Jan-Hendrik Richardus

Prevalence of urogenital Chlamydia trachomatis increases significantly with level of urbanisation and suggests targeted screening approaches: results from the first national population based study in the Netherlands

Objectives:Chlamydia trachomatis (Chlamydia) is the most prevalent sexually transmitted bacterial infection and can cause considerable reproductive morbidity in women. Chlamydia screening programmes have been considered but policy recommendations are hampered by the lack of population based data. This paper describes the prevalence of Chlamydia in 15–29 year old women and men in rural and urban areas, as determined through systematic population based screening organised by the Municipal Public Health Services (MHS), and discusses the implications of this screening strategy for routine implementation. Methods: Stratified national probability survey according to “area address density” (AAD). 21 000 randomly selected women and men in four regions, aged 15–29 years received a home sampling kit. Urine samples were returned by mail and tested by polymerase chain reaction (PCR). Treatment was via the general practitioner, STI clinic, or MHS clinic. Results: 41% (8383) responded by sending in urine and questionnaire. 11% (2227) returned a refusal card. Non-responders included both higher and lower risk categories. Chlamydia prevalence was significantly lower in rural areas (0.6%, 95% CI 0.1 to 1.1) compared with very highly urbanised areas (3.2%, 95% CI 2.4 to 4.0). Overall prevalence was 2.0% (95% CI 1.7 to 2.3): 2.5% (95% CI 2.0 to 3.0%) in women and 1.5% (95% CI 1.1 to 1.8) in men. Of all cases 91% were treated. Infection was associated with degree of urbanisation, ethnicity, number of sex partners, and symptoms. Conclusion: This large, population based study found very low prevalence in rural populations, suggesting that nationwide systematic screening is not indicated in the Netherlands and that targeted approaches are a better option. Further analysis of risk profiles will contribute to determine how selective screening can be done.

A prediction rule for selective screening of Chlamydia trachomatis infection

Background: Screening for Chlamydia trachomatis infections is aimed at the reduction of these infections and subsequent complications. Selective screening may increase the cost effectiveness of a screening programme. Few population based systematic screening programmes have been carried out and attempts to validate selective screening criteria have shown poor performance. This study describes the development of a prediction rule for estimating the risk of chlamydial infection as a basis for selective screening. Methods: A population based chlamydia screening study was performed in the Netherlands by inviting 21 000 15–29 year old women and men in urban and rural areas for home based urine testing. Multivariable logistic regression was used to identify risk factors for chlamydial infection among 6303 sexually active participants, and the discriminative ability was measured by the area under the receiver operating characteristic curve (AUC). Internal validity was assessed with bootstrap resampling techniques. Results: The prevalence of C trachomatis (CT) infection was 2.6% (95% CI 2.2 to 3.2) in women and 2.0% (95% CI 1.4 to 2.7) in men. Chlamydial infection was associated with high level of urbanisation, young age, Surinam/Antillian ethnicity, low/intermediate education, multiple lifetime partners, a new contact in the previous two months, no condom use at last sexual contact, and complaints of (post)coital bleeding in women and frequent urination in men. A prediction model with these risk factors showed adequate discriminative ability at internal validation (AUC 0.78). Conclusion: The prediction rule has the potential to guide individuals in their choice of participation when offered chlamydia screening and is a promising tool for selective CT screening at population level.

Comparability of published perinatal mortality rates in Western Europe: the quantitative impact of differences in gestational age and birthweight criteria

Objective To quantify the impact of publication criteria on differences in published national perinatal mortality rates among Western European countries.

Substandard factors in perinatal care in The Netherlands: a regional audit of perinatal deaths

BACKGROUND To determine: 1) whether substandard factors were present in cases of perinatal death, and to what extent another course of action might have resulted in a better outcome, and 2) whether there were differences in the frequency of substandard factors by level of care, particularly between midwives and gynecologists/obstetricians and between home and hospital births. METHODS Population-based perinatal audit, with explicit evidence-based audit criteria. SETTING The northern part of the province of South-Holland in The Netherlands. All levels of perinatal care (primary, secondary and tertiary care, and home and hospital births) were included. CASES Three hundred and forty-two cases of perinatal mortality (24 weeks of pregnancy--28 days after birth). MAIN OUTCOME MEASURES Scores by a Dutch and a European audit panel. Score 0: no substandard factors identified; score 1, 2 or 3: one or more substandard factors identified, which were unlikely (1), possibly (2) or probably (3) related to the perinatal death. RESULTS In 25% of the perinatal deaths (95% Confidence Interval: 20-30%) a substandard factor was identified that according to the Dutch panel was possibly or probably related to the perinatal death. These were mainly maternal/social factors (10% of all perinatal deaths; most frequent substandard factor: smoking during pregnancy), and antenatal care factors (10% of all perinatal deaths; most frequent substandard factor: detection of intra-uterine growth retardation). We did not find statistically significant differences in scores between midwives and gynecologists/obstetricians or between home and hospital births. The European panel identified more substandard factors, but these were again equally distributed by level of care. CONCLUSIONS Perinatal deaths might be partly preventable in The Netherlands. There is no evidence that the frequency of substandard factors is related to specific aspects of the perinatal care system in The Netherlands.

