Long term effects of exposure to viral infections in utero

Common maternal infections during pregnancy and childhood leukaemia in the offspring: findings from six international birth cohorts

BACKGROUND

Previous epidemiological studies have found positive associations between maternal infections and childhood leukaemia; however, evidence from prospective cohort studies is scarce. We aimed to examine the associations using large-scale prospective data.

METHODS

Data were pooled from six population-based birth cohorts in Australia, Denmark, Israel, Norway, the UK and the USA (recruitment 1950s-2000s). Primary outcomes were any childhood leukaemia and acute lymphoblastic leukaemia (ALL); secondary outcomes were acute myeloid leukaemia (AML) and any childhood cancer. Exposures included maternal self-reported infections [influenza-like illness, common cold, any respiratory tract infection, vaginal thrush, vaginal infections and urinary tract infection (including cystitis)] and infection-associated symptoms (fever and diarrhoea) during pregnancy. Covariate-adjusted hazard ratio (HR) and 95% confidence interval (CI) were estimated using multilevel Cox models.

RESULTS

Among 312 879 children with a median follow-up of 13.6 years, 167 leukaemias, including 129 ALL and 33 AML, were identified. Maternal urinary tract infection was associated with increased risk of any leukaemia [HR (95% CI) 1.68 (1.10-2.58)] and subtypes ALL [1.49 (0.87-2.56)] and AML [2.70 ([0.93-7.86)], but not with any cancer [1.13 (0.85-1.51)]. Respiratory tract infection was associated with increased risk of any leukaemia [1.57 (1.06-2.34)], ALL [1.43 (0.94-2.19)], AML [2.37 (1.10-5.12)] and any cancer [1.33 (1.09-1.63)]; influenza-like illness showed a similar pattern but with less precise estimates. There was no evidence of a link between other infections and any outcomes.

CONCLUSIONS

Urinary tract and respiratory tract infections during pregnancy may be associated with childhood leukaemia, but the absolute risk is small given the rarity of the outcome.

Association of mental health problems in childhood with prenatal and postnatal physical growth

Aims

The present study was conducted to examine (i) prenatal and postnatal patterns of growth in relation to the risk of later mental health problems in children and (ii) the possible mediating effect of these patterns of growth in the association between parental socioeconomic status (SES) and children’s mental health.

Subjects and methods

The present study is part of a blinded, matched case control study, involving a retrospective analysis of prospectively collected data from routine examinations at community health services for children and adolescents. The sample comprised 80 patients, referred between the age of 6–13 years to the Community Mental Health Centre in Maastricht, and 320 matched population controls.

Results

Children coming from unemployed families weighed less at birth, but postnatal growth was not associated with this or other indicators of SES. Although children using mental health care were somewhat smaller at birth, there was no evidence that leanness during childhood was a risk factor for the development of mental health problems.

Conclusions

The present results showed some evidence for the impact of intrauterine development on children’s mental health problems. In addition, neither prenatal nor postnatal physical growth were on the pathway between parental SES and children’s mental health problems.

Maternal Infection in Pregnancy and Childhood Leukemia: A Systematic Review and Meta-analysis

OBJECTIVE

To summarize the published evidence regarding the association between maternal infection during pregnancy and childhood leukemia.

STUDY DESIGN

In this systematic review and meta-analysis (PROSPERO number, CRD42018087289), we searched PubMed and Embase to identify relevant studies. We included human studies that reported associations of at least one measure of maternal infection during pregnancy with acute lymphoblastic leukemia (ALL) or all childhood leukemias in the offspring. One reviewer extracted the data first using a standardized form, and the second reviewer independently checked the data for accuracy. Two reviewers used the Newcastle-Ottawa Scale to assess the quality of included studies. We conducted random effects meta-analyses to pool the ORs of specific type of infection on ALL and childhood leukemia.

RESULTS

This review included 20 studies (ALL, n = 15; childhood leukemia, n = 14) reported in 32 articles. Most (>65%) included studies reported a positive association between infection variables and ALL or childhood leukemia. Among specific types of infection, we found that influenza during pregnancy was associated with higher risk of ALL (pooled OR, 3.64; 95% CI, 1.34-9.90) and childhood leukemia (pooled OR, 1.77; 95% CI, 1.01-3.11). Varicella (pooled OR, 10.19; 95% CI, 1.98-52.39) and rubella (pooled OR, 2.79; 95% CI, 1.16-6.71) infections were also associated with higher childhood leukemia risk.

CONCLUSIONS

Our findings suggest that maternal infection during pregnancy may be associated with a higher risk of childhood leukemia.

