Decline of mumps antibodies in type 1 (insulin-dependent) diabetic children and a plateau in the rising incidence of type 1 diabetes after introduction of the mumps-measles-rubella vaccine in Finland. Childhood Diabetes in Finland Study Group

BCG Vaccination and the Risk of Type 1 Diabetes Mellitus: A Systematic Review and Meta-Analysis

(1) Background: Type 1 diabetes mellitus (T1D) is an autoimmune disease characterized by progressive and irreversible autoimmune destruction of pancreatic beta cell islets, resulting in absolute insulin deficiency. To date, several epidemiologic and observational studies have evaluated the possible impact of BCG vaccination on T1D development, but the results are controversial. To elucidate this issue, we aimed to conduct a systematic review and meta-analysis of published cohort studies in this field. (2) Methods: A systematic search was performed for relevant studies published up to 20 September 2022 using Pubmed/Medline, Embase, and Scopus. Cohort studies, containing original information about the association between T1D and BCG vaccination, were included for further analysis. Pooled estimates and 95% confidence intervals (CI) for the risk ratio of T1D in BCG-vaccinated individuals compared to unvaccinated ones were assessed using the fixed effect model. (3) Results: Out of 630 potentially relevant articles, five cohort studies met the inclusion criteria. The total population of all included studies was 864,582. The overall pooled risk ratio of T1D development in BCG vaccinated and unvaccinated individuals was found to be 1.018 (95% CI 0.908-1.141, I²: 0%). (4) Conclusions: Our study revealed no protective or facilitative effect of prior BCG vaccination in T1D development.

Environmental Factors as Diabetic Mediators: A Mechanistic Approach

Despite substantial investment in research and treatment options, diabetes mellitus remains a pressing public health concern with potential epidemic proportions globally. There are reports that by the end of 2040, 642 million people will be suffering from diabetes. Also, according to an estimation, 1.6 million deaths were caused directly by diabetes in 2016. Diabetes is a metabolic disorder characterized by impaired glucose regulation in the body due to the destruction of pancreatic β-cells or insulin resistance. Genetic propensity, unhealthy and imbalanced diet, obesity and increasing urbanization are the common risk factors for diabetes. Besides this, it has been reported that environmental pollutants like organic pesticides, heavy metals, and air pollutants act as strong predisposing factors for diabetes owing to their highly bio-accumulative nature. These pollutants disturb glucose homeostasis either by up-regulating or down-regulating the expression of diabetic marker genes like insulin (INS) and glucokinase (GCK). Unfortunately, the molecular mechanism of the role of pollutants in causing diabetes is not very clear. This mechanistic review provides evidence of different environmental determinants, including persistent organic pollutants (POPs), air pollutants, toxic metals, etc., in inducing diabetes and proposes a framework for the possible mechanisms involved. It also illuminates the current status and future challenges, which will not only broaden our understanding but can also be a reasonable platform for further investigation.

Viruses and Type 1 Diabetes: From Enteroviruses to the Virome

For over a century, viruses have left a long trail of evidence implicating them as frequent suspects in the development of type 1 diabetes. Through vigorous interrogation of viral infections in individuals with islet autoimmunity and type 1 diabetes using serological and molecular virus detection methods, as well as mechanistic studies of virus-infected human pancreatic β-cells, the prime suspects have been narrowed down to predominantly human enteroviruses. Here, we provide a comprehensive overview of evidence supporting the hypothesised role of enteroviruses in the development of islet autoimmunity and type 1 diabetes. We also discuss concerns over the historical focus and investigation bias toward enteroviruses and summarise current unbiased efforts aimed at characterising the complete population of viruses (the “virome”) contributing early in life to the development of islet autoimmunity and type 1 diabetes. Finally, we review the range of vaccine and antiviral drug candidates currently being evaluated in clinical trials for the prevention and potential treatment of type 1 diabetes.

Side Effects of Vaccination: A Consumer's Guide to Cause and Effect

Credit

This lesson is good for 0.2 CE units, with a passing grade of 70%.

Objectives

1. To describe historical examples of adverse events truly and spuriously associated with vaccination. 2. To describe a rational basis for deciding whether adverse events are causally or coincidentally linked to a medication. 3. To demonstrate how to apply this rational basis to a variety of exposure—outcome associations.

Side Effects of Vaccination: A Consumer's Guide to Cause and Effect

Credit

This lesson is good for 0.2 CE units, with a passing grade of 70%.

Objectives

1. To describe historical examples of adverse events truly and spuriously associated with vaccination. 2. To describe a rational basis for deciding whether adverse events are causally or coincidentally linked to a medication. 3. To demonstrate how to apply this rational basis to a variety of exposure—outcome associations.

Seroprotection status of hepatitis B and measles vaccines in children with type 1 diabetes mellitus

BACKGROUND

Type 1 diabetes mellitus (T1DM) is speculated to have an impaired immunological response to vaccines. This paper aimed to investigate the presence of specific antibodies against hepatitis B virus (HBV) and measles in diabetic children who had been immunized according to the standard national calendar of immunization.

METHODS

Two hundred and one diabetic children and 140 healthy controls were prospectively evaluated. Antibodies against hepatitis B (anti-HBs) and measles were detected in all individuals who completed the vaccination schedule. We noted onset of T1DM, duration of the disease, diabetes-related autoantibodies and mean HbA1c levels.

RESULTS

Some 72.6% of diabetics and 82.1% of controls had anti-HBs (+) (p=0.04). We found a reduced efficacy of measles vaccination in anti-HBs (-) diabetic children (p=0.009), even though there was no significant difference between the study and control groups. Onset of the disease was earlier in anti-HBs (-) diabetics than in controls (p=0.038). No difference with respect to other parameters was found.

CONCLUSIONS

Our data showed a reduced seroprotection rate for HBV vaccination in diabetic children and for measles with anti-HBs (-) diabetics. Larger studies should be encouraged to confirm the vaccine efficacy in diabetic children and to elucidate possible pathogenic mechanisms.

