COVID-19 cases in spectators returning to Finland from UEFA Euro 2020 matches in Saint Petersburg.

UEFA Euro 2020 tournament was scheduled to take place in 2020, but due to the coronavirus disease 2019 (COVID-19) pandemic was rescheduled to start on 11 June 2021. Approximately 4500 Finnish spectators participated, travelling between Finland and Russia during the period of 16 to 30 June to attend matches played on 16 and 21 June. A total of 419 persons returning from Russia or with a connection to Russia were detected positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Of the 321 sequenced samples 303 turned out to be of the Delta variant. None of these cases was hospitalised. In the following weeks findings of the Delta variant increased rapidly. Thus, EURO 2020 travel-related imported cases likely facilitated this rapid surge of Delta variant, but this impact would likely have been seen with the typical increase in the number of travellers entering Finland later in the summer.

Serological survey in the Finnish human population implies human-to-human transmission of Ljungan virus or antigenically related viruses.

Ljungan virus (LV) is a picornavirus related to human parechoviruses (HPeV). The virus has been found in bank voles (Myodes glareolus) and several other rodent species, and suggested to have zoonotic potential. Thus far, seroepidemiological data on LV infections in humans are scarce. In this study, we aimed to characterize the demographic and geographical distribution of LV-reactive antibodies in Finland, and to investigate its occurrence in patients suspected of having a rodent-borne disease, nephropathia epidemica (NE) caused by Puumala hantavirus (PUUV). Using an immunofluorescence assay (LV strain 145SLG), we screened human sera (n = 1378) and found LV-reactive antibodies in 36% of samples. The probability of possessing LV-reactive antibodies peaked at age of 14 years, suggesting that most infections occur in childhood. The prevalence of LV-reactive antibodies was significantly higher in the urbanized area surrounding Helsinki than in more rural Central Finland. These findings are uncharacteristic of a rodent-borne pathogen, and therefore we consider human-to-human transmission of one or several Ljungan-like viruses as a likely cause for most of the observed antibody responses.

Outbreak of Influenza A(H1N1) in a Kidney Transplant Unit-Protective Effect of Vaccination.

Seasonal influenza vaccination is recommended for patients with end-stage renal disease (ESRD), despite suggested inferior efficacy among these patients. We characterize an outbreak of influenza A(H1N1) in a kidney transplant unit. Altogether 23 patients were treated on the ward for postoperative care after kidney transplantation during the outbreak. After the first positive case, all patients were tested with nasopharyngeal swab tests and 7 patients were diagnosed with influenza A(H1N1). Altogether 17/23 patients had received adequate seasonal influenza vaccination, of whom 2/17 tested positive for influenza (one asymptomatic, one with mild cough). Five of six unvaccinated patients were diagnosed with influenza A(H1N1); 3/5 suffered from severe respiratory failure and were treated with ventilator support in the ICU, but all died due to acute respiratory distress syndrome, whereas 2/5 suffered from mild viral pneumonitis and recovered fully. The risk of influenza infection and mortality was significantly increased in unvaccinated patients (odds ratio 37.5 [95% CI 2.7-507.5, p = 0.01] and 6.7 [95% CI 2.3-18.9, p = 0.003], respectively). Influenza A(H1N1) had a high mortality in our cohort of nonvaccinated immunosuppressed patients early after kidney transplantation. None of the vaccinated patients developed serious disease, supporting the role of vaccination also for ESRD patients.

Low incidence of severe bacterial infections in hospitalised patients with COVID-19: A population-based registry study.

