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M P Koopmans

Publications and source records attributed to M P Koopmans.

At least 19 recordsLinked to original sources
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

Etiology of gastroenteritis in sentinel general practices in the netherlands.

Data from a general practice-based, case-control study on gastroenteritis and the pathogens related to this disease were used to study the association between specific pathogens and the infected patients' ages and symptoms. For comparison, the occurrence of these pathogens in control patients, stratified by age, also is presented. In children with gastroenteritis who were <5 years of age, rotavirus (in 21% of patients) and Norwalk-like virus (NLV; in 15%) were the most common pathogens. Among patients who were 5-14 years of age, Campylobacter species (in 16% of patients) and Giardia lamblia (in 10%) were the most common pathogens. In the older patients, Campylobacter species was also the most common pathogen (8% to 15% of patients). In addition, several symptoms in case patients were associated with specific pathogens. Blood in the stool was associated with infection with Campylobacter species. In patients with fever, Salmonella species, Campylobacter species, and rotavirus were detected relatively often. Vomiting was associated with NLV and rotavirus. This is the first study in The Netherlands and one of the first studies in the world that has investigated a broad range of pathogens recovered from an unselected population of patients who had consulted general practitioners because of gastroenteritis.

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

Hospital admissions for rotavirus infection in the Netherlands.

The development of a vaccine against rotavirus (RV) infection has necessitated the estimation of the number of hospitalizations for RV infection in the Netherlands. During 1998, pediatricians have reported all hospitalizations with RV infection and supplied information on the duration of admission, clinical picture, indication for admission, and treatment. Also, data from the National Disease Registry on hospitalizations for gastroenteritis (International Classification of Disease codes 006.6. 006.8, 009, and 558.9) and laboratory surveillance data for 1996-1998 were combined in a linear regression model to indirectly estimate the incidence and proportion of hospitalizations attributable to RV infection. The direct estimate of admissions for RV infection in children aged <5 years was 0.9 per 1000, and the indirect estimate was 2.7 per 1000 in 1998 (1996, 3.4; 1997, 1.6). The proportion of hospitalizations for gastroenteritis attributable to RV ranged from 32% in 1997 to 58% in 1996.

Child, Hospitalized↗
PubMed2000

Genetic polymorphism across regions of the three open reading frames of "Norwalk-like viruses".

Genomic characterization of Norwalk-like human caliciviruses (NLVs) originating from outbreaks and sporadic cases of acute gastroenteritis has revealed surprisingly high levels of diversity, even in the RNA polymerase gene, which is anticipated to be highly conserved. Since information on antigenic relationship is limited, due to the lack of a tissue culture system for these viruses, strains mostly are described on the basis of their genetic relatedness. However, the lack of uniformly applied criteria has led to a confusing array of strains with different groups employing different names for similar genetic lineages. Our goal was to conduct a structured analysis of genomic relationships among NLV strains in an attempt to provide an interim framework for genotyping. We assembled a panel of 31 potentially distinct genogroup I (GGI) and genogroup II (GGII) NLVs that reflected the diversity seen in strains detected by our laboratories and in published sequences. Phylogenetic analysis of sequences from regions of the open reading frames (ORF) 1, 2 and 3 was performed in order to investigate genomic relationships. The strains sequenced fell into seven phylogenetic groups in GGI and at least five phylogenetic groups in GGII, based on greater than 80% nucleotide identity in the region of ORF2 encoding the N-terminus of the capsid protein, and consistent clustering with high bootstrap values irrespective of the method used. Analysis of the ORF1 and ORF3 regions supported for most strains the clustering as established for those derived from ORF2. In the ORF1 region, used by most laboratories for diagnostic RT-PCR, clustering was consistent when a putative genotype border was set at 15% nucleotide mismatches for viruses in GGI and at 10% for viruses in GGII. Two strains grouped within different clusters based on ORF1 and ORF2 indicating that recombination may have occurred. We discuss the implications of these observations for the classification and typing of NLVs.

Caliciviridae↗
PubMed2000

Infectious gastro-enteritis: an uncommon cause of diarrhoea in adult allogeneic and autologous stem cell transplant recipients.

