Absence of measles viral genomic sequence in intestinal tissues from Crohn's disease by nested polymerase chain reaction

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.

Molecular mimicry, inflammatory bowel disease, and the vaccine safety debate

Preventive immunization has provided one of the major advances in population health during the past century. However, a surprising cultural phenomenon is the emergence of concerns about immunization safety, in part due to prominently controversial biomedical studies. One ongoing theoretical safety concern is the possibility of human molecular mimicry by measles, mumps, rubella (MMR) antigens. The study of Polymeros et al. in this BMC Medicine presents a systematic evaluation and refutation of this safety concern. This provides significant new scientific evidence in support of the safety of pediatric vaccines, which will inform the ongoing policy and cultural understanding of this important public health measure.

Current knowledge and systematic review of viruses associated with Crohn's disease

The aetiology of Crohn's disease (CD) is currently unknown. A viral trigger was proposed more than 40 years ago and has been the focus of many investigations. We summarised the current literature surrounding the association between viruses and CD and conducted a systematic review of all studies investigating this association quantitatively. Studies were identified by searching for 13 specific virus names or the general term 'virus' and 'Crohn's disease' in search engines PubMed and OVID. A total of 1315 studies were identified, of which 78 studies had a laboratory result. Of the 78, 46 case-control studies met all the inclusion criteria for forest plot analysis. The most common viruses studied were EBV, CMV and measles virus (MV). Forest plot analysis for each virus was carried out (fitted using random effects) and identified evidence of an association between CD and CMV (risk ratio [RR] 1.602, 95% confidence interval [CI] 1.069 to 2.400) with some suggestion that EBV may also be associated with CD (RR 1.366, 95% CI 0.996 to 1.873). However, there was evidence of large heterogeneity in the results from the identified studies for EBV. There was little evidence of an association with CD for MV, human herpes virus 6, human herpes virus 8, human simplex virus, varicella-zoster virus, mumps virus, Rubella virus, rotavirus, norovirus and adenovirus. There is still some question around whether CD is associated with the presence of a currently known virus.

Environmental risk factors for inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the gastrointestinal tract and is associated with significant morbidity. The etiology of IBD has been extensively studied during the last several decades; however, causative factors in disease pathology are not yet fully understood. IBD is thought to result from the interaction between genetic and environmental factors that influence the normal intestinal commensal flora to trigger an inappropriate mucosal immune response. Although many IBD susceptibility genes have been discovered, similar advances in defining environmental risk factors have lagged. A number of environmental risk factors have been explored, including smoking, appendectomy, oral contraceptives, diet, breastfeeding, infections/ vaccinations, antibiotics, and childhood hygiene. However, most of these factors have demonstrated inconsistent findings, thus making additional studies necessary to better understand the etiology of IBD.

Review article: diet and inflammatory bowel disease--epidemiology and treatment

BACKGROUND

Diet is thought to have an important role in the immunopathogenesis and treatment of inflammatory bowel disease (IBD).

AIM

To identify dietary constituents as risk factors for development of IBD and the therapeutic efficacy of dietary modifications or enteral nutrition in IBD.

METHODS

The Medline and the Cochrane Library were searched for clinical trials and meta-analyses in the scope of diet and nutrition in IBD.

RESULTS

There are many studies in small cohorts of patients that claim that intake of certain diet constituents like fat, refined sugar, fruits, vegetables and fibre affect the expression of IBD. These are often compromised by insufficient data or methodological limitations and do not provide unequivocal evidence to incriminate any particular dietary factor. Among various dietary interventions, none has shown striking efficacy with the possible exception of complete enteral nutrition. Enteral nutrition appears effective in both active and quiescent Crohn's disease (CD), but independent meta-analyses have shown enteral nutrition to be inferior to corticosteroids in the management of active CD, when assessed on an intention-to-treat basis.

CONCLUSIONS

The current levels of knowledge concerning dietary risk factors for IBD, and the therapeutic efficacy of dietary and nutritional interventions need to be supported by well-designed trials in large cohorts of patients.

Hygiene hypothesis in inflammatory bowel disease: A critical review of the literature

The hygiene hypothesis is thought to be a significant contributor to the growing incidence of inflammatory bowel disease (IBD) around the world, although the evidence for specific factors that underlie the hygiene hypothesis in IBD is unclear. We aimed to systematically review the literature to determine which hygiene-related factors are associated with the development of IBD. Publications identified from a broad based MEDLINE and Current Contents search between 1966 and 2007 on key terms relevant to the 'hygiene hypothesis' and IBD including H pylori exposure, helminths, cold chain hypothesis, measles infection and vaccination, antibiotic use, breastfeeding, family size, sibship, urban upbringing, day care attendance and domestic hygiene were reviewed. The literature suggests that the hygiene hypothesis and its association with decreased microbial exposure in childhood probably plays an important role in the development of IBD, although the strength of the supporting data for each of the factors varies considerably. The most promising factors that may potentially be associated with development of IBD include H pylori exposure, helminths, breastfeeding and sibship. However, the vast majority of studies in this area are plagued by serious methodological shortcomings, particularly the reliance on retrospective recall of information making it difficult to truly ascertain the importance of a 'hygiene hypothesis' in IBD. The 'hygiene hypothesis' in IBD is an important area of research that may give clues to the aetiology of this disease. Directions for future research are recommended.

