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Biomedical subjects

A I Bartelds

Publications and source records attributed to A I Bartelds.

At least 19 recordsLinked to original sources
PubMed2003

[The 2002/2003 influenza season in the Netherlands and the vaccine composition for the 2003/2004 season].

As in the 2000/2001 and 2001/2002 seasons, the influenza epidemic in the 2002/2003 season started late (week 7 of 2003) and was only moderate in size. Influenza A (H3N2) and B viruses were detected in equal numbers among patients of general practitioners and these two viruses were therefore equally responsible for the epidemic. However, H3N2 viruses dominated isolates taken from hospitals. In haemagglutination-inhibition (HI) assays most of the H3N2 viruses proved highly reactive with antiserum to the vaccine-reference strain A/Moscow/10/99. This was also true for a number of isolates, including those obtained from nursing home residents, closely related to the reference strain A/Finland/170/03. However, an estimated 4% of the H3N2 isolates belonged to the variant A/Fujian/411/02 from China, which constituted the majority of the H3N2 viruses isolated in Europe in the later phase of the season. This variant reacted poorly with antiserum to A/Moscow/10/99. In H1 tests all influenza A(H1N1)-virus isolates and all B-virus isolates were closelyrelated to the corresponding vaccine-reference strains. Taking this data into consideration, the World Health Organization has advised the same vaccine composition for the 2003/2004 season as for the 2002/2003 season, namely: A/Moscow/10/99 (H3N2), A/New Caledonia/20/99 (H1N1) and B/Hong Kong/330/01. There is the possibility of a mismatch occurring between the H3N2-vaccine strain and the circulating H3N2 viruses in the coming influenza season. In March and April 2003 there was an outbreak of influenza-A (H7N7) fowl plague in the Netherlands. A special monitoring survey revealed that 91 people who had handled infected poultry became infected with the H7N7 virus. One of these later died as a result of this. None of the avian and human H7N7-virus isolates examined contained human or porcine influenza-A virus genes.

Global Health↗
PubMed2001

[2000/01 influenza season and the vaccine composition for the season 2001/'02].

In the 2000/01 season, the size of the influenza epidemic in the Netherlands was exceptionally small. Since the start of the Continuous Morbidity Registration of the Netherlands Institute of Primary Health Care (NIVEL) in 1970, the peak incidence of influenza-like illnesses has never been so low. The aetiology of the epidemic was also unusual. Most remarkable was the relatively extensive circulation of subtype H1N1 and the low activity of subtype H3N2. The epidemic started in week 1 of 2001 and ended in week 8. The antigenic properties of the influenza A (H1N1) viruses closely resembled those of the vaccine strain A/New Caledonia/20/99. This new variant of subtype H1N1 was first isolated in Asia in 1995 and was only (sporadically) detected in the Netherlands in the 1999/2000 season. Phylogenetic analysis showed that these viruses represent a new line of subtype H1N1. Following the influenza-activity caused by H1N1 viruses in the 2000/01 season, a small number of B and H3N2 viruses were also isolated up to week 19. Antigenically, these viruses were identical to those obtained in the previous years. On the basis of the antigenetic analyses presented, it can be concluded that the vaccine provided good protection against the circulating influenza viruses in the 2000/01 season. The World Health Organization recommends that influenza vaccines intended for use in the 2001/02 season of the northern hemisphere should contain the following, or antigenically similar, strains: A/Moscow/10/99 (H3N2), A/New Caledonia/20/99 (H1N1), and B/Sichuan/379/99.

Global Health↗
PubMed2001

Sensor, a population-based cohort study on gastroenteritis in the Netherlands: incidence and etiology.

A prospective population-based cohort study with a nested case-control study was conducted to estimate the incidence of gastroenteritis and the associated pathogens in the general Dutch population. Follow-up of two consecutive cohorts was performed by weekly reporting cards from December 1998 to December 1999. Cases and controls in the case-control study supplied a questionnaire and stool samples. The standardized gastroenteritis incidence was 283 per 1,000 person-years. The incidence rose with increasing level of education and was higher for persons with a history of diarrhea and for young children. Bacterial pathogens accounted for 5% of cases, bacterial toxins for 9%, parasites for 6%, and viral pathogens for 21%, with Norwalk-like virus (NLV) as the leading pathogen in 11% of cases. The gastroenteritis incidence was higher than that reported for England, but lower than for the United States. In community cases, viral pathogens are the leading cause of gastroenteritis, with NLV being the number one cause of illness in all age groups but one. In many countries, preventive measures are implemented to decrease bacterial infections. However, additional prevention of viral infections, especially NLV, might significantly decrease the number of gastroenteritis cases in the community.

