Trond Rasmussen

Longitudinal observation of parechovirus in stool samples from Norwegian infants

Parechoviruses are assumed to be common infectious agents, but their epidemiologic and pathogenic properties are not well known. The aim of the present study was to assess the prevalence and molecular epidemiology of Parechovirus in Norwegian infants, as well as to investigate whether the presence of virus correlated with symptoms of infection. A group of 102 infants was longitudinally followed: 51 infants with a high genetic risk for type 1 diabetes (aged 3–35 months), and 51 children without this genotype (aged 3–12). Stool samples were obtained each month, and symptoms of infection were recorded regularly on questionnaires. Human parechovirus was detected in 11.3% of 1,941 samples examined by real‐time RT‐PCR. There was a distinct seasonality, peaking from September to December. By 12 months of age, 43% of the infants had had at least one infection, while 86% of the infants had encountered the virus by the end of the second year. Based on the VP1 sequence, human parechovirus 1 was the most prevalent type (76%), followed by human parechovirus 3 (13%), human parechovirus 6 (9%), an unclassified human parechovirus (1%), and human parechovirus 2 (1%). Ljungan virus, a murine parechovirus, was examined with a separate real‐time RT‐PCR, but no virus was detected. There was no significant association between infections and the following symptoms: coughing, sneezing, fever, diarrhea or vomiting. In conclusion, human parechovirus infects frequently infants at an early age without causing disease. J. Med. Virol. 80:1835–1842, 2008.

Maternal BMI before pregnancy, maternal weight gain during pregnancy, and risk of persistent positivity for multiple diabetes-associated autoantibodies in children with the high-risk HLA genotype: the MIDIA study.

OBJECTIVE To assess whether maternal BMI before pregnancy and weight gain during pregnancy predicted the risk of islet autoimmunity in genetically susceptible children. RESEARCH DESIGN AND METHODS Of 46,939 newborns screened for the high-risk HLA genotype DR4-DQ8/DR3-DQ2, 1,003 were positive and 885 were followed with serial blood samples tested for autoantibodies to insulin, GAD, and insulinoma-associated protein 2 (IA2). The end point was defined as repeated positivity for two or three autoantibodies or the onset of type 1 diabetes (islet autoimmunity). RESULTS Thirty-six children developed islet autoimmunity, of whom 10 developed type 1 diabetes. Both maternal BMI ≥30 kg/m2 before pregnancy and maternal weight gain ≥15 kg predicted the increased risk of islet autoimmunity (hazard ratio [HR] 2.5, P = 0.023, and HR 2.5, P = 0.015, respectively), independent of maternal diabetes. CONCLUSIONS Maternal weight may predict risk of islet autoimmunity in offspring with a high genetic susceptibility for type 1 diabetes.

Human Enterovirus RNA in Monthly Fecal Samples and Islet Autoimmunity in Norwegian Children With High Genetic Risk for Type 1 Diabetes The MIDIA study

OBJECTIVE To test whether the frequency of human enterovirus RNA in fecal samples collected monthly from early infancy was associated with development of multiple islet autoantibodies in children with the highest risk HLA genotype. RESEARCH DESIGN AND METHODS Individuals carrying the HLA DRB1*0401-DQA1*03-DQB1*0302/DRB1*03-DQA1*05-DQB1*02 genotype were identified at birth and followed with monthly stool samples from age 3 to 35 months. Blood samples taken at age 3, 6, 9, and 12 months and then annually were tested for autoantibodies to insulin, GAD 65 and IA-2. Among 911 children, 27 developed positivity for two or more islet autoantibodies in two or more consecutive samples (case subjects). Two control subjects per case subject were matched by follow-up time, date of birth, and county of residence. Stool samples were analyzed for enterovirus with a semiquantitative real-time RT-PCR. RESULTS The frequency of human enterovirus RNA in stool samples from case subjects before seroconversion (43 of 339, 12.7%) did not differ from the frequency in control subjects (94 of 692, 13.6%) (P = 0.97). Results remained essentially unchanged after adjustment for potential confounders, restriction to various time windows before seroconversion, or infections in the 1st year of life or after inclusion of samples collected after seroconversion. There was no difference in the average quantity of enterovirus RNA or in the frequency of repeatedly positive samples. The estimated relative risk for islet autoimmunity per enterovirus RNA–positive sample during follow-up (nested case-control analysis) was 1.12 (95% CI 0.66–1.91). CONCLUSIONS There was no support for the hypothesis that fecal shedding of enteroviral RNA is a major predictor of advanced islet autoimmunity.

