Serogroup distribution of urogenital Chlamydia trachomatis in urban ethnic groups in The Netherlands.

The prevalence of Chlamydia trachomatis varies between ethnic groups in The Netherlands. It is, however, unknown whether this is associated with specific serogroups. The objective of this study was to determine whether serogroup distribution is associated with ethnic origin in the region of The Hague, The Netherlands. Serogroups of 370 microbiologically confirmed C. trachomatis-positive samples were analysed. The samples were obtained from 247 women and 123 men between January and October 2008, of self-reported Dutch Caucasian, Dutch Antillean, Surinamese, N. African/Turkish or other descent. We observed a difference in serogroup distribution comparing Dutch Caucasian women to Dutch Antillean women (χ2 for distribution P = 0·035). Serogroup C was more common in Dutch Antillean women, whereas serogroup B was less common (P = 0·03). This difference was not observed for Dutch Antillean men. The observed difference in distribution of C. trachomatis serogroups between ethnic groups is relevant for further transmission studies.

Difficulties in diagnosing terminal ileitis due to Yersinia pseudotuberculosis.

We report three patients with terminal ileitis and positive fecal cultures with Yersinia pseudotuberculosis. From one patient, a virulence plasmid (pYV)-negative Y. pseudotuberculosis was isolated, which represents the second finding of a pYV-negative isolate associated with human disease. All patients were treated with ciprofloxacin and fully recovered. Since conventional culture methods for yersiniosis are gradually replaced with molecular tests not recognizing Y. pseudotuberculosis, we recommend to include a specific culture medium or to apply a specific polymerase chain reaction (PCR) assay on fecal samples from patients suspected of terminal ileitis.

In vitro evaluation of the performance of Granada selective enrichment broth for the detection of group B streptococcal colonization.

A broth for the screening of group B streptococcal (GBS) carriage during pregnancy is about to be introduced. Simulating conditions in everyday practice, we have compared the sensitivity of this Granada tube broth (GT) with that of classical Amies transport medium (AT) in vitro. A total of 1,485 GT and 1,485 AT were tested with 33 well-characterized GBS strains in three different concentrations, five different incubation times, and three different temperatures. After initial incubation at room temperature (RT) or 4°C, GT were placed at 37°C. GT were scored for the presence of orange pigment. GT and AT were subcultured on blood agar (BA). Pigment was observed in 98% of GT incubated at 37°C. GBS could be cultured in 91%, 73%, and 55% of GT incubated at 37°C, RT, or 4°C, respectively. For AT, these percentages were only 20% at 37°C, 52% at RT, and 59% at 4°C. When GT initially incubated at RT or 4°C were subsequently incubated at 37°C, the sensitivity improved significantly. We conclude that GT is a more sensitive GBS transport and culture medium than the conventional method, especially for low inocula and prolonged transport/incubation times. GT does not exclude the presence of GBS, and should always be incubated at 37°C and subcultured on solid agar for optimal sensitivity.

Analyses of multiple-site and concurrent Chlamydia trachomatis serovar infections, and serovar tissue tropism for urogenital versus rectal specimens in male and female patients.

OBJECTIVES: The aims of this study were: to determine the incidence of concurrent infections on a serovar level; to determine the incidence of multiple anatomical infected sites on a detection and genotyping level and analyse site-specific serovar distribution; to identify tissue tropism in urogenital versus rectal specimens. METHODS: Chlamydia trachomatis-infected patients in two populations were analysed: 75 visiting the outpatient department of obstetrics and gynaecology of the MC Haaglanden, and 358 visiting the outpatient sexually transmitted disease clinic, The Hague, The Netherlands. The PACE 2 assay (Gen-Probe) was used to detect C trachomatis from urethral, cervical, vaginal, oropharyngeal and anorectal swabs. C trachomatis genotyping was performed on all C trachomatis positive samples, using the CT-DT genotyping assay. RESULTS: Samples from 433 patients (256 female and 177 male) with confirmed C trachomatis infection were analysed. In 11 patients (2.6%), concurrent serovars in one anatomical sample site were present. In 62 (34.1%) female and four (9.3%) male patients, multiple sample site infections were found. A substantial percentage of women tested at the cervical/vaginal and rectal site were found to be positive at both sites (36.1%, 22/61). In men, D/Da and G/Ga serovars were more prevalent in rectal than urogenital specimens (p=0.0081 and p=0.0033, respectively), while serovar E was more prevalent in urogenital specimens (p=0.0012). CONCLUSIONS: The prevalence of multiple serovar infections is relatively low. Significant differences in serovar distribution are found in rectal specimens from men, with serovar G/Ga being the most prominent, suggesting tissue tropism.