Adolescent↗
PubMed2001

A comparison of gastroenteritis in a general practice-based study and a community-based study.

We compared gastroenteritis cases that consulted a general practitioner (GP) with those who did not in a community-based study and also with those in a GP-based study. We aimed to identify factors associated with consultation, and with inclusion of cases by GPs, and secondly to study the effects on the frequency of detection of pathogens. Furthermore, we estimated the under-ascertainment by GPs. Both studies were performed in The Netherlands in the same population in an overlapping time-period. Overall, 5% of community cases consulted a GP. Cases who consulted suffered from more severe episodes than non-consulting cases. Inclusion of cases by GPs, instead of a study team, caused a selection of more severe cases with more chronic symptoms. When extrapolating data from GP-based studies, it should be taken into account that, in general practice, gastroenteritis due to bacteria and Giardia lamblia is a relatively large proportion of that in the community and gastroenteritis due to Norwalk-like viruses is a relatively small proportion. The incidence of gastroenteritis in general practices was estimated between 14 and 35 per 1000 person years.

Adolescent↗
PubMed2000

Results of molecular detection of Mycoplasma pneumoniae among patients with acute respiratory infection and in their household contacts reveals children as human reservoirs.

During a 30-month prospective study in The Netherlands, the distribution of Mycoplasma pneumoniae and respiratory viruses among 1172 patients with acute respiratory infection (ARI) who were treated in the outpatient general practitioner setting was studied. M. pneumoniae, as detected by polymerase chain reaction analysis, was present in 39 (3.3%) patients. The infection rate was similar in all age groups. Nose and throat samples collected from 79 household contacts of M. pneumoniae-positive index patients revealed M. pneumoniae in 12 (15%) cases. The frequency of M. pneumoniae among household contacts of index patients treated with appropriate antibiotics and untreated index patients was similar. Nine of the 12 M. pneumoniae-positive household contacts were <16 years old (P=.02), and 4 (44%) of them did not develop ARI. Apparently, children are a relevant reservoir for M. pneumoniae.

Acute Disease↗
PubMed2000

[Influenza season 1999/2000 and vaccine composition for the season 2000/01].

The first signs of influenza activity in the Netherlands during the 1999/2000 influenza season were the isolation of an influenza A (H3N2) virus in week 40 and of two more in week 43 of 1999. From week 50 onwards, a strong increase of the clinical influenza activity was observed which reached its peak in weeks 1 and 2 of 2000 and then rapidly declined. The clinical influenza activity was associated with the isolation of predominantly influenza A (H3N2) viruses. Near the end of the epidemic, influenza A (H1N1) and influenza B viruses were isolated sporadically. The antigenic properties of the influenza A (H3N2) viruses resembled those of the epidemic strains isolated in the previous season and the vaccine strain A/Sydney/5/97. This influenza season, influenza B viruses did not play a significant role and they matched the vaccine strain B/Yamanashi/166/98. In addition, a small number of influenza A (H1N1) viruses were isolated. Some of these viruses resembled the old variant of influenza A (H1N1) viruses, A/Bayern/7/95, whilst others showed a close antigenic relationship with the vaccine strain recommended for the next influenza season, A/New Caledonia/20/99. For the influenza season 2000/'01, it is recommended by the World Health Organization that the vaccines contain the following (or similar) virus strains: A/Moscow/10/99 (H3N2), A/New Caledonia/20/99 (H1N1) and B/Beijing/184/93.

Disease Outbreaks↗
PubMed2000

Population estimates of persons presenting to general practitioners with influenza-like illness, 1987-96: a study of the demography of influenza-like illness in sentinel practice networks in England and Wales, and in The Netherlands.

Incidence data by age of new episodes of influenza-like illness reported by sentinel general practice networks in England and Wales and in The Netherlands over a 10-year period were examined to provide estimates of the consulting population during influenza epidemic periods. Baseline levels of recording in each age group were calculated from weeks in which influenza viruses were not circulating and the excess over baseline calculated to provide the population estimates during influenza epidemics. Influenza A/H3N2 epidemics were associated with higher population estimates for consultations than influenza B, especially in the age groups 0-4 and 65 years and over. In the intervening age groups, population estimates were more consistent regardless of the virus type. Both networks reported simultaneous peaking of incidence rates in all of the age groups. There were substantial increases in the number of persons reporting other respiratory illnesses during influenza epidemics. Population estimates of the consulting population provide the only secure basis for which health services resource utilization during influenza epidemics can be estimated.