Population prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae in the Netherlands. should asymptomatic persons be tested during Population-based chlamydia Screening also for gonorrhoea or only if chlamydial infection is found?

BackgroundScreening and active case finding for Chlamydia trachomatis (CT) is recommended to prevent reproductive morbidity. However insight in community prevalence of gonococcal infections and co-infections with Neisseria gonorrhoea (NG) is lacking.MethodsNested study within a large population-based Chlamydia Screening Pilot among 21.000 persons 15–29 year. All CT-positive (166) and a random sample of 605 CT-negative specimens were as well tested for gonococcal infection.ResultsOverall Chlamydia prevalence in the Pilot was 2.0% (95% CI: 1.7–2.3), highest in very urban settings (3.2%; 95% CI: 2.4–4.0) and dependent of several risk factors. Four gonococcal infections were found among 166 participants with CT infection (4/166 = 2.4%; 95% CI: 0.1%–4.7%). All four had several risk factors and reported symptoms. Among 605 CT-negative persons, no infection with NG could be confirmed.ConclusionA low rate of co-infections and a very low community prevalence of gonococcal infections were found in this population based screening programme among young adults in the Netherlands. Population screening for asymptomatic gonococcal infections is not indicated in the Netherlands. Although co-infection with gonorrhoea among CT-positives is dependent on symptoms and well-known algorithms for elevated risks, we advise to test all CT-positives also for NG, whether symptomatic or asymptomatic.

The spatial distribution of leprosy cases during 15 years of a leprosy control program in Bangladesh: An observational study

BackgroundAn uneven spatial distribution of leprosy can be caused by the influence of geography on the distribution of risk factors over the area, or by population characteristics that are heterogeneously distributed over the area. We studied the distribution of leprosy cases detected by a control program to identify spatial and spatio-temporal patterns of occurrence and to search for environmental risk factors for leprosy.MethodsThe houses of 11,060 leprosy cases registered in the control area during a 15-year period (1989–2003) were traced back, added to a geographic database (GIS), and plotted on digital maps. We looked for clusters of cases in space and time. Furthermore, relationships with the proximity to geographic features, such as town center, roads, rivers, and clinics, were studied.ResultsSeveral spatio-temporal clusters were observed for voluntarily reported cases. The cases within and outside clusters did not differ in age at detection, percentage with multibacillary leprosy, or sex ratio. There was no indication of the spread from one point to other parts of the district, indicating a spatially stable endemic situation during the study period. The overall risk of leprosy in the district was not associated with roads, rivers, and leprosy clinics. The risk was highest within 1 kilometer of town centers and decreased with distance from town centers.ConclusionThe association of a risk of leprosy with the proximity to towns indicates that rural towns may play an important role in the epidemiology of leprosy in this district. Further research on the role of towns, particularly in rural areas, is warranted.

The spatial distribution of leprosy in four villages in Bangladesh: an observational study.

BackgroundThere is a higher case-detection rate for leprosy among spatially proximate contacts such as household members and neighbors. Spatial information regarding the clustering of leprosy can be used to improve intervention strategies. Identifying high-risk areas within villages around known cases can be helpful in finding new cases.MethodsUsing geographic information systems, we created digital maps of four villages in a highly endemic area in northwest Bangladesh. The villages were surveyed three times over four years. The spatial pattern of the compounds – a small group of houses – was analyzed, and we looked for spatial clusters of leprosy cases.ResultsThe four villages had a total population of 4,123. There were 14 previously treated patients and we identified 19 new leprosy patients during the observation period. However, we found no spatial clusters with a probability significantly different from the null hypothesis of random occurrence.ConclusionSpatial analysis at the microlevel of villages in highly endemic areas does not appear to be useful for identifying clusters of patients. The search for clustering should be extended to a higher aggregation level, such as the subdistrict or regional level. Additionally, in highly endemic areas, it appears to be more effective to target complete villages for contact tracing, rather than narrowly defined contact groups such as households.

Social contact patterns and leprosy disease: a case-control study in Bangladesh

Socioeconomic and culturally defined social contact patterns are expected to be an important determinant in the continuing transmission of Mycobacterium leprae in leprosy-endemic areas. In a case-control study in two districts in Bangladesh, we assessed the association between social contact patterns and the risk of acquiring clinical leprosy. Social contacts of 90 recently diagnosed patients were compared to those of 199 controls. Leprosy was associated with a more intensive social contact pattern in the home [odds ratio (OR) 1·09, 95% confidence interval (CI) 1·00-1·19, P = 0·043] and in the nearby neighbourhood (OR 1·07, 95% CI 1·03-1·11, P = 0·001). Although it is known that M. leprae spreads most easily within households of infected persons, in endemic areas social contacts within the neighbourhood, village or urban ward, also appear to be important for transmission. We advise that disease control measures in leprosy-endemic areas should not be limited to households, but include high-risk groups in the nearby neighbourhood of patients.

Substandard factors in perinatal care in The Netherlands

Background. To determine: 1) whether substandard factors were present in cases of perinatal death, and to what extent another course of action might have resulted in a better outcome, and 2) whether there were differences in the frequency of substandard factors by level of care, particularly between midwives and gynecologists/obstetricians and between home and hospital births.