Significantly higher serologic responses of Chlamydia trachomatis B group serovars versus C and I serogroups.

Chlamydia trachomatis serovars are divided into three serogroups, namely serogroup B, serogroup I (Intermediate) and serogroup C, and subsequently into 19 different serovars. Worldwide, serogroup B is the most prevalent followed by serogroup I. Clear differences have been observed in the duration of infection and growth kinetics between serovars from different serogroups in murine and cell culture models. Reasons for these observed differences are bacterial and host related, and are not well understood. The aim of this study was to determine the differences in immunoglobulin (Ig) G responses between the three serogroups in a group of patients infected with different serovars. Serovars were assessed from 235 C. trachomatispositive patients and quantitative IgG responses were determined. Analyses of variance were used to compare the IgG responses between the three serogroups. Of the serovars, 46% were B group (with serovar E the most prevalent: 35.3%), 39.6% were I group and 14.3% were C group. A highly significant difference in serologic response was shown when comparing the mean IgG concentrations (AU/mL) of patients having serovars in the most prevalent serogroup compared to the other serogroups: B = 135, C = 46 and I = 60 (B vs. C and B vs. I, P < 0.001). In conclusion, the most prevalent serovars generate the highest serologic responses.

Description of the ICTI consortium: an integrated approach to the study of Chlamydia trachomatis infection.

The use of an integrated approach to the study of Chlamydia trachomatis infection of the female genital tract, presented at the mini-symposium "Chlamydia trachomatis infections" and described in the thesis of Joseph M. Lyons, has resulted in the creation of the ICTI consortium. The ICTI consortium is based on strong interaction and collaboration between basic scientists, clinicians, epidemiologists, and health care policy makers. This translational approach will help to further the valuable insight into the immunopathogenesis of this sexually transmitted infection (STI) and the development of new intervention strategies, including the vaccines and screening programs necessary to effectively diagnose, treat and prevent C. trachomatis infection. A background of the need for this integrated approach is presented and the goals and participants of the consortium are described.

Comparison of serological assays for detection of Chlamydia trachomatis antibodies in different groups of obstetrical and gynecological patients.

New serological enzyme immunoassays (EIAs) were compared with microimmunofluorescence (MIF) as a "gold standard" to detect Chlamydia trachomatis antibodies in different groups of obstetrical, gynecological, and subfertile patients. There were no significant differences in seroprevalence rates, except for the group of C. trachomatis-positive patients (P < 0.01). Test characteristics were calculated for Chlamydia-EIA (Biologische Analysensystem GmbH, Lich, Germany) and pELISA (Medac, Wedel, Germany). pELISA seems to be a good alternative to MIF. It has high specificity and is easier to perform.

Clinical characteristics of Chlamydia trachomatis infections in a general outpatient department of obstetrics and gynaecology in the Netherlands.

OBJECTIVE: Evaluation of prevalence and risk factors of Chlamydia trachomatis infections in an outpatient obstetric and gynaecological population. METHODS: A prospective, observational study was performed at an inner city hospital in The Hague, Netherlands. 1368 women attending the outpatient department of obstetrics and gynaecology participated in the study. For detection of C trachomatis infections we used amplification of CT rRNA in urine samples (Gen Probe/AMPLIFIED-CT) and DNA probe for detection of CT rRNA from a urethral, endocervical and anal swab (Gen Probe/PACE 2). RESULTS: The overall prevalence of C trachomatis infections in our general obstetric and gynaecological population was 4.5%. The prevalence in women under 30 years of age was 8. 1%. We found age and postcoital bleeding to be significant risk factors. We did not find significant differences between women from different ethnic origin or between women using different kinds of contraceptives. 12 (19.4%) patients with C trachomatis infections were found positive by urine test only, and 15 (24.2%) only by DNA probe. CONCLUSIONS: Age is the most important risk factor in our population (overall prevalence 4.5%, prevalence in women under 20 years of age 15.8%). Analyses of urine and of endocervical specimens are complementary for the determination of the prevalence of C trachomatis infections in women. Cost effectiveness analysis is needed to determine to what extent age based screening and/or antibiotic prophylaxis before intrauterine manipulations is indicated.

Poliovirus circulation among schoolchildren during the early phase of the 1992-1993 poliomyelitis outbreak in The Netherlands.