Adolescent↗
PubMed2000

Low prevalence of Chlamydia pneumoniae and Mycoplasma pneumoniae among patients with symptoms of respiratory tract infections in Dutch general practices.

Acute respiratory disease is one of the most common reasons to consult a general practitioner. A substantial part of these diseases cannot be explained by an infection with a virus or a common pathogenic bacterium. To study this diagnostic deficit, the prevalence of Chlamydia pneumoniae and Mycoplasma pneumoniae infections was determined in two groups of patients consulting a general practitioner. DNA of C. pneumoniae and M. pneumoniae was detected by a polymerase chain reaction (PCR) in nose/throat swabs from six (1.1%), and from seven (1.3%) patients, respectively, of 557 patients consulting a general practitioner for complaints suggestive for a virus infection during the 1994/1995 respiratory infections season. Two patients remained C. pneumoniae PCR-positive for at least 4 weeks. All others were negative within 3 weeks. Double infections of C. pneumoniae and influenza virus (3/6), and of M. pneumoniae and respiratory syncytial virus (1/7) or rhinovirus (1/7) were diagnosed. During the 1992/1993 season, attempts to isolate C. pneumoniae in cell culture or to detect C. pneumoniae DNA by PCR using throat swabs were all negative for 80 patients with a sore throat, although serological data suggested a C. pneumoniae infection in 13 (16%) patients. A specimen from another patient of this group was M. pneumoniae PCR-positive and the corresponding serum specimens showed a persistent high antibody titre. In summary, the prevalence of acute C. pneumoniae and M. pneumoniae infections was less than 2% in patients consulting a general practitioner.

Acute Disease↗
PubMed2000

Chlamydia pneumoniae and Mycoplasma pneumoniae in children with acute respiratory infection in general practices in The Netherlands.

In this retrospective study Chlamydia pneumoniae and Mycoplasma pneumoniae infections were detected by polymerase chain reaction (PCR) in samples (n = 457) from children presenting with acute respiratory infection to general practitioners during 1992-97. Samples were collected in autumn and winter, and from 1994 onwards in spring and summer also. Overall, C. pneumoniae and M. pneumoniae were detected in throat or nasal samples by PCR in 3.1% and 2.4% of the cases, respectively. The proportion of both C. pneumoniae and M. pneumoniae infections varied between 0% and 6.9% over the years studied, whereas seasonal proportions varied from 1.8 to 9.1% and 1.2 to 4.5%, respectively. For both microorganisms the lowest proportion was detected during winter and the highest in summer. C. pneumoniae could already be detected by PCR in patients under 4 y of age, an observation not made in sero-epidemiological studies. In conclusion, both C. pneumoniae and M. pneumoniae infections play a minor role in children presenting with acute respiratory infection.

Acute Disease↗
PubMed2000

Hormone replacement therapy: changes in frequency and type of prescription by Dutch GPs during the last decade of the millennium.

OBJECTIVE: The present study was conducted in order to determine the change of frequency and type of hormone replacement therapy (HRT) regimen newly prescribed by Dutch GPs. METHODS: A comparison was made of two data sets (multi-stage random samples) collected in 1987/88 and from 1995 to 1998 concerning women 40 years and older who were newly prescribed HRT. RESULTS: Compared with 1987/88, 50% more patients were newly prescribed HRT in 1998 (2.0 in 1987/88 and 3.0 in 1998 per 1000 registered women, P < 0.01). The age distribution remained about the same, with a peak between 50 and 54 years in each year of registration. Unopposed oestrogens (including plasters) were prescribed less frequently (1.3 per thousand in 1987/88 versus 0.7 per thousand in 1998, P < 0.001), and combinations of oestrogen and progestogen more frequently in 1998 (0. 2 per thousand in 1987/88 versus 1.8 per thousand in 1998, P < 0. 01). Sequential therapy was prescribed slightly more frequently than continuous therapy (65% sequential therapy in 1995; 55% in 1998). The most frequent reason for starting HRT in 1995-1998 was climacteric symptoms (89-98%), followed by osteoporosis prevention (16-28%) and early menopause (13-25%). Rarely were preventive goals the only reason (6%) for prescribing HRT. CONCLUSIONS: The number of HRT prescriptions increased by 50% over the last decade of the millennium. The age distribution remained the same. There was a tendency to shift from prescribing unopposed oestrogens to combinations of oestrogens and progestogens. Alleviation of climacteric symptoms was the main reason for prescribing HRT throughout the registration period. Prescription of HRT for prevention of osteoporosis and/or cardiovascular disease has so far not been adopted on a large scale by Dutch GPs.