BACKGROUND: Bacterial infections complicating COVID-19 are rare but present a challenging clinical entity. The aim of this study was to evaluate the incidence, aetiology and outcome of severe laboratory-verified bacterial infections in hospitalised patients with COVID-19. METHODS: All laboratory-confirmed patients with COVID-19 admitted to specialised healthcare hospitals in the Capital Province of Finland during the first wave of COVID-19 between 27 February and 21 June 2020 were retrospectively studied. We gathered the blood and respiratory tract culture reports of these patients and analysed their association with 90-day case-fatality using multivariable regression analysis. RESULTS: A severe bacterial infection was diagnosed in 40/585 (6.8%) patients with COVID-19. The range of bacteria was diverse, and the most common bacterial findings in respiratory samples were gram-negative, and in blood cultures gram-positive bacteria. Patients with severe bacterial infection had longer hospital stay (mean 31; SD 20 days) compared to patients without (mean 9; SD 9 days; p < 0.001). Case-fatality was higher with bacterial infection (15% vs 11%), but the difference was not statistically significant (OR 1.38 CI95% 0.56-3.41). CONCLUSIONS: Severe bacterial infection complicating COVID-19 was a rare occurrence in our cohort. Our results are in line with the current understanding that antibiotic treatment for hospitalised COVID-19 patients should only be reserved for situations where a bacterial infection is strongly suspected. The ever-evolving landscape of the pandemic and recent advances in immunomodulatory treatment of COVID-19 patients underline the need for continuous vigilance concerning the possibility and frequency of nosocomial bacterial infections.

Association of celiac disease genes with inflammatory bowel disease in Finnish and Swedish patients.

Some genetic loci may affect susceptibility to multiple immune system-related diseases. In the current study, we investigated whether the known susceptibility loci for celiac disease (CelD) also associate with Crohn's disease (CD) and/or ulcerative colitis (UC), the two main forms of inflammatory bowel disease (IBD), in Finnish patients. A total of 45 genetic markers were genotyped in a Finnish data set comprising 699 IBD patients and 2482 controls. Single-marker association with IBD and its subphenotypes was tested. A meta-analysis with a Swedish UC data set was also performed. A total of 12 single-nucleotide polymorphisms associated with CD and/or UC (P<0.05). In the subphenotype analysis, rs6974491-ELMO1 (P=0.0002, odds ratio (OR): 2.20) and rs2298428-UBE2L3 (P=5.44 × 10(-5), OR: 2.59) associated with pediatric UC and CD, respectively. In the meta-analysis, rs4819388-ICOSLG (P=0.00042, OR: 0.79) associated with UC. In the subphenotype meta-analysis, rs1738074-TAGAP (P=7.40 × 10(-5), OR: 0.61), rs6974491-ELMO1 (P=0.00052, OR: 1.73) and rs4819388-ICOSLG (P=0.00019, OR: 0.75) associated with familial UC, pediatric UC and sporadic UC, respectively. Multiple CelD risk loci also confer susceptibility for CD and/or UC in the Finnish and Swedish populations. Certain genetic risk variants may furthermore predispose an individual for developing a particular disease phenotype.

Association study of FUT2 (rs601338) with celiac disease and inflammatory bowel disease in the Finnish population.

Homozygosity for a nonsense mutation in the fucosyltransferase 2 (FUT2) gene (rs601338G>A) leads to the absence of ABH blood groups (FUT2 non-secretor status) in body fluids. As the secretor status has been shown to be a major determinant for the gut microbial spectrum, assumed to be important in the gut immune homeostasis, we studied the association of rs601338-FUT2 with celiac disease (CelD) and inflammatory bowel disease (IBD) in the Finnish population. Rs601338 was genotyped in CelD (n = 909), dermatitis herpetiformis (DH) (n = 116), ulcerative colitis (UC) (n = 496) and Crohn's disease (CD) (n = 280) patients and healthy controls (n = 2738). CelD showed significant genotypic [P = 0.0074, odds ratio (OR): 1.28] and recessive (P = 0.015, OR: 1.28) association with the rs601338-AA genotype. This was also found in the combined CelD+DH dataset (genotype association: P = 0.0060, OR: 1.28; recessive association: P < 0.011, OR: 1.28). The A allele of rs601338 showed nominal association with dominant protection from UC (P = 0.044, OR: 0.82) and UC+CD (P = 0.035, OR: 0.84). The frequency of non-secretors (rs601338-GG) in controls, CelD, DH, UC and CD datasets was 14.7%, 18%, 18.1%, 14.3% and 16.1%, respectively. No association was evident in the DH or CD datasets alone. In conclusion, FUT2 non-secretor status is associated with CelD susceptibility and FUT2 secretor status may also play a role in IBD in the Finnish population.