Infant Feeding in Relation to Islet Autoimmunity and Type 1 Diabetes in Genetically Susceptible Children: The MIDIA Study

OBJECTIVE We aimed to study the association of breast-feeding duration and age at the introduction of solid foods with the risk of islet autoimmunity and type 1 diabetes in genetically susceptible children. RESEARCH DESIGN AND METHODS Newborns were recruited from the Norwegian general population during 2001–2007. After genetic screening of nearly 50,000 newborns, 908 children with the high-risk HLA genotype were followed up with blood samples and questionnaires at age 3, 6, 9, and 12 months and then annually. Complete infant diet data were available for 726 children. RESULTS Any breast-feeding for 12 months or longer predicted a decreased risk of developing type 1 diabetes compared with any breast-feeding for less than 12 months before and after adjusting for having a first-degree relative with type 1 diabetes, vitamin D supplementation, maternal education, sex, and delivery type (hazard ratio 0.37 [95% CI 0.15–0.93]). Any breast-feeding for 12 months or longer was not associated with islet autoimmunity but predicted a lower risk of progression from islet autoimmunity to type 1 diabetes (hazard ratio 0.35 [95% CI 0.13–0.94]). Duration of full breast-feeding was not significantly associated with the risk of islet autoimmunity or type 1 diabetes nor was age at introduction of solid foods or breast-feeding at the time of introduction of any solid foods. CONCLUSIONS These results suggest that breast-feeding for 12 months or longer predict a lower risk of progression from islet autoimmunity to type 1 diabetes among genetically predisposed children.

Enterovirus RNA in Peripheral Blood May Be Associated with the Variants of rs1990760, a Common Type 1 Diabetes Associated Polymorphism in IFIH1

Objective Polymorphisms in the IFIH1 (common rs1990760 and four rare rs35667974, rs35337543, rs35744605, rs35732034) have been convincingly associated with type 1 diabetes. The encoded protein (interferon-induced helicase C domain-containing protein 1) senses double-stranded RNA during replication of Picornavirales, including Enterovirus, a genus suspected in the etiology of type 1 diabetes. We therefore investigated whether the polymorphisms are associated with differences in the frequency of enterovirus RNA in blood. Research Design and Methods The study included 1001 blood samples, each from a child participating in the Norwegian ‘Environmental Triggers of Type 1 Diabetes: the MIDIA study’. The enterovirus RNA was tested using qualitative semi-nested real-time reverse transcriptase PCR on RNA extracted from frozen cell packs after removal of plasma. Stool samples previously analyzed for enterovirus RNA were available in 417 children. Results The genotypes of IFIH1 rs1990760 were associated with different frequencies of enterovirus RNA in blood (7.0%, 14.4% and 9.5% bloods were enterovirus positive among children carrying the Ala/Ala, Ala/Thr and Thr/Thr genotypes, respectively, p = 0.012). This association remained essentially unchanged after adjustment for age and calendar year. The presence of enterovirus in the concomitantly sampled stool further increased the likelihood of enterovirus RNA in blood (odds ratio 2.40, CI 95% 1.13–4.70), but did not affect the association with IFIH1 rs1990760. The rare polymorphisms (individually, or pooled) were not significantly associated with enterovirus RNA in blood. Conclusions The common IFIH1 SNP may modify the frequency of enterovirus RNA in blood of healthy children. This effect can help explain the association of IFIH1 with type 1 diabetes.

Longitudinal study of parechovirus infection in infancy and risk of repeated positivity for multiple islet autoantibodies: the MIDIA study.

