Biomedical subjects

Mads Melbye

Publications and source records attributed to Mads Melbye.

80 records · Page 5Linked to original sources

PubMed2002

A population-based study of measles, mumps, and rubella vaccination and autism.

BACKGROUND: It has been suggested that vaccination against measles, mumps, and rubella (MMR) is a cause of autism. METHODS: We conducted a retrospective cohort study of all children born in Denmark from January 1991 through December 1998. The cohort was selected on the basis of data from the Danish Civil Registration System, which assigns a unique identification number to every live-born infant and new resident in Denmark. MMR-vaccination status was obtained from the Danish National Board of Health. Information on the children's autism status was obtained from the Danish Psychiatric Central Register, which contains information on all diagnoses received by patients in psychiatric hospitals and outpatient clinics in Denmark. We obtained information on potential confounders from the Danish Medical Birth Registry, the National Hospital Registry, and Statistics Denmark. RESULTS: Of the 537,303 children in the cohort (representing 2,129,864 person-years), 440,655 (82.0 percent) had received the MMR vaccine. We identified 316 children with a diagnosis of autistic disorder and 422 with a diagnosis of other autistic-spectrum disorders. After adjustment for potential confounders, the relative risk of autistic disorder in the group of vaccinated children, as compared with the unvaccinated group, was 0.92 (95 percent confidence interval, 0.68 to 1.24), and the relative risk of another autistic-spectrum disorder was 0.83 (95 percent confidence interval, 0.65 to 1.07). There was no association between the age at the time of vaccination, the time since vaccination, or the date of vaccination and the development of autistic disorder. CONCLUSIONS: This study provides strong evidence against the hypothesis that MMR vaccination causes autism.

Autistic Disorder↗

PubMed2002

Frequency of atopy in the Arctic in 1987 and 1998.

Few studies have measured the frequency of atopy with objective measures, and most of these studies have been done in industrialised countries. We analysed serum samples from 859 15-80-year-old Greenlanders who had participated in population-based screening campaigns in 1987 and in 1998. We defined atopy as a positive result in an assay that tests for specific IgE against the eight most common inhalant allergens in one pool (grass, birch, mugwort, dog, cat, horse, Cladosporum herbarum, house dust mite). The frequency of atopy doubled between 1987 (39 [10%] of 392) and 1998 (87 [19%] of 467; risk ratio 1.88 [95% CI 1.31-2.68]). This increase was largest in 15-19-year olds, but also occurred in older people, suggesting that the risk factors responsible for the increase in atopy do not operate only in childhood.

Adolescent↗

PubMed2002

Hematopoietic and lymphatic cancers in relatives of patients with infectious mononucleosis.

BACKGROUND: Young adults with a history of Epstein-Barr virus (EBV)-related infectious mononucleosis have an increased risk for Hodgkin's lymphoma. EBV is detected in Hodgkin's lymphoma Reed-Sternberg cells from some patients, but in young adult patients, it is detected at a relatively low frequency in these cells. Hodgkin's lymphoma and infectious mononucleosis are both associated with high social class, and unknown confounding factors that are also associated with socioeconomic status might explain or contribute to the apparent association between these diseases. To indirectly assess the importance of socioeconomic status on the association between these diseases, we determined the risk for hematopoietic and lymphatic cancers in first-degree relatives of patients with confirmed EBV-related infectious mononucleosis. METHODS: We identified parents, siblings, and offspring of 17,045 persons with serologically confirmed EBV-related infectious mononucleosis. Subjects in these cohorts were linked with the population-based Danish Cancer Register to identify those developing hematopoietic/lymphatic cancers after the index patient was diagnosed with infectious mononucleosis. The relative risk for cancer in the infectious mononucleosis family members was expressed as standardized incidence ratios (SIRs; i.e., the ratio between the number of cancers observed and the number of cancers expected, obtained from age-specific, sex-specific, and period-specific incidence rates). RESULTS: We identified 8052 parents, 5264 siblings, and 28,605 offspring of patients with EBV-related infectious mononucleosis who were followed for a total of 892,213 person-years at risk. The risk for Hodgkin's lymphoma was unaltered in the combined group of first-degree relatives of these patients (SIR = 0.99; 95% confidence interval [95% CI] = 0.62 to 1.59; number of cases [n] = 17), in the group of parents (SIR = 0.83; 95% CI = 0.31 to 2.22; n = 4), in the group of siblings (SIR = 0.96; 95% CI = 0.31 to 2.97; n = 3), and in the group of offspring (SIR = 1.08; 95% CI = 0.58 to 2.02; n = 10). CONCLUSION: The unremarkable risk for Hodgkin's lymphoma in family members of patients with EBV-related infectious mononucleosis indicates that socioeconomic confounding is an unlikely explanation for the association between EBV-related infectious mononucleosis and Hodgkin's lymphoma.