Viruses in type 1 diabetes

Environmental factors play an important role in the pathogenesis of type 1 diabetes and can determine if a genetically susceptible individual develops the disease. Increasing evidence suggest that among other exogenous agents certain virus infections can contribute to the beta-cell damaging process. Possible viral etiology of type 1 diabetes has been explored extensively but the final proof for causality is still lacking. Currently, the group of enteroviruses (EVs) is considered as the strongest candidate. These viruses have been found in the pancreas of type 1 diabetic patients, and epidemiological studies have shown more EV infections in diabetic patients than in controls. Prospective studies, such as the Type 1 Diabetes Prediction and Prevention (DIPP) study in Finland, are of fundamental importance in the evaluation viral effects as they can cover all stages of the beta-cell damaging process, including those preceding the initiation of the process. DIPP study has carried out the most comprehensive virological analyses ever done in prospective cohorts. This article summarizes the findings from these analyses and discuss them in the context of the existing other knowledge and the prospects for intervention studies with EV vaccines or antiviral drugs.

Environmental trigger(s) of type 1 diabetes: why so difficult to identify?

Type 1 diabetes (T1D) is one of the most common chronic diseases with childhood onset, and the disease has increased two- to fivefold over the past half century by as yet unknown means. T1D occurs when the body's immune system turns against itself so that, in a very specific and targeted way, it destroys the pancreatic β-cells. T1D results from poorly defined interactions between susceptibility genes and environmental determinants. In contrast to the rapid progress in finding T1D genes, identification and confirmation of environmental determinants remain a formidable challenge. This review article will focus on factors which have to be evaluated and decision to take before starting a new prospective cohort study. Considering all the large ongoing prospective studies, new and more conclusive data than that obtained so far should instead come from international collaboration on the ongoing cohort studies.

Type I diabetes mellitus: genetic factors and presumptive enteroviral etiology or protection

We review type 1 diabetes and host genetic components, as well as epigenetics and viruses associated with type 1 diabetes, with added emphasis on the enteroviruses, which are often associated with triggering the disease. Genus Enterovirus is classified into twelve species of which seven (Enterovirus A, Enterovirus B, Enterovirus C, and Enterovirus D and Rhinovirus A, Rhinovirus B, and Rhinovirus C) are human pathogens. These viruses are transmitted mainly by the fecal-oral route; they may also spread via the nasopharyngeal route. Enterovirus infections are highly prevalent, but these infections are usually subclinical or cause a mild flu-like illness. However, infections caused by enteroviruses can sometimes be serious, with manifestations of meningoencephalitis, paralysis, myocarditis, and in neonates a fulminant sepsis-like syndrome. These viruses are often implicated in chronic (inflammatory) diseases as chronic myocarditis, chronic pancreatitis, and type 1 diabetes. In this review we discuss the currently suggested mechanisms involved in the viral induction of type 1 diabetes. We recapitulate current basic knowledge and definitions.

The emerging global epidemic of type 1 diabetes

Type 1 diabetes mellitus (T1D) can occur at any age, with a peak in incidence around puberty. Classification between T1D and type 2 diabetes becomes more challenging with increasing age of onset of T1D over time develops in genetically predisposed individuals. The main susceptibility is conferred with human leukocyte antigen (HLA) genes. Some of the geographic variation in incidence and familial aggregation is explained by differences in HLA haplotypes. In many populations, the incidence is somewhat higher in males than in females, and a 1.3- to 2.0-fold male excess in incidence after about 15 years of age exists in most populations. The incidence of childhood-onset T1D varies markedly among countries. East Asian and native American populations have low incidences (approximately 0.1-8 per 100 000/year), while the highest rates are found in Finland (>60 per 100 000/year), Sardinia (40 per 100 000/year), and Sweden (47 per 100 000/year). The risk is highest in European-derived populations. About 10 %-20 % of newly diagnosed childhood cases of T1D have an affected first-degree relative. Those with an affected sibling or parent have a cumulative risk of 3 %-7 % up to about 20 years of age, as compared with <1 % in the general population. The cumulative incidence among the monozygotic co-twins of persons with T1D is less than 50 %. Thus, the majority of genetically predisposed people do not develop T1D. Studies assessing temporal trends have shown that the incidence of childhood-onset T1D has increased in all parts of the world. The average relative increase is 3 %-4 % per calendar year. For instance, in Finland, the incidence today is 5 times higher than 60 years ago. At the same time, the age at onset of T1D in children has become younger. It is strongly believed that nongenetic factors are important for the development of T1D and its increase, but the causative evidence is missing. The causes for this increasing trend and current epidemic still remain unknown.

Why is type 1 diabetes increasing?

A series of studies have reported a constant global rise in the incidence of type 1 diabetes. Epidemiological and immunological studies have demonstrated that environmental factors may influence the pathogenesis, leading to a cell-mediated pancreatic β-cell destruction associated with humoral immunity. The search for the triggering factor(s) has been going on for the past century, and yet they are still unknown. This review provides an overview of some of the most well-known theories found in the literature: hygiene, viral, vitamin D deficiency, breast milk and cow's milk hypotheses. Although the hygiene hypothesis appears to be the most promising, positive evidence from animal, human and epidemiological studies precludes us from completely discarding any of the other hypotheses. Moreover, due to contrasting evidence in the literature, a single factor is unlikely to cause an increase in the incidence of diabetes all over the world, which suggests that a multifactorial process might be involved. Although the immunological mechanisms are still unclear, there seems to be some overlap between the various hypotheses. It is thought that the emphasis should be shifted from a single to a multifactorial process and that perhaps the 'balance shift' model should be considered as a possible explanation for the rise in the incidence of type 1 diabetes.

Prevention or acceleration of type 1 diabetes by viruses

Type 1 diabetes is an autoimmune disease characterized by the destruction of insulin-producing pancreatic β-cells. Even though extensive scientific research has yielded important insights into the immune mechanisms involved in pancreatic β-cell destruction, little is known about the events that trigger the autoimmune process. Recent epidemiological and experimental data suggest that environmental factors are involved in this process. In this review, we discuss the role of viruses as an environmental factor on the development of type 1 diabetes, and the immune mechanisms by which they can trigger or protect against this pathology.