Tapia G, Cinek O, Rasmussen T, Grinde B, Stene LC, Rønningen KS. Longitudinal study of parechovirus infection in infancy and risk of repeated positivity for multiple islet autoantibodies: the MIDIA study.

No Ljungan Virus RNA in Stool Samples From the Norwegian Environmental Triggers of Type 1 Diabetes (MIDIA) Cohort Study

OBJECTIVE Ljungan virus (LjV) has been proposed as a potential environmental factor for type 1 diabetes. The objective was to test for any association of LjV with type 1 diabetes. RESEARCH DESIGN AND METHODS A nested case-control design was used to test for any association between the development of pre-diabetic autoimmunity and presence of LjV in stool samples (n = 3,803) in the Norwegian Environmental Triggers of Type 1 Diabetes (MIDIA) study. The children followed were 27 infants who developed pre-diabetic autoimmunity during or shortly after the sampling period, 54 matched control subjects, and 94 other children. RESULTS No LjV RNA was detected. CONCLUSIONS The results indicate that LjV is rare in young children. LjV does not seem to be involved in the development of human type 1 diabetes.

Self‐reported lower respiratory tract infections and development of islet autoimmunity in children with the type 1 diabetes high‐risk HLA genotype: the MIDIA study

To test whether self‐reported lower respiratory tract infections in early infancy predicted risk for islet autoimmunity in genetically predisposed children.

Predictors of sub-clinical enterovirus infections in infants: a prospective cohort study

BACKGROUND Enterovirus infections are common, although most often sub-clinical. The present purpose was to assess the impact of breastfeeding and other factors on enterovirus infections in infancy. METHODS A prospective observational study was carried out on a population-based cohort of 639 Norwegian infants aged 3-12 months. The outcome was enterovirus RNA measured in monthly stool samples. Data on underlying determinants, such as dietary feeding and household factors, were reported in parental questionnaires. Multivariable logistic regression was performed to allow for common confounders. Statistical analyses were performed by GLLAMM using Stata 9.2, which corrects for subject-specific random effects. RESULTS The prevalence of enterovirus in stools was 11.1% (475/4279). Risk of enterovirus infection decreased with increasing number of daily breastfeeds; the effect was most pronounced at the age of 3 months [odds ratio (OR), 0.85; 95% confidence interval (CI) 0.8-0.9, P < 0.001], gradually declining thereafter, reaching no effect at 11 months. Increased risk was associated with having one or more sibling(s) (OR 1.89; 95% CI 1.2-3.0), particularly if they attended daycare (OR 2.46; 95% CI 1.4-4.2), and with increasing exposure to other children (OR 1.04; 95% CI 1.0-1.1). There was a tendency towards higher prevalence of infection when a households drinking water came from a well, and a protective effect of owning a dog or cat. CONCLUSIONS Several factors may modify the risk for enterovirus infections in the first year of life. This study supports the protective effect of breastfeeding. The protection decreased with age and increased with dose of ingested milk.

Enterobius vermicularis and risk factors in healthy Norwegian children.

Background: The prevalence of Enterobius vermicularis in neighboring countries of Norway show large variation. The goal of this study was to investigate the prevalence among Norwegian children and possible risk factors. Methods: The children were participants in “Environmental Triggers of Type 1 Diabetes: the MIDIA study.” The study involved 2 groups with different genetic risks of type 1 diabetes: A high-risk group carries the Human Leukocyte Antigen genotype conferring the highest risk for type 1 diabetes and a nonhigh-risk group consisting of children without this genotype. Scotch tape samples were collected on 3 consecutive days and examined by light microscopy. Results: A total of 18% (72/395) of children were positive for E. vermicularis. The highest prevalence (34%) was in children 6–11 years of age. Only 2 children were prior known positives. Increased number of siblings was linked to more infections, and there were fewer infections in the children with the high-risk genotype. Conclusion: E. vermicularis is a common parasite in Norwegian children. The likelihood of E. vermicularis infection depends on family size and prevalence increases with age. The reduced number of infections in the children carrying the high-risk genotype for type 1 diabetes is intriguing and should be investigated further.