[Environmental risk factors in Crohn's disease and ulcerative colitis (excluding tobacco and appendicectomy)]

A rapid increase in the incidence of Crohn's disease and ulcerative colitis in developed countries, the occurrence of Crohn's disease in spouses, and a lack of complete concordance in monozygotic twins are strong arguments for the role of environmental factors in inflammatory bowel disease (IBD). Research in the field of environmental factors in IBD is based upon epidemiological (geographical and case-control), clinical and experimental studies. The role of two environmental factors has clearly been established in IBD. Smoking is a risk factor for Crohn's disease and a protective factor for ulcerative colitis; appendectomy is a protective factor for ulcerative colitis. Many other environmental factors for IBD have been investigated, including infectious agents, diet, drugs, stress and social status. They are detailed in the present review. Among them, atypical Mycobacteria, oral contraceptives and antibiotics could play a role in Crohn's disease. To date, three hypotheses associate environmental factors with the pathophysiology of IBD (loss of tolerance of intestinal immune system towards commensal bacterial flora): the hygiene, infection and cold chain hypotheses. Much work remains to be done to identify risk factors for IBD. Research identifying environmental factors that might cause a predisposition to IBD is useful. It may lead to disease prevention in subjects who are genetically predisposed and disease improvement in patients.

Epitope shared by functional variant of organic cation/carnitine transporter, OCTN1, Campylobacter jejuni and Mycobacterium paratuberculosis may underlie susceptibility to Crohn’s disease at 5q31

Campylobacter jejuni and Mycobacterium paratuberculosis have been implicated in the pathogenesis of Crohn's disease. The presence of bacterial metabolites in the colonic lumen causing a specific breakdown of fatty acid oxidation in colonic epithelial cells has been suggested as an initiating event in inflammatory bowel disease (IBD). l-Carnitine is a small highly polar zwitterion that plays an essential role in fatty acid oxidation and ATP generation in intestinal bioenergetic metabolism. The organic cation/carnitine transporters, OCTN1 and OCTN2, function primarily in the transport of l-carnitine and elimination of cationic drugs in the intestine. High-resolution linkage disequilibrium mapping has identified a region of about 250kb in size at 5q31 (IBD5) encompassing the OCTN1 and -2 genes, to confer susceptibility to Crohn's disease. Recently, two variants in the OCTN1 and OCTN2 genes have been shown to form a haplotype which is associated with susceptibility to Crohn's. We show that OCTN1 and OCTN2 are strongly expressed in target areas for IBD such as ileum and colon. Further, we have now identified a nine amino acid epitope shared by this functional variant of OCTN1 (Leu503Phe) (which decreases the efficiency of carnitine transport), and by C. jejuni (9 aa) and M. paratuberculosis (6 aa). The prevalence of this variant of OCTN1 (Phe503:Leu503) is 3-fold lower in unaffected individuals of Jewish origin (1:3.44) compared to unaffected individuals of non-Jewish origin (1:1). We hypothesize that a specific antibody raised to this epitope during C. jejuni or M. paratuberculosis enterocolitis would cross-react with the intestinal epithelial cell functional variant of OCTN1, an already less efficient carnitine transporter, leading to an impairment of mitochondrial beta-oxidation which may then serve as an initiating event in IBD. This impairment of l-carnitine transport by OCTN1 may respond to high-dose l-carnitine therapy.

Detection of species-specific helicobacter ribosomal DNA in intestinal biopsy samples from a population-based cohort of patients with ulcerative colitis

The inflammatory bowel diseases are considered an abnormal host immune response to an environmental stimulus. Evidence suggests a role for intestinal bacteria in initiating and/or providing an ongoing stimulus for inflammation in inflammatory bowel disease. Helicobacter pylori is the major cause of active chronic gastritis and peptic ulcers in humans and has been linked to gastric carcinoma and lymphoma. Studies in various animal models, particularly mice, have identified enterohepatic Helicobacter species that are capable of causing hepatitis and enterocolitis. We hypothesize that Helicobacter species may have a role in maintaining inflammation in humans with inflammatory bowel disease. In order to investigate this, biopsy specimens were obtained from patients with and without inflammatory bowel disease. DNA was extracted from the tissues and subjected to PCR with primers designed to detect the ribosomal DNA of members of the Helicobacter species. DNA from six biopsy samples from 60 inflammatory bowel disease patients tested positive. This included 5 of 33 ulcerative colitis patients that were positive compared to 0 of 29 age-matched controls (P < 0.04). Sequencing of the bands produced by PCR amplification revealed >or=99% homology with H. pylori. These results indicate that a member of the Helicobacter species may be involved in some cases of ulcerative colitis.