Vaccination and risk of type 1 diabetes mellitus in active component U.S. Military, 2002-2008

AIMS/HYPOTHESIS

To evaluate whether vaccination increases the risk of type 1 diabetes mellitus in active component U.S. military personnel.

METHODS

We conducted a retrospective cohort study among active component U.S. military personnel age 17-35 years. Individuals with first time diagnoses of type 1 diabetes between January 1, 2002 and December 31, 2008 were identified using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. We used Poisson regression to estimate risk ratios between individual vaccine exposures and type 1 diabetes. Secondary analyses were performed controlling for receipt of multiple vaccines and available demographic variables.

RESULTS

Our study population consisted of 2,385,102 individuals followed for approximately 7,644,098 person-years of service. This included 1074 incident type 1 diabetes cases. We observed no significant increased risk of type 1 diabetes after vaccination with anthrax vaccine adsorbed (AVA) [RR=1.00; 95% CI (0.85, 1.17)], smallpox vaccine [RR=0.84; 95% (CI 0.70, 1.01)], typhoid vaccine [RR=1.03; 95% CI (0.87, 1.22)], hepatitis B vaccine [RR=0.83; 95% CI (0.72, 0.95)], measles mumps rubella vaccine (MMR) [RR=0.71, 95% CI (0.61, 0.83)], or yellow fever vaccine [RR=0.70; 95% CI (0.59, 0.82)].

CONCLUSIONS

We did not find an increased risk of diagnosed type 1 diabetes and any of the study vaccines. We recommend that follow-up studies using medical record review to confirm case status should be considered to corroborate these findings.

The changing epidemiology of type 1 diabetes: why is it going through the roof?

The incidence of type 1 diabetes is increasing and this may double the burden of disease in our youngest by 2020. The recent increase in incidence is mostly happening in the very young and those with moderate genetic susceptibility. Many environmental factors have been implicated, but no major determinants have been clearly identified, and the mechanisms of involvement remain elusive. This review summarizes current research efforts directed at understanding the possible reasons for this increase, including the role of viruses, gut microbiota, early life feeding patterns, perinatal factors and childhood growth patterns. It also provides a road map for future research directions.

Immune cell crosstalk in type 1 diabetes

The development of type 1 diabetes involves a complex interaction between pancreatic beta-cells and cells of both the innate and adaptive immune systems. Analyses of the interactions between natural killer (NK) cells, NKT cells, different dendritic cell populations and T cells have highlighted how these different cell populations can influence the onset of autoimmunity. There is evidence that infection can have either a potentiating or inhibitory role in the development of type 1 diabetes. Interactions between pathogens and cells of the innate immune system, and how this can influence whether T cell activation or tolerance occurs, have been under close scrutiny in recent years. This Review focuses on the nature of this crosstalk between the innate and the adaptive immune responses and how pathogens influence the process.

The rising incidence of type 1 diabetes mellitus and the role of environmental factors--three decade experience in a primary care health center in Saudi Arabia

BACKGROUND

The incidence of type 1 diabetes has been increasing all over the world including Saudi Arabia and environmental factors have been suggested to play an important role in its etiology.

OBJECTIVE

The aim of this study was to evaluate if there are any contributory roles of various environmental factors in the rising incidence of type 1 diabetes in children in the Eastern Province of Saudi Arabia.

METHODS

We conducted a retrospective study of Saudi Arab subjects (n = 119) diagnosed between 1980 and 2009 with type 1 diabetes and these subjects were classified to six groups on the basis of the onset of diabetes.

RESULTS

119 subjects (61 boys and 58 girls) with confirmed diagnosis of type 1 diabetes met the study eligibility criteria. 89 children (74%) presented with ketoacidosis. The mean age of onset was 4 3/4 years for Group II and age of onset increased to above 8 years on subsequent years. Excessive weight gain was noted in all study groups. No etiological influences of maternal age at birth, birth order, birth weight, early introduction of cow's milk and cereals, infections and vaccines as well as nitrate levels in drinking water were noted in any of the groups. The predicted doubling of diabetes in young children below 5 years as in previous studies was not found in our study.

CONCLUSIONS

The rising incidence of type 1 diabetes over the last 30 years is not proved to have been influenced by various environmental factors.

Approaches in type 1 diabetes research: A status report

Type 1 diabetes is a multifactorial disease with an early age of onset, in which the insulin producing beta cell of the pancreas are destroyed because of autoimmunity. It is the second most common chronic disease in children and account for 5% to 10% of all diagnosed cases of diabetes. India is having an incidence of 10.6 cases/year/100,000, and recent studies indicate that the prevalence of type 1 diabetes in India is increasing. However in view of poor health care network, there is no monitoring system in the country. Of the 18 genomic intervals implicated for the risk to develop type 1 diabetes, the major histocompatibility complex (MHC) region on chromosome 6p21.31 has been the major contributor estimated to account for 40-50%, followed by 10% frequency of INS-VNTR at 5' flanking region of the insulin gene on chromosome 11p15.5. However, population studies suggest that > 95% of type 1 diabetes have HLA-DR3 or DR4, or both, and in family studies, sibling pairs affected with type 1 diabetes have a non-random distribution of shared HLA haplotypes. As predisposing genetic factors such as HLA alleles are known, immunological interventions to prevent type 1 diabetes are of great interest. In the present study we have reviewed the status of molecular genetics of the disease and the approaches that need to be adopted in terms of developing patient and suitable control cohorts in the country.

Infection with viruses from several families triggers autoimmune diabetes in LEW*1WR1 rats: prevention of diabetes by maternal immunization

OBJECTIVE

The contribution of antecedent viral infection to the development of type 1 diabetes in humans is controversial. Using a newer rat model of the disease, we sought to 1) identify viruses capable of modulating diabetes penetrance, 2) identify conditions that increase or decrease the diabetogenicity of infection, and 3) determine whether maternal immunization would prevent diabetes.

RESEARCH DESIGN AND METHODS

About 2% of LEW*1WR1 rats develop spontaneous autoimmune diabetes, but disease penetrance is much higher if weanling rats are exposed to environmental perturbants including Kilham rat virus (KRV). We compared KRV with other viruses for diabetogenic activity.

