Role of rapid antibody and ELISA tests in the evaluation of serological response in patients with SARS-CoV-2 PCR positivity

From 7 to 8 days after the onset of symptoms in COVID-19 infection, the sensitivity of serological tests was found to be higher than that of nucleic acid tests. The aims of this study were to investigate antibody levels in patients with SARS-CoV-2 infection, to examine the relationship between antibody levels and virus load, and to evaluate the performance of 2 different commercial kits. A total of 103 patients with confirmed SARS-CoV-2 infection were included in the study. Antibodies against SARS-CoV-2 in serum samples taken from patients were investigated simultaneously with anti-SARS-CoV-2 IgG and IgA ELISAs (Euroimmun) and COVID-19 (SARS-CoV-2) IgG/IgM (Deep Blue) kits. No positivity was detected with any of the test kits in 18 (17.4%) of the 103 samples. In symptomatic patients, 100% of IgM and IgA tests were found to be positive in the group sampled after 10 days, while 100% of IgG tests were found positive after 20 days. The sensitivity of the Deep Blue COVID-19 IgG antibody kit was calculated as 81.48% and the specificity was 97.96%. While there was no statistically significant difference between the PCR CT and ELISA OD values, a positive correlation was found between the ELISA OD values and the days since the date of symptom initiation. The sensitivity and specificity of the rapid antibody test used in this study were found to be quite high. In conditions where ELISA tests cannot be applied, it is thought that it can give an idea in terms of the presence of antibodies as a simple and fast test. Although ELISA tests are valuable in the diagnosis of COVID-19 during the acute period, they are tests that can be used safely in the diagnosis of previous infections and seroepidemiological studies.

Epidemiological, Clinical, and Laboratory Features of Children With COVID-19 in Turkey

Objectives: The aim of this study is to identify the epidemiological, clinical, and laboratory features of coronavirus disease 2019 (COVID-19) in children. Methods: A retrospective study was conducted by pediatric infectious disease specialists from 32 different hospitals from all over Turkey by case record forms. Pediatric cases who were diagnosed as COVID-19 between March 16, 2020, and June 15, 2020 were included. Case characteristics including age, sex, dates of disease onset and diagnosis, family, and contact information were recorded. Clinical data, including the duration and severity of symptoms, were also collected. Laboratory parameters like biochemical tests and complete blood count, chest X-ray, and chest computed tomography (CT) were determined. Results: There were 1,156 confirmed pediatric COVID-19 cases. In total, male cases constituted 50.3% (n = 582) and females constituted 49.7% (n = 574). The median age of the confirmed cases was 10.75 years (4.5-14.6). Of the total cases, 90 were younger than 1 year of age (7.8%), 108 were 1-3 years of age (9.3%), 148 were 3-6 years of age (12.8%), 298 were 6-12 years of age (25.8%), 233 were 12-15 years of age (20.2%), and 268 cases were older than 15 years of age (23.2%). The most common symptom of the patients at the first visit was fever (50.4%) (n = 583) for a median of 2 days (IQR: 1-3 days). Fever was median at 38.4°C (38.0-38.7°C). The second most common symptom was cough (n = 543, 46.9%). The other common symptoms were sore throat (n = 143, 12.4%), myalgia (n = 141, 12.2%), dyspnea (n = 118, 10.2%), diarrhea (n = 112, 9.7%), stomachache (n = 71, 6.1%), and nasal discharge (n = 63, 5.4%). When patients were classified according to disease severity, 263 (22.7%) patients were asymptomatic, 668 (57.7%) patients had mild disease, 209 (18.1%) had moderate disease, and 16 (1.5%) cases had severe disease. One hundred and forty-nine (12.9%) cases had underlying diseases among the total cases; 56% of the patients who had severe disease had an underlying condition (p < 0.01). The need for hospitalization did not differ between patients who had an underlying condition and those who do not have (p = 0.38), but the need for intensive care was higher in patients who had an underlying condition (p < 0.01). Forty-seven (31.5%) of the cases having underlying conditions had asthma or lung disease (38 of them had asthma). Conclusions: To the best of our knowledge, this is one of the largest pediatric data about confirmed COVID-19 cases. Children from all ages appear to be susceptible to COVID-19, and there is a significant difference in symptomatology and laboratory findings by means of age distribution.