Multiple norovirus outbreaks linked to imported frozen raspberries.

In 2009, the number of foodborne norovirus outbreaks in Finland seemed markedly high, and many outbreaks seemed to be linked to imported frozen raspberries. We reviewed the data regarding all notified foodborne outbreaks in 2009 in Finland in order to assess the magnitude of the problem and to summarize the information on raspberry-linked outbreaks. Between March and August, 13 norovirus outbreaks affecting about 900 people could be linked to imported frozen raspberries. Two raspberry samples corresponding to two batches of raspberries were positive for norovirus. These two batches proved to have been the likely source in six of the 13 outbreaks. Analytical studies had not been conducted for six outbreaks, and virological test results were inconclusive in two. However, combining epidemiological and microbiological methods often enabled finding the source, as exemplified in investigation of a large school outbreak. To ensure prompt control measures in similar situations in the future, both aspects of outbreak investigations should be strengthened.

Increased incidence of Mycoplasma pneumoniae infection in Finland, 2010-2011.

The number of cases of Mycoplasma pneumoniae infection detected by laboratory-based surveillance increased in Finland in late 2010. During 2011, the number of cases was four times higher than during the previous epidemic in 2005. The 2011 epidemic affected mostly school-age children. The increased number of cases was probably not due to changes in laboratory procedures, but public interest may have had an effect, since the number of Google queries followed closely the epidemic curve.

Detection of SARS-CoV-2 nucleocapsid antigen from serum can aid in timing of COVID-19 infection.

SARS-CoV-2 RNA can be detected in respiratory samples for weeks after onset of COVID-19 disease. Therefore, one of the diagnostic challenges of PCR positive cases is differentiating between acute COVID-19 disease and convalescent phase. The presence of SARS-CoV-2 nucleocapsid antigen in serum and plasma samples of COVID-19 patients has been demonstrated previously. Our study aimed to characterize the analytical specificity and sensitivity of an enzyme-linked immunosorbent assay (Salocor SARS-CoV-2 Antigen Quantitative Assay Kit© (Salofa Ltd, Salo, Finland)) for the detection of SARS-CoV-2 nucleocapsid antigen in serum, and to characterize the kinetics of antigenemia. The evaluation material included a negative serum panel of 155 samples, and 126 serum samples from patients with PCR-confirmed COVID-19. The specificity of the Salocor SARS-CoV-2 serum nucleocapsid antigen test was 98.0 %. In comparison with simultaneous positive PCR from upper respiratory tract (URT) specimens, the test sensitivity was 91.7 %. In a serum panel in which the earliest serum sample was collected two days before the collection of positive URT specimen, and the latest 48 days after (median 1 day post URT sample collection), the serum N antigen test sensitivity was 95.6 % within 14 days post onset of symptoms. The antigenemia resolved approximately two weeks after the onset of disease and diagnostic PCR. The combination of simultaneous SARS-CoV-2 antigen and antibody testing appeared to provide useful information for timing of COVID-19. Our results suggest that SARS-CoV-2 N-antigenemia may be used as a diagnostic marker in acute COVID-19.

Rotavirus genotypes co-circulating in Europe between 2006 and 2009 as determined by EuroRotaNet, a pan-European collaborative strain surveillance network.