MMR Vaccination and Autism

It has been suggested that vaccination with the measles-mumps-rubella (MMR) vaccine causes autism. The wide-scale use of the MMR vaccine has been reported to coincide with the apparent increase in the incidence of autism. Case reports have described children who developed signs of both developmental regression and gastrointestinal symptoms shortly after MMR vaccination.A review of the literature revealed no convincing scientific evidence to support a causal relationship between the use of MMR vaccines and autism. No primate models exist to support the hypothesis. The biological plausibility remains questionable and there is a sound body of epidemiological evidence to refute the hypothesis. The hypothesis has been subjected to critical evaluation in many different ways, using techniques from molecular biology to population-based epidemiology, and with a vast number of independent researchers involved, none of which has been able to corroborate the hypothesis.

Communicating science to the public: MMR vaccine and autism

Media attention and consequent public concerns about vaccine safety followed publication of a small case-series of children who developed autism after receipt of the measles-mumps-rubella (MMR) vaccine. Many well-controlled studies performed subsequently found no evidence that MMR vaccine causes autism. However, despite these studies, some parents remain concerned that the MMR vaccine is not safe. We will discuss the origins of the hypothesis that the MMR vaccine causes autism, studies performed to test the hypothesis, how these studies have been communicated to the public, and some suggested strategies for how this communication can be improved.

Cytokine tissue levels as markers of disease activity in pediatric Crohn disease

The mucosal immune system is overactivated in Crohn disease (CD) and viral infections have been associated with clinical exacerbations. To investigate the potential association between mucosal inflammation and the cytokines involved in the early response to viruses, we analyzed colonic tissue levels of IL-2Ralpha, interferon-alpha, and IL-15 in CD. Patients undergoing diagnostic colonoscopy were classified into controls (n = 22) and three CD groups based on the histologic severity of inflammation and clinical activity: a) severely active CD (n = 3); b) mild to moderately active CD (n = 14); and c) quiescent CD (n = 23). Rectal biopsies (two per patient) were homogenized and cytokine levels determined by ELISA kits. Statistical analysis was performed by ANOVA with Tukey and Scheffé tests. IL-2Ralpha levels were increased in the active CD group compared with the quiescent CD group: a) 405 +/- 87, b) 159 +/- 31, and c) 33 +/- 15 pg/mg DNA (p < 0.001). The latter group was similar to controls (39 +/- 20 pg/mg DNA). Furthermore, a linear correlation (r = 0.98) between IL-2Ralpha and disease activity (Van Hees index) was observed. IL-15 levels were also higher in active compared with quiescent CD and controls: a) 0.69 +/- 0.23 and b) 0.72 +/- 0.31 versus c) 0.28 +/- 0.21 and 0.28 +/- 0.14 pg/mg DNA for controls (p < 0.05). Interferon-alpha levels were undetectable in all samples. Our data suggest that IL-2Ralpha tissue levels correlate with CD activity. IL-15 is also overproduced in inflamed CD tissue. The lack of a parallel elevation of interferon-alpha does not support a role for viral induction of IL-15 in inflamed CD samples.

Measles-mumps-rubella vaccine and the development of autism

The measles-mumps-rubella (MMR) vaccine has been postulated to cause a form of autism characterized by regression and bowel symptoms, and onset occurring shortly after vaccination. It is also claimed that, as a result, there has been a dramatic increase in autism prevalence. These hypotheses have now been tested in a number of epidemiologic studies that are reviewed in this article. None has found any evidence of the existence of a phenotypically distinct form of autism in children who received the MMR vaccine or of a clustering of onset symptoms in children who are autistic after receiving the MMR vaccine. There is no proof that the overall risk of autism is higher in children who were vaccinated with MMR or of an increase in autism prevalence associated with the use of the MMR vaccine. No epidemiologic evidence suggests an association between MMR vaccination and autism. Moreover, epidemiologic evidence against such an association is compelling.

Comparative evaluation of measles virus-specific RT-PCR methods through an international collaborative study

Comparison of RT-PCR assays established in house at various places revealed that laboratories could differ in sensitivity by as much as 1,000-fold in terms of the ability to detect measles virus sequences in clinical samples. The study indicates that PCR findings, positive or negative, are questionable if they are not supported by the associated data demonstrating the overall sensitivity of the assay applied. Measles virus-specific RT-PCR-based assays need to be validated using standard virus preparation or nucleic acid-based target templates. A correlation between real-time quantitative PCR and the conventional PCR for measles virus is highly desirable.

Does the MMR vaccine and secretin or its receptor share an antigenic epitope?

In a subgroup of children with autism-spectrum like conditions symptoms seem to appear as a 'regression' (in normal development). It has been postulated that the onset of such autistic symptoms may involve an autoimmune response against the central nervous system and that the antigenic determinant could possibly be gastrointestinal in origin. It has been suggested that the presence of the measles virus and 'autistic enterocolitis' demonstrates the possibility that the MMR triple vaccine may be mediating the inflammation with possible production of antibodies against the virus containing vaccine. Such an antibody may share antigenic determinant to molecules found in the gut. We propose that this may be secretin or its receptor, found in the gut as well as in the central nervous system. The antibody response to the gut may also conceivably occur in the brain at a critical time in development. The modulation of development by secretin may be a static event possibly occurring at a specific time in early childhood development and if it involves an autoimmune response then a disruption in development may result. These hypothesized events can only occur if the MMR vaccine shares antigenic determinants that resemble secretin or any of its receptor types and remains to be studied.