The incidence and aetiology of acute diarrhoea in 60 adult allogeneic or autologous stem cell transplant (SCT) recipients was determined in a prospective study. Stool specimens were obtained prior to SCT and on days +20, +40, +60 and +100 post transplant. Microbiological evaluation was performed for pathogenic bacteria, fungi, parasites and viruses. Forty-seven patients were evaluable of whom 31 had a total of 48 acute diarrhoeal episodes. Diarrhoea occurred in 79% of allogeneic and 47% of autologous SCT recipients (P < 0.05). Intestinal infections were found in three of 48 (6%) diarrhoeal episodes. Clostridium difficile with positive toxin was cultured twice and one stool specimen was positive for cryptosporidium. Intestinal pathogens were identified in 13 out of 172 stool specimens from asymptomatic patients and included: rotavirus (4), adenovirus (3), C. difficile, toxin positive (2), and others (4). Graft-versus-host disease was confirmed by biopsy in two of 36 episodes of diarrhoea in allogeneic patients, and in three patients a relationship between reactivation of cytomegalovirus and diarrhoea was suspected. In 40 of 48 (83%) episodes of diarrhoea no clear aetiology could be found.

Adult↗
PubMed2000

Mucosal and systemic immunity against poliovirus in mice transgenic for the poliovirus receptor: the poliovirus receptor is necessary for a virus-specific mucosal IgA response.

In view of the planned eradication of poliovirus, the suitability of transgenic mice bearing the human receptor for poliovirus (PVRtg mice) as a nonprimate animal model to study mucosal immunity against poliovirus was investigated. After intraperitoneal (ip) priming followed by ip or oral booster with live poliovirus, PVRtg mice had detectable IgA and IgG responses. The IgA response was restricted to PVRtg mice and could not be induced by oral immunization. After ip priming, PVRtg mice did shed virus in the stool, whereas control mice did not. Moreover, the amount of virus shed in the stools of PVRtg mice that had an IgA response after immunization was significantly lower than that of nonimmunized mice. A virus-specific mucosal IgA response is dependent on expression of the poliovirus receptor and is influenced by the route of immunization and the virus strain. PVRtg mice are a suitable model for the study of poliovirus-specific immunity and protection against poliovirus infection.

Animals↗
PubMed2000

Antibody responses to antigenic sites 1 and 3 of serotype 3 poliovirus after vaccination with oral live attenuated or inactivated poliovirus vaccine and after natural exposure.

Three important antigenic sites involved in virus neutralization on polioviruses in mouse experiments have been identified. These sites are located at the surface of the virion and have been designated antigenic sites 1, 2, and 3. In mice, the antibody response to antigenic site 1 of serotype 3 poliovirus is considered to be immunodominant, but little is known about the immunogenicity of these sites in humans. In the present study, we developed inhibition enzyme-linked immunosorbent assays specific for antigenic sites 1 and 3 to measure antibody responses to these sites in fully vaccinated inactivated poliovirus vaccine (IPV) (n = 63) and oral live attenuated poliovirus vaccine (OPV) (n = 63) recipients and in naturally infected persons (n = 25). Similar levels of antibodies to site 1 in IPV and OPV vaccinees were detected. However, significantly more OPV recipients (88.7%) had detectable antibodies to antigenic site 3 (P < 0.01) than did IPV-vaccinated persons (63. 1%). After an IPV booster vaccination, both previously IPV- and OPV-vaccinated persons responded with a significant increase in antibodies to sites 1 and 3 (P < 0.01). We conclude that the immune response to serotype 3 poliovirus in humans consists of both site 1- and site 3-specific antibodies and that these responses can be induced by either OPV or recent IPV vaccination.

Antibodies, Monoclonal↗
PubMed2000

Molecular detection and epidemiology of Sapporo-like viruses.

Sapporo-like viruses (SLVs) are associated with acute gastroenteritis in humans. Due to a limited supply of available reagents for diagnosis, little is known about the incidence and pathogenicity of these viruses. We have developed a first-generation generic reverse transcriptase (RT) PCR assay based on a single primer pair targeting the RNA polymerase gene. With this assay, 55 (93%) of the 59 stool specimens collected in a 10-year period of time (1988 to 1998) and containing typical caliciviruses by electron microscopy tested positive and could be confirmed by Southern hybridization. By phylogenetic analysis, most SLV strains could be classified into one of the three recently described genotypes. However, three samples clustered separately, forming a potential new genotype. We sequenced the complete capsid gene of one of the strains in this cluster: Hu/SLV/Stockholm/97/SE. Alignment of the capsid sequences showed 40 to 74% amino acid identity among strains of the different clusters. Phylogenetic analysis of the aligned sequences confirmed the placing of Hu/SLV/Stockholm/97/SE into a new distinct genetic cluster. This is the first report on the development of a broadly reactive RT-PCR assay for the detection of SLVs.

Adult↗
PubMed2000

Simultaneous detection and genotyping of "Norwalk-like viruses" by oligonucleotide array in a reverse line blot hybridization format.

