ICOS expression is required for maintenance but not the formation of germinal centers in the spleen in response to P. yoelii infection.

Inducible T cell co-stimulator (ICOS) plays a key role in the differentiation and maintenance of follicular helper T (Tfh) cells and thus germinal center (GC) formation. Previously, our lab showed in a Plasmodium chabaudi infection model that Icos -/- mice were significantly impaired in their ability to form GCs despite a persistent infection and thus a continued antigen (Ag) load. Here, we show that resolution of a primary infection with P. yoelii , was delayed in Icos -/- mice. This phenotype was associated with a reduction in the accumulation of Tfh-like and GC Tfh cells and an early deficiency in Ag-specific antibody (Ab) production. However, Icos -/- mice could form GCs, though they were less frequent in number than in wild-type (WT) mice. Nonetheless, the Ag-specific Abs from Icos -/- mice lacked signs of affinity maturation, suggesting functional defects associated with these GCs. Eventually, these GC structures dissipated more rapidly in Icos -/- mice than in WT mice. Moreover, the ability of Icos -/- mice to form these GC structures is not reliant on the high Ag load associated with P. yoelii infections, as GC formation was preserved in Icos -/- mice treated with atovaquone. Finally, mice were unable to form secondary GCs in the absence of ICOS after re-challenge. Overall, these data demonstrate the necessity of ICOS in the maintenance of Tfh cells, the formation and maintenance of sufficient numbers of functioning GCs, and the ability to generate new GC structures after re-infection with P. yoelii .

Dynamics of bacterial blight disease in resistant and susceptible rice varieties

Bacterial blight (X. oryzae pv. oryzae) is a serious disease in rice across the world. To better control the disease, it is important to understand its epidemiology and how key aspects of this (e.g. infection efficiency, and spatial spread) change according to environment (e.g. local site conditions and season), management, and in particular, variety resistance. To explore this, we analysed data on the disease progress on resistant and susceptible varieties of rice grown at four sites in the Philippines across five seasons using a combination of mechanistic modelling and statistical analysis. Disease incidence was generally lower in the resistant variety. However, we found no evidence that the primary infection efficiency was lower in resistant varieties, suggesting that differences were largely due to reduced secondary spread. Despite secondary spread being attributed to splash dispersal which is exacerbated by wind and rain, the wetter sites of Pila and Victoria in south Luzon tended to have lower infection rates than the drier sites in central Luzon. Likewise, we found spread in the dry season can be substantial and should therefore not be ignored. In fact, we found site to be a greater determinant of the number of infection attempts suggesting that other environmental and management factors had greater effect on the disease than climate. Primary infection was characterised by spatially-random observations of disease incidence. As the season progressed, we observed an emerging short-range (1.6 m–4 m) spatial structure suggesting secondary spread was predominantly short-range, particularly where the resistant variety was grown.

Primary Actinomycosis of the Leg: A Case Report and Literature Review

Actinomycosis is an indolent, slowly progressive, suppurative infection caused by gram-positive branching bacteria of the genus Actinomyces. The disease actinomycosis most commonly occurs in 3 body regions: cervicofacial (55% of patients), abdominopelvic (20%), and pulmonothoracic (15%). Primary infection of an extremity is an uncommon feature of actinomycosis. We present a case of rare primary Actinomycosis of the lower extremity.

Similar severity of influenza primary and re-infections in pre-school children requiring outpatient treatment due to febrile acute respiratory illness: prospective, multicentre surveillance study (2013–2015)