Etiopathogenesis of inflammatory bowel disease: the importance of the pediatric perspective

Inflammatory bowel disease (IBD) is now recognized as a common chronic disease affecting children and adolescents. This article will review recent advances made in the fields of genetics, epidemiology, gut ecology, and immunology regarding the etiopathogenesis of IBD, with particular emphasis on the contributions made by pediatric studies. Areas where further study of the pediatric age group would be beneficial will be highlighted.

The bacterial flora in inflammatory bowel disease: current insights in pathogenesis and the influence of antibiotics and probiotics

The pathogenesis of inflammatory bowel disease (IBD) remains unknown, although in recent years more data have become available. The contribution of genetic and environmental factors is evident, and the luminal bacterial flora plays a major role in the initiation and perpetuation of chronic IBD. Animal models of IBD have shown that colitis does not occur in a germ-free environment. In human IBD, inflammation is present in parts of the gut containing the highest bacterial concentrations. Moreover, the terminal ileum, caecum and rectum are areas of relative stasis, providing prolonged mucosal contact with luminal contents. Enhanced mucosal permeability may play a pivotal role in maintaining a chronic inflammatory state, due to a genetic predisposition or as a result of direct contact with bacteria or their products. A detective epithelial barrier may cause a loss of tolerance to the normal enteric flora. Furthermore, an increased mucosal absorption of viable bacteria and bacterial products is found in IBD. Serum and secreted antibodies are increased and mucosal T-lymphocytes that recognize luminal bacteria are present. However, there is evidence that the immune system reacts over aggressively towards the normal luminal flora rather than the flora being altered in IBD. Several approaches have been used in attempts to discover a specific microbial agent in the cause of IBD. These include demonstration of the presence of organisms or specific antigens in affected tissues, culture of microbes firm the affected tissues, demonstration of serological responses to several agents, and localization and detection of individual pathogen-specific nucleic acid sequences in affected tissue by in situ hybridization and polymerase chain reaction. So far, no specific micro-organism has been directly associated with the pathogenesis of IBD. Analysis of the luminal enteric flora, however, has revealed differences in the composition of this flora compared to healthy controls. In Crohn disease, concentrations of Bacteroides, Eubacteria and Peptostreptococcus are increased, whereas Bifidobacteria numbers are significantly reduced. Furthermore, in ulcerative colitis, concentrations of facultative anaerobic bacteria are increased. The arrival of new molecular techniques qualifying and quantifying the complex intestinal flora has induced a revival of interest in this microflora. Therapeutic approaches geared towards changing the environment at the mucosal border have been attempted by the use of elemental diets, total parenteral nutrition, surgical diversion of the faecal stream and antibiotics. Over the past few years, the use of probiotics in IBD and other intestinal disorders has gained attention. Strengthened by promising experimental data and commercial interests, research in this field is rapidly expanding. Manipulation of the colonic bacteria with antibiotic drugs and probiotic agents may prove to be more effective and better tolerated than immunosuppressants in the future.

Measles vaccination and inflammatory bowel disease: controversy laid to rest?

The increasing incidence of Crohn's disease has lead to speculation about changes in exposures to environmental or infectious agents. Considerable attention has focused on the role of measles infection and/or vaccination in the pathogenesis of Crohn's disease and ulcerative colitis. Current evidence regarding the association between measles vaccination and inflammatory bowel disease (IBD) comprises analytic epidemiological studies, a case-series report and ecological studies. The first of these, a 1995 cohort study, found an association between measles vaccination and Crohn's disease and ulcerative colitis, but was widely questioned on methodological grounds. This was followed by a 1997 case-control study showing no association between measles vaccination and IBD. In 1998, public concern was rekindled by a report of 12 children with nonspecific colitis, ileal-lymphoid-nodular hyperplasia, and developmental disorders largely attributed to measles-mumps-rubella vaccine, but the nature of the report limited its scientific conclusions. Two additional studies, one case-control and one cohort, then followed and neither found an association with measles vaccination. Of the several ecological studies of measles vaccine coverage or measles schedule changes, none found an association with rates of IBD. The role of measles infection in IBD has been examined more extensively with studies of in utero measles exposure, measles infection early in life, and laboratory based investigations. An initial report of high rates of Crohn's disease among pregnancies affected by measles infection was followed by negative studies. Numerous case-control and ecological studies of children with measles infections early in life have also had discordant findings. Of three recent cohort studies, two showed no relationship between infection with early measles exposure and risk for IBD, while one found an approximate 3-fold elevation in risk. Laboratory investigations into persistent measles infection and IBD have been contentious. While some investigators have claimed to find persistent measles infection among patients with IBD, others, using highly sensitive polymerase chain reaction techniques, have not been able to replicate the findings. Recent controversy has centred on whether there is any evidence for molecular mimicry in the pathogenesis of IBD. In summary, available evidence does not support an association between measles-containing vaccines and risk of IBD, nor between measles infection and IBD. While further research is necessary into the causal factors underlying Crohn's disease and ulcerative colitis, continued public education efforts are needed to reassure the public about vaccine safety and to prevent declines in vaccine coverage.