RESULTS

Both KRV and rat cytomegalovirus (RCMV) induced diabetes in up to 60% of LEW*1WR1 rats, whereas H-1, vaccinia, and Coxsackie B4 viruses did not. Simultaneous inoculation of KRV and RCMV induced diabetes in 100% of animals. Pretreatment of rats with an activator of innate immunity increased the diabetogenicity of KRV but not RCMV and was associated with a moderate rate of diabetes after Coxsackie B4 and vaccinia virus infection. Inoculation of LEW*1WR1 dams with both KRV and RCMV prior to pregnancy protected weanling progeny from virus-induced diabetes in a virus-specific manner.

CONCLUSIONS

Exposure to viruses can affect the penetrance of autoimmune diabetes in genetically susceptible animals. The diabetogenicity of infection is virus specific and is modified by immunomodulation prior to inoculation. Maternal immunization protects weanlings from virus-induced diabetes, suggesting that modification of immune responses to infection could provide a means of preventing islet autoimmunity.

Infection and type 1 diabetes mellitus - a two edged sword?

Infection by various viral and bacterial pathogens has long been proposed as one of the etiologies of autoimmune diabetes. Many theories, ranging from direct cytolysis of pancreatic islet cells to immunological processes such as antigen mimicry and polyclonal lymphocyte activation, tried to explain the epidemiological correlation between infections and diabetes, supported by information from human and animal studies. However, a direct correlation and exact mechanism continue to elude investigators due to scarce and conflicting data. Interestingly, there is also data to support an opposite role for infection in the development of type 1 diabetes, as several pathogens demonstrated a protective effect from this disease. This article reviews the current data available from clinical studies and animal models, while trying to explain the different mechanisms underlying these findings.

Infectious diseases and Type 1 diabetes in children

Type 1 diabetes (T1D) is an autoimmune disease triggered by environmental factors. Among those of infectious origin, viruses mostly associated to T1D are rubella virus, enteroviruses (Rotavirus, Coxackie B), Cytomegalovirus and mumps virus. The role of bacterial infections is still controversial, acting either as modulators or precipitating factors of an already started autoimmune process. Polymorphic genes of innate immunity, such as Toll-like receptors, nucleotide-binding oligomerization domain (NOD) 1 and NOD2 and mannose-binding lectin (MBL) genes, did not show a strict association with T1D onset, while protein tyrosine phosphatase (PTPN22), cytotoxic T-lymphocyte antigen (CTLA)4 and natural killer cells immunoglobulin-like receptor (KIR) genes appear to play an important role. However, the adaptive immune response genes (HLA) still provide the major contribution to T1D susceptibility. Here, we review the mechanism by which microorganisms might induce autoimmunity.

Prevalence of allergic symptoms among children with diabetes mellitus type 1 of different socioeconomic status

The aim of the study was to assess the possible associations between allergies and type 1 diabetes mellitus (DM1), stratified by social class. We studied 127 children with DM1 with a median age of 10.8 yr and 150 controls of comparable age and sex distribution. The parents completed questionnaires on their education and occupation and on their children's history of allergic symptoms, breast-feeding, viral infections, and measles-mumps-rubella (MMR) vaccination. Lower family's social class was more frequently encountered among the DM1 families than in the controls (OR = 0.56, 95% CI: 0.35-0.92). The occurrence of any allergic symptoms among children with DM1 (35.45%) was not significantly different from the controls (38.78%), neither in the total group (OR = 0.87, 95% CI: 0.52-1.45) nor in the stratified analysis by social class. Similar findings were observed regarding the different types of allergic symptoms. In the univariate analysis, breast-feeding, the experience of viral infections, and MMR vaccination were found to be protective of DM1 presentation in both upper and lower social classes. In the multiple logistic regression analysis, the experience of more than 2 infections/yr (OR = 0.12, 95% CI: 0.04-0.34), the origin from middle and upper social classes (OR = 0.42, 95% CI: 0.22-0.80) and breast-feeding (OR = 0.58, 95% CI: 0.31-1.07) were protective of DM1 occurrence. In children with DM1, the presence of allergic symptoms was not associated with the development of DM1. Among the environmental factors, the origin from middle or upper social classes, breast-feeding, the experience of viral infections, and MMR vaccination were found to have a protective effect on DM1 presentation.

The importance of CTLA-4 polymorphism and human leukocyte antigen genotype for the induction of diabetes-associated cytokine response in healthy school children

BACKGROUND

Type 1 diabetes (T1D) is an autoimmune disease associated with the destruction of pancreatic beta cells and genetically linked to human leukocyte antigen (HLA) class II DR3-DQ2 and DR4-DQ8 haplotypes. The +49A/G polymorphism of the immunoregulatory cytotoxic T-lymphocyte antigen 4 (CTLA-4) gene is also associated with T1D. Genetic and environmental risk factors precede the onset of T1D, which is characterized by a T helper 1 cell-dominating cytokine response to diabetes-related autoantigens.

AIM

To investigate immunological differences between healthy children with and without CTLA-4 +49A/G and HLA genetic susceptibility for T1D.

STUDY DESIGN

Young, 7-15 years of age, healthy subjects (n = 58) were investigated to test whether CTLA-4 +49A/G genotype was associated with enzyme-linked immunospot assay T-cell responses to T1D-related autoantigens. Because T1D is primarily HLA-DQ associated, we stratified the healthy subjects by HLA genotypes associated with the disease.

RESULTS

Peptide of heat shock protein 60 induced a higher interferon-gamma (IFN-gamma) response in subjects with risk-associated CTLA-4 polymorphism (GG genotype) (p = 0.02) while glutamic acid decarboxylase 65-induced interleukin-4 (IL-4) secretion was lower in GG genotype subjects (p = 0.02).

CONCLUSION

The increased IFN-gamma response and lower IL-4 response toward diabetes-related autoantigens shown in CTLA-4 +49 GG risk subjects show a possible mechanism for the association between CTLA-4 and T1D.

