Dynamic changes of IgM and IgG antibodies in asymptomatic patients as an effective way to detect SARS-CoV-2 infection.

BACKGROUND: COVID-19 has become a global pandemic, and close contacts and asymptomatic patients are worthy of attention. METHODS: A total of 1844 people in close contacts with 76 COVID-19 patients were investigated, and nasopharyngeal swabs and venous blood were collected for centralized medical quarantine observation. Real-time fluorescence was used to detect SARS-CoV-2 nucleic acid in nasopharyngeal swabs of all close contacts, and the colloidal gold method was used to detect serum-specific antibodies. Levels of IgM- and IgG-specific antibodies were detected quantitatively through chemiluminescence from the first nucleic acid turned negative date (0 week) and on weekly intervals of ≤1 week, 1-2 weeks, 2-3 weeks, 3-4 weeks, 4-5 weeks, 5-6 weeks, and 6-7 weeks. RESULTS: The total positive rate of the colloidal gold method (88.5%, 23/26) was significantly higher (χ2  = 59.182, p < 0.001) than that of the healthy control group (2.0%, 1/50). There was significant difference in IgG concentration at different time points (0-7 weeks) after negative nucleic acid conversion (χ2  = 14.034, p = 0.029). Serum IgG levels were significantly higher at weekly time points of 4-5 weeks (Z = -2.399, p = 0.016), 5-6 weeks (Z = -2.049, p = 0.040), and 6-7 weeks (Z = -2.197, p = 0.028) compared with 1-2 weeks after negative nucleic acid conversion. However, there was no significant difference (χ2  = 4.936, p = 0.552) in IgM concentration between time points tested (0-7 weeks) after negative nucleic acid conversion. The positive rates of IgM and IgG in asymptomatic patients (χ2  = 84.660, p < 0.001) were significantly higher than those in the healthy control group (χ2  = 9.201, p = 0.002) within 7 weeks of negative nucleic acid conversion. CONCLUSIONS: The IgG concentration in asymptomatic cases remained at a high level after nucleic acid turned negative. Nucleic acid detection combined with IgM and IgG antibody detection is an effective way to screen asymptomatic infections.

Cryptococcal antigen carriage among HIV infected children aged 6 months to 15 years at Laquintinie Hospital in Douala.

BACKGROUND: Up to 15% of deaths of people living with HIV is attributable to meningeal cryptococcosis, with nearly 75% occuring in sub-Saharan Africa. Although rare in children, it is a major cause of morbidity and mortality in people living with HIV. A strong association between cryptococcal antigenemia and the development of meningeal cryptococcosis has been shown in adults. Thus, in 2018, the World Health Organization published an updated version of its guidelines for the diagnosis, prevention and management of cryptococcal infection in adults, adolescents and the HIV-infected child. GOAL: To determine the prevalence of cryptococcal antigenemia and to identify its determinants in children infected with HIV. METHODS: An analytical cross-sectional study was carried out at the approved treatment center of Laquintinie hospital in Douala over a period of 4 months. Children were recruited consecutively after informed parental consent. Cryptococcal antigenemia and CD4 assay were performed using a Cryptops® immunochromatographic rapid diagnostic test and flow cytometry, respectively. The data collected included the socio-demographic, clinical and paraclinical variables of the children, as well as their antecedents. Data analysis was performed using Epiinfo software version 3.1 and SPSS 21.0. The significance threshold was set at 5%. RESULTS: A total of 147 children were enrolled. The mean age was 9.8 ± 4.09 years. The majority were on antiretroviral therapy (142, 96.60%). Only 13 (8.80%) were in severe immunosuppression. No child showed signs of meningeal cryptococcosis. The prevalence of cryptococcal antigenemia was 6.12%. Severe immunosuppression [OR: 10.03 (1.52-65.91), p = 0.016] and contact with pigeons [OR: 9.76 (1.14-83.65), p = 0.037] were independent factors significantly associated with the carriage of the cryptococcal antigen. CONCLUSION: We recommend screening for cryptococcal antigenemia and routine treatment with fluconazole of all HIV positive children with cryptococcal antigen whether symptomatic or not.

Alterations of lipid metabolism provide serologic biomarkers for the detection of asymptomatic versus symptomatic COVID-19 patients.