Challenges to vaccine safety

The end of the 20th century saw the realization of a goal that was previously only dreamed about: the near elimination of many deadly infectious diseases through universal vaccination. As one disease after another has been driven from memory, it is vaccination programs themselves that have come to occupy the public's mind. With increased scrutiny comes the promise that vaccines will become even safer, but there is also the threat that ill-founded concerns will result in reduced immunization rates, and diseases will resurge. This article reviews scientific data relating to current vaccine safety concerns.

Routine childhood immunizations

The immunizations recommended in the 2001 Childhood Immunization Schedule are safe and effective. Newly approved vaccines, like the pneumococcal conjugate vaccine, hold the promise of eliminating or dramatically reducing persistent causes of childhood morbidity and mortality in the United States.

Measles is more prevalent in Crohn's disease patients. A multicentre Israeli study

The question whether there is a transmissible pathogenetic agent as a cause for Crohn's disease, remains unanswered. Measles virus has been the subject of many intensive studies, in the attempt to find a role for it in the pathogenesis of inflammatory bowel disease. Whether an early infection with measles virus may predispose to Crohn's disease in later life is still not clear. We conducted a large scale multicentre study, in order to obtain sufficient data to answer this question. To do so, we compared inflammatory bowel disease patients, with Crohn's disease or ulcerative colitis, with two matched control groups: clinical controls, and community controls. A total of 531 patients, 271 with ulcerative colitis and 260 with Crohn's disease were interviewed, as well as 903 matched controls. Blood from 104 inflammatory bowel disease patients and 50 controls was tested for antibodies to measles virus. We did not find any differences related to measles vaccination, either in Crohn's disease or in ulcerative colitis. Exposure to measles in childhood was more frequent in Crohn's disease patients than in their controls, the difference being statistically significant (p < 0.05) in relation to community controls. The presence of IgG antibodies to measles virus was higher in patients with Crohn's disease than in patients with ulcerative colitis or controls (p = 0.084). Another observation of interest was the finding that Crohn's disease patients who had measles in childhood, more frequently had large bowel disease than those who had not had measles. These data lead us to postulate that there may be a role for measles infection in Crohn's disease, even if, at present, this role remains unclear.

Measles-mumps-rubella vaccine and autistic spectrum disorder: report from the New Challenges in Childhood Immunizations Conference convened in Oak Brook, Illinois, June 12-13, 2000

BACKGROUND

Parents and physicians are understandably concerned about the causes and treatment of autism, a devastating disease that affects the entire family. Although much has been learned about autism, there are many gaps in our knowledge about what causes the disorder and how it can be prevented. Autistic symptoms occur along a spectrum, often referred to as autistic spectrum disorder (ASD). Concern has been raised about a possible association between measles-mumps-rubella (MMR) vaccine and inflammatory bowel disease (IBD) and ASD, especially autism with regression. Also, increased requests for educational services related to ASD have raised concerns about possible increases in the incidence of ASD.

METHODS

On June 12-13, 2000, the American Academy of Pediatrics (AAP) convened a conference titled "New Challenges in Childhood Immunizations" in Oak Brook, Illinois. At this conference, parents, practitioners, and scientists presented information and research on MMR vaccine and ASD. Attendees included representatives from select AAP committees and sections as well as federal and other organizations that address related issues. The multidisciplinary panel of experts reviewed data on what is known about the pathogenesis, epidemiology, and genetics of ASD and the available data on hypothesized associations with IBD, measles, and MMR vaccine. Supplemental information was requested from authors who have proposed the hypotheses and other experts in relevant areas.

RESULTS

Autism is a complex disorder of uncertain and probably multiple etiologies. Genetic predisposition to ASD may involve as many as 10 genes. Many experts believe that the abnormal brain development in autism occurs before 30 weeks' gestation in most instances. In utero rubella is a known cause of autism. Animal model data support the biologic plausibility that exposure to yet unrecognized infectious or other environmental agents could cause ASD. Several factors may contribute to apparent increases in incidence of ASD in recent years. Most data indicate increased recognition and reporting as primary factors, but the epidemiologic data are insufficient to determine if there has been a true increase in the incidence of ASD. Increased reporting of ASD in recent years has occurred long after the introduction of MMR vaccine in the United States in 1971 and widespread use of this vaccine in the 1970s for routine immunization of children at 12 to 15 months of age. Appropriate detailed studies are needed to define the true incidence and prevalence of ASD. Epidemiologic studies in Europe indicate no association between MMR vaccine and ASD. Some children with ASD have gastrointestinal symptoms, but an increased rate of any specific gastrointestinal disorder in children with ASD has not been established. Studies to detect evidence of measles virus in intestinal tissue specimens from patients with IBD or autism with gastrointestinal symptoms have not used uniform techniques. Several laboratories have found no evidence of measles viruses in tissue specimens from patients with IBD, but 2 groups have found evidence of measles virus using different techniques. A group that found evidence of measles virus in affected tissue specimens from patients with IBD has also reported detecting portions of measles virus in peripheral blood lymphocytes and intestinal tissue specimens from patients with autism and gastrointestinal disorders. Finding a portion of a virus using molecular techniques does not constitute evidence for a causal relationship, because some viruses persist in unaffected hosts. Additional controlled studies in several laboratories are needed to determine if portions of measles virus persist in intestinal and other tissues of people with and without gastrointestinal disease and/or ASD.