Adult↗
PubMed1999

[Influenza season 1998/99; composition of vaccine for 1999/2000].

The first indication of influenza activity in the Netherlands in the 1998/'99 season was the isolation of an influenza B virus in week 47 of 1998. In subsequent weeks influenza activity slowly increased, reaching a peak in week 6 of 1999. After a gradual decline for three weeks a second peak was reached in week 8 of 1999. The first wave of influenza activity was primarily caused by influenza B viruses, whereas during the second wave predominantly influenza A viruses of the A/H3N2 subtype were isolated. The antigenic properties of the influenza A viruses resembled those of the viruses isolated in the previous season and the vaccine strain A/Sydney/5/97. The influenza B viruses did not completely match with B/Harbin/7/94 which is most commonly used for vaccine production. The vaccine, however, did provide good protection against the epidemic strains of influenza. This season influenza A/H1N1 viruses did not play a significant part and only a small number of viruses of this subtype were isolated at the end of the season. For the influenza season 1999/2000 it is recommended by the World Health Organization that the vaccines contain the following (or similar) virus strains: A/Sydney/5/97 (H3N2), A/Beijing/262/95 (H1N1) and B/Beijing/184/93.

Guidelines as Topic↗
PubMed1999

Mammography requests in general practice during the introduction of nationwide breast cancer screening, 1988-1995.

Introducing an organised breast cancer screening programme for certain age groups in a population might induce opportunistic screening in adjacent (non-invited) age groups and influence health behaviour in the target population. We analysed the effect of the start of the Dutch national screening programme on the number of mammographies requested by 43-45 general practices for the age groups 30-39, 40-49, 50-69 and 70+ years, using logistic regression analysis. In all age groups an immediate increase was observed in the number of mammography requests after the start of the screening, which was largest and statistically significant in the target population of the screening programme (age 50-69 years). More than 2 years after the start of screening, the number of mammography requests in all age groups had decreased to the level before the start and in the age group 50-69 years the number of mammographies was significantly lower than before the screening started. The unexpected increase in mammographies after the start of the breast cancer screening programme might be related to registry problems or to the process of building up the screening programme. Eventually there was a decrease in the number of mammographies in the target population, probably an effect of the introduction of the national screening programme. Opportunistic screening was not clearly demonstrated in adjacent age groups.

Adult↗
PubMed1999

The duration and magnitude of influenza epidemics: a study of surveillance data from sentinel general practices in England, Wales and the Netherlands.

Weekly incidence data for influenza-like illness, routinely collected in sentinel general practices in England and Wales and in the Netherlands over 10 winter periods (week 37 in one year to week 20 in the next, 1987/1988-1996/1997) were examined in conjunction with matching virus isolate data to define epidemic periods of influenza in the two countries. We first defined the background rates of recording influenza-like illness which occurred at times when only sporadic or no isolations of virus were reported. The background rates were similar in the two networks with mean weekly incidence in England and Wales of 28.1 per 100,000 (all ages) and in the Netherlands 29.8. Epidemic periods defined as lying above the upper 95% confidence level of the background rate lasted on an average of about 10 weeks. Once epidemics were recognised, peak incidence was generally achieved within 4 weeks. The excess population (all ages) consulting general practitioners during influenza epidemic periods was calculated from the difference between the observed and background incidence rates, and expressed as a percentage of the total population. In the 10 periods surveyed, the percentage of the population consulting and diagnosed with influenza-like illness in England and Wales ranged from 0.4% in 1991/1992 to 1.7% in 1989/1990 and in the Netherlands from 0.5% in 1990/ 1991 to 2.1% in 1989/1990. The duration and epidemic periods were broadly similar in the two countries though the excess consulting population during the 10 epidemics studied averaged 0.85% in England and Wales compared with 1.39% in the Netherlands. There were substantial differences between the two countries in the impact of influenza in individual years, as measured in the consulting population even though the predominant virus (sub)types were similar.

Disease Outbreaks↗
PubMed1998

[The influenza season 1997/'98 and the vaccine composition for 1998/'99].