COVID-19 pandemic exerts a health care emergency around the world. The illness severity is heterogeneous. It is mostly unknown why some individuals who are positive for SARS-CoV-2 antibodies stay asymptomatic while others show moderate to severe disease symptoms. Reliable biomarkers for early detection of the disease are urgently needed to attenuate the virus's spread and help make early treatment decisions. Bioactive sphingolipids play a crucial role in the regulation of viral infections and pro-inflammatory responses involved in the severity of COVID-19. However, any roles of sphingolipids in COVID-19 development or detection remain unknown. In this study, lipidomics measurement of serum sphingolipids demonstrated that reduced sphingosine levels are highly associated with the development of symptomatic COVID-19 in the majority (99.24%) SARS-CoV-2-infected patients compared to asymptomatic counterparts. The majority of asymptomatic individuals (73%) exhibited increased acid ceramidase (AC) in their serum, measured by Western blotting, consistent with elevated sphingosine levels compared to SARS-CoV-2 antibody negative controls. AC protein was also reduced in almost all of the symptomatic patients' serum, linked to reduced sphingosine levels, measured in longitudinal acute or convalescent COVID-19 samples. Thus, reduced sphingosine levels provide a sensitive and selective serologic biomarker for the early identification of asymptomatic versus symptomatic COVID-19 patients.

Integrating gut microbiome and host immune markers to understand the pathogenesis of Clostridioides difficile infection.

Clostridioides difficile (C.difficile) infection is the most common cause of healthcare-associated infection and an important cause of morbidity and mortality among hospitalized patients. A comprehensive understanding of C.difficile infection (CDI) pathogenesis is crucial for disease diagnosis, treatment, and prevention. Here, we characterized gut microbial compositions and a broad panel of innate and adaptive immunological markers in 243 well-characterized human subjects (including 187 subjects with both microbiota and immune marker data), who were divided into four phenotype groups: CDI, Asymptomatic Carriage, Non-CDI Diarrhea, and Control. We found that the interactions between gut microbiota and host immune markers are very sensitive to the status of C.difficile colonization and infection. We demonstrated that incorporating both gut microbiome and host immune marker data into classification models can better distinguish CDI from other groups than can either type of data alone. Our classification models display robust diagnostic performance to differentiate CDI from Asymptomatic carriage (AUC~0.916), Non-CDI Diarrhea (AUC~0.917), or Non-CDI that combines all other three groups (AUC~0.929). Finally, we performed symbolic classification using selected features to derive simple mathematic formulas that explicitly quantify the interactions between the gut microbiome and host immune markers. These findings support the potential roles of gut microbiota and host immune markers in the pathogenesis of CDI. Our study provides new insights for a microbiome-immune marker-derived signature to diagnose CDI and design therapeutic strategies for CDI.

Evaluation of hepatic enzymes activities in COVID-19 patients.

SARS-CoV-2 or Coronavirus disease 2019 (COVID-19) outbreak which caused by the severe acute respiratory syndrome, has rapidly spread over the world. The exact mechanism how this virus will affect the liver remained elusive. The aim of this study was to evaluate the liver function in patients with severe acute respiratory syndrome coronavirus 2 and potential causes of hepatic enzymes disease in these patients. Clinical characteristics and laboratory findings were collected from patients with COVID-19 who were admitted to the corona center in Erbil city/Kurdistan region of Iraq, from March 10 to July 10, 2020. Serum was collected from patients with COVID-19 and liver enzyme tests were measured. Liver alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total bilirubin (TBIL) were analyzed in these patients. Of the 74 patients, 25 (34.7%) had abnormal ALT activity, 28 (40%) had abnormal AST activity, 12 (20.3%) had abnormal ALP activity, and 39 (52.7%) had abnormal total bilirubin P-value < 0.05. The inflammatory biomarkers CRP and IL-6 in COVID-19 patients with abnormal liver function test (4.9 ± 1.0 mg/dl) and (231.2 ± 35.7 pg/ml) respectively. The levels of both biomarkers were statistically significantly higher than COVID-19 patients with normal liver function test (2.1 ± 0.5 mg/dl) and (2.1 ± 0.5 mg/dl) respectively, P-value < 0.05. However, CRP and IL-6 were not statistically significant different between male and female COVID-19 patients P-value < 0.05. In conclusion, we found that most of the patients with SARS-CoV-2 have abnormal hepatic enzyme activities and that is might related to virus replication in the liver.

Identifying additional risk factors for arterial and venous thrombosis among pediatric antiphospholipid antibodies carriers.