EuroRotaNet, a laboratory network, was established in order to determine the diversity of co-circulating rotavirus strains in Europe over three or more rotavirus seasons from 2006/2007 and currently includes 16 countries. This report highlights the tremendous diversity of rotavirus strains co-circulating in the European population during three years of surveillance since 2006/2007 and points to the possible origins of these strains including genetic reassortment and interspecies transmission. Furthermore, the ability of the network to identify strains circulating with an incidence of ≥1% allowed the identification of possible emerging strains such as G8 and G12 since the beginning of the study; analysis of recent data indicates their increased incidence. The introduction of universal rotavirus vaccination in at least two of the participating countries, and partial vaccine coverage in some others may provide data on diversity driven by vaccine introduction and possible strain replacement in Europe.

Evaluation of three rapid lateral flow antigen detection tests for the diagnosis of SARS-CoV-2 infection.

INTRODUCTION: The COVID-19 pandemic has led to high demand of diagnostic tools. Rapid antigen detection tests have been developed and many have received regulatory acceptance such as CE IVD or FDA markings. Their performance needs to be carefully assessed. MATERIALS AND METHODS: 158 positive and 40 negative retrospective samples collected in saline and analyzed by a laboratory-developed RT-PCR test were used to evaluate Sofia (Quidel), Standard Q (SD Biosensor), and Panbio™ (Abbott) rapid antigen detection tests (RADTs). A subset of the specimens was subjected to virus culture. RESULTS: The specificity of all RADTs was 100 % and the sensitivity and percent agreement was 80 % and 85 % for Sofia, 81 % and 85 % for Standard Q, and 83 % and 86 % for Panbio™, respectively. All three RADTs evaluated in this study reached a more than 90 % sensitivity for samples with a high viral load as estimated from the low Ct (Cycle threshold) values in the reference RT-PCR. Virus culture was successful in 80 % of specimens with a Ct value <25. CONCLUSIONS: As expected, the RADTs were less sensitive than RT-PCR. However, they benefit from the speed and ease of testing, and lower price as compared to RT-PCR. Repeated testing in appropriate settings may improve the overall performance.

Laboratory-based surveillance of COVID-19 in the Greater Helsinki area, Finland, February-June 2020.

OBJECTIVES: The aim was to characterise age- and sex-specific severe acute respiratory syndrome coronavirus disease-2 (SARS-CoV-2) RT-PCR sampling frequency and positivity rate in Greater Helsinki area in Finland during February-June 2020. We also describe the laboratory capacity building for these diagnostics. METHODS: Laboratory registry data for altogether 80,791 specimens from 70,517 individuals was analysed. The data included the date of sampling, sex, age and the SARS-CoV-2 RT-PCR test result on specimens collected between 1 February and 15 June 2020. RESULTS: Altogether, 4057/80,791 (5.0%) of the specimens were positive and 3915/70,517 (5.6%) of the individuals were found positive. In all, 37% of specimens were from male and 67% from female subjects. While the number of positive cases was similar in male and female subjects, the positivity rate was significantly higher in male subjects: 7.5% of male and 4.4% of female subjects tested positive. The highest incidence/100,000 was observed in those aged ≥80 years. The proportion of young adults in positive cases increased in late May 2020. Large dips in testing frequency were observed during every weekend and also during public holidays. CONCLUSIONS: Our data suggest that men pursue SARS-CoV-2 testing less frequently than women. Consequently, a subset of coronavirus disease-2019 infections in men may have gone undetected. People sought testing less frequently on weekends and public holidays, and this may also lead to missing of positive cases. The proportion of young adults in positive cases increased towards the end of the study period, which may suggest their returning back to social behaviour with an increased risk of infection.

Exposure to dogs is associated with a decreased tumour necrosis factor-α-producing capacity in early life.

