Displaying 1-7 letters out of 7 published
Differentiation of MRSA and MRSE by rapid molecular assay
I read with interest in the molecular testing approach described by J.E. Moore et al. This testing approach utilizes the Oxoid salt meat broth (without selective reagents or antimicrobials) to enhance bacterial growth from the screening swabs. The molecular assay was based on the facts that the mecA gene locus is present in both MRSE and methicillin-resistant Staphylococcus aureus (MRSA) and that the femB gene is present only in Staphylococcus aureus (regardless of susceptibility to methicillin).
In their study of screening swabs obtained from the 75 patients, 2 patients were found to be have MRSA by the PCR assay (positive for both mecA and femB; lane 6 in Figure 1). However, a swab containing both MRSE and methicillin-susceptible S. aureus (MSSE), present simultaneously in the same patient, could also yield the same positive results for both genetic loci. How would this rapid molecular assay be able to differentiate between a patient colonized with MRSA and a patient colonized with both MSSA and MRSE (a more common clinical finding)?
J E Moore, B C Millar, M Crowe, J Buchanan, M Watabe, P G Murphy, X Yongmin, K Milligan, and A McClelland. Molecular determination of carriage of the mecA locus in coagulase negative staphylococci in screening swabs from patients in an intensive care unit. Mol Pathol 2003;56:63.
Does leptin resistance contribute to infections in patients with diabetes?
Leptin is a protein hormone structurally similar to IL-2, which regulates food intake and metabolic and endocrine function. It has an important role in regulatory role in the immune response mainly acting as a T cell growth factor. Moreover, it also effects cytokine production, monocyte/macrophage activation, wound healing, angiogenesis and hamatopoiesis. Leptin concentrations rapidly increase during infection and inflammation. Low levels of leptin which may occur in starvation or malnutrition is associated with impaired cellular immunity, impaired delayed type hypersensitive responses and thymic atrophy contributing to increased susceptibility to infection.
High leptin concentrations are seen in obese and diabetic individuals, the concentrations of leptin rising with increasing insulin resistance. However, despite high leptin levels there is leptin resistance or defective leptin in these individuals. Therefore, leptin resistance, along with many other factors may also contribute to the increase incidence of infection seen among diabetic patients. Diabetic patients are more susceptible to infections such as tuberculosis and candidiasis, which require a good cellular immune response to overcome infection. Since, leptin is important in the regulation of the cellular immune responses leptin resistance may be a contributing factor for th high incidence of such infections. Therefore, the role of leptin in infections in diabetic patients should be further examined.
(1) Fantuzzi G, Faggioni R. Leptin in the regulation of immunity, inflammation, and hematopoiesis. J Leukoc Biol 2000 Oct;68(4):437-46
(2) Matarese G. Leptin and the immune system: how nutritional status influences the immune response. Eur Cytokine Netw 2000 Mar;11(1):7-14
(3) Fischer S, Hanefeld M, Haffner SM, Fusch C, Schwanebeck U, Kohler C, Fucker K, Julius U. Insulin-resistant patients with type 2 diabetes mellitus have higher serum leptin levels independently of body fat mass. Acta Diabetol 2002 Sep;39(3):105-10
(4) Lee JH, Reed DR, Price RA. Leptin resistance is associated with extreme obesity and aggregates in families. Int J Obes Relat Metab Disord 2001 Oct;25(10):1471-3.
A new syndrome requires essential clinical and developmental descriptive data
The study by Ulhmann et al. published recently  is the third empirical article from Wakefield and colleagues supposedly describing a new syndrome of which a form of autism might be a component. Thus, it was surprising that Ulhmann et al. article did not contain a proper Subjects section providing the necessary background clinical characteristics which are required both for a proper evaluation of the significance of the results and for allowing replication by independent research groups. The behavioral and diagnostic characteristics of the 91 'affected' children included as patients in the paper are totally lacking. Nowhere in the paper the word 'autism' appears nor do the authors refer to regression in the developmental course of these children. Patients are vaguely described as being 'affected' with 'developmental disorders' (what is meant by this is unclear unless the disorders in question are further qualified) and the qualification of 'pervasive' for these disorders is not even used.