BACKGROUND: Antiphospholipid antibodies (aPL) have been extensively reported in children, but investigations into thrombotic risks associated with aPL positivity in pediatric patients is scarce. Positive aPL are not uncommon in pediatric connective tissue diseases (CTD), but identification and management of these patients is challenging due to lack of validated criteria and a paucity of data. In this study, we identify potential additional risk factors for thrombosis in a unique cohort of pediatric aPL positive carriers. METHODS: Retrospective chart review was performed on 491 pediatric patients with CTD seen in our institution from 2001 to 2019. Patients without persistently moderate to high titer aPL at least 12 weeks apart were excluded. Univariate analysis was performed to evaluate correlation between different risk factors and thrombotic events. RESULTS: Seventy-one aPL positive children with underlying CTD are included in this cohort. The majority (87%) are female and of Hispanic ethnicity (56%). Mean age of the cohort at the diagnosis of connective tissue disease is 12.7 (SD 2.6) years, and mean age of first positive aPL is 13.3 (SD 2.5) years. Average length of follow-up is 4.3 (SD 2.5) years. Four (5.6%) patients experienced arterial thrombosis, and 11 (15.5%) had venous thrombosis. Fifty-seven (80.3%) patients did not have any thromboembolic events. Among traditional risk factors and signs of endothelial injury, only Raynaud's phenomena demonstrated significant association with arterial thrombosis (OR = 8.4, 95%CI 1.13-111, P = 0.039), and hypertension or anti-hypertensive use demonstrated significant association with venous thrombosis (OR = 8.387, 95%CI 1.2 - 94, P = 0.02). CONCLUSION: Data from our cohort suggest that Raynaud's phenomenon is a potential predictor of arterial thrombosis while the presence of hypertension or anti-hypertensive medication use is a potential predictor of venous thrombosis in aPL positive pediatric carriers. Further studies investigating pediatric aPL profiles and risk factors for development of thrombosis are needed to help guide clinicians in caring for these challenging patients.

Trend of 25-hydroxycholesterol and 27-hydroxycholesterol plasma levels in patients affected by active chronic hepatitis B virus infection and inactive carriers.

Hepatitis B virus (HBV) infection is a global health problem with different immunological phases and therapeutic approaches. The serological condition of inactive carrier (IC) was recently well defined as a clinical and virological stable status, in which specific treatment is usually deferred, while the active chronic hepatitis B (CHB) condition requires an immediate treatment strategy. Recently, a possible broad antiviral effect of oxysterols, in particular 25-hydroxycholesterol (25OHC) and 27-hydroxycholesterol (27OHC), was observed, as most likely linked to the positive modulation of innate immunity, but no clear evidence is available about their possible role in chronic HBV infection. Thus, we examined the relationship between the plasma levels of oxysterols and the disease condition of 40 HBV patients, without treatment at the start of the study. Of these, 33 were ICs and 7 were active CHB subjects. A marked reduction of 25OHC and 27OHC plasma levels was detectable in all active CHB recruited patients, while the plasma values observed in ICs all remained within the physiological range. No difference was observed between the two groups of patients with regard to the plasma levels of 24-hydroxycholesterol (24OHC). Further, the plasma level of 27OHC ≥ 140 µg/L was shown to be predictive of an inactive carrier status. This cohort study points to 27OHC as a good candidate biomarker to differentiate active and inactive CHB status. An increasing bulk of research reports is supporting the very likely contribution of this oxysterol to the immunological control of chronic hepatitis B.

Humoral signatures of protective and pathological SARS-CoV-2 infection in children.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic continues to spread relentlessly, associated with a high frequency of respiratory failure and mortality. Children experience largely asymptomatic disease, with rare reports of multisystem inflammatory syndrome in children (MIS-C). Identifying immune mechanisms that result in these disparate clinical phenotypes in children could provide critical insights into coronavirus disease 2019 (COVID-19) pathogenesis. Using systems serology, in this study we observed in 25 children with acute mild COVID-19 a functional phagocyte and complement-activating IgG response to SARS-CoV-2, similar to the acute responses generated in adults with mild disease. Conversely, IgA and neutrophil responses were significantly expanded in adults with severe disease. Moreover, weeks after the resolution of SARS-CoV-2 infection, children who develop MIS-C maintained highly inflammatory monocyte-activating SARS-CoV-2 IgG antibodies, distinguishable from acute disease in children but with antibody levels similar to those in convalescent adults. Collectively, these data provide unique insights into the potential mechanisms of IgG and IgA that might underlie differential disease severity as well as unexpected complications in children infected with SARS-CoV-2.