Viral infections as potential triggers of type 1 diabetes

During the last decades, the incidence of type 1 diabetes (T1D) has increased significantly, reaching percentages of 3% annually worldwide. This increase suggests that besides genetical factors environmental perturbations (including viral infections) are also involved in the pathogenesis of T1D. T1D has been associated with viral infections including enteroviruses, rubella, mumps, rotavirus, parvovirus and cytomegalovirus (CMV). Although correlations between clinical presentation with T1D and the occurrence of a viral infection that precedes the development of overt disease have been recognized, causalities between viruses and the diabetogenic process are still elusive and difficult to prove in humans. The use of experimental animal models is therefore indispensable, and indeed more insight in the mechanism by which viruses can modulate diabetogenesis has been provided by studies in rodent models for T1D such as the biobreeding (BB) rat, nonobese diabetic (NOD) mouse or specific transgenic mouse strains. Data from experimental animals as well as in vitro studies indicate that various viruses are clearly able to modulate the development of T1D via different mechanisms, including direct beta-cell lysis, bystander activation of autoreactive T cells, loss of regulatory T cells and molecular mimicry. Data obtained in rodents and in vitro systems have improved our insight in the possible role of viral infections in the pathogenesis of human T1D. Future studies will hopefully reveal which human viruses are causally involved in the induction of T1D and this knowledge may provide directions on how to deal with viral infections in diabetes-susceptible individuals in order to delay or even prevent the diabetogenic process.

How robust is the evidence for viruses in the induction of type 1 diabetes?

Viruses associated with type 1 diabetes have eluded definition as causal, with the exception of rubella virus. False-negative results may have occurred due to the focus on subjects at symptomatic onset, who may be heterogeneous and differently affected by viruses. In addition, assays have not always been sufficiently sensitive to deal with transient infections, and pancreatic tissue is scarce. Longitudinal studies of at-risk subjects and more sensitive DNA techniques now reveal that at initiation of islet autoimmunity, enteroviruses have only a small role, but are more likely to be important at symptomatic onset. Rotaviruses remain associated with initiation of islet autoimmunity, and generate strong T cell responses in the young.

CTLA-4 gene polymorphisms and susceptibility to type 1 diabetes mellitus: a HuGE Review and meta-analysis

The authors performed a meta-analysis of 33 studies examining the association of type 1 diabetes mellitus with polymorphisms in the cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) gene, including the A49G (29 comparisons), C(-318)T (three comparisons), and (AT)n microsatellite (six comparisons) polymorphisms. The studies included 5,637 cases of type 1 diabetes and 6,759 controls (4,775 and 5,829, respectively, for analysis of the A49G polymorphism). The random-effects odds ratio for the *G (Ala) allele versus the *A (Thr) allele was 1.45 (95% confidence interval (CI): 1.28, 1.65), with significant between-study heterogeneity (p < 0.001). The effect size tended to be higher in type 1 diabetes cases with age of onset <20 years (odds ratio (OR) = 1.61), and there was a significant association between the presence of glutamic acid decarboxylase-65 autoantibodies and the *G allele among type 1 diabetes cases (OR = 1.49). Larger studies showed more conservative results (p = 0.011). After exclusion of studies with fewer than 150 subjects and studies with significant deviation from Hardy-Weinberg equilibrium in the controls, the summary odds ratio was 1.40 (95% CI: 1.28, 1.54). Available data showed no strong association for the 106-base-pair allele of the microsatellite polymorphism (OR = 0.99, 95% CI: 0.64, 1.55) or the *T allele of the C(-318)T polymorphism (OR = 0.92, 95% CI: 0.45, 1.89). This meta-analysis demonstrates that the CTLA-4*G genotype is associated with type 1 diabetes.

Consequence or coincidence? The occurrence, pathogenesis and significance of autoimmune manifestations after viral vaccines

BACKGROUND

Viruses and virus-induced lymphokines may have an important role in the pathogenesis of autoimmunity (Schattner A. Clin Immunol Immunopathol; 1994). The occurrence and significance of autoimmune manifestations after the administration of viral vaccines remain controversial.

METHODS

Medline search of all relevant publications from 1966 through June 2004 with special emphasis on search of each individual autoimmune manifestation and vaccination, as well as specifically searching each viral vaccine for all potential autoimmune syndromes reported. All relevant publications were retrieved and critically analyzed.

RESULTS

The most frequently reported autoimmune manifestations for the various vaccinations, were: hepatitis A virus (HAV)--none; hepatitis B virus (HBV)--rheumatoid arthritis, reactive arthritis, vasculitis, encephalitis, neuropathy, thrombocytopenia; measles, mumps and rubella vaccine (MMR)--acute arthritis or arthralgia, chronic arthritis, thrombocytopenia; influenza--Guillain-Barre syndrome (GBS), vasculitis; polio--GBS; varicella--mainly neurological syndromes. Even these 'frequent' associations relate to a relatively small number of patients. Whenever controlled studies of autoimmunity following viral vaccines were undertaken, no evidence of an association was found.

CONCLUSIONS

Very few patients may develop some autoimmune diseases following viral vaccination (in particular - arthropathy, vasculitis, neurological dysfunction and thrombocytopenia). For the overwhelming majority of people, vaccines are safe and no evidence linking viral vaccines with type 1 diabetes, multiple sclerosis (MS) or inflammatory bowel disease can be found.

Zinc and nitrate in the ground water and the incidence of Type 1 diabetes in Finland

AIMS

In Finland, the risk of childhood Type 1 diabetes varies geographically. Therefore we investigated the association between spatial variation of Type 1 diabetes and its putative environmental risk factors, zinc and nitrates.

METHODS

The association was evaluated using Bayesian modelling and the geo-referenced data on diabetes cases and population.

RESULTS

Neither zinc nor nitrate nor the urban/rural status of the area had a significant effect on the variation in incidence of childhood Type 1 diabetes.

CONCLUSIONS

The results showed that although there was no significant difference in incidence between rural and urban areas, there was a tendency to increasing risk of Type 1 diabetes with the increasing concentration of NO3 in drinking water. The fact that no significant effect was found may stem from the aggregated data being too crude to detect it.

