Estimation of changes in the force of infection for intestinal and urogenital schistosomiasis in countries with schistosomiasis control initiative-assisted programmes.

BACKGROUND: The last decade has seen an expansion of national schistosomiasis control programmes in Africa based on large-scale preventative chemotherapy. In many areas this has resulted in considerable reductions in infection and morbidity levels in treated individuals. In this paper, we quantify changes in the force of infection (FOI), defined here as the per (human) host parasite establishment rate, to ascertain the impact on transmission of some of these programmes under the umbrella of the Schistosomiasis Control Initiative (SCI). METHODS: A previous model for the transmission dynamics of Schistosoma mansoni was adapted here to S. haematobium. These models were fitted to longitudinal cohort (infection intensity) monitoring and evaluation data. Changes in the FOI following up to three annual rounds of praziquantel were estimated for Burkina Faso, Mali, Niger, Tanzania, Uganda, and Zambia in sub-Saharan Africa (SSA) according to country, baseline endemicity and schistosome species. Since schistosomiasis transmission is known to be highly focal, changes in the FOI at a finer geographical scale (that of sentinel site) were also estimated for S. mansoni in Uganda. RESULTS: Substantial and statistically significant reductions in the FOI relative to baseline were recorded in the majority of, but not all, combinations of country, parasite species, and endemicity areas. At the finer geographical scale assessed within Uganda, marked heterogeneity in the magnitude and direction of the relative changes in FOI was observed that would not have been appreciated by a coarser-scale analysis. CONCLUSIONS: Reductions in the rate at which humans acquire schistosomes have been achieved in many areas of SSA countries assisted by the SCI, while challenges in effectively reducing transmission persist in others. Understanding the underlying heterogeneity in the impact and performance of the control intervention at the level of the transmission site will become increasingly important for programmes transitioning from morbidity reduction to elimination of infection. Such analyses will require a fine-scale approach. The lack of association found between programmatic variables, such as therapeutic treatment coverage (recorded at district level) and changes in FOI (at sentinel site level) is discussed and recommendations are made.

Parasitological and malacological surveys reveal urogenital schistosomiasis on Mafia Island, Tanzania to be an imported infection.

To confirm the local endemicity of Schistosoma haematobium on Mafia Island, Tanzania, conjoint parasitological and malacological surveys were undertaken in July 2006 with parasitological investigations supplemented with case-history questionnaires. A total of 238 children (125 girls and 113 boys, mean age of 13.9 years) across 9 primary schools were examined. The prevalence of micro-haematuria and egg-patent infection was 18.1% (CI95=9.6-33.6) and 4.2% (CI95=1.9-7.6), respectively but a strong female bias was observed for micro-haematuria (5.6F:1M) contrasting with a strong male bias for the presence of eggs (1F:4M). All egg-patent infections were of light-intensity (<10eggs/10ml). No clear associations between infection prevalence and local water-contact, by school, were found and all 10 of the egg-positive children had a travel history to the nearby mainland or Zanzibar. Inspection of community diagnostic registers at Kilindoni Hospital revealed a low proportion (<2%) of egg-patent infection for 20,306 samples tested in the 2000-2005 period. A total of 43 freshwater sites, a third of which were previously sampled in 1999 and 2002, were surveyed and 11 species of freshwater mollusc were found. Four species of Bulinus (B. nasutus, B. forskalii, B. barthi and B. sp.) were encountered across 13 sites with B. nasutus restricted to 3 of these towards the north of the island. No collected snail was observed to shed schistosome cercariae. Further characterisation of B. nasutus and S. haematobium included infection challenge on two occasions, with miracidia obtained from egg-patent children from Mafia and Unguja islands as well as DNA barcoding of snails and schistosomes. B. nasutus was shown refractory to infection. With the substantial travel to and from Mafia, the refractory nature of local snails and evidence from DNA barcoding in schistosomes and snails, we conclude that urogenital schistosomiasis is an imported infection.

Age and gender effects in self-reported urinary schistosomiasis in Tanzania.