Application of a Pneumococcal Serotype-specific Urinary Antigen Detection Test for Identification of Pediatric Pneumonia in Burkina Faso.

BACKGROUND: Serotype-specific diagnosis of pneumococcal community-acquired pneumonia in children under age 5 years would mark a major advancement for understanding pneumococcal epidemiology and supporting vaccine decision-making. METHODS: A Luminex technology-based multiplex urinary antigen detection (UAD) diagnostic assay was developed and subsequently validated in adults, but its applicability to children is unknown. This study aimed to set appropriate cutoffs for use of the UAD in a healthy pediatric population and apply these cutoffs in children with pneumonia in sub-Saharan Africa. The cutoffs were determined by assessing 379 urines obtained from healthy children under age 5 years from the Bobo-Dioulasso area for serotypes included in 13-valent pneumococcal conjugate vaccine (UAD-1) and the 11 other serotypes unique to 23-valent pneumococcal polysaccharide vaccine (UAD-2). RESULTS: Based on the assigned cutoff values, among 108 children who met the World Health Organization consolidation endpoint criteria, UAD-1 and UAD-2 were positive in 23.3% and 8.3%, respectively; among 364 children with clinically suspected pneumonia who did not meet the World Health Organization criteria, UAD-1 and UAD-2 were positive for 6.6% and 3.6%, respectively. Pneumococcal carriage prevalence was similar among pneumonia cases (30%) versus controls (35%) as was semiquantitative carriage density. CONCLUSIONS: UAD-1 and UAD-2 were able to distinguish community controls from children with pneumonia, particularly pneumonia with consolidation. Future studies are needed to confirm these results and more fully assess the contribution of pneumococcal carriage and concurrent viral infection.

IgG reactivity profile to Paracoccidioides spp. antigens in people with asymptomatic Paracoccidioidomycosis.

Introduction. Paracoccidioidomycosis (PCM) is a systemic mycosis caused by Paracoccidioides spp. As the disease is known to affect mostly men over 40 years old who previously worked handling soil, some cities of agricultural economy in endemic regions may have more cases of paracoccidioidal infection.Gap statement. The true frequency of PCM cannot be established in Brazil because it is not a disease of mandatory reporting. The detection of paracoccidioidal infection may assist in the planning of health services, in order to provide early detection of the disease and to prevent its worsening or even progression to death. In addition, little is described about sera reactivity with antigens from different species of Paracoccidiodes, especially P. lutzii.Aim. Current research was conducted in an inland municipality of southern Brazil, in order to assess infection rate within this endemic region of PCM disease.Methodology. ELISA was employed to evaluate 359 sera from random volunteers from Guarapuava, Paraná, Brazil, to detect IgG against cell-free antigens (CFA) from P. restrepiensis B339, P. americana LDR3 and P. lutzii LDR2. Confirmatory ELISA employed gp43 from B339. Reduction of cross-reactions was sought by treatment with sodium metaperiodate (SMP-CFA, SMP-gp43). Immunoblot was performed with 37 selected sera among those reactive in ELISA. Epidemiological profile was assessed by questionnaire.Results. ELISA reactivity was: CFA/SMP-CFA in general 37.3/17.8 %, B339 25.3/14.5 %, LDR3 24.5/1.4 %, LDR2 8.3/5.8 %; gp43/SMP-gp43 7.2/4.7 %. There were sera reactive with multiple CFAs. In immunoblot, five sera showed the same reaction profile with P. lutzii's antigens as PCM disease sera. Rural residence and soil-related professions were risk factors for paracoccidioidal infection.Conclusion. The low prevalence is in accordance with previous reports of lower PCM disease endemicity in Guarapuava than in other areas of Paraná. Although P. brasiliensis seems to be the prevalent strain of the region, 21 sera from people who only lived in Guarapuava reacted with P. lutzii LDR2. CFA-ELISA with whole antigens seems a good option for serological screening in epidemiological surveys.

Antibody dynamics to SARS-CoV-2 in asymptomatic COVID-19 infections.