Earlier reports by Wakefield and colleagues [2,3] have consistently lacked basic descriptive clinical information on the research subjects. Thus, the methods used to arrive at the diagnosis of pervasive developmental disorders in these reports were unstandardized, were not uniform across subjects, and no reliability data were ever provided. Furthermore, Wakefield et al. included in their earlier series of 60 children  with 'autistic enterocolitis', 1 child with attention deficit hyperactvity disorder (ADHD), 1 child with dyslexia, and 1 child with schizophrenia. Does the 'new syndrome' apply to a subgroup of children with an autistic-spectrum disorder or does it apply to any child whose behavior deteriorates irrespective of the underlying psychiatric or developmental status? Although this is not made explicit in the study description, one must assume that the sample of 91 children studied by Uhlmann et al.  includes those children described in the two earlier reports; if so, these questions about the sample diagnostic heterogeneity need answering for the reader to make sense of these findings.
The first steps in the delineation of a new syndrome consist in a precise description of the semiological-clinical features of the syndrome in order to subsequently test for its validity using a range of epidemiological, therapeutic, genetic, or biological strategies. Wakefield and colleagues articulated that the distinctive features of the putative new syndrome ('autistic enterocolitis') were a combination of developmental regression and gastro-intestinal symptoms . Yet, they have failed to provide basic descriptive clinical data on these features. In addition to provide the diagnostic breakdown of their sample, the authors should also provide clear answers to the following questions :
· Did the 91 children in this sample have developmental regression?
· If yes, how was regression assessed? And how was it established that the development was unambiguously normal prior to the loss ?
· Which skills were lost (language? eye contact? pretend play ?)? And at what level were these skills before the loss occurred?
· At which age did the loss occur (the initial claim that the regression occurred within 14 days of MMR first immunisation was apparently subsequently abandoned by Wakefield)? How long did the regression last, and what was the subsequent pattern of development?
· What were the language and IQ levels (a basic requirement in all autism studies) of these children when assessed in Wakefield's protocol?
· What were the actual type, age of onset, duration and severity of both gastro-intestinal symptoms and neurological signs indirectly alluded to in these reports? And what was their timing relative to developmental symptoms?
One year ago, before one Institute of Medicine Committee and in other occasions, we publicly requested from Dr Wakefield that he would provide clarification about the confused clinical picture generated in his articles and communications. More than one year later, it is remarkable that no beginning of an answer has been offered and how insensitive Wakefield and coauthors have generally been to requests of clarifications coming from their peers. But it is the obvious failure of the review process, apparent in this new publication, that raises the most concerns. Whether or not autism experts were involved as reviewers of the manuscript, no care has ultimately been taken by reviewers and/or the editors to address this very basic issue of sample description, so essential for both the general readership and the scientific question. This seriously jeopardizes future attempts to replicate the findings by independent groups; and unfortunately, your decision to publish an article with such deficiencies has contributed to maintain the scientific uncertainty and confusion over this putative syndrome.
The onus should now be firmly placed on Wakefield et al. to provide measurable, quantified evidence on clinical characteristics and symptom patterns in their samples, both for the recent Uhlmann et al.'s paper and for any future publication.
Eric Fombonne, MD
Canada Research Chair in Child and Adolescent Psychiatry
Professor, McGill University
Director of the Department of Psychiatry
Montreal Children's Hospital
4018 Ste-Catherine West
Montreal H3Z 1P2
 Uhlmann V, Martin CM, Sheils O, Pilkington L, Silva I, Killalea A, Murch SB, Wakefield AJ, O'Leary JJ. Potential viral pathogenic mechanism for new variant inflammatory bowel disease. J Mol Pathol 2002;55: 84-90.