Background Influenza virus infections in immunologically naïve children (primary infection) may be more severe than in children with re-infections who are already immunologically primed. We compared frequency and severity of influenza virus primary and re-infections in pre-school children requiring outpatient treatment. Methods Influenza-unvaccinated children 1–5 years of age presenting at pediatric practices with febrile acute respiratory infection < 48 h after symptom onset were enrolled in a prospective, cross-sectional, multicenter surveillance study (2013–2015). Influenza types/subtypes were PCR-confirmed from oropharyngeal swabs. Influenza type/subtype-specific IgG antibodies serving as surrogate markers for immunological priming were determined using ELISA/hemagglutination inhibition assays. The acute influenza disease was defined as primary infection/re-infection by the absence/presence of influenza type-specific immunoglobulin G (IgG) and, in a second approach, by the absence/presence of subtype-specific IgG. Socio-demographic and clinical data were also recorded. Results Of 217 influenza infections, 178 were due to influenza A (87 [49%] primary infections, 91 [51%] re-infections) and 39 were due to influenza B (38 [97%] primary infections, one [3%] re-infection). Children with “influenza A primary infections” showed fever with respiratory symptoms for a shorter period than children with “influenza A re-infections” (median 3 vs. 4 days; age-adjusted p = 0.03); other disease characteristics were similar. If primary infections and re-infections were defined based on influenza A subtypes, 122 (87%) primary infections (78 “A(H3N2) primary infections”, 44 “A(H1N1)pdm09 primary infections”) and 18 (13%) re-infections could be classified (14 “A(H3N2) re-infections” and 4 “A(H1N1)pdm09 re-infections”). Per subtype, primary infections and re-infections were of similar disease severity. Children with re-infections defined on the subtype level usually had non-protective IgG titers against the subtype of their acute infection (16 of 18; 89%). Some patients infected by one of the influenza A subtypes showed protective IgG titers (≥ 1:40) against the other influenza A subtype (32/140; 23%). Conclusions Pre-school children with acute influenza A primary infections and re-infections presented with similar frequency in pediatric practices. Contrary to expectation, severity of acute “influenza A primary infections” and “influenza A re-infections” were similar. Most “influenza A re-infections” defined on the type level turned out to be primary infections when defined based on the subtype. On the subtype level, re-infections were rare and of similar disease severity as primary infections of the same subtype. Subtype level re-infections were usually associated with low IgG levels for the specific subtype of the acute infection, suggesting only short-time humoral immunity induced by previous infection by this subtype. Overall, the results indicated recurring influenza virus infections in this age group and no or only limited heterosubtypic antibody-mediated cross-protection.

Severe fetal symptomatic infection from human cytomegalovirus following non-primary maternal infection: report of two cases

Introduction Human cytomegalovirus (HCMV) is the most common congenital infection, expecially severe after a maternal primary infection; sequelae in neonates born to mothers experiencing a non-primary infection have been already reported. Hereby, two cases of severe fetal HCMV disease in seroimmune gravidas referred to our Unit are described. Cases presentation Case 1 A fetus at 21 weeks’ gestation with signs of anemia and brain abnormalities at ultrasound (US), described at magnetic resonance (MR) imaging as ependymal irregularity and bilateral asymmetric parenchimal thinning; amniotic fluid sample was positive for HCMV although the woman had a previous immunity; after termination of pregnancy, autopsy demonstrated a thicken layer of disorganized neurons on the right cortical plate, while on the left there was a morphological pattern coherent with polymicrogyria. Case 2 A fetus at 20 weeks’ gestation with anemia, moderate atrio-ventricular insufficiency, hepatosplenomegaly but no major cerebral lesions. Fetal blood was positive for HCMV, although unexpected for pre-pregnancy maternal immunity, and intrauterine transfusion was needed. A cesarean section at 34 weeks gestation was performed due to worsening condition of the fetus, who had a birthweight of 2210 grams, needed platelet transfusions but MR examination and clinical evaluation were normal. Conclusion The impact of non-primary maternal infection on pregnancy outcome is unknown and fetal brain damage in HCMV seroimmune transmitter-mothers can occur as a consequence of maternal re-infection or reactivation for a hypotetic different role of HCMV-primed CD4+ or CD8+ T-cells in fetal brain, with progressive brain lesions coexistent in the first case and with severe unexpected anemia in the second case. A previous maternal HCMV immunity should not exempt to test anemic fetuses for such infection, nor to consider a potential transplacental transmission.