BACKGROUND: The missing asymptomatic COVID-19 infections have been overlooked because of the imperfect sensitivity of the nucleic acid testing (NAT). Globally understanding the humoral immunity in asymptomatic carriers will provide scientific knowledge for developing serological tests, improving early identification, and implementing more rational control strategies against the pandemic. MEASURE: Utilizing both NAT and commercial kits for serum IgM and IgG antibodies, we extensively screened 11 766 epidemiologically suspected individuals on enrollment and 63 asymptomatic individuals were detected and recruited. Sixty-three healthy individuals and 51 mild patients without any preexisting conditions were set as controls. Serum IgM and IgG profiles were further probed using a SARS-CoV-2 proteome microarray, and neutralizing antibody was detected by a pseudotyped virus neutralization assay system. The dynamics of antibodies were analyzed with exposure time or symptoms onset. RESULTS: A combination test of NAT and serological testing for IgM antibody discovered 55.5% of the total of 63 asymptomatic infections, which significantly raises the detection sensitivity when compared with the NAT alone (19%). Serum proteome microarray analysis demonstrated that asymptomatics mainly produced IgM and IgG antibodies against S1 and N proteins out of 20 proteins of SARS-CoV-2. Different from strong and persistent N-specific antibodies, S1-specific IgM responses, which evolved in asymptomatic individuals as early as the seventh day after exposure, peaked on days from 17 days to 25 days, and then disappeared in two months, might be used as an early diagnostic biomarker. 11.8% (6/51) mild patients and 38.1% (24/63) asymptomatic individuals did not produce neutralizing antibody. In particular, neutralizing antibody in asymptomatics gradually vanished in two months. CONCLUSION: Our findings might have important implications for the definition of asymptomatic COVID-19 infections, diagnosis, serological survey, public health, and immunization strategies.

Antibody responses after COVID-19 infection in patients who are mildly symptomatic or asymptomatic in Bangladesh.

OBJECTIVES: Studies on serological responses following coronavirus disease-2019 (COVID-19) have been published primarily in individuals who are moderately or severely symptomatic, but there are few data from individuals who are mildly symptomatic or asymptomatic. METHODS: We measured IgG, IgM, and IgA to the receptor-binding domain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by using enzyme-linked immunosorbent assay in mildly symptomatic (n = 108) and asymptomatic (n = 63) on days 1, 7, 14, and 30 following RT-PCR confirmation in Bangladesh and when compared with pre-pandemic samples, including healthy controls (n = 73) and individuals infected with other viruses (n = 79). RESULTS: Mildly symptomatic individuals developed IgM and IgA responses by day 14 in 72% and 83% of individuals, respectively, while 95% of individuals developed IgG response, and rose to 100% by day 30. In contrast, individuals infected with SARS-CoV-2 but who remained asymptomatic developed antibody responses significantly less frequently, with only 20% positive for IgA and 22% positive for IgM by day 14, and 45% positive for IgG by day 30 after infection. CONCLUSIONS: These results confirm immune responses are generated following COVID-19 who develop mildly symptomatic illness. However, those with asymptomatic infection do not respond or have lower antibody levels. These results will impact modeling needed for determining herd immunity generated by natural infection or vaccination.

Natural History of Untreated HBeAg-Positive Chronic HBV Infection With Persistently Elevated HBV DNA but Normal Alanine Aminotransferase.

OBJECTIVES: Nucleos(t)ide analogues (NUCs) are not routinely recommended for patients with hepatitis B e antigen-positive chronic hepatitis B virus (HBV) infection who have persistently elevated serum HBV DNA level (>20,000 IU/mL) but normal alanine aminotransferase (<40 IU/L) level. Here, we evaluated the cumulative risks of hepatocellular carcinoma (HCC) in such patients (the untreated persistently elevated serum HBV DNA [pEDNA] group) compared with inactive carriers (the IC group). METHODS: Patients with untreated pEDNA (n = 126) and IC (n = 621) were enrolled between 2006 and 2012. Patients with cirrhosis or HCC at enrollment or a history of NUC treatment were excluded. RESULTS: The cumulative HCC risks at 5 and 9 years in the untreated pEDNA group were 1.1% and 1.9%, which were comparable with those of the IC group (P = 0.549). Inverse probability of treatment weighting and propensity score matching also showed similar HCC risks. In the untreated pEDNA group, there were no cases of HCC in the subgroup with serum HBV DNA level >1,000,000 IU/mL (immune-tolerant phase), which was significantly (P = 0.002) different compared with those with an intermediate serum HBV DNA level (20,000-1,000,000 IU/mL). DISCUSSION: The cumulative HCC risk in the untreated pEDNA group was minimal and comparable with that of the IC group. Further studies are required to determine whether early NUC treatment, indeed, reduces the HCC risk in patients with an intermediate serum HBV DNA level.

