sample collection for those with the consistent results by ELISA and DFA were 12.0 d for ADV, 9.6 d for PIV2, 9.5 d for IFV, and 5.3 d for RSV, respectively, and by IFA and DFA were 15.0 d for PIV3, 9.2 d for ADV, and 7.4 d for RSV, respectively. Among all age groups, the consistent rate of serum viral IgM and antigen detections was highest in children younger than 3 years old. Although there were differences between serum IgM antibody and viral antigen detections, specific IgM antibody detection was of value in early and rapid etiological diagnosis of pediatric ALRI, especially for young children. It could provide serologic evidence of respiratory virus infection. The diagnostic rate of pathogen could be improved if it was used in combination with viral antigen diagnostic methods.