During the 1992-1993 outbreak of poliomyelitis in The Netherlands, we examined 866 childrenat 7 schools for evidence of infection with the outbreak virus, poliovirus type 3(PV3), to determine the extent of the outbreak and the protection of the herd immunity. Seventy-seven children (8.9%) showed evidence of recent wild-type PV3 infection, as determined by virus isolation and/or poliovirus type-specific IgM assay. Most infected children lived in the same area as the index case patient, attended an orthodox-reformed (OR) primary school, and had not been vaccinated. At the OR school, as many as 22% of children immunized with inactive poliovirus vaccine were found to have evidence of recent infection, which is a significantly lower rate than that among unvaccinated children (59.5%). No evidence of vaccination was seen in 25.5%-43.1% of children at OR schools. Seroprevalence of antibodies against the 3 types of poliovirus suggested that no poliovirus circulation had occurred between the 1978 and 1992-1993 outbreaks.

Surveillance of acute flaccid paralysis in The Netherlands, 1992-94.

Detection and investigation of all cases of acute flaccid paralysis (AFP) in children below 15 years of age are among the criteria for poliomyelitis-free certification. In the absence of poliomyelitis the incidence of AFP is around 1 per 100,000 children aged < 15 years. In the Netherlands, surveillance of AFP began in October 1992 under the supervision of the Dutch Paediatric Surveillance System (NSCK). Over 90% of clinically active paediatricians participated in the monthly reporting of new cases of AFP. From October 1992 to December 1994 (27 months), 52 cases of AFP were reported. The incidence was 0.7 per 100,000 over the period, and reported cases were evenly distributed throughout the country. The main cause of AFP was Guillain-Barré syndrome. The average time between onset of symptoms and visiting a doctor was less than 3 days. The median reporting delay was 29 days, although the system was not intended as surveillance for action. Virological examination of faeces was carried out for only 40.4% of AFP patients. The start of the NSCK surveillance system coincided with the 1992-93 outbreak of poliomyelitis in the Netherlands, but only 7 of the 18 children with paralytic poliomyelitis were reported through the AFP surveillance system. For certification purposes, the present AFP surveillance system in the Netherlands needs to be improved with respect to coverage by including neurologists, rapidity of reporting, and completeness of laboratory investigations.

Outbreaks of paralytic poliomyelitis, 1976-1995.

During 1976-1995, 48 outbreaks of paralytic poliomyelitis with a cumulative total of approximately 17,000 cases were reported worldwide. Outbreaks occurred on most continents, affected from 0.1 to 52 persons per 100,000 total population (median, 4.4), lasted 2-25 months (median, 7), typically involved unvaccinated or inadequately vaccinated subgroups within highly immunized communities, and were primarily caused by poliovirus type 1 (74%). Cases in developing countries occurred predominantly among children <2 years of age, while those in industrialized countries tended to occur in older persons who had escaped natural infection earlier in life and who had not been vaccinated or had received poliovirus vaccine of inadequate potency. Partial genomic sequencing studies indicated that at least 15 outbreaks resulted from importation of wild polioviruses, primarily from the Indian subcontinent. These findings illustrate the potential for wide dissemination of wild poliovirus infection and underscore the critical need for maintaining high levels of immunity in all countries and for more aggressive vaccination efforts in areas in which polio is endemic.

Circulation of poliovirus during the poliomyelitis outbreak in The Netherlands in 1992-1993.

A population-based study on the circulation of epidemic poliovirus during 1992-1993 outbreak in the Netherlands was carried out in order to assess whether the virus circulated outside the group of people who reject vaccinations on religious grounds and outside the area where these groups form sociodemographically closely knit network. The prevalence of poliovirus excretion was estimated in a cross-sectional study with a random sample of 2,400 children aged 5-14 years and 3,000 adults age 40-64 years; the sample was drawn from the municipal population registers in four regions (three inside and one outside the risk area). Fecal samples of virus isolation and characterization were submitted by mail, and a questionnaire was completed with age, sex, type and level of education, vaccination history, and religious denomination. Both a completed questionnaire and a fecal sample were received from 3,182 persons (response, 58.9%). Wild poliovirus was isolated only from children within the risk group and in the area at risk. The crude excretion rate of the epidemic poliovirus type 3 per 1,000 persons was 2.5, but it amounted to 70.7 for those belonging to Orthodox Reformed churches. The prevalence of vaccine virus excretion per 1,000 persons was 10.2 for children and 5.2 for adults. It was concluded that, during the 1992-1993 outbreak, the risk of poliovirus was restricted to religious subpopulations rejecting vaccination. The lack of evidence of poliovirus circulation outside these groups at risk supports the hypothesis that herd immunity is sufficiently maintained in a population vaccinated with inactivated polio vaccine.