Adult↗

PubMed2002

Genotypic analysis at multiple loci across Kaposi's sarcoma herpesvirus (KSHV) DNA molecules: clustering patterns, novel variants and chimerism.

BACKGROUND: The genomes of human Kaposi's sarcoma-associated herpesvirus (KSHV) display several levels of DNA sequence heterogeneity and subgrouping that show distinctive clustering patterns in related human populations. The four major subtype patterns for the hypervariable ORF-K1 protein correlate closely with the principal diasporas resulting from the migration of modern humans out of East Africa and suggest that KSHV is an ancient human virus that is transmitted primarily in a familial fashion with consequent very low recombination rates. However, chimeric genomes have also been detected, especially with regard to the presence of P versus M alleles of the ORF-K15 gene. OBJECTIVES: To understand further the genetic organization and evolutionary history of KSHV, especially with regard to possible new subtypes, recombinant genomes, constant region loci and clustering in particular ethnic groups or among classic versus epidemic cases in the same geographic area. STUDY DESIGN: Direct PCR DNA sequencing was carried out on the ORF-K1 and ORF-K15 genes at the extreme left and right hand sides, as well as on six other internal loci of diagnostic samples collected from 70 new KSHV-positive patients in Israel, South Korea, Sicily, Scandinavia, Brazil, Uganda, South Africa and the US. RESULTS AND CONCLUSIONS: Our overall results from more than 135 KSHV genomes from many different human population groups now provides evidence for seven distinct subtypes of KSHV genomes (referred to as A/P, B/P, C/P, D/P, M, N and Q). However, the two most closely related subtypes (A/P and C/P) are only differentiated at the LHS side of the genome, and the three most distantly related forms (M, N and Q) appear to exist only as small chimeric segments that are remnants from the RHS of more ancient forms of the virus. By analyzing multiple conserved loci across the B subtype genomes that predominate in sub-Saharan Africa, we can also now recognize three to four distinct B genome subgroups with varying patterns of inter and intratypic mosaicism. Analysis of classic KS genomes from Israel has revealed that the ORF-K1 clade referred to as A1' predominates in Ashkenazi Jewish immigrants from Russia, whereas C2 and C6 variants predominate in North African Sephardi Jews. A variety of chimeric genomes containing C2 or C3 ORF-K1 genes are disseminated among classic KS cases throughout Europe and Asia including Israel, Sicily, Scandinavia, South Korea, and Taiwan. Comparison of the genomes from classic versus AIDS-associated KSHV in the US indicates that it was derived originally by reactivation and spread of a subset of the endogenous viruses carried by descendants of immigrants from endemic areas of Northern and Eastern Europe, the Mediterranean and sub-Saharan Africa.

Acquired Immunodeficiency Syndrome↗

PubMed2002

Maternal vaginal microflora during pregnancy and the risk of asthma hospitalization and use of antiasthma medication in early childhood.

BACKGROUND: Infants with wheezing and allergic diseases have a microflora that differs from that of healthy infants. The fetus acquires microorganisms during birth when exposed to the maternal vaginal microflora. It is therefore conceivable that the maternal vaginal microflora might influence the establishment of the infant flora and, as a consequence, the development of wheezing and allergic diseases. OBJECTIVE: We sought to study the associations between the composition of the maternal vaginal microflora and the development of wheezing and asthma in childhood. METHODS: We performed a population-based cohort study in Denmark. Vaginal samples for bacterial analysis were obtained during pregnancy. A total of 2927 women (80% of the invited women) completed the study and had 3003 live infants. Infant wheezing was assessed as one or more hospitalizations for asthma between 0 and 3 years of age. Asthma was assessed as use of 3 or more packages of antiasthma medication between 4 and 5 years of age. RESULTS: Maternal vaginal colonization with Ureaplasma urealyticum during pregnancy was associated with infant wheezing (odds ratio [OR], 2.0; 95% CI, 1.2-3.6), but not with asthma, during the fifth year of life. Maternal colonization with staphylococci (OR, 2.2; 95% CI, 1.4-3.4) and use of antibiotics in pregnancy (OR, 1.7; 95% CI, 1.1-2.6) were associated with asthma during the fifth year of life. CONCLUSION: The composition of the maternal vaginal micro-flora might be associated with wheezing and asthma in the offspring up to 5 years of age.