Do the circulating Pre-S/S quasispecies influence hepatitis B virus surface antigen levels in the HBeAg negative phase of HBV infection?

BACKGROUND: Virus, host factors and their interplay influence Hepatitis B surface Antigen serum levels during Hepatitis B Virus (HBV) infection course and treatment. AIM: To study the Pre-S/S circulating quasispecies in a cohort of untreated, HBeAg negative, genotype-D, HBsAg carriers. METHODS: We studied 260 carriers: 71 with HBeAg negative infection (ENI; HBV-DNA ≤2000 IU/mL); 42 Grey Zone (GZ; HBV-DNA ≤20 000 IU/mL); 82 chronic hepatitis (CH) and 65 cirrhosis (CI) (HBV-DNA > 20 000 IU/mL). Population sequencing was applied to identify Pre-S/S gene mutations responsible for any amino acid substitution or potential biological/antigenic implications (M-muts) on HBsAg. RESULTS: HBsAg serum levels were lower in ENI + GZ than in CH + CI (2.61 [-1.10/4.06] vs 3.62 [2.41/4.92] log10 IU/mL, P < 0.001) and in CI than CH (3.48 [2.41/4.38] vs 3.66 [2.57/4.92] log10 IU/mL, P < 0.001). M-muts were found in 73 (28.1%) cases: 5 (7.0%) ENI, 3 (7.1%) GZ, 26 (31.7%) CH, 39 (60.0%) CI (P < 0.001) and mostly in Pre-S2 (17.6%) than Pre-S1 (5.8%) and Small-S (10.8%; P < 0.001). Overall HBsAg serum levels were higher in carriers with M-muts (3.56 [0.95/4.38] vs 3.17 [-1.10/4.92] log10 IU/mL, P < 0.001), but comparable in carriers with or without M-mut when considering separately ENI + GZ (2.84 [0.95/3.89] vs 2.61 [-1.10/4.06] log10 IU/mL, P = 0.330] and CH + CI (3.57 [2.67/4.38] vs 3.63 [2.41/4.92] log10 IU/mL, P = 0.37). Infection phase (ß: 0.422, P < 0.001), age (ß: -0.260, P < 0.001), ALT (ß: -0.103, P = 0.045), liver stiffness (ß: -0.118, P = 0.039) and HBV-DNA (ß: 0.384, P < 0.001), but not M-mut were independently associated with HBsAg serum levels. CONCLUSIONS: In HBeAg negative, genotype-D, carriers Pre-S/S heterogeneity increases with severity of liver disease, but does not influence HBsAg serum levels, that in low viraemic carriers are associated with an effective control of HBV.

Factors influencing PCV13 specific antibody response in Danish children starting in day care.

This study examines different factors influencing the 13-valent pneumococcal conjugate vaccine (PCV13) specific antibody response in 8-13 months old Danish children starting in day care. We present secondary findings to the ProbiComp study, which included nose swabs, buccal swabs and blood samples from the children before entering day care (baseline) and again after 6 months. Pneumococci isolated from nose swabs were identified by latex agglutination kit and Quellung reaction. Luminex-based assay was used for antibody measurements against specific anti-pneumococcal capsular IgG. Buccal gene expression was analyzed by qPCR. Statistical analyses were performed in R and included Pearson's Chi-squared test, Welch two sample t-test and linear regression models. The PCV13 antibody response was unaffected by whether the children were carriers or non-carriers of any pneumococcal serotype. Having siblings increased the risk of carrying serotype 21 before day care (p = 0.020), and having siblings increased the PCV13 antibody response at the end of study (p = 0.0135). Hepatitis B-vaccination increased the PCV13 antibody response before day care attendance (p = 0.005). The expression of IL8 and IL1B was higher in children carrying any pneumococcal serotype at baseline compared to non-carriers (p = 0.0125 and p = 0.0268 respectively).

Muskrats are greater carriers of pathogenic Leptospira than coypus in ecosystems with temperate climates.