The belgrade childhood diabetes study: association of infections and vaccinations on diabetes in childhood

PURPOSE

The aim of this study was to investigate whether individual infections or combination of infections or vaccination affect the risk of developing diabetes in childhood.

METHODS

A case-control study was conducted in Belgrade during the period between 1994 and 1997. A total of 105 recent onset diabetics were compared with 210 controls chosen among children with skin disease (the first control group). Cases and controls were individually matched by age (+/-1 year), sex, and place of residence. Eighty-six diabetic children were also compared with their brothers/sisters (the second control group).

RESULTS

After adjustment for confounding variables, independent association with diabetes was found for infections during the 6 months preceding the onset of the disease, when cases were compared with both the first control group (OR=4.23, 95% CI, 1.95-9.17, p<0.001) and the second control group (OR=4.68, 95% CI, 2.09-10.47, p<0.001), and for regular vaccination when cases were compared with the first control group (OR=0.08, 95% CI, 0.01-0.50, p=0.03).

CONCLUSION

The results obtained support the hypotheses that infections play a role in the development of type 1 diabetes and that regular vaccination has a preventive effect.

Vaccinations May Induce Diabetes-Related Autoantibodies in One-Year-Old Children

Vaccinations have been discussed as one among many environmental candidates contributing to the immune process that later may lead to type 1 diabetes. ABIS (All Babies in Southeast Sweden) is a prospective cohort study following a nonselected birth cohort of general population. In a randomly selected sample collection from 4400 children, GADA and IA-2A have been determined at the age of 1 year. The information on vaccinations was collected from questionnaires answered by the parents and was related to beta cell autoantibodies. When studying the induction of autoantibodies using the autoantibody level of 90th percentile as cutoff level, hemophilus influenza B (HIB) vaccination appeared to be a risk factor for IA-2A [OR 5.9 (CI 1.4-24.4; p = 0.01)] and for GADA [OR 3.4 (CI 1.1-10.8; p = 0.04)] in logistic regression analyses. Furthermore, the titers of IA-2A were significantly higher (p < 0.01 in Mann-Whitney test) in those children who had got HIB vaccination. When 99th percentile was used as cutoff to identify the children at risk of type 1 diabetes, BCG vaccination was associated with increased prevalence of IA-2A (p < 0.01). We conclude that HIB vaccination may have an unspecific stimulatory polyclonal effect increasing the production of GADA and IA-2A. This might be of importance under circumstances when the beta cell-related immune response is activated by other mechanisms.

A new look at viruses in type 1 diabetes

Type 1 diabetes (T1D) results from the destruction of pancreatic beta cells. Genetic factors are believed to be a major component for the development of T1D, but the concordance rate for the development of diabetes in identical twins is only about 40%, suggesting that nongenetic factors play an important role in the expression of the disease. Viruses are one environmental factor that is implicated in the pathogenesis of T1D. To date, 14 different viruses have been reported to be associated with the development of T1D in humans and animal models. Viruses may be involved in the pathogenesis of T1D in at least two distinct ways: by inducing beta cell-specific autoimmunity, with or without infection of the beta cells, [e.g. Kilham rat virus (KRV)] and by cytolytic infection and destruction of the beta cells (e.g. encephalomyocarditis virus in mice). With respect to virus-mediated autoimmunity, retrovirus, reovirus, KRV, bovine viral diarrhoea-mucosal disease virus, mumps virus, rubella virus, cytomegalovirus and Epstein-Barr virus (EBV) are discussed. With respect to the destruction of beta cells by cytolytic infection, encephalomyocarditis virus, mengovirus and Coxsackie B viruses are discussed. In addition, a review of transgenic animal models for virus-induced autoimmune diabetes is included, particularly with regard to lymphocytic choriomeningitis virus, influenza viral proteins and the Epstein-Barr viral receptor. Finally, the prevention of autoimmune diabetes by infection of viruses such as lymphocytic choriomeningitis virus is discussed.

The epidemiology of type 1 diabetes in children in Philadelphia 1990-1994: evidence of an epidemic

OBJECTIVE

To determine the epidemiology of type 1 diabetes in children in Philadelphia from 1990 to 1994, and to identify whether an epidemic occurred during that time period.

RESEARCH DESIGN AND METHODS

This is a descriptive epidemiological study using a retrospective population-based registry in Philadelphia, PA, a city with large white, African-American, and Hispanic (Puerto Rican) populations. All hospitals in Philadelphia that admit children were identified. All charts meeting the following criteria were reviewed: 1) newly diagnosed type 1 diabetes, 2) children 0-14 years of age, 3) children residing in Philadelphia at the time of diagnosis, and 4) those diagnosed from 1 January 1990 to 31 December 1994. Standard type 1 diabetes registry data were abstracted from the charts. Ascertainment of the completeness of the hospital registry was validated by data from the Philadelphia School District. Communicable disease records were reviewed to identify epidemics from 1987 to 1995.

RESULTS

A total of 209 cases were identified, and the combined hospital and school registry was determined to be 96% complete. The overall age-adjusted incidence rate in Philadelphia was 13.3/100,000/year. The highest rate by race continues to be in the Hispanic population (15.5). The incidence in African-American children has increased markedly (12.8), particularly in the 10- to 14-year age-group (22.9). An epidemic of type 1 diabetes occurred from January to June 1993, approximately 2 years after a measles epidemic in Philadelphia.

CONCLUSIONS

The overall incidence of type 1 diabetes in Philadelphia is similar to other U.S. registries. The incidence in the Hispanic population continues to be among the highest of any U.S. ethnic group. The marked increase in incidence in the African-American population may be due in part to misclassification of cases actually having type 2 diabetes. The 1993 epidemic may have been due to beta-cell autoimmunity triggered by the measles virus.

Childhood vaccinations, vaccination timing, and risk of type 1 diabetes mellitus

OBJECTIVES

To evaluate suggested associations between childhood vaccinations, particularly against hepatitis B and Haemophilus influenzae type b, and risk of developing type 1 diabetes; and to determine whether timing of vaccination influences risk.