Anti-Bacterial Agents↗

PubMed2002

Does cross-sex transmission increase the severity of polio infection? A study of multiple family cases.

Previous studies have suggested that transmission of measles virus from the opposite sex increases the severity of infection; however, the role of gender in the transmission of other infections has not been examined. Multiple polio cases within a family usually occur simultaneously, and are therefore likely to be secondary to a common subclinical index case. The few clinical polio cases that appear much later than any other clinical case are likely to be tertiary cases. If cross-sex transmission increases the severity of infection then multiple polio cases would tend to affect the same sex, i.e. the opposite sex to that of the subclinical index case. In order to assess this phenomenon we identified 6345 records of individuals hospitalized with poliomyelitis in Copenhagen between 1919 and 1953. The severity and gender of suspected secondary and tertiary cases were analysed among all multiple household cases. Overall, 70% of the 133 sibling pairs having polio simultaneously were same-sex pairs, which differed significantly from the expected 52% (chi2 = 9.1; p < 0.01). Tertiary cases with exposure to the opposite sex were more likely to be paralytic than cases with exposure to the same sex [relative risk (RR) = 2.86 (95% confidence interval 1.08-7.58)1. In families with adult polio cases, possible tertiary cases were more common among fathers (7/24) than among mothers (1/35) [RR = 10.21 (1.34-77.72)]. We examined whether the excess of male polio cases was more pronounced in small families where the mother would play a relatively larger role in disease transmission and found that the male:female excess decreased with increasing birth order (p = 0.02) and family size (p = 0.09). The strong tendency towards same-sex pairs in 2-case families suggests that gender plays an important role in the severity of polio infection. Cross-sex transmission may increase the severity of polio and mothers may contribute to the higher prevalence of polio cases among boys.

Adolescent↗

PubMed2002

The polio model. Does it apply to polio?

BACKGROUND: According to the polio model, severity of disease increases with age at infection. Firstborn children and people belonging to small families are generally infected later and should accordingly have a higher risk of severe polio. However, this model does contradict other explanations of severity of childhood infections including the intensive-exposure model. METHODS: To evaluate the deductions from the polio model we performed a study based on medical records from 5590 historical polio cases from the county of Copenhagen 1940-1953. The relative risk (RR) of polio according to age, birth order and sibship size was evaluated using census data from 1940 and 1950. RESULTS: Severity of polio measured as frequency of paralysis or mortality did not show a steady increase with age, but a U-shaped curve being highest for the youngest as well as the oldest patients. The incidence of polio and paralytic polio was higher in families with several children compared with single children (RR = 1.13, 95% CI : 1.0-1.3). Furthermore, the incidence was higher in later-born children (P(trend) < 0.0001). However, as predicted from the intensive-exposure model, second-born children aged 1-4 years in two-child families had a higher risk of paralytic polio than first-born children (RR = 1.47, 95% CI : 1.1-2.0), whereas the opposite relationship was found for those aged > or = 5 years (RR = 0.65, 95% CI : 0.5-0.9). CONCLUSION: The polio model's prediction about the impact of age, sibship size and birth order on polio incidence and severity found only limited support. A model emphasizing intensity of exposure as a risk factor for severity may account better for the epidemiology of polio infection.

Adolescent↗

PubMed2002

Population-based study of acute respiratory infections in children, Greenland.

Acute respiratory infections (ARI) are frequent in Inuit children, in terms of incidence and severity. A cohort of 294 children <2 years of age was formed in Sisimiut, a community on the west coast of Greenland, and followed from 1996 to 1998. Data on ARI were collected during weekly visits at home and child-care centers; visits to the community health center were also recorded. The cohort had respiratory symptoms on 41.6% and fever on 4.9% of surveyed days. The incidence of upper and lower respiratory tract infections was 1.6 episodes and 0.9 episodes per 100 days at risk, respectively. Up to 65% of the episodes of ARI caused activity restriction; 40% led to contact with the health center. Compared with studies from other parts of the world, the incidence of ARI appears to be high in Inuit children.

Acute Disease↗