 Wakefield A, Murch S, Anthony A, et al. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet 1998;351:637-41.
 Wakefield A, Anthony A, Murch S, et al. Enterocolitis in children with developmental disorders. Am J Gastroenterol 2000;95:2285-95.
 Fombonne E, Chakrabarti S. No evidence for a new variant of measles- mumps-rubella-induced autism. Pediatrics 2001;108(4):E58.
 Halsey NA. Publication by Uhlmann et al. and commentary [electronic response to Uhlmann et al. Potential viral pathogenic mechanism for new variant inflammatory bowel disease. molpath.com 2002 http://mp.bmjjournals.com/cgi/eletters/54/6/DC1 (accessed 27 May 2002)
The value of epidemiology
We write in response to the letter by Professor John O’Leary (April 17th) and the editorial by Morris and Aldulaimi, which both mention “epidemiology” with some disdain. Morris and Aldulaimi’s claim that “epidemiology is a blunt tool”, is sadly misinformed. There are many disciplines within medical research, and each have their uses for differing research purposes. Unfortunately, researchers often fail to understand disciplines outside their own field. Questions of therapy are best answered by randomised, controlled, clinical trials. However, there are some research questions, particularly questions of aetiology and harm, which cannot usually be answered by clinical trials or case series, but require epidemiological studies. A classic example is the research finding of Sir Richard Doll and Sir Austin Bradford Hill that smoking causes lung cancer – this research question was answered by a case control study, which is an observational epidemiological study.  Case series analyses rank low on the scale of levels of evidence, but nevertheless, can be useful in describing new diseases or clinical conditions. A good example is the recognition of what we now know as HIV as a new disease, which was first described as a case series of pneumocystis carinii pneumonia in homosexual men.  However, the study of Uhlmann and colleagues, by using “controls” and comparing them to “cases” relies (ironically) on epidemiology to make its point. The User’s Guide To The Medical Literature published in JAMA provides useful guidelines for evaluating the validity and of this study. The first question we need to answer is “were there clearly identified groups that were similar with respect to important determinants of outcome other than the one of interest?”  The answer is no. Of cases, 85.5% were boys compared to 67% of controls (p <_0.01. xmlns:question="urn:x-prefix:question" the="the" age="age" range="range" of="of" cases="cases" was="was" _3-14="_3-14" years="years" compared="compared" to="to" _0-17="_0-17" for="for" controls.="controls." _3="_3" although="although" we="we" are="are" given="given" no="no" information="information" on="on" process="process" selection="selection" and="and" controls="controls" it="it" seems="seems" were="were" a="a" convenience="convenience" sample="sample" whatever="whatever" specimens="specimens" available="available" at="at" time="time" rather="rather" than="than" prospectively="prospectively" collected="collected" matched="matched" sample.="sample." also="also" specimen="specimen" collection="collection" _="_" all="all" know="know" control="control" may="may" have="have" come="come" from="from" _5="_5" ago="ago" past="past" year.="year." second="second" question:_="question:_" outcomes="outcomes" exposures="exposures" measured="measured" in="in" same="same" way="way" groups="groups" being="being" presence="presence" measles="measles" virus="virus" detected="detected" tissue="tissue" been="been" but="but" without="without" knowing="knowing" details="details" when="when" why="why" is="is" uncertain="uncertain" since="since" tests="tests" not="not" be="be" as="as" sensitive="sensitive" older="older" specimens.="specimens." diagnosis="diagnosis" developmental="developmental" disorder="disorder" unclear="unclear" diagnostic="diagnostic" whether="whether" excluded="excluded" nor="nor" case="case" definition="definition" disorder.