Poliomyelitis in The Netherlands: a review of population immunity and exposure between the epidemics in 1978 and 1992.

An overview of serological and virological studies on poliomyelitis in the Netherlands between two epidemics in 1978 and 1992 is given. Three unvaccinated patients acquired poliomyelitis abroad. In the Netherlands vaccination coverage with quadruple DPT-IPV vaccine is very high. The strong immunogenicity of inactivated poliovirus vaccine was confirmed in a cohort of children, reflected in age-stratified antibody profiles of the population. Adults born in the pre vaccination era appeared in general protected, but 10-25% of persons born between 1930 and 1945 lacked neutralizing antibodies. Revaccination induced a booster type of antibody response in 75-90% of such persons, indicating immunological memory and protection. Virological studies on adopted children from other countries, patients with indications for viral examination, and river waters showed that the Netherlands was regularly exposed to polio virus (PV), without signs of indigenous transmission. Persons found to carry PV or their close contacts had travelled to a PV endemic country. Most of 557 isolates were vaccine-derived, only 8% were wild type viruses. Despite their presence, up to 1992 the well-known susceptibles for PV in the Netherlands were shielded by the herd immunity of the Dutch population.

Poliomyelitis outbreak in an unvaccinated community in The Netherlands, 1992-93.

An outbreak of poliomyelitis occurred in the Netherlands between September, 1992, and February, 1993, after 14 years without endemic cases. The outbreak was due to poliovirus type 3 and involved 71 patients, of whom 2 died and 59 had paralysis. The patients were aged between 10 days and 61 years (median 18 years). None of the patients had been vaccinated, and all but 1 belonged to a socially and geographically clustered group of people who refuse vaccination for religious reasons. Control measures were taken within 5 days of notification of the first patient and included a wide offer of vaccination with the trivalent oral poliovirus vaccine to the population at risk. Sequence analysis of the viral genome showed closest similarity (96.7%) with a strain isolated in India in 1992, indicating that the virus probably originates from the Indian subcontinent. The difference, however, is still too large to assume direct import. Extensive outbreak investigation at schools, in the environment, at virus diagnostic laboratories, and in the general population showed no evidence of widespread circulation of the epidemic virus outside the groups at risk and area where these groups live. As in the previous outbreak in 1978, the general population, including the majority of unvaccinated people who live dispersed in the population, seemed to be well-protected against poliomyelitis.

[Poliomyelitis in The Netherlands, 1979-1991: immunity and exposure]. / Poliomyelitis in Nederland, 1979-1991: immuniteit en blootstelling.

An overview is presented of serological and virological studies on poliovirus immunization and circulation in the Netherlands, performed between 1979 and 1991. In this period, only three patients with poliomyelitis were notified. All had acquired the infection abroad. The vaccinations in the national immunization programme, using inactivated poliovirus vaccine, build a strong immunity. This can also be seen in age-stratified serological profiles of the Dutch population. In these surveys, persons from the time at which vaccination was offered have neutralizing antibodies. Older persons, especially those born between 1930 and 1945, sometimes lack antibodies. However, 85-90% of them show a rapid booster response upon vaccination, demonstrating immunological memory. Hence, they will be protected against poliomyelitis upon contact with wild poliovirus. Virological data show a regular import of poliovirus, especially in adoptive children tested on entry into the Netherlands, coming from developing countries. Nearly all other virus isolates in Dutchmen were related to import from such countries. None of the imported patients or other persons in whom poliovirus was detected spread the virus over the country. It demonstrates that as a rule the herd immunity of the well-vaccinated Dutch population is good. Exceptions occur, however, as demonstrated by the epidemics in 1978 and 1992. Large socio-geographic clusters of susceptible people who refuse vaccinations are not sufficiently protected.

[Virological and serological aspects of the Dutch polio epidemic in 1992]. / Virologische en serologische aspecten van de Nederlandse polio-epidemie in 1992.

During the 1992 poliovirus type 3 outbreak in the Netherlands virological and serological investigations were conducted. No molecular epidemiological link was traced between poliovirus type 3 that caused the outbreak of poliomyelitis in the Netherlands and isolates from previous epidemics investigated. Serological neutralization assessments indicate that the inactivated poliomyelitis vaccine used in the Dutch national immunization schedule induces immunity to the causative agent.