CONCLUSIONS

Although the possible association with MMR vaccine has received much public and political attention and there are many who have derived their own conclusions based on personal experiences, the available evidence does not support the hypothesis that MMR vaccine causes autism or associated disorders or IBD. Separate administration of measles, mumps, and rubella vaccines to children provides no benefit over administration of the combination MMR vaccine and would result in delayed or missed immunizations. Pediatricians need to work with families to ensure that children are protected early in the second year of life from these preventable diseases. Continued scientific efforts need to be directed to the identification of the causes of ASD.

No evidence of persistent mumps virus infection in inflammatory bowel disease

BACKGROUND AND AIM

There is controversy regarding whether paramyxovirus infection is causally associated with inflammatory bowel disease (IBD). The latest cohort study claimed that atypical measles and mumps infections in childhood may be risk factors for later IBD. This study was conducted to clarify the validity of a causal link between persistent mumps virus infection and IBD.

SUBJECTS AND METHODS

(1) Amplification of the mumps virus genome was performed in both intestinal specimens (ulcerative colitis 15, Crohn's disease 15, control 10) and peripheral blood lymphocytes (PBL) (ulcerative colitis seven, Crohn's disease six, control three) by reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern hybridisation using primers specific to the viral genome encoding phosphoprotein or haemagglutinin-neuraminidase. (2) Titre of serum antimumps IgG was measured in 16 patients with ulcerative colitis, in 16 patients with Crohn's disease, and in 16 normal controls using an enzyme linked immunosorbent assay.

RESULTS

(1) The mumps virus genome was not detected by RT-PCR in intestinal specimens or PBL in any case. (2) Antimumps IgG titre was positive in 7/16 ulcerative colitis, 10/16 Crohn's disease, and 11/16 control specimens. The mean (SEM) titre of antimumps IgG was 12.281 (7.831) in ulcerative colitis, 7.675 (1.608) in Crohn's disease, and 8.637 (1.969) in controls, with no significant difference between the three groups.

CONCLUSION

We could not find any evidence to support a causal link between persistent mumps virus infection and IBD.

Measles virus and Crohn's disease: a critical appraisal of the current literature

The etiology of inflammatory bowel disease (IBD) is unknown. Recent reports in the literature have suggested that measles virus, both wild-type and vaccine-attenuated, might be a risk factor for Crohn's disease. We used the well-accepted Bradford-Hill criteria to evaluate the possible causal association between measles and IBD. Although the association may be biologically plausible, the literature lacks consistency, specificity, strength, and dose response. The current literature does not support an association between measles virus and IBD.

Measles vaccination and inflammatory bowel disease: a national British Cohort Study

OBJECTIVE

Measles vaccination has been suggested as a risk for inflammatory bowel disease. Atypical age of measles infection has also been associated with Crohn's disease. This study was designed to examine the relationship of measles vaccination and age of measles vaccination with later inflammatory bowel disease.

METHODS

A prospective population-based national birth cohort was used, of those born in 1 wk in April 1970 in Great Britain. The data are from 7616 responding members of the 1970 British Cohort Study with complete vaccination data, who were traced at age 26 yr. A diagnosis of Crohn's disease, ulcerative colitis, and diabetes mellitus (a control disease) was obtained by survey at age 26 yr, and confirmed by physicians. Vaccination data were from survey at age 5 yr. Measles and mumps infection data were obtained from the survey at age 10 yr. Adjustment was made for sex, household crowding in childhood, and father's social class at birth.

RESULTS

No statistically significant association was found between measles vaccination status at 5 yr and Crohn's disease (adjusted odds ratio [OR] 0.67, 95% confidence interval [CI] 0.27-1.63), ulcerative colitis (adjusted OR 0.57, 95% CI 0.20-1.61), or diabetes (adjusted OR 0.75, 95% CI 0.33-1.74). There was a statistically significant trend (p = 0.040) with increasing age of measles vaccination for risk of Crohn' s disease, although this was based on very few cases vaccinated after age 2 yr.

CONCLUSIONS

In this cohort, monovalent measles vaccination status is not associated with inflammatory bowel disease by age 26 yr. Older age at measles vaccination needs to be examined in other studies to confirm whether it is a genuine risk for Crohn's disease.

Further evidence of the absence of measles virus genome sequence in full thickness intestinal specimens from patients with Crohn's disease

Specimens of macroscopically inflamed and normal intestine along with mesenteric lymph nodes were obtained at resection from patients with Crohn's disease. The samples were systematically examined by RT-PCR-nested PCR targeting N, M and H gene regions of the measles virus genome. None of the samples examined gave any evidence of the persistence of measles virus in the intestine of Crohn's disease patients. The study supports previous findings produced by this laboratory and others using highly sensitive measles virus specific PCR diagnostic technology.