="disorder." third="third" follow="follow" up="up" sufficiently="sufficiently" long="long" complete="complete" there="there" up.="up." fourth="fourth" temporal="temporal" relationship="relationship" correct="correct" provided="provided" current="current" study="study" can="can" refer="refer" back="back" by="by" wakefield="wakefield" et="et" al="al" his="his" _1998="_1998" where="where" support="support" hypothesis="hypothesis" that="that" ibd="ibd" followed="followed" autism.="autism." fact="fact" among="among" _12="_12" described="described" onset="onset" bowel="bowel" symptoms="symptoms" lacking="lacking" half="half" _4="_4" remaining="remaining" _6="_6" children="children" behavioural="behavioural" actually="actually" preceded="preceded" symptoms.5="symptoms.5" fifth="fifth" dose-response="dose-response" gradient="gradient" none="none" has="has" shown.="shown." does="does" estimate="estimate" risk="risk" crude="crude" odds="odds" ratio="ratio" _60.9="_60.9" _95="_95" ci="ci" _19.4-205="_19.4-205" mv="mv" with="with" this="this" syndrome="syndrome" calculated="calculated" data.="data." higher="higher" smoking="smoking" causing="causing" lung="lung" cancer="cancer" such="such" high="high" levels="levels" if="if" indeed="indeed" causal="causal" factor="factor" yet="yet" confirmed="confirmed" one="one" would="would" expect="expect" see="see" epidemiological="epidemiological" evidence="evidence" it.="it." evidence.="evidence." _6-10="_6-10" do="do" well="well" remember="remember" before="before" even="even" apply="apply" bradford-="bradford-" hill="hill" criteria="criteria" causation="causation" new="new" prerequisite="prerequisite" itself="itself" precise="precise" definition.="definition." p="p">References
(1) Doll R, Hill AB. Lung cancer and other causes of death in relation to smoking: a second report on the mortality of British doctors. Br Med J 1956;2:1071
(2) Anonymous. Pneumocystis pneumonia--Los Angeles. MMWR - Morbidity & Mortality Weekly Report 1981;30:250-2.
(3) Uhlmann V, Martin CM, Sheils O, et al. Potential viral pathogenic mechanism for new variant inflammatory bowel disease. Mol Path 2002;55:0-6
(4) Levine M, Walter S, Lee H, Haines T, Holbrook A, Moyer V. Users' guides to the medical literature. IV. How to use an article about harm. Evidence- Based Medicine Working Group. JAMA 1994;271:1615-9.
(5) Wakefield AJ, Murch SH, Anthony A, et al. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet 1998;351:637-41.
(6) Taylor B, Miller E, Farrington CP, et al. Autism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association. Lancet 1999;353:2026-9.
(7) Taylor B, Miller E, Lingam R, Andrews N, Simmons A, Stowe J. Measles, mumps, and rubella vaccination and bowel problems or developmental regression in children with autism: population study. BMJ 2002;324:393-6.
(8) DeStefano F, Chen RT. Autism and measles, mumps, and rubella vaccine: No epidemiological evidence for a causal association. J Pediatr 2000;136:125-6.
(9) Feeney M, Ciegg A, Winwood P, Snook J. A case-control study of measles vaccination and inflammatory bowel disease. The East Dorset Gastroenterology Group. Lancet 1997;350:764-6.
(10) Patja A, Davidkin I, Kurki T, Kallio MJ, Valle M, Peltola H. Serious adverse events after measles-mumps-rubella vaccination during a fourteen-year prospective follow-up. Pediatr Infect Dis J 2000;19:1127-34.
Dr C R MacIntyre
National Centre for Immunisation Research and Surveillance of Vaccine
New Children’s Hospital
Re: Publication by Uhlmann et al and commentaryDear Editor
In May 2000, Dr Neal Halsey was the senior author of an extensive review of the proceedings of a meeting convened to examine the very issues to which he alludes to in his opening paragraph . This meeting, to which we refer later in our response, was convened by the American Academy of Pediatrics (AAP) and the Centre for Disease Control and Prevention.
Dr Halsey has made certain observations in relation to our manuscript, which are dealt with below .