Heterogeneous pathways of maternal-fetal transmission of human viruses (review)

Several viruses can pass the maternal-fetal barrier, and cause diseases of the fetus or the newborn. Recently, however, it became obvious, that viruses may invade fetal cells and organs through different routes without acute consequences. Spermatozoa, seminal fluid and lymphocytes in the sperm may transfer viruses into the human zygotes. Viruses were shown to be integrated into human chromosomes and transferred into fetal tissues. The regular maternal-fetal transport of maternal cells has also been discovered. This transport might implicate that lymphotropic viruses can be released into the fetal organs following cellular invasion. It has been shown that many viruses may replicate in human trophoblasts and syncytiotrophoblast cells thus passing the barrier of the maternal-fetal interface. The transport of viral immunocomplexes had also been suggested, and the possibility has been put forward that even anti-idiotypes mimicking viral epitopes might be transferred by natural mechanisms into the fetal plasma, in spite of the selective mechanisms of apical to basolateral transcytosis in syncytiotrophoblast and basolateral to apical transcytosis in fetal capillary endothelium. The mechanisms of maternal-fetal transcytosis seem to be different of those observed in differentiated cells and tissue cultures. Membrane fusion and lipid rafts of high cholesterol content are probably the main requirements of fetal transcytosis. The long term presence of viruses in fetal tissues and their interactions with the fetal immune system might result in post partum consequences as far as increased risk of the development of malignancies and chronic pathologic conditions are discussed.

No association between prenatal viral infection and depression in later life--a long-term cohort study of 6152 subjects

OBJECTIVE

Previous studies have suggested a role for prenatal viral infections in the etiology of schizophrenia; however, little is known about depression. We examined whether in-utero viral infections result in increased risk of depression in later life.

METHOD

We identified a cohort (n = 3076) born between 1946 and 1980, whose mothers suffered known viral infections in pregnancy. Subjects were individually matched by birthdate, sex, and area of birth to another cohort (n = 3076) from the UK National Health Service Central Register (NHSCR). These 2 cohorts, one exposed to viruses prenatally, the other not known to have been exposed, were then followed-up to June 1996 by sending a morbidity questionnaire to their primary care physicians. This included specific items on affective disorders, schizophrenia, mental handicap (mental retardation), epilepsy, as well as other central nervous system disorders and specified physical illness, all coded according to the International Classification of Diseases, Ninth Edition. Death certificates were supplied by the NHSCR. A method for matched-pair cohort data calculated the relative risk and 95% confidence intervals for depression in the exposed and unexposed cohorts by varying type of viral exposure.

RESULTS

The response to the questionnaire was high (85%). There was no overall increased risk for depression associated with viral exposure; a narrow confidence interval surrounded unity (RR = 1.0, 95% CI 0.8 to 1.2); effects for individual viral exposures were all scattered around unity.

CONCLUSIONS

The results provide no support for the hypothesis that in-utero exposure to viral infection is associated with risk of subsequent nonpsychotic affective disorder. Further analyses on schizophrenia, bipolar disorder, and mental illness other than depression are required.

Causes of childhood leukaemia and lymphoma

Childhood cancer is rare comprising less than 1% of all malignancies diagnosed each year in developed countries. Leukaemia is the commonest form of cancer in children accounting for around a third of all childhood cancer, with acute lymphoblastic leukaemia (ALL) being the most prevalent. Biologically specific subtypes of ALL and acute myeloblastic leukaemia (AML), the other major morphological type of childhood leukaemia, are characterised by chromosomal changes. Whilst over 200 genes have been associated with chromosomal translocations, to date, only MLL, TEL, and AML1 have been linked with childhood leukaemia. Interestingly, there is increasing evidence to support the theory that gene rearrangements such as these may originate in utero. As with many other human diseases, both genetic and environmental factors have been implicated in the aetiology of the disease. Although much has been documented with regard to diet, smoking, alcohol consumption and recreational and prescription drug use during pregnancy, there is no consistent evidence to support a link with any of these factors and childhood leukaemia. However, findings from studies investigating prenatal and early life exposures are often based on small numbers of cases as both the type of cancer and exposure are rare. Furthermore, accurate information relating to past exposures can be difficult to obtain and is often reliant on self-reporting. To further our understanding of the aetiology of childhood leukaemia and lymphoma, there are areas which clearly warrant investigation. These include collection of parental dietary folate data combined with genetic analysis of the folate related genes, in utero exposure to DNA topoisomerase II inhibitors, and the possible effects of assisted reproduction technology on disease susceptibility.