Safety of routine childhood vaccinations. An epidemiological review

Immunisations have been one of the most cost-effective public health interventions in human history. Despite remarkable progress, several challenges face immunisation programs worldwide. Paradoxically, despite vaccines' clear effectiveness in reducing risks of diseases that were previously widely prevalent and caused substantial morbidity and mortality, current vaccination policies have become increasingly controversial due to concerns about vaccine safety. Vaccines, like other pharmaceutical products, are not entirely risk-free. While most known adverse effects are minor and self-limited, some vaccines have been associated with very rare but serious adverse effects. Because such rare effects are often not evident until vaccines come into widespread use, ongoing surveillance programs to monitor vaccine safety are needed. Such monitoring will be essential if the public is to accept the increasing number of new vaccines made possible by biotechnology. The interpretation of data from vaccine safety research is complex and is associated with some uncertainty. Effectively communicating this uncertainty and continuing to improve understanding of rare risks and risk factors are essential for "mature" immunisation programs to maintain public confidence in immunisations.

A comparison of methotrexate with placebo for the maintenance of remission in Crohn's disease. North American Crohn's Study Group Investigators

BACKGROUND

Patients with Crohn's disease often have relapses. Better treatments are needed for the maintenance of remission. Although methotrexate is an effective short-term treatment for Crohn's disease, its role in maintaining remissions is not known.

METHODS

We conducted a double-blind, placebo-controlled, multicenter study of patients with chronically active Crohn's disease who had entered remission after 16 to 24 weeks of treatment with 25 mg of methotrexate given intramuscularly once weekly. Patients were randomly assigned to receive either methotrexate at a dose of 15 mg intramuscularly once weekly or placebo for 40 weeks. No other treatments for Crohn's disease were permitted. We compared the efficacy of treatment by analyzing the proportion of patients who remained in remission at week 40. Remission was defined as a score of 150 or less on the Crohn's Disease Activity Index.

RESULTS

Forty patients received methotrexate, and 36 received placebo. At week 40, 26 patients (65 percent) were in remission in the methotrexate group, as compared with 14 (39 percent) in the placebo group (P=0.04; absolute reduction in the risk of relapse, 26.1 percent; 95 percent confidence interval, 4.4 percent to 47.8 percent). Fewer patients in the methotrexate group than in the placebo group required prednisone for relapse (11 of 40 [28 percent] vs. 21 of 36 [58 percent], P=0.01). None of the patients who received methotrexate had a severe adverse event; one patient in this group withdrew because of nausea.

CONCLUSIONS

In patients with Crohn's disease who enter remission after treatment with methotrexate, a low dose of methotrexate maintains remission.

Early measles virus infection is associated with the development of inflammatory bowel disease

OBJECTIVE

The measles virus has been implicated as a possible etiological agent in the development of inflammatory bowel disease (IBD). Measles infection at an early age is associated with subacute sclerosing panencephalitis, a degenerative neurological condition caused by persistent measles infection of the central nervous system. We sought to determine whether infection with measles virus at an early age was also associated with an increased risk of developing IBD.

METHODS

Patients with measles infection diagnosed before the age of 5 yr were identified through the diagnostic indices of the Mayo Clinic and the Rochester Epidemiology Project. A questionnaire was used to ascertain a subsequent history of IBD, which was confirmed by records from the subjects' physicians. The risks of developing Crohn's disease and ulcerative colitis were calculated relative to expected rates for these conditions in the Olmsted County, Minnesota population.

RESULTS

Of 1164 eligible cases, 662 (57%) completed the questionnaire. There were six confirmed cases of Crohn's disease and six of ulcerative colitis. The expected number of cases was 1.9 for Crohn's disease (standardized incidence ratio [SIR] 3.1, 95% confidence interval [CI] 1.1-6.8) and 2.0 for ulcerative colitis (SIR 3.0, CI 1.1-6.5). There was a trend towards a higher risk of developing IBD with an earlier age of infection.

CONCLUSIONS

Early measles infection is associated with an increased risk of developing Crohn's disease and ulcerative colitis. The risk may be higher with earlier infection.

Endothelial cell autoantibodies are a marker of disease susceptibility in inflammatory bowel disease but apparently not linked to persistent measles virus infection

Intestinal vasculitis caused by persistent measles virus infection of intestinal endothelial cells was described in Crohn's disease. Furthermore, endothelial cell autoantibodies have been demonstrated in inflammatory bowel disease (IBD). Autoantibodies against intestinal endothelial cells were visualized by indirect immunofluorescence in patients with IBD, in their healthy first-degree relatives, in patients with infectious enterocolitis, and in healthy, unrelated controls. In intestinal tissue specimens of 22 antibody-positive IBD patients a search for the measles virus genome was performed. Endothelial cell autoantibodies were significantly more frequent in patients with IBD, in both groups of first-degree relatives, and in patients with infectious enterocolitis than in the healthy controls (P = 0.0002 or less). The measles virus genome was found in none of the intestinal biopsies. Endothelial cell autoantibodies are not a genetic but rather an epigenetic (infectious) marker of disease susceptibility. The expression of these autoantibodies is unlikely to be triggered by a persistent measles virus infection.