No differences exist for specimen collection between cases and controls. Frozen biopsies, taken from all cases and controls, having been procured with a sterilised instrument, are placed, individually, in sterile containers. The container is sealed and immersed in liquid nitrogen. It is not opened again until it reaches the laboratory of Professor O'Leary in Dublin. At the Royal Free Hospital the procedure takes place 5 floors from where any laboratory work on measles virus has been carried out. Contamination is not an issue. All paraffin-embedded material from cases and controls had similar anti-contamination procedures applied, and had no contact with any environment where measles is handled. It is notable that measles virus has also been detected in specimens sent directly to Professor O'Leary's lab from other hospitals, including those in the US. Those analysing the biopsies in Professor O'Leary's lab have no knowledge of the clinical details of case or control children. The code of the initial molecular analyses that form part of the study was broken in public.
False positive results are highly unlikely given the exactness of the controls used for TaqMan PCR, solution-phase PCR and in cell PCR. Control RNAs consistently yielded negative results, as described in the paper. Extraction controls of duplicate RNAs from cervical, breast and thyroid biopsies etc.were again, consistently negative. PCRs were set up at two geographically distant laboratories in Dublin.
In addition there was judicious use of Taq Man PCR controls, including no template (NTC), no amplification controls (NAC), no probe controls (NPC), asymmetric Taq Man PCR controls, irrelevant primers, irrelevant probe etc.
Differential detection of virus in inflamed versus normal tissue is highly unlikely since virus is not detected in ileal biopsies from children with established inflammatory diseases. In addition, gene-dosage correction assays were performed which specifically sought to address the issue of PCR inhibition, both in and between samples. Again, Dr Halsey's suggestion that we may be merely looking at persistence of portions of the measles virus in selected individuals with lymphonodular hyperplasia (LNH) is incorrect. As indicated in the paper, we did not identify MV genomes in children with isolated LNH, without co-existent developmental disorder.
The assays were designed to detect both wild type and vaccine strains of MV, and not to differentiate between them. Strain specific assignation is currently underway.
Children with developmental disorders were diagnosed on the autistic spectrum. They were investigated for gastrointestinal symptoms. The patients were consecutively investigated in order to avoid selection bias.
Biopsies were mucosal, whereas the seat of the granulomatous inflammation in Crohn's disease (the site of measles virus detection by Wakefield and others) is submucosal/serosal. The reason for including inflammatory controls was to address precisely the question as to whether or not measles virus genomic RNA was sequestered in foci of non-specific inflammation. It did not.
Appendicectomies were also included in this study. As pointed out in the paper, the identification of Warthin Finkeldy giant cells indicative of MV infection is described in the appendix. The authors believed that the inclusion of an appendicectomy control cohort was appropriate to define the prevalence of MV infection in a randomly selected population of children.
Detailed study of the individual children with regressive autism and intestinal symptoms has identified, beyond doubt, a novel syndrome that includes an immune-mediated entero-colitis [3-6]. Epidemiology is wholly inadequate in its ability to assess, let alone refute, the validity of these findings. Please would Dr Halsey identify the scientific literature that demonstrates that chronic ileo-colonic lymphoid nodular hyperplasia - the condition from which these children suffer - is a normal response.
Dr Halsey himself has confirmed, quite correctly, that if a biological reason exists to account for any adverse reactions due to atypical viral concurrent infections, then large comparative studies should be performed. Clearly, one study of subacute sclerosing panencephalitis showing an association between measles and chicken pox  and another one not showing such an association  does not necessarily clarify the situation in relation to atypical/concurrent viral infections.
Somewhat disingenuously, Dr Halsey raises an issue in relation to communications between the AAP and Professor O'Leary in the fall of 2000. Professor O'Leary wishes to correct, for the record, the erroneous statement made by Dr Halsey. The correspondence between the AAP and Professor O'Leary was in fact in relation to a special meeting, referred to above, that was convened to consider the issue of autism and possible links to MMR vaccine. At that time Professor O'Leary explained verbally and in writing to representatives of the AAP that he was unable to attend for personal reasons. He informed the AAP that the findings were being submitted for peer review and that further communications were inappropriate.