METHODS

We conducted a case-control study within 4 health maintenance organizations (HMOs) that participate in the Vaccine Safety Datalink project of the Centers for Disease Control and Prevention. Study eligibility was restricted to children who met the following criteria: 1) born during 1988 through 1997; 2) HMO member since birth; 3) continuously enrolled for first 6 months of life; and 4) at least 12 months of HMO membership before diabetes incidence date (or index date for controls) unless incidence date was before 12 months of age. All 4 HMOs maintain registries of their members who have diabetes, and we used the registries to identify potential cases of diabetes. We conducted chart reviews to verify that potential cases met the World Health Organization epidemiologic case definition for type 1 diabetes mellitus (ie, a physician's diagnosis of diabetes plus treatment with daily insulin injections). We defined the incidence date of diabetes as the first date that the child received a diagnosis of diabetes. We attempted to match 3 controls to each case. Controls had the same eligibility criteria as cases and were matched to individual cases on HMO, sex, date of birth (within 7 days), and length of health plan enrollment (up to the incidence or index date). The index date for controls was defined as the incidence date of the case to which the control was matched. Chart abstraction was performed by trained chart abstractors using standardized forms. In addition to complete vaccination histories, the chart abstraction forms for both cases and controls included information on sociodemographic characteristics, selected medical conditions, history of breastfeeding, and family medical history. We used conditional logistic regression to estimate the odds ratio (OR) of diabetes associated with vaccination, with vaccine exposure defined as before the diabetes incidence date (or index date for controls).

RESULTS

Two hundred fifty-two confirmed cases of diabetes and 768 matched controls met the study eligibility criteria. The OR (95% confidence interval) for the association with type 1 diabetes was 0.28 (0.07-1.06) for whole cell pertussis vaccine (predominantly in combination as diphtheria, tetanus toxoids and pertussis vaccine), 1.36 (0.70-2.63) for measles-mumps-rubella, 1.14 (0.51-2.57) for Haemophilus influenzae type b, 0.81 (0.52-1.27) for hepatitis B vaccine, 1.16 (0.72-1.89) for varicella vaccine, and 0.92 (0.53-1.57) for acellular pertussis-containing vaccines. Compared with children who had not received hepatitis B vaccine, the OR of diabetes was 0.51 (0.23-1.15) for children vaccinated at birth and 0.86 (0.54-1.35) for those first vaccinated against hepatitis B at 2 months of age or later. Race and ethnicity and family history of diabetes were independently associated with risk of type 1 diabetes, but adjustment for these factors did not materially alter the ORs for any of the vaccines.

CONCLUSIONS

In this large, population-based, case-control study, we did not find an increased risk of type 1 diabetes associated with any of the routinely recommended childhood vaccines. Our study adds to previous research by providing data on newer vaccines, including hepatitis B, acellular pertussis, and varicella vaccines. For the older vaccines, our results are generally in agreement with previous studies in not finding any increased risks. Ours is the first epidemiologic study to evaluate the possibility that timing of vaccination is related to risk of clinical diabetes in children. Our results on hepatitis B vaccine do not support the hypothesis; risk of type 1 diabetes was not different between infants vaccinated at birth and those who received their first vaccination later in life. The results of our study and the preponderance of epidemiologic evidence do not support an association between any of the recommended childhood vaccines and an increased risk of type 1 diabetes. Suggestions that diabetes risk in humans may be altered by changes in the timing of vaccinations also are unfounded.

Epidemiology of autoimmune reactions induced by vaccination

In order for vaccinations to 'work', the immune system must be stimulated. The concern that immunizations may lead to the development of autoimmune disease (AID) has been questioned. Since AID occur in the absence of immunizations, it is unlikely that immunizations are a major cause of AID. Epidemiological studies are needed, however, to assess whether immunizations may increase the risk in some susceptible individuals. This paper discusses the evidence for and against vaccination as a risk factor for AID. Evidence for immunizations leading to AID come from several sources including animal studies, single and multiple case reports, and ecologic association. However more rigorous investigation has failed to confirm most of the allegations. Unfortunately the question remains difficult to address because for most AIDs, there is limited knowledge of the etiology, background incidence and other risk factors for their development. This information is necessary, in the absence of experimental evidence derived from controlled studies, for any sort of adequate causality assessment using the limited data that are available. Several illustrative examples are discussed to highlight what is known and what remains to be explored, and the type of epidemiological evidence that would be required to better address the issues. Examples include the possible association of immunization and multiple sclerosis (and other demyelinating diseases), type 1 diabetes mellitus, Guillain-Barre Syndrome, idiopathic thrombocytopenic purpura, and rheumatoid arthritis.

Month of birth and risk of developing insulin dependent diabetes in south east Sweden

Environmental factors very early in life may be important for later development of insulin dependent diabetes. Because several of these factors, such as infections, vary with season, we predicted a difference in birth pattern compared with the general population among children who develop diabetes. In a population based study we analysed all 1248 children from seven paediatric departments in the south east part of Sweden to evaluate whether there is such a relation. There was a significant difference in birth pattern in patients with diabetes compared with the general population. Children who developed diabetes at the age of 10-15 years accounted for most of this difference. Boys had a more pronounced difference in birth pattern than girls. Children diagnosed with diabetes during years of high incidence, as well as children with an infection before diagnosis of diabetes, showed a significantly different birth pattern compared with the background population. These results indicate that there is a difference in birth pattern in children who develop diabetes compared with the background population. This supports the theory that environmental factors early in life play a role in the development of diabetes many years later.

Association between type 1 diabetes and Haemophilus influenzae type b vaccination: birth cohort study

OBJECTIVES

To determine the effect of Haemophilus influenzae type b vaccination and its timing on the risk of type 1 diabetes in Finnish children.

DESIGN

Cumulative incidence and relative risk of type 1 diabetes was compared among three birth cohorts of Finnish children: those born during the 24 months before the H influenzae type b vaccination trial, those in the trial cohort who were vaccinated at 3 months of age and later with a booster vaccine, and those in the trial cohort who were vaccinated at 24 months of age only. The probability of type 1 diabetes was estimated using regression analysis assuming that there were no losses to 10 year follow up and no competing risks.