First-line noninvasive management of cytomegalovirus primary infection in pregnancy

Objectives To introduce a first-line noninvasive antenatal management of maternal cytomegalovirus (CMV) primary infection based on ultrasound (US) and magnetic resonance imaging (MRI). Amniocentesis (AC) is used as a second-line tool in cases of abnormalities compatible with fetal CMV infection on US and/or MRI screening. Methods Between January 2011 and October 2018, pregnant women referred with a CMV primary infection on antibody screening were followed up by monthly US scans and a brain MRI at approximately 32 weeks. In cases with US and/or MRI abnormalities compatible with congenital CMV infection, AC was performed to confirm the diagnosis. Results Ninety pregnant women with a primary CMV infection were included (89 singleton and one twin pregnancy). The first-line screening by US and/or MRI was normal for 72 of 91 fetuses (79%). At birth, 19 of these 72 neonates (26%) had a positive urine sample for CMV but were asymptomatic. US and/or MRI abnormalities were identified in 19 fetuses (21%). AC confirmed a fetal CMV infection in 16 fetuses (84%); 12 pregnancies were terminated, and four were continued, with three symptomatic neonates at birth and one poor neurodevelopmental outcome at postnatal follow-up. Conclusions First-line noninvasive management of maternal CMV primary infection based on serial US scans and brain MRI can be offered to identify fetuses with severe symptomatic congenital CMV infection and reduce the number of ACs without compromising the fetal outcome.

Risk of SARS-CoV-2 reinfections in children: prospective national surveillance, January 2020 to July 2021, England

BackgroundReinfection after primary SARS-CoV-2 infection is uncommon in adults, but little is known about the risks, characteristics, severity or outcomes of reinfection in children.MethodsWe used national SARS-CoV-2 testing data in England to estimate the risk of reinfection ≥90 days after primary infection from 01 January 2020 to 31 July 2021, which encompassed both the Alpha and Delta waves in England. Disease severity was assessed by linking reinfection cases to national hospitalisation, intensive care admission and death registrations datasets.FindingsReinfection rates closely followed community infection rates, with a small peak during the Alpha wave and a larger peak during the Delta wave. In children aged ≤16 years, there were 688,418 primary infections and 2,343 reinfections. The overall reinfection rate was 66·88/100,000 population, being higher in adults (72.53/100,000) than in children (21·53/100,000). Reinfection rates after primary infection were 0·68% overall, 0·73% in adults and 0·34% in children. Of the 109 reinfections in children admitted to hospital, 78 (72%) had underlying comorbidities. Hospitalisation rates were similar for the first (64/2343, 2·73%) and second episode (57/2343, 2·43%). Intensive care admission was rare after primary infection (n=7) or reinfection (n=4), mainly in children with comorbidities. 44 deaths occurred after primary infection within 28 days of diagnosis (44/688,418, 0·01%), none after possible reinfections.InterpretationThe risk of SARS-CoV-2 reinfection is strongly related to exposure due to community infection rates, especially during the Delta variant wave. Children had a lower risk of reinfection than adults, but reinfections were not associated with more severe disease or fatal outcomes.FundingPHE/UKHSAResearch in ContextEvidence Before this studyWe searched PubMed with the terms “COVID-19” or “SARS-CoV-2” with “reinfection” to identify publications relating to SARS-CoV-2 reinfections from 01 January until 15 November 2021. There were few publications relating to SARS-CoV-2 reinfections, and these primarily related to adults. Published studies reported very low rates of reinfection during the first few months after primary infection in adults. COVID-19 vaccines provide effective immune protection against SARS-CoV-2 infection, but recent studies have reported increasing risk of breakthrough infection with time since primary vaccination due to waning immunity. Several SARS-CoV-2 variants, including the beta, gamma and delta variants have been shown to partially evade immunity after natural infection and vaccination, potentially increasing the risk of reinfections and breakthrough infections, respectively. Data on reinfections in children are lacking and restricted mainly to case reports in immunocompromised children.Added Value of This StudyWe used national SARS-CoV-2 testing data during the first 19 months of the pandemic to estimate the risk of reinfection in children compared to adults during a period that encompassed both the Alpha and the Delta variant waves in England. We found that the risk of reinfection correlated with the risk of SARS-CoV-2 exposure and therefore, closely reflected community infection rates, with most reinfections occurring during the Delta variant wave. Whilst acknowledging the limitation of using national testing data, we found that children had a lower risk of reinfection compared to adults and that the risk of reinfection in children increased with age. Reinfections were not associated with severe disease in terms of hospitalization or intensive care admission and there were no fatalities within 28 days of the reinfection episode in children.Implications of all the Available EvidenceSARS-CoV-2 reinfections are rare in children, especially younger children, and occurred mainly during the Delta wave in England. Reinfections were not associated with more severe disease or fatal outcomes in children. COVID-19 vaccination will provide further protection against primary infections and reinfections in children.