"Norwalk-like viruses" (NLVs) are the most common cause of outbreaks of nonbacterial gastroenteritis worldwide. To date, the method most widely used for typing of NLV strains is sequencing and subsequent phylogenetic analysis of reverse transcription (RT)-PCR products, which has revealed the existence of stable distinct lineages (genotypes). This typing method is rather costly, not routinely used in clinical laboratories, and not very suitable for the analysis of large numbers of samples. Therefore, we have developed a rapid and simple method for genotyping of NLVs. The method, designated reverse line blot hybridization, is based on the nucleotide divergence of a region of the gene for RNA polymerase which can be used to classify NLVs into genotypes. NLV RNA was amplified by RT-PCR and then hybridized to 18 different membrane-bound oligonucleotides that were able to discriminate among 13 NLV genotypes. Application of the method to a panel of 132 positive stool samples from 34 outbreaks and 20 sporadic cases of gastroenteritis collected in a 6-year period (1994 to 1999) resulted in successful genotyping of 124 samples (94%), as confirmed by phylogenetic analysis. The nucleotide sequences of the remaning eight strains (6%) from three outbreaks did not cluster with the known NLV genotypes. Phylogenetic analysis of the complete and partial open reading frame 2 (capsid gene) sequences of these strains revealed the existence of one novel genotype (Alphatron) and one potentially novel genotype (Amsterdam). This novel method, which allows simultaneous detection and genotyping of NLVs, is useful in the diagnosis and typing of NLVs obtained from outbreaks and in large-scale epidemiological studies.

Caliciviridae Infections↗
PubMed1999

Induction of mucosal immunity by inactivated poliovirus vaccine is dependent on previous mucosal contact with live virus.

The inactivated poliovirus vaccine (IPV) is used for protection against poliomyelitis in The Netherlands. It is not clear, however, whether IPV vaccination can lead to priming of the mucosal immune system and the induction of IgA. It has been demonstrated that IPV vaccination is able to induce strong memory IgA responses in the serum of persons who have been naturally exposed to wild-type poliovirus. This has led to the hypothesis that IPV vaccination is able to induce poliovirus-specific IgA at mucosal sites in persons who have been previously primed with live poliovirus at mucosal sites. To test this hypothesis, the kinetics of the IgA response in serum and saliva after IPV vaccination were examined in persons previously vaccinated with oral poliovirus vaccine (OPV) or IPV. ELISA and enzyme-linked immunospot assays were used for the detection of poliovirus-specific IgA responses. In addition, B cell populations were separated on the basis of the expression of mucosal (alpha4beta7 integrin) and peripheral homing receptors (L-selectin). Parenteral IPV vaccination was able to boost systemic and mucosal IgA responses in previously OPV-vaccinated persons only. None of the previously vaccinated IPV recipients responded with the production of IgA in saliva. In agreement with this finding, a large percentage of the poliovirus-specific IgA-producing lymphocytes detected in previous OPV recipients expressed the alpha4beta7 integrin. It is concluded that IPV vaccination alone is insufficient to induce a mucosal IgA response against poliovirus. In mucosally (OPV-) primed individuals, however, booster vaccination with IPV leads to a strong mucosal IgA response.

Adult↗
PubMed1999

Lessons from diagnostic investigations of patients with poliomyelitis and their direct contacts for the present surveillance of acute flaccid paralysis.

One of the key strategies for the global eradication of poliomyelitis is the virological investigation of stool samples in cases of acute flaccid paralysis (AFP) to exclude poliovirus as a possible cause. Clinical specimens from a serotype 3 outbreak provided an opportunity to examine the potential of newly developed methods for the diagnosis of poliomyelitis. The virus isolation rate was maximal (89.6%) during the first 2 weeks after the onset of paralysis and then dropped sharply to 18.6%. In contrast, a high percentage of patients tested positive for poliovirus-specific IgM (93.9%) in the early phase of the infection and remained positive for up to 8 weeks. Virus isolation would have correctly identified only 54.9% of the AFP cases. This rate would have been increased to 92% through the use of the poliovirus-specific IgM ELISA. The IgM ELISA could serve as an important additional tool for the rapid diagnosis of poliomyelitis.

Acute Disease↗
PubMed1999

A Sabin vaccine-derived field isolate of poliovirus type 1 displaying aberrant phenotypic and genetic features, including a deletion in antigenic site 1.