John J O'Leary MD, DPhil, MSc, MRCPath, FFPathRCPI.
on behalf of the authors
(1) Halsey NA, Hyman SL and the Conference Writing Panel. Measles, mumps, and rubella vaccine and autistic spectrum disorder: report, from the new challenges in childhood immunizations conference convened in Oak Brook, Illinois. Pediatrics; 2000;107:E84
(2) Ulmann V., Martin CM., Shiels O., Pilkington L., Silva I., Lillalea A., Murch SH., Wakefield AJ., O'Leary JJ. Potential viral pathogenic mechanism for new variant inflammatory bowel disease. Molecular Pathology. 2002;55:1-6
(3) Wakefield AJ, Murch SH, Anthony A,, Linnell J, Casson DM, Malik M, et al. Ileal-lymphoid nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet. 1998:351: 637-641.
(4) Wakefield AJ., Anthony A., Murch SH., Thomson M., Montgomery SM., Davis S., Walker-Smith JA. Enterocolitis in children with developmental disorders. Am J Gastroenterol. 2000;95:2285-2295
(5) Furlano R., Anthony A., Day R., Brown A., McGavery L., Thomson M., et al. Quantitative immunohistochemistry shows colonic epithelial pathology and gd-T cell infiltration in autistic enterocolitis. J Pediatrics 2001;138:366-372
(6) Torrente F., Machado N., Perez-Machado M., Furlano R., Thomson M., Davies S., et al. Enteropathy with T cell infiltration and epithelial IgG deposition jn autism. Molecular Psychiarty 2002 (in press).
(7) F-D-C Reports, Inc., The Pink Sheet, Nov 13th 1995;pp11
(8) Detels R, Brody JA, McNew J, Edgar AH. Further epidemiological studies of subacute sclerosing panencephalitis. Lancet 1973;2:11-14.
(9) Halsey NA., Modlin JF., Jabbour JT., Dubey L., Eddins DL., Ludwig DD. Risk factors in subacute sclerosing panencephalitis: a case-control study. Am J Epidemiol. 1980;111:415-424
Publication by Uhlmann et al and commentary
In the light of the big impact of this article , the authors may have a responsibility to address and explain the following questions and problems.
a) The reaction specificity is confirmed in primer/probe sets only for measles virus F and H gene, which are utilized in TaqMan RT-PCR (Fig. 2). The specificity of the set for N gene should also be established to provide a better reliability of RT in situ PCR results.
b) The discrepancy between the band density of the PCR amplicons in agarose gel (Fig. 2A) and the luminescent intensity of the hybridized bands (Fig. 2B and 2C) clearly demonstrates that this primer/probe sets are not suitable for quantitative analyses including TaqMan RT-PCR. In F gene PCR amplicons, the agarose gel bands from positive controls are densest (lanes 1 and 2). However, the strongest signal in the Southern blot was obtained from the affected child 2 (lane 4), indicating the affinities between PCR amplicons and the specific probe vary on a case-by- case basis. Furthermore, in H gene PCR amplicons from the affected children, the intensity of hybridized bands (Fig. 2C, lanes 10-13) is not proportional to the density of agarose gel bands (Fig. 2A, lanes 10-13).
c) TaqMan RT-PCR standards generated by cloning of PCR products must be sequenced and the cloned inserts should be checked, because amplicons are not necessarily pure.
d) For the expanded speculation about virus-reservoirs and virus-host interactions in the DISCUSSION, authors should reveal the number of affected patients whose samples were evaluated by the combination of RT in situ PCR and immunohistochemistry (Fig. 4 maybe show just one patient).
e) In the combination of RT in situ PCR and immunohistochemistry, a specific marker for lymphocytes should also be utilized.