Molecular characterization of human adenoviruses associated with respiratory infection in Turkey

Human adenoviruses (HAdVs) are responsible for various clinical diseases. Molecular epidemiological studies of respiratory HAdVs are limited in Turkey. To determine the main genotypes and epidemiological characteristics of HAdVs in patients with respiratory symptoms. HAdV PCR-positive extracts of nasal/nasopharyngeal specimens sent to the Turkish Public Health Institution from various cities of Turkey in 2015-2016 were investigated by seminested PCR. Partial sequence analysis of the hexon gene of HAdVs was performed. SPSSv.24.0 was used. A total of 23/68 (33.82%) HAdV-positive samples were amplified. Mastadenovirus B, C, D, and F were detected and mastadenovirus B (10/23; 43.5%) and C (10/23; 43.5%) were predominant strains. Interestingly, HAdV-F known to have gastrointestinal system tropism was detected in two patients with respiratory symptoms. HAdV-B3 was the most prevalent genotype (9/23; 39.1%). Also, HAdV-B7 is defined as a reemerging pathogen. It is noteworthy that there is a cluster of four HAdV-C strains showing a close paraphyletic relationship with HAdV-2/6 intertypic recombination. To our knowledge, this is the first study showing that HAdV-B7 reemerging pathogen circulating in patients with respiratory infections in our country. It is also necessary to emphasize that HAdV-2/6 recombinant strains were detected in this study for the first time in Turkey.

Molecular characterization of the influenza A(H1N1)pdm09 isolates collected in the 2015-2016 season and comparison of HA mutations detected in Turkey since 2009

Influenza A(H1N1)pdm09 pandemic virus causing the 2009 global outbreak moved into the post-pandemic period, but its variants continued to be the prevailing subtype in the 2015-2016 influenza season in Europe and Asia. To determine the molecular characteristics of influenza A(H1N1)pdm09 isolates circulating during the 2015-2016 season in Turkey, we identified mutations in the hemagglutinin (HA) genes and investigated the presence of H275Y alteration in the neuraminidase genes in the randomly selected isolates. The comparison of the HA nucleotide sequences revealed a very high homology (>99.5%) among the studied influenza A(H1N1)pdm09 isolates, while a relatively low homology (96.6%-97.2%), was observed between Turkish isolates and the A/California/07/2009 vaccine virus. Overall 14 common mutations were detected in HA sequences of all 2015-2016 influenza A(H1N1)pdm09 isolates with respect to the A/California/07/2009 virus, four of which located in three different antigenic sites. Eleven rare mutations in 12 HA sequences were also detected. Phylogenetic analysis revealed that all characterized influenza A(H1N1)pdm09 isolates formed a single genetic cluster, belonging to the genetic subclade 6B.1, defined by HA amino acid substitutions S84N, S162N, and I216T. Furthermore, all isolates showed an oseltamivir-sensitive genotype, suggesting that Tamiflu (Oseltamivir) could still be the drug of choice in Turkey.

Genetic variability human respiratory syncytial virus subgroups A and B in Turkey during six successive epidemic seasons, 2009-2015

Human respiratory syncytial virus (HRSV) is most important viral respiratory pathogen of acute lower respiratory tract infections in infants and young children worldwide. The circulating pattern and genetic characteristics in the HRSV attachment glycoprotein gene were investigated in Turkey during six consecutive seasons from 2009 to 2015. HRSVA was dominant in the all epidemic seasons except 2011‐2012 season. Partial sequences of the HVR2 region of the G gene of 479 HRSVA and 135 HRSVB were obtained. Most Turkish strains belonged to NA1, ON1, and BA9, which were the predominant genotypes circulating worldwide. Although three novel genotypes, TR‐A, TR‐BA1, and TR‐BA2, were identified, they were not predominant. Clinical data were available for 69 HRSV‐positive patients who were monitored due to acute lower respiratory tract illness. There were no significant differences in the clinical diagnosis, hospitalization rates, laboratory findings and treatment observed between the HRSVA and HRSVB groups, and co‐infections in this study. The major population afflicted by HRSV infections included infants and children between 13 and 24 months of age. We detected that the CB1, GB5, and THB strains clustered in the same branch with a bootstrap value of 100%. CB‐B and BA12 strains clustered in the same branch with a bootstrap value of 65%. The BA11 genotype was clustered in the BA9 genotype in our study. The present study may contribute on the molecular epidemiology of HRSV in Turkey and provide data for HRSV strains circulating in local communities and other regions worldwide.