BACKGROUND: It appears that contacts with furred animals early in life and already during gestation contribute to the immunological development in humans, but the mechanisms and relevant exposures are not clear. OBJECTIVE: To investigate whether exposure to animals during pregnancy and the first year of life is associated with early immune development, determined as stimulated cytokine responses of children at birth and at age 1 year. METHODS: Cord blood (n=228) and peripheral venous blood (n=200) samples 1 year after birth were collected and stimulated with Gram-positive superantigen Staphylococcal enterotoxin B, Gram-negative bacterial lipopolysaccharide (LPS) and the combination of mitogenic phorbol 12-myristate 13-acetate and calcium ionophore ionomycin (P/I) for 24 and 48 h. TNF-α, IFN-γ, IL-5, IL-8 and IL-10 responses were measured by ELISA. For each cytokine, the time-point with the highest response was chosen for further analyses. Animal contacts were surveyed by self-administered questionnaires. RESULTS: Dog ownership was associated with decreased TNF-α-producing capacity at birth (P/I: median 841 vs. 881 pg/10(6) WBC, P=0.05) and 1 year after birth (P/I: 1290 vs. 1530, P=0.01; LPS: 425 vs. 508, P=0.02). Associations remained significant after adjustment for potential confounders. Cat ownership was not associated with cytokine production. CONCLUSION: Having a dog in the household in infancy and already during pregnancy may be associated with reduced innate immune responses in early childhood. The observed attenuation of cytokine production may help in preventing exaggerated immune responses against harmless antigens later in life. Thus, intensive exposure to dogs in early life may be beneficial during normal immune maturation.

Production of interleukin-5, -10 and interferon-γ in cord blood is strongly associated with the season of birth.

BACKGROUND: The effect of labour and different labour-related factors on the cord blood (CB) cell cytokine production is still relatively unknown. OBJECTIVE: To study the relationships between the production of IL-5, IL-10 and IFN-γ in CB samples and maternal, early neonatal and birth-related factors. METHODS: Whole-blood samples were collected after birth (n=423) and they were stimulated for 24 and 48 h with a combination of phorbol ester and ionomycin. Production of IL-5, IL-10 and IFN-γ was determined using ELISA. Maternal, early neonatal and birth-related variables were recorded prospectively during pregnancy, and during and after delivery. RESULTS: After multivariable adjustment for confounders, the strongest predictor of IL-5, IL-10 and IFN-γ production in CB cell samples was the season of birth. Children born in the spring had significantly lower cytokine responses compared with those born in the fall. IL-5 production was inversely associated with female gender of the child and maternal smoking. If corrections for white blood cell (WBC) counts were not performed, IL-5 production was also significantly associated with the mode of delivery. Respectively, the production of IL-10 and IFN-γ was inversely associated with prostaglandin induction before birth. CONCLUSION: Environmental exposure to pollen and ultraviolet irradiation during gestation may have an effect on the cytokine profile of the offspring in CB because children born in the spring or winter showed the lowest IL-5, IL-10 and IFN-γ responses. The production of IL-10 and IFN-γ was also inversely associated with prostaglandin labour induction before birth. Other labour-related factors were not significantly associated with production of IL-5, IL-10 and IFN-γ after WBC count correction.

Rotavirus surveillance in europe, 2005-2008: web-enabled reporting and real-time analysis of genotyping and epidemiological data.

BACKGROUND: The first European rotavirus surveillance network, EuroRotaNet, comprising 16 laboratories in 15 European countries, has been established. METHODS: Fecal samples from gastroenteritis cases positive for group A rotavirus antigen were collected from multiple European countries from 2005 to mid-2008 and were subjected to G and P genotyping. Epidemiological data collected included age, sex, geographical location, setting, dates of onset and sample collection, and clinical symptoms. RESULTS: A total of 8879 rotavirus-positive samples were characterized: 2129 cases were from the 2005-2006 season, 4030 from the 2006-2007 season, and 2720 from the ongoing 2007-2008 season. A total of 30 different G and P type combinations of strains circulated in the region from 2005 through 2008. Of these strains, 90% had genotypes commonly associated with human infections-G1P[8], G2P[4], G3P[8], G4P[8], and G9P[8]-and 1.37% represented potential zoonotic introductions. G1P[8] remained the most prevalent genotype in Europe as a whole, but the incidence of infection with G1P[8] rotavirus strains was <50% overall, and all 3 seasons were characterized by a significant diversity of cocirculating strains. The peak incidence of rotavirus infection occurred from January through May, and 81% of case patients were aged <2.5 years. Conclusions. Data gathered through EuroRotaNet will provide valuable background information on the rotavirus strain diversity in Europe before the introduction of rotavirus vaccines, and the network will provide a robust method for surveillance during vaccine implementation.