Humoral beta-cell autoimmunity is rare in patients with the congenital rubella syndrome

The congenital rubella syndrome (CRS) is associated with increased risk for diabetes and thyroid disease. However, the mechanisms by which the rubella virus may cause these diseases are poorly characterized. Previous studies were carried out before modern immunological methods were available. The present study aimed at evaluating whether autoimmune mechanisms are involved in the pathogenesis by analysing antibodies to biochemically characterized autoantigens. The incidence of clinical diabetes, thyroid disease, coeliac disease and related antibodies (islet cell antibodies, ICA; insulin autoantibodies, IAA; antibodies to the tyrosine phosphatase related IA-2 molecule, IA-2 A and glutamic acid decarboxylase, GADA; thyroid peroxidase, TPO; tissue transglutaminase, TTGA; and gliadin, AGA) and HLA risk genotypes were analysed in 37 subjects affected by or exposed to rubella during fetal life (mean age 22.5 years). One patient had diabetes and four patients had clinical hypothyroidism at the time of the examination. ICA, IAA, GADA or IA-2 A were not detected in any of the patients, while five patients tested positive for TPO antibodies. Coeliac disease or TTGA were not observed. Eight patients carried the HLA-DR3-associated HLA-DQB1*02-DQA1*05 haplotype. These results provide no evidence of an increased frequency of markers for humoral beta-cell autoimmunity in patients with CRS suggesting that diabetes in CRS may be caused by other than autoimmune mechanisms.

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.

Early child-care and preschool experiences and the risk of childhood acute lymphoblastic leukemia

An infectious etiology for childhood acute lymphoblastic leukemia (ALL) has been suggested, yet few studies have focused on the role of early child care. Day-care histories were examined in a case-control study of ALL in New York State. Cases (n = 255) were diagnosed at one of four referral centers between 1980 and 1991; controls (n = 760) were randomly selected from livebirths in the 31 counties served by the referral centers. Self-administered questionnaires were mailed to the parents of cases and controls in 1995. Day-care histories were censored at the age of diagnosis for cases and at an equivalent date for controls. The odds ratio for children who stayed at home compared with those who attended day care for >36 months was 1.32 (95% confidence interval (CI): 0.70, 2.52); the odds ratios for 1-18 and 19-36 months of day care were 1.74 (95% CI: 0.89, 3.42) and 1.32 (95% CI: 0.64, 2.71), respectively. Elimination of cases with T-cell ALL enhanced the risk. Starting care at an earlier age was not associated with a decreased risk of ALL. These findings do not support the hypothesis that infrequent contact with peers during early childhood could delay exposure to infectious diseases and increase the risk of ALL.

The risk profile of childhood leukaemia in Greece: a nationwide case-control study

The risk profile of childhood leukaemia in Greece was studied through a case-control investigation that included all 153 incident cases of the disease, ascertained throughout the country during 1993 and 1994, and two hospital controls for every case matched for gender, age and place of residence. The data were analysed using conditional logistic regression and the associations are expressed in terms of adjusted odds ratios (OR) and their 95% confidence intervals. Cases were born to mothers of a higher standard education, the OR for an increment of four schooling years being 1.48 (1.17-1.87) and had higher birth weight, the OR for an increment of 500g being 1.36 (1.04-1.77). Pet ownership and birth after a pregnancy with anaemia were associated with increased risk, the ORs being 2.18 (1.14-4.16) and 2.60 (1.39-4.86) respectively. From the frequency analyses, indicative inverse associations were found with birth order, household crowding and previous hospitalization with allergic diseases, whereas indicative positive associations were found with diabetes mellitus during pregnancy and with neonatal jaundice. Substantial or significant elevations were not found with respect to maternal smoking and coffee drinking during pregnancy, diagnostic radiography and ultrasonographic examinations or blood transfusions. A significant inverse association with maternal consumption of alcohol could be due to multiple comparisons, but a detrimental effect can probably be excluded. A non-significant positive association with total shots of viral vaccinations and a weak non-significant inverse association with breast feeding were also found. We interpret the findings of this study as being compatible with acute childhood leukaemia being linked with delayed development of herd immunity to fairly common infectious agents, in conjunction with accelerated perinatal and early post-natal growth.

Leukaemia and non-Hodgkin's lymphoma in children and young adults: are prenatal and neonatal factors important determinants of disease?