SETTING

Finland (total population 5 million and annual birth rate 1.3%).

SUBJECTS

128 936 children born from 1 October 1983 to 1 September 1985, and 116 352 children born from 1 October 1985 to 31 August 1987.

MAIN OUTCOME MEASURES

Probability of type 1 diabetes among children vaccinated with H influenzae type b and non-vaccinated children.

RESULTS

No statistically significant difference was found at any time during the 10 year follow up in the risk of type 1 diabetes between the children born before the vaccination period and those vaccinated at the age of 24 months only (relative risk 1.01). The difference in the risk between the cohort vaccinated first at the age of 3 months and the cohort vaccinated at the age of 24 months only was not statistically significant either (1.06).

CONCLUSION

It is unlikely that H influenzae type b vaccination or its timing cause type 1 diabetes in children.

Month of birth and subsequent development of type I diabetes (IDDM)

The aim of this study was to find out whether there is a seasonal pattern in the month of birth of children with IDDM in Israel and whether this pattern, if present, differs from that of total live births. One thousand and ninety-five out of 1,188 children and adolescents (0-17 years) who developed IDDM in Israel between 1980-1993 and whose month of birth was known were included in the study. Separate analysis was made for Jews (n = 987) who have a high incidence (10-18/105) and Arabs (n = 108) with a low incidence (2.9/105) of IDDM. The pattern of total live birth distribution in Israel over a 20-year period served as control. A significantly different seasonal pattern was found in the two IDDM populations. Whereas the Jews had the lowest number of births in winter (January-March) and the highest in spring (April-June), the Arabs presented an inverse pattern in the first months of the year. The distribution of births of the children who developed IDDM was different from that observed in total live births in the Jewish population. The findings in the Jewish population in Israel (a high incidence group) support the hypothesis that IDDM is triggered in some children by viral infections transmitted by the mother during pregnancy or in the early postnatal period. In the Arab population (a low incidence group) a protective (immune and/or genetic) mechanism may exist.

Interaction of genetic and environmental factors in the pathogenesis of insulin-dependent diabetes mellitus

The current concept of the pathogenesis of insulin-dependent diabetes mellitus (IDDM) is based on the view that environmental factors, either alone or in combination, trigger in a genetically, susceptible individual an autoimmune process which leads to the destruction of the insulin-secreting beta cells. The identification of environmental risk factors for IDDM is of utmost importance with regard to possibilities for implementing preventive measures. Studies on the interaction between genetic and environmental factors may be complicated by the observations that genetic markers, e.g. HLA risk alleles, may vary from one population to another, and combinations of predisposing genes may differ between populations. In addition, the role of a given environmental trigger in initiating the autoimmune process may be variable in various individuals depending on the genetic set-up and other host-related characteristics. As prevention trials are already being initiated, and genetic screening is essential in the identification of individuals at increased risk of IDDM, it is crucial to learn more about the interaction of genetic and environmental factors in this disease.

Low mumps antibody levels induced by mumps-measles-rubella vaccinations in type 1 diabetic children

Mumps-measles-rubella vaccination-induced antibody responses were studied in Type 1 diabetic children to find out the possible aberrations in mumps antibody responsiveness previously seen after natural mumps in Type 1 diabetic children. Mumps, measles, and rubella virus antibodies were studied in 364 newly diagnosed Type 1 diabetic subjects, their 240 non-diabetic siblings and 59 age- and sex-matched, unrelated, non-diabetic control subjects who all had received mumps-measles-rubella vaccine but had not had the respective infections. Sera were collected from all children at the time of the diagnosis of diabetes in the index case which was on average 2.5 years after the mumps-measles-rubella vaccination. The levels of IgG class mumps virus antibodies were lower in diabetic patients than in their non-diabetic siblings (p < 0.0005). This difference was most pronounced in males as male patients had significantly lower IgG mumps antibody levels than female patients. Rubella and measles IgG antibodies did not differ between patients and control subjects. The results are in accordance with previous studies suggesting a selective decrease in mumps antibody levels in Type 1 diabetic children. As the exposure to mumps virus had been exactly the same in all study groups, low mumps antibodies in diabetic children suggest decreased responsiveness rather than different number of past infections in these patients.

The elimination of indigenous measles, mumps, and rubella from Finland by a 12-year, two-dose vaccination program

BACKGROUND

In the 1970s measles, mumps, and rubella were rampant in Finland, and rates of immunization were inadequate. In 1982 a comprehensive national vaccination program began in which two doses of a combined live-virus vaccine were used.

METHODS

Public health nurses at 1036 child health centers administered the vaccine to children at 14 to 18 months of age and again at 6 years, and also to selected groups of older children and young adults. Vaccination was voluntary and free of charge. In follow-up studies, we focused on rates of vaccination, reasons for noncompliance, adverse reactions, immunogenicity, persistence of antibody, and incidence of the three diseases. Since 1987, paired serum samples have been collected from all patients with suspected cases of measles, mumps, or rubella.

RESULTS

Over a period of 12 years, 1.5 million of the 5 million people in Finland were vaccinated. Coverage now exceeds 95 percent. The vaccine was efficient and safe, even in those with a history of severe allergy. No deaths or persistent sequelae were attributable to vaccination. The most frequent complication requiring hospitalization was acute thrombocytopenic purpura, which occurred at a rate of 3.3 per 100,000 vaccinated persons. The 99 percent decrease in the incidence of the three diseases was accompanied by an increasing rate of false positive clinical diagnoses. In 655 vaccinated patients with clinically diagnosed disease, serologic studies confirmed the presence of measles in only 0.8 percent, mumps in 2.0 percent, and rubella in 1.2 percent. The few localized outbreaks were confined to patients in the partially vaccinated age groups. There are now fewer than 30 sporadic cases of each of the three diseases per year, and those are probably imported.

CONCLUSIONS

Over a 12-year period, an immunization program using two doses of combined live-virus vaccine has eliminated indigenous measles, mumps, and rubella from Finland. Serologic studies show that most reported sporadic cases are now due to other causes, but a continued high rate of vaccination coverage is essential to prevent outbreaks resulting from exposure to imported disease.