The 1997/'98 influenza season in the Netherlands was marked by influenza A/H3N2 activity which never reached a true epidemic level. There was no real peak activity either but a prolonged period of increased activity of approximately eight weeks with a maximum in week 13, when sentinel physicians reported 16.6 cases of influenza-like illness per 10,000 inhabitants. It was not until week 18 of 1998 that the influenza activity declined to baseline levels. During the season, almost exclusively influenza A/H3N2 viruses were isolated, of which the majority resembled the new strain influenza A/Sydney/5/97 (H3N2). Further analysis of these variant viruses revealed that, although there was some cross-reactivity with the vaccine strain (A/Nanchang/933/95), no optimal protection could be expected to be induced by the vaccine. Antigenic characterisation of the sporadic influenza A/H1N1 and influenza B viruses showed that these were related to the vaccine strains. As a result of these findings, the World Health Organization (WHO) recommended to change the H3N2 strain in the influenza vaccine for the season 1998/'99 to an influenza A/Sydney/5/97(H3N2)-like strain. Based on epidemiological data from other countries, it was also decided to change the influenza A/H1N1 component to an influenza A/Beijing/262/95 (H1N1)-like strain.

Disease Outbreaks↗
PubMed1997

[Influenza in the 1996/'97 season; vaccine composition for the 1997/'98 season].

The first indication of flu activity in the Netherlands in the 1996/'97 season was the isolation of an A/H3N2 influenza virus in week 48 of 1996. In subsequent weeks influenza viruses were isolated sporadically. The clinical influenza activity increased from week I of 1997 and reached its peak in week 4 of 1997. Simultaneously with the increase of clinical influenza activity, an increasing number of influenza viruses were isolated. The epidemic had a relatively small extent. Initially, A/H3N2 influenza viruses were predominant, but in the second half of the epidemic an increasing number of influenza B viruses were isolated as well. The A/H3N2 viruses were antigenically fairly strongly distinct from the variants prevalent in the preceding years. This season influenza A/HINI viruses did not play a significant role and only one virus of this subtype was isolated. All influenza A/H3N2, A/HINI and B viruses isolated were antigenically similar to the vaccine strains.

Adolescent↗
PubMed1996

[Influenza in the 1995/'96 season; vaccine composition for the 1996/'97 season].

The 1995/'96 season in the Netherlands was marked by an influenza A/H3N2 epidemic that peaked in week 5I. In this week, 39 patients with influenza-like illness per 10,000 inhabitants contacted the sentinel physicians. With two exceptions, influenza A/H3N2 viruses exclusively were isolated during this epidemic period. In the first few months of 1996, a substantial number of influenza A/H1N1 and influenza B viruses were isolated as well. Serological characterization of the circulating viruses revealed that they all resembled the virus strains of the influenza vaccine of 1995/'96, which therefore probably will have provided good protection. Based on the epidemiological data from other countries and the fact that similar H3N2 viruses have been circulating since 1993, the World Health Organization has recommended to exchange the H3N2 component of the 1996/'97 vaccine for a Wuhan/353/95 (H3N2)-like strain.

Humans↗
PubMed1996

Is the incidence of diabetes increasing in all age-groups in The Netherlands? Results of the second study in the Dutch Sentinel Practice Network.

OBJECTIVE: To assess possible changes in the incidence of diabetes in all age-groups in The Netherlands during a 10-year period (1980-1983/1990-1992). RESEARCH DESIGN AND METHODS: Since 1970, a network of sentinel stations (the Dutch Sentinel Practice Network) consisting of approximately 1% of the Dutch population has been in operation to gain insight into the morbidity patterns of the Dutch population as recorded by general practitioners. One of the items recorded from 1990 to 1992 was the incidence of diabetes. The first study with a similar design that registered the incidence of diabetes was conducted from 1980 to 1983. RESULTS: The overall incidence of diabetes increased significantly by 12.1% in the period between the two studies. This overall increase can largely be attributed to a statistically significant increase in the age-group 45-64 years (30.5%). Although not statistically significant, the 36% increase of diabetes in the age-group 0-19 years is in accordance with the increase of type I diabetes based on the first and second nationwide retrospective studies covering the total Dutch population. CONCLUSIONS: There is a marked increase in the incidence of diabetes in the age-group 45-64 years. This selective increase is probably not due to a real rise caused by changes in exposure to risk factors but to an earlier recognition of symptoms and signs of diabetes followed by blood glucose measurements and/or to more intensive case finding in general practice.

Adolescent↗