f) It is described in the figure legend that the samples from four affected children in Fig. 2 are fresh frozen biopsies. However, the number information of sample types (fresh frozen biopsies or fixed and embedded tissues) in both cases and controls is missing from the MATERIALS AND METHODS.
g) Some results of control experiments are missing in the RESULTS.
h) Authors should explain or address possible reasons of the discrepant results of TaqMan RT-PCR and RT in situ PCR in several cases ("six were positive by TaqMan RT-PCR but negative by in situ PCR, and five were positive by in situ PCR only").
i) Details of the gene dosage correction, reliability of the standard curves, and the criteria for positive results should be addressed in TaqMan RT-PCR methods.
j) What is the purpose of the optimization of N2, H2, and F2 primer pairs?
k) Case codes or serial case numbers should be used for further constructive discussions.
l) The results of TaqMan RT-PCR should be separately demonstrated for F and H genes.
Shinji Ijichi, M.D.
Institute for EGT (www.iegt.org)
8-3 Nagahama, Shimokoshiki-mura, Satsuma-gun,
Kagoshima 896-1411, Japan
(1) Uhlmann V, Martin CM, Sheils O, Pilkington L, Silva I, Killalea A, Murch SB, Wakefield AJ, O'Leary JJ. Potential viral pathogenic mechanism for new variant inflammatory bowel disease. J Clin Pathol: Mol Pathol 2002;55:0-6.
Publication by Uhlmann et al and commentary
Given the high level of public concern about MMR, inflammatory bowel disease and autism in recent years, investigators have a special responsibility to use rigorous study methods and to report essential details of their studies so that other scientists can properly interpret the results. Unfortunately, important details regarding several study methods were not provided in the recent study by Uhlmann et al. The journal reviewers, editors, and authors of the accompanying editorial did not fulfill their obligations to identify these shortcomings and set a high standard for the evaluation and publication of research on this topic.
In addition to the authors’ interpretation of the results, there are several possible explanations for the study findings:
a) Contamination of some specimens during collection or processing.
b) False positive results.
c) Differences in specimen collection and processing for cases and controls.
d) Persistence of measles virus (or portions of measles virus) in lymphoid tissue following measles disease or vaccination with differential detection of virus in inflamed vs. normal tissue.
e) Persistence of portions of measles virus in selected individuals who also have lymphonodular hyperplasia.
Following Professor John O’Leary’s presentation almost two years ago to a congressional subcommittee in the United States, many questions and concerns were raised about the limited description of the methods provided presented in his online publication. The American Academy of Pediatrics wrote to him in the fall of 2000 requesting more detail on his methods, but he never responded. Since he has chosen to publish these results, I am surprised by the failure to address concerns that were raised earlier. The following points regarding the epidemiologic methods employed in this study should be addressed. Other scientists with more laboratory expertise may address problems with the specific laboratory methods.
1. Specimen collection. The specimens were obtained from the gastroenterology unit at the Royal Free Hospital. Dr. Andrew Wakefield and his colleagues have been studying measles and measles vaccine viruses in this laboratory for several years. Therefore, the possibility of specimen contamination during collection or processing cannot be ruled out. Studies should be designed to collect specimens from patients with inflammatory bowel disease and controls by investigators who are not actively working with these viruses in their clinics or laboratories. The specimens should be processed in laboratories free of any measles viruses and aliquots sent to several different laboratories with the capability of detecting measles viruses using several different techniques.
2. Blinding or masking. No mention is made of masking laboratory investigators as to which specimens come from cases or controls. The code should be broken only after the studies are completed and investigators commit themselves to the results.
3. Concurrent collection of cases and controls. No mention is made as to the timing of the collection of specimens from cases and controls. If the control specimens were obtained after collection of specimens from cases, differences in methods could have been used in the handling of specimens. For example, some laboratories have had problems with inadvertent contamination and then taken steps to eliminate this problem.