Knowledge on the possible sources of human leptospirosis, other than rats, is currently lacking. To assess the distribution pattern of exposure and infection by Leptospira serogroups in the two main semi-aquatic rodents of Western France, coypus (Myocastor coypus) and muskrats (Ondatra zibethicus), results of micro-agglutination testing and renal tissue PCR were used. In coypus, the apparent prevalence was 11% (n = 524, CI95% = [9% - 14%]), seroprevalence was 42% (n = 590, CI95% = [38% - 46%]), and the predominant serogroup was Australis (84%). In muskrats, the apparent prevalence was 33% (n = 274, CI95% = [27% - 39%]), seroprevalence was 57% (n = 305, CI95% = [52% - 63%]), and the predominant serogroup was Grippotyphosa (47%). Muskrats should therefore be considered an important source of Grippotyphosa infection in humans and domestic animals exposed in this part of France.

Optimal cutoff of mean corpuscular volume (MCV) for screening of alpha-thalassemia 1 trait.

AIM: To identify the optimal cutoff of mean corpuscular volume (MCV) for screening of alpha-thalassemia 1 trait. METHODS: The database of pregnant women who attended antenatal care clinic at Department of Obstetrics and Gynecology, Chiang Mai University during January 1st, 2015 to December 31st, 2017 was accessed and reviewed. A total of 1264 cases who had MCV ≤80 fL and met the inclusion criteria were enrolled to the study. Cases with hemoglobin level ≤10.0 gm/dL, iron deficiency anemia, chronic medical diseases and other types of thalassemia trait except alpha-thalassemia 1 trait were excluded. RESULTS: After exclusion, 438 cases were available for analysis. Of them, 139 were alpha-thalassemia 1 trait. Based on the receiver operating characteristic curves, the best cutoff value of MCV for screening of alpha-thalassemia 1 trait was ≤76.15 fL, giving 100% sensitivity, and 60.9% specificity with the area under curve of 0.925. Compared to the conventional cutoff (≤80 fL), the new cutoff gave much less false positive tests (117 vs 299 cases), whereas capability to detect alpha-thalassemia 1 trait was the same. CONCLUSION: With the new MCV cutoff (≤76.15 fL) as a secondary cutoff for screening alpha-thalassemia 1 carrier, a substantial number of positive cases requiring DNA analysis could be avoided without compromising the detection efficacy.

[Malaria: immuno-permissive management in the prevention of transfusional malaria]. / Paludisme : gestion des immuno-tolérants dans la prévention du risque transfusionnel.

Malaria is a potentially life-threatening tropical infectious disease caused by a parasite that infects erythrocytes. Its transmission is vectorial, but the transfusion of infected red blood cells can cause a delicate diagnosis of transmitted malaria. Prevention is based on the selection of donors at risk by the search for antibodies reflecting past infection, in the absence of a sufficiently sensitive parasite detection technique to prevent all risks. Recent cases of transfusion malaria have reiterated that this preventive measure does not allow screening of all asymptomatic carriers.

Low genetic diversity and complexity of submicroscopic Plasmodium falciparum infections among febrile patients in low transmission areas in Senegal.

INTRODUCTION: Submicroscopic Plasmodium infections are common in malaria endemic countries, but very little studies have been done in Senegal. This study investigates the genetic diversity and complexity of submicroscopic P. falciparum infections among febrile patients in low transmission areas in Senegal. MATERIALS AND METHODS: Hundred and fifty blood samples were collected from febrile individuals living in Dielmo and Ndiop (Senegal) between August 2014 and January 2015, tested for microscopic and sub-microscopic P. falciparum infections and characterized for their genetic diversity and complexity of infections using msp-1 and msp-2 genotyping. RESULTS: Submicroscopic P. falciparum infections were 19.6% and 25% in Dielmo and Ndiop, respectively. K1 and 3D7 were the predominant msp-1 and msp-2 allelic types with respective frequencies of 67.36% and 67.10% in microscopic isolates and 58.24% and 78% in submicroscopic ones. Frequencies of msp-1 allelic types were statistically comparable between the studied groups (p>0.05), and were respectively 93.54% vs 87.5% for K1, 60% vs 54.83% for MAD20 and 41.93% vs 22.5% for RO33 while frequencies of msp-2 allelic types were significantly highest in the microscopy group for FC27 (41.93% vs 10%, Fisher's Exact Test, p = 0.001) and 3D7 (61.29% vs 32.5%, Fisher's Exact Test, p = 0.02). Multiplicities of infection were lowest in submicroscopic P. falciparum isolates. CONCLUSIONS: The study revealed a high submicroscopic P. falciparum carriage among patients in the study areas, and that submicroscopic P. falciparum isolates had a lower genetic diversity and complexity of malaria infections.