Detection and sequencing of measles virus from peripheral mononuclear cells from patients with inflammatory bowel disease and autism

It has been reported that measles virus may be present in the intestine of patients with Crohn's disease. Additionally, a new syndrome has been reported in children with autism who exhibited developmental regression and gastrointestinal symptoms (autistic enterocolitis), in some cases soon after MMR vaccine. It is not known whether the virus, if confirmed to be present in these patients, derives from either wild strains or vaccine strains. In order to characterize the strains that may be present, we have carried out the detection of measles genomic RNA in peripheral mononuclear cells (PBMC) in eight patients with Crohn's disease, three patients with ulcerative colitis, and nine children with autistic enterocolitis. As controls, we examined healthy children and patients with SSPE, SLE, HIV-1 (a total of eight cases). RNA was purified from PBMC by Ficoll-paque, followed by reverse transcription using AMV; cDNAs were subjected to nested PCR for detection of specific regions of the hemagglutinin (H) and fusion (F) gene regions. Positive samples were sequenced directly, in nucleotides 8393-8676 (H region) or 5325-5465 (from noncoding F to coding F region). One of eight patients with Crohn disease, one of three patients with ulcerative colitis, and three of nine children with autism, were positive. Controls were all negative. The sequences obtained from the patients with Crohn's disease shared the characteristics with wild-strain virus. The sequences obtained from the patients with ulcerative colitis and children with autism were consistent with being vaccine strains. The results were concordant with the exposure history of the patients. Persistence of measles virus was confirmed in PBMC in some patients with chronic intestinal inflammation.

Immunohistochemical analysis of the distribution of measles related antigen in the intestinal mucosa in inflammatory bowel disease

BACKGROUND

Measles virus is implicated in the aetiology of Crohn's disease. This measles hypothesis is mainly supported by immunohistochemical findings that the measles related antigen is present in the intestine of patients with Crohn's disease. Recently we isolated this antigen from the intestine of a patient with Crohn's disease using a molecular cloning technique and produced the monoclonal antibody against it (designated 4F12).

AIM

To discover whether the measles related antigen is uniquely present in Crohn's disease.

SUBJECTS/METHODS

Colonic mucosa samples from 20 patients with Crohn's disease, 20 with ulcerative colitis, 11 with non-inflammatory bowel disease (IBD) colitis, and nine controls were immunohistochemically stained with the anti-measles monoclonal antibody 4F12. The numbers of positive cells, the ratio of positive cells to nucleated cells, and the staining intensity of the positive cells were compared. Furthermore, the distribution of the measles antigen in other human organs was examined.

RESULTS

Both the number of positive cells and the ratio of positive cells to nucleated cells were significantly increased in Crohn's disease, ulcerative colitis, and non-IBD colitis compared with controls (p<0.05) but were similar among the three disease groups. The staining intensity of the positive cells was also similar among the three disease groups. Small numbers of positive cells were observed in the oesophagus, stomach, duodenum, jejunum, and lung.

CONCLUSIONS

The presence of the measles related antigen in the colonic mucosa was not unique to Crohn's disease. These results, together with the observation that such a measles related antigen was derived from host protein, do not support the hypothesis that measles virus causes Crohn's disease.

Viruses and inflammatory bowel disease: is there evidence for a causal association?

There has been a resurgent interest in potential microbial etiologies of inflammatory bowel disease (IBD). Over the past decade there have been both epidemiological and tissue studies exploring the potential role of paramyxoviruses in IBD, particularly Crohn's disease. This article will review the evidence and hence plausibility of a causal association between these viruses and IBD.

Epstein-Barr virus infection of the colon with inflammatory bowel disease

OBJECTIVE

Epstein-Barr virus (EBV)-infected cells can evoke severe host immune responses, as shown in infectious mononucleosis and EBV-associated gastric carcinoma. To investigate the possible pathological role of EBV in inflammatory bowel disease (IBD), we tested for the presence of EBV in the colon in IBD patients.

METHODS

Surgically resected colonic specimens of 11 patients with Crohn's disease, five patients with ulcerative colitis, nine noninflammatory controls (disease-free area of the colorectal carcinoma), and 10 appendicitis cases were tested using highly sensitive in situ hybridization for EBV-encoded small RNA1 (EBER-1).

RESULTS

EBER-1 was detected in 63.6% of Crohn's disease cases and 60% of ulcerative colitis cases, but not at all in noninflammatory controls and appendicitis cases. EBER-1-positive cells were very rare in the noninflammatory areas of colonic specimens from IBD patients. EBER-1-positive cells were nonepithelial cells (mainly B lymphocytes and a few histiocyte-shaped cells) located in erosive or ulcerative areas of the colonic specimens.

CONCLUSION

The limited presence of EBV-infected cells in the diseased areas of IBD colonic specimens indicated that EBV infection may be related to such diseases.