Poliovirus strains derived from the oral poliovirus vaccine (Sabin) can be differentiated from wild-type poliovirus by tests based on either immunological or genetic properties of the strains. The characterization of a recently identified poliovirus type 1 isolate with exceptional properties is described. Initial phenotypic analysis of the virus by use of polyclonal absorbed antisera suggested a wild-type character. However, the different genomic analyses all confirmed the Sabin-derived character of the virus. All 17 plaques isolated from the strain shared these properties, thus excluding the possibility of a mixture of a wild-type and a Sabin-derived strain. To elucidate the properties of this virus further, the nucleotide sequences of the P1 region and most of the 5' non-coding region were established. Although the nucleotide identity with Sabin 1 was more than 99.4%, mutations were observed in regions encoding three major antigenic sites; the deduced amino acid substitutions confirmed the aberrant results of micro-neutralization assays with site-specific monoclonal antibodies. The most striking feature was the existence of a hexanucleotide deletion in the VP1 gene, which gave rise to a two amino acid deletion in the BC loop. In spite of these antigenic changes, the strain was readily serotyped as poliovirus type 1 under standard conditions. Likewise, replication of the virus under cell culture conditions was not affected by these mutations or by the deletion. Standard polio vaccination protects against this aberrant virus, and its epidemiological significance remains open.

Amino Acid Sequence↗
PubMed1999

Molecular detection of Norwalk-like caliciviruses in sewage.

In this study, Norwalk-like virus (NLV) RNA was detected by reverse transcriptase PCR (RT-PCR) in sewage water concentrates. Sequence analysis of the RT-PCR products revealed identical sequences in stools of patients and related sewage samples. In 6 of 11 outbreak-unrelated follow-up samples, multiple NLV genotypes were present. Levels as high as 10(7) RNA-containing particles per liter were found. These data show that high loads of NLVs may be present in sewage and warrant further studies addressing the efficacy of NLV removal by sewage water treatment processes.

Caliciviridae Infections↗
PubMed1999

Genetic basis for immunological aberrations in poliovirus Sabin serotype 3 strains imported in the netherlands.

During the characterization of poliovirus type 3 strains imported in The Netherlands, Sabin serotype 3 strains that reacted with both specific antisera against Sabin-like (vaccine) and non-Sabin-like (wild-type) strains by the intratypic strain differentiation assay have been found. The present study was done to determine the pathogenic potential of these virus strains for humans. Characterization of these so-called double-reactive strains with neutralizing monoclonal antibodies (MAbs) against the major antigenic sites of serotype 3 Sabin virus led to the identification of two groups with different antigenic properties. Six of the seven strains were resistant to neutralization with MAbs against sites 2B and 3B and one strain was neutralized by all the MAbs in a manner similar to that for the Sabin serotype 3 virus. Partial sequencing of the coding regions confirmed the antigenic changes for all six antigenically distinct strains. By inoculation of these viruses into transgenic mice which express the human poliovirus receptor, one strain was identified as highly neurovirulent, three were identified as intermediate, and three were identified as attenuated. Sera from vaccinated persons efficiently neutralized the mutants. Our data suggest that some double-reactive strains are a potential risk to the unvaccinated community but not to the vaccinated population.

Animals↗
PubMed1998

Age-stratified seroprevalence of neutralizing antibodies to astrovirus types 1 to 7 in humans in The Netherlands.

Astroviruses are a new family of positive-stranded RNA viruses that cause gastroenteritis in a wide range of animals and in humans. Seven types of astrovirus, tentatively considered serotypes, have been distinguished by enzyme-linked immunosorbent assays (ELISA) or immunoelectron microscopy, but it is unclear whether the serotype designation is used properly. To test human sera for the presence of neutralizing antibodies and to type field strains, neutralization tests (NT) using CaCo2 tissue-culture-adapted astrovirus strains 1 to 7 and the corresponding rabbit reference sera were developed. In rabbits, neutralizing antibodies were predominantly serotype specific, with the exception of low-level cross-reactivity in astrovirus serotype 4 reference serum with astrovirus serotype 1 virus. Similarly, in humans, no evidence of cross-reactivity was found for the serotype combinations tested (all except the combination 1 and 7 and the combination 6 and 7). Typing by NT was concordant with typing by ELISA and genotyping, with one exception. The seroprevalence rates of neutralizing antibodies in an age-stratified sample of the population in Utrecht Province (n = 242) were 91% for astrovirus serotype 1, 69% for astrovirus serotype 3, 56% for astrovirus serotype 4, 36% for astrovirus serotype 5, 31% for astrovirus serotype 2, 16% for astrovirus serotype 6, and 10% for astrovirus serotype 7. Acquisition of antibodies was slower among persons seropositive for astrovirus serotype 5 than among those seropositive for astrovirus serotypes 1 to 4, suggesting that the epidemiology of serotype 5 astrovirus is different from that of astrovirus serotypes 1 to 4.

Adolescent↗