Performance of six SARS-CoV-2 immunoassays in comparison with microneutralisation.

There is an urgent need for reliable high-throughput serological assays for the management of the ongoing COVID-19 pandemic. Preferably, the performance of serological tests for a novel virus should be determined with clinical specimens against a gold standard, i.e. virus neutralisation. We compared the performance of six commercial immunoassays for the detection of SARS-COV-2 IgG, IgA and IgM antibodies, including four automated assays [Abbott SARS-COV-2 IgG (CE marked), Diasorin Liaison® SARS-COV-2 S1/S2 IgG (research use only, RUO), and Euroimmun SARS-COV-2 IgG and IgA (CE marked)], and two rapid lateral flow (immunocromatographic) tests [Acro Biotech 2019-nCoV IgG/IgM (CE marked) and Xiamen Biotime Biotechnology SARS-COV-2 IgG/IgM (CE marked)] with a microneutralisation test (MNT). Two specimen panels from serum samples sent to Helsinki University Hospital Laboratory (HUSLAB) were compiled: the patient panel (N=70) included sera from PCR confirmed COVID-19 patients, and the negative panel (N=81) included sera sent for screening of autoimmune diseases and respiratory virus antibodies in 2018 and 2019. The MNT was carried out for all COVID-19 samples (70 serum samples, 62 individuals) and for 53 samples from the negative panel. Forty-one out of 62 COVID-19 patients showed neutralising antibodies.The specificity and sensitivity values of the commercial tests against MNT, respectively, were as follows: 95.1 %/80.5 % (Abbott Architect SARS-CoV-2 IgG), 94.9 %/43.8 % (Diasorin Liaison SARS-CoV-2 IgG; RUO), 68.3 %/87.8 % (Euroimmun SARS-CoV-2 IgA), 86.6 %/70.7 % (Euroimmun SARS-CoV-2 IgG), 74.4 %/56.1 % (Acro 2019-nCoV IgG), 69.5 %/46.3 % (Acro 2019-nCoV IgM), 97.5 %/71.9 % (Xiamen Biotime SARS-CoV-2 IgG), and 88.8 %/81.3 % (Xiamen Biotime SARS-CoV-2 IgM). This study shows variable performance values. Laboratories should carefully consider their testing process, such as a two-tier approach, in order to optimize the overall performance of SARS- CoV-2 serodiagnostics.

Prolonged norovirus outbreak in a Finnish tertiary care hospital caused by GII.4-2006b subvariants.

Norovirus outbreaks are difficult to control in hospitals. Cohorting and contact isolation, disinfective surface cleaning and hand hygiene are key elements in outbreak control. A new norovirus variant, GII.4.-2006b, spreading across many continents, caused an exceptionally long epidemic period in Finland, from November 2006 to June 2007. Here, we describe the clinical and molecular characteristics of a norovirus outbreak in a large tertiary care hospital in Finland. Altogether 240 (18%) patients and 205 (19%) healthcare workers fell ill in the 504 bedded main building of Helsinki University Central Hospital during December 2006 to May 2007. The epidemic curve had three peaks in January, February and April, and different wards were affected each time. During the outbreak, 502 patient stool specimens were tested for norovirus RNA, 181 (36%) of which were positive. Molecular analysis of 48 positive specimens revealed three main subvariants of GII.4.-2006b circulating temporally within distinct wards. Of all microbiologically confirmed cases, 121 (67%) were nosocomial and nine (5%) died within 30 days of diagnosis. Molecular analysis suggested that the three main GII.4-2006b subvariants entered the hospital with gastroenteritis patients, and the nosocomial spread within wards coincided with the epidemic peaks. Active control measures, including temporary closure of the wards, ultimately confined the single-ward outbreaks. A prolonged outbreak in the community was probably the source for the prolonged outbreak period in the hospital.