4. Genetic sequencing. The authors have not provided key information regarding the viruses detected by RT-PCR. Was there variability in the genetic sequences of these viruses? All viruses mutate and some variability is expected. If there is no heterogeneity in the viruses obtained, this suggests the possibility of specimen contamination.
5. Cases. The 91 'affected patients' are inadequately described. The results section indicates that these patients had developmental disorders, but this is not noted in the methods and the types of disorders are not mentioned. What were the reasons that the children were biopsied? What proportion of all children examined had lymphonodular hyperplasia and how were the patients studied here selected?
6. Controls. The controls appear to have been selected on the basis of being developmentally normal, but they include a variety of conditions including patients with Crohn’s disease and ulcerative colitis. In previous publications, Dr Wakefield has used patients with Crohn’s disease and ulcerative colitis as cases and reported that many of these patients had positive results for tests of measles virus in intestinal tissue. Were the patents studied here a subset of patients previously published selected on the basis of being negative for measles?
7. Terminology. The authors coined the term 'New variant inflammatory bowel disease'. This term appears to have been chosen to attract attention and public concern because of the heightened awareness of new variant Creutzfeld Jacob disease. The evidence presented here and in recent epidemiologic studies does not indicate that there is a new disorder or that there is an increased risk of inflammatory bowel disease in patients with autism or related conditions.[3,4] Lymphonodular hyperplasia may be a normal response to a variety of stimuli.
8. 'Atypical exposure'. The authors cite one small epidemiologic study suggesting a possible increased frequency of chickenpox and measles infections occurring within 6 months in children who subsequently developed subacute sclerosing panencephalitis (SSPE). However, the authors failed to cite a subsequent larger study that found no differences in rates of chickenpox, mumps or rubella occurring within 6 months of measles for children who developed SSPE as compared to matched controls.
Measles viruses may persist in persons who do not develop SSPE. However, the data presented here are inadequate to come to such a conclusion. Moreover, if portions of the measles virus or the intact virus are maintained in lymphoid tissue following infection or vaccination, detection of portions of the virus could be enhanced in the presence of inflammatory conditions. I encourage these investigators to participate in coordinated efforts to further investigate the hypothesis and to limit speculation regarding the results of this study. Provision of the missing key information in their recent study would help this process.
The recent publication does not change any of the conclusions from our recent review of this topic and I continue to support the use of MMR vaccine for prevention of important childhood diseases.
Neal A. Halsey, MD
Director, Institute for Vaccine Safety
Professor and Director, Division of Disease Control
Johns Hopkins Bloomberg School of Public Health
Baltimore, Maryland, USA
(1)Uhlmann V, Martin CM, Sheils O, Pilkington L, Silva I, Killalea A, Murch SB, Wakefield AJ, O'Leary JJ. Potential Viral Pathogenic Mechanism For New Variant Inflammatory Bowel Disease. J Clin Pathol: Mol Pathol 2002;55:0-6.
(2)Kawashima H, Mori T, Kashiwagi Y, Takekuma K, Hoshika A, Wakefield A. Detection and sequencing of measles virus from peripheral mononuclear cells from patients with inflammatory bowel disease and autism. Dig Dis Sci 2000;45(4):723-9.
(3)Halsey NA, Hyman SL. 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. Pediatrics 2001;107(5):E84.
(4)Fombonne E, Chakrabarti S. No evidence for a new variant of measles- mumps-rubella-induced autism. Pediatrics 2001;108(4):E58.
(5)Detels R, Brody JA, McNew J, Edgar AH. Further epidemiological studies of subacute sclerosing panencephalitis. Lancet 1973;2(7819):11- 4.
(6)Halsey NA, Modlin JF, Jabbour JT, Dubey L, Eddins DL, Ludwig DD. Risk factors in subacute sclerosing panencephalitis: a case-control study. Am J Epidemiol 1980;111(4):415-24.