Current practices of management of maternal and congenital Cytomegalovirus infection during pregnancy after a maternal primary infection occurring in first trimester of pregnancy: Systematic review

Introduction Congenital CMV infection is the first worldwide cause of congenital viral infection but systematic screening of pregnant women and newborns for CMV is still debated in many countries. Objectives This systematic review aims to provide the state of the art on current practices concerning management of maternal and congenital CMV infection during pregnancy, after maternal primary infection (PI) in first trimester of pregnancy. Data sources Electronically searches on databases and hand searches in grey literature. Study eligibility criteria and participants Primary outcome was listing biological, imaging, and therapeutic management interventions in two distinct populations: population 1 are pregnant women with PI, before or without amniocentesis; population 2 are pregnant women with congenitally infected fetuses (after positive amniocentesis). Secondary outcome was pregnancy outcome in population 2. Results Out of 4,134 studies identified, a total of 31 studies were analyzed, with 3,325 pregnant women in population 1 and 1,021 pregnant women in population 2, from 7 countries (Belgium, France, Germany, Israel, Italy, Spain and USA). In population 1, ultrasound (US) examination frequency was 0.75/month, amniocentesis in 82% cases, maternal viremia in 14% and preventive treatment with hyperimmune globulins (HIG) or valaciclovir in respectively 14% and 4% women. In population 2, US examination frequency was 1.5/month, magnetic resonance imaging (MRI) in 44% cases at 32 weeks gestation (WG), fetal blood sampling (FBS) in 24% at 28 WG, and curative treatment with HIG or valaciclovir in respectively 9% and 8% patients. Conclusions This systematic review illustrates management of maternal and congenital CMV during pregnancy in published and non-published literature, in absence of international consensus. Systematic review registration PROSPERO CRD42019124342

Viral Cutaneous Infections in Swimmers: A Preliminary Study

Molluscum contagiosum (MC) and warts are common viral infections of the skin. Data regarding the prevalence of MC and verruca in swimmers are very poor and lacking in the literature. The purpose of this study was to determine the incidence of Molluscum Contagiosum (MC) and warts cases among young competitive swimmers participating in Greek swimming clubs. Of 244 swimmers enrolled in this study, 12.3% reported MC and 43% warts, during their swimming career, diagnosed and treated by dermatologists. There was no difference between sexes for MC but diagnoses of warts were higher in females. Axillae and trunk were the most common sites of primary infection for MC but warts mainly appeared on the soles. The incidence of MC and warts in swimmers who use outdoor facilities was higher. In our study, the incidence of warts and MC in Greek swimmers is considered high. Moist walking surfaces, placing towels on locker room benches, and sharing equipment are behaviors that cause infections. An early diagnosis of warts and MC lesions must be implemented in every swimmer through dermatological examination. Taking proper measures for reducing the risk of warts and MC transmission in Greek swimmers is mandatory.