Detection of human norovirus from frozen raspberries in a cluster of gastroenteritis outbreaks.

We describe a cluster of norovirus outbreaks affecting about 200 people in Southern Finland in September and October 2009. All outbreaks occurred after consumption of imported raspberries from the same batch intended for the catering sector. Human norovirus genotype GI.4 was found in frozen raspberries. The berries were served in toppings of cakes in separate catering settings or mixed in curd cheese as a snack for children in a daycare center. The relative risk for consumption of the berry dish was 3.0 (p

Exposure to environmental bacteria may have differing effects on tumour necrosis factor-alpha and interleukin-6-producing capacity in infancy.

BACKGROUND: Our previous study showed an association between increased concentration of endotoxin in house dust and elevated IFN-gamma responses in neonates. The impact of other microbial agents on immune responses in infancy is poorly known. OBJECTIVE: To examine whether stimulated cytokine responses of mothers and their children are associated with concentrations of other microbial markers in addition to endotoxin in house dust samples. METHODS: Mitogen-stimulated production of IFN-gamma, IL-4, IL-6 and TNF-alpha was measured in cord blood and in peripheral blood of mothers (n=29) and their children (n=29) 3 months after birth. Gas chromatography mass spectrometric analysis was applied to measure the concentrations of ergosterol (marker of fungal biomass), muramic acid (indicating the presence of Gram-positive bacteria) and 3-hydroxy fatty acids (C(10:0)-C(14:0), indicating the presence of Gram-negative bacteria) in house dust. Endotoxin was determined with Limulus assay. RESULTS: Significant mother-to-child correlations were observed in stimulated production of TNF-alpha and IL-6 3 months after birth. 3-hydroxy fatty acid (C(10:0)-C(14:0)) levels in bed dust were inversely associated with the production of TNF-alpha and IL-6 in blood samples of mothers and their 3-month-old children. High concentrations of muramic acid in floor dust were related to increased production of TNF-alpha and IL-6 at the age of 3 months. In contrast to endotoxin, none of the other microbial markers were significantly associated with enhanced IFN-gamma-producing capacity from birth to 3 months. CONCLUSIONS: Exposure to Gram-negative bacteria and their components may be associated with down-regulated immune responses in early infancy, indicated as an impaired production of pro-inflammatory cytokines following mitogen stimulation. Gram-positive bacteria and their constituents seem to have opposite effects. Of the measured markers, exposure to bioactive endotoxin appears to have the strongest impact on T-helper type 1 responses.

Genetic evidence for panmixia in a colony-breeding crater lake cichlid fish.

Fine-scaled genetic structuring, as seen for example in many lacustrine fish, typically relates to the patterns of migration, habitat use, mating system or other ecological factors. Because the same processes can also affect the propensity of population differentiation and divergence, assessments of species from rapidly speciating clades, or with particularly interesting ecological traits, can be especially insightful. For this study, we assessed the spatial genetic relationships, including the genetic evidence for sex-biased dispersal, in a colony-breeding cichlid fish, Amphilophus astorquii, endemic to Crater Lake Apoyo in Nicaragua, using 11 polymorphic microsatellite loci (n = 123 individuals from three colonies). We found no population structure in A. astorquii either within colonies (no spatial genetic autocorrelation, r ~0), or at the lake-wide level (pairwise population differentiation FST = 0-0.013 and no clustering), and there was no sex-bias (male and female AIc values bounded 0) to this lack of genetic structure. These patterns may be driven by the colony-breeding reproductive behaviour of A. astorquii. The results suggest that strong philopatry or spatial assortative mating are unlikely to explain the rapid speciation processes associated with the history of this species in Lake Apoyo.