A medical record-based study of leukaemia and non-Hodgkin's lymphoma diagnosed before the age of 30 years was carried out at three hospitals in the south of England. Findings for 177 cases and 354 age- and sex-matched controls are presented here. For documented viral infection in pregnancy, the odds ratio (OR) was 6.0 [95% confidence interval (CI) 1.2-29.7] for leukaemia and infinity (95% CI 1.24-infinity) for non-Hodgkin's lymphoma. Mothers of leukaemic cases were more likely to be anaemic, the OR for a pregnancy haemoglobin below 10 g being 3.8 (95% CI 1.3-11.1). An association with birthweight was found for acute myeloid leukaemia, the OR for birthweights > 3500 g being 6.2 (95% CI 1.3-29.8). Further, the preceding siblings of those diagnosed with any form of leukaemia were also more likely to weigh > 3500 g at birth (OR 2.2; 95% CI 1.1-4.4). Overall, leukaemic cases appeared to be comparatively robust at birth with respect to other indicators of well-being, the ORs for jaundice, phototherapy, admission to special care nursery and neonatal intensive care all being less than 1.0. Further, no relation between childhood leukaemia and neonatal administration of intramuscular vitamin K was noted (OR 0.6, 95% CI 0.3-1.4; for acute lymphoblastic leukaemia diagnosed between the ages of 1 and 6 years).

Premorbid abnormalities in mania, schizomania, acute schizophrenia and chronic schizophrenia

The aim of this study was to examine the hypothesis that differences in outcome among affective and non-affective psychoses are associated with differences in the degree of developmental deviance. We conducted a retrospective survey of first contact cases treated over a 20-year period in a psychiatric hospital serving a catchment area in South London. All patients with non-depressive functional psychosis residing in the catchment area who received their first psychiatric treatment between 1965 and 1984 were included in the study. Cases were classified according to the relative chronicity of their illness into four non-overlapping groups: mania, schizomania, acute schizophrenia and chronic schizophrenia. There was a linear trend in the association between illness chronicity and proxy measures of development deviance, such as premorbid unemployment, single status and poor academic achievement. Compared to individuals with mania, schizophrenic patients had a 3-6 times increased risk of premorbid abnormality. For patients with schizomania and acute schizophrenia, the risk was 1.5-3 times greater than for manic subjects. We conclude that the prevalence of premorbid abnormalities is highest among chronic schizophrenia, but similar disturbances also occur, to a lesser degree, in less disabling affective and non-affective psychotic disorders.

Crohn's disease: pathogenesis and persistent measles virus infection

The Inflammatory Bowel Disease Study Group at the Royal Free Hospital School of Medicine has tested the hypothesis that the primary pathological abnormality in Crohn's disease is in the mesenteric blood supply. Early morphological studies involved arterial perfusion-fixation and either resin casting and scanning electron microscopy or vascular immunostaining of resected intestine affected by Crohn's disease. Granulomatous and lymphocytic damage to intramural blood vessels, even in macroscopically normal areas, was observed. We put forward possible mechanisms by which a chronic ischemic process might account for many of the idiosyncracies of Crohn's disease. It was proposed that persistent viral infection of the mesenteric microvascular endothelium might underly this vasculitic process; based on certain behavioral characteristics of measles virus, including its tropism for the submucosal endothelium of the intestine, this agent was investigated further. This report reviews the preliminary evidence from both epidemiological and basic scientific data for persistent measles virus in the intestine of patients with Crohn's disease. Possible mechanisms for virus persistence and subsequent reactivation are discussed. In conclusion, we believe that Crohn's disease may be a chronic granulomatous vasculitis in reaction to a persistent infection with measles virus within the vascular endothelium. This granulomatous inflammation, perhaps aggravated by either a hypercoagulable state or mechanical stress, results in the clinical features of Crohn's disease.

A fifty-year follow-up of congenital rubella

50 patients with congenital rubella, born in 1939-43, were reviewed in 1967. Here we report their outcome in 1991. Since 1967, there have been 7 deaths (3 cardiovascular, 3 malignant disease, 1 AIDS). 40 had full clinical assessment. The prevalence of diabetes mellitus is similar to that in 1967: 4 of the 5 reported diabetic then, remain so, and there is 1 new case. 1 subject has malignant melanoma and 3 have died from cancer. Although the incidence of malignant disease is not increased, the death rate is (standardised mortality rate 6.0, 95% CI 1.24-17.57). Longer follow-up will be required to confirm this observation.

Viruses, immunity and mental disorder

Are viruses the cause of mental illness, or does stress or mental disorder produce impaired immunity, with increased susceptibility to infection? These two separate but not unrelated questions have been debated periodically and there has been much renewed interest recently, with increased sophistication in immunology and widespread topical concern about immunodeficiency. The neuropsychiatry of the acquired immunodeficiency syndrome (AIDS) (Snider et al, 1983; Carne & Adler, 1986; Wortis, 1986; Burton, 1987; Fenton, 1987) and the validity of a ‘post-viral fatigue syndrome’ as a clinical entity (Behan, 1983; Southern & Oldstone, 1986; Dawson, 1987; David et al, 1988) are not discussed here, but have been dealt with in the editorials and reviews cited.