Emergence of West Nile virus infections in humans in Turkey, 2010 to 2011

In 2010, 47 human cases of West Nile virus (WNV)infection, including 12 laboratory-confirmed and 35 probable cases, were identified in Turkey. These were the first cases detected during routine surveillance.The patients were from 15 provinces, mainly located in the western part of the country. Incidence was 0.19/100,000 with a maximum of 1.39 in Sakarya province.Forty of the total 47 cases showed neuroinvasive manifestation. Median age was 58 years with a range of four to 86. Ten of the patients died. Enhanced surveillance in humans and animals and mosquito control measures were implemented. The WNV infections were included in the national notifiable diseases list as of April 2011. In 2011, three probable and two confirmed cases of WNV infection were diagnosed in provinces where infections had been detected in the previous year, supporting a lower activity than 2010. However,detection of WNV infections in humans in 2010 and 2011 consecutively, may indicate that WNV has become endemic in the western part of Turkey. Field epidemiological studies were undertaken to understand more about the nature of infection in Turkey.

Emergence of West Nile virus infections in humans in Turkey, 2010 to 2011

In 2010, 47 human cases of West Nile virus (WNV) infection, including 12 laboratory-confirmed and 35 probable cases, were identified in Turkey. These were the first cases detected during routine surveillance. The patients were from 15 provinces, mainly located in the western part of the country. Incidence was 0.19/100,000 with a maximum of 1.39 in Sakarya province. Forty of the total 47 cases showed neuroinvasive manifestation. Median age was 58 years with a range of four to 86. Ten of the patients died. Enhanced surveillance in humans and animals and mosquito control measures were implemented. The WNV infections were included in the national notifiable diseases list as of April 2011. In 2011, three probable and two confirmed cases of WNV infection were diagnosed in provinces where infections had been detected in the previous year, supporting a lower activity than 2010. However, detection of WNV infections in humans in 2010 and 2011 consecutively, may indicate that WNV has become endemic in the western part of Turkey. Field epidemiological studies were undertaken to understand more about the nature of infection in Turkey.

Swine influenza A (H1N1) virus infection in infants

There are few reports on pandemic swine influenza A (H1N1) virus infection in very young infants. We aimed to discuss the clinical characteristics and management of the H1N1 influenza infection in very young infants. Clinical characteristics of ten infants diagnosed with H1N1 influenza virus infection during the 2009 outbreak season in a tertiary neonatal intensive care unit were evaluated. The diagnosis was confirmed by testing of respiratory samples with pandemic H1N1 influenza specific real-time PCR assay. Of the 46 patients with fever or respiratory problems, ten (22%) were diagnosed with H1N1 influenza virus infection during the 2009 (October-December) peak outbreak season. All infants including the preterms were admitted from home, seven (70%) were full-term and three (30%) were preterm. Median age of the patients at admission was 24.5 days. Fever and cough were the most common symptoms. Apnea was the initial symptoms in three patients. Two patients required oxygen support, one of which, a preterm baby, had been mechanically ventilated for 2 days. Mean duration of hospitalization was 7.8 ± 4.9 days. Chest radiography revealed radio-opacities on both lung fields in six patients. In addition, two patients had co-infection. All patients with proven infection were given oseltamivir medication. Recovery was achieved in all patients with no residual deficits or side effects from the antiviral oseltamivir treatment. The H1N1 influenza virus infection in very young infants appears to be mild to moderate in severity. The outcomes of the infants may be influenced by antiviral therapy. Treatment with antiviral oseltamivir appears to have no major adverse effects.