OBJECTIVES: To characterize age-gender prevalence profiles of urinary schistosomiasis according to the questionnaire responses, compare the profiles to field survey data from selected regions, and determine if the profiles varied spatially throughout Tanzania. METHODS: In 2004, a national school-based questionnaire survey for self-reported schistosomiasis and blood in urine (BIU) was conducted in all regions of mainland Tanzania, to assist targeted mass distribution of praziquantel. Field survey data were collected in six north-western and five coastal regions using microscopic examination of urine samples for the presence of Schistosoma haematobium eggs and assessment of micro-haematuria with chemical reagent strips. Bayesian logistic regression models were created to calculate age-gender profiles adjusted for demographic and ecological covariates and spatial correlation in the questionnaire data. Separate odds ratios (OR) for age-gender effects were calculated in each administrative area. RESULTS: Data were obtained from > 2.5 million schoolchildren. Boys had higher prevalence of self-reported schistosomiasis and BIU than girls. In boys, prevalence according to the questionnaire and field surveys followed similar age profiles. However, in girls, prevalence according to the field surveys increased in older age groups, but flattened out or decreased according to the questionnaire, indicating the latter underestimated prevalence in older girls. In the models, little spatial correlation was evident in the OR for the age-gender effects, suggesting that these did not vary spatially. CONCLUSION: Age-gender patterns of urinary schistosomiasis were consistent in different geographical areas of Tanzania. Because the questionnaire underestimated prevalence in older girls, we propose that upward calibration of observed prevalence is done for older females only.

The control of schistosomiasis and soil-transmitted helminths in East Africa.

As a result of support from the Bill and Melinda Gates Foundation, schistosomiasis and intestinal or soil-transmitted helminth infections have been the subject of national control programmes in three Eastern and Southern African countries: Uganda, the United Republic of Tanzania and Zambia. Here, we review the significant progress made in their control efforts and highlight the different approaches being adopted to ensure programme effectiveness and sustainability. Although a positive start has been made to reduce morbidity resulting from schistosomiasis and soil-transmitted helminth infections in these countries, it is imperative that support is identified to sustain the programmes until these infections are no longer a public health problem and children can therefore be given a healthy start to life.

Bayesian spatial analysis and disease mapping: tools to enhance planning and implementation of a schistosomiasis control programme in Tanzania.

OBJECTIVE: To predict the spatial distributions of Schistosoma haematobium and S. mansoni infections to assist planning the implementation of mass distribution of praziquantel as part of an on-going national control programme in Tanzania. METHODS: Bayesian geostatistical models were developed using parasitological data from 143 schools. RESULTS: In the S. haematobium models, although land surface temperature and rainfall were significant predictors of prevalence, they became non-significant when spatial correlation was taken into account. In the S. mansoni models, distance to water bodies and annual minimum temperature were significant predictors, even when adjusting for spatial correlation. Spatial correlation occurred over greater distances for S. haematobium than for S. mansoni. Uncertainties in predictions were examined to identify areas requiring further data collection before programme implementation. CONCLUSION: Bayesian geostatistical analysis is a powerful and statistically robust tool for identifying high prevalence areas in a heterogeneous and imperfectly known environment.

Schistosoma mansoni in pregnancy and associations with anaemia in northwest Tanzania.

Schistosomiasis among pregnant women has been inadequately investigated. In order to determine the importance of Schistosoma mansoni in this subgroup, we conducted a cross-sectional survey of 972 women in Tanzania and investigated the prevalence of Schistosoma mansoni, hookworm and malaria and their associations with anaemia. Overall, 63.5% of women were infected with S. mansoni, with prevalence highest among younger women and decreasing with increasing age. The prevalence of hookworm was 56.3%, and 16.4% of women had malaria parasitaemia. Overall, 66.4% of women were anaemic. Increased risk of anaemia was associated with heavy infection with S. mansoni but not hookworm or Plasmodium falciparum parasitaemia.

Familial and cultural perceptions and beliefs of oral hygiene and dietary practices among ethnically and socio-economicall diverse groups.

UNLABELLED: OBJECTIVE; The aim of this international study was to develop a valid and reliable psychometric measure to examine the extent to which parents' attitudes about engaging in twice-daily tooth brushing and controlling sugar snacking predict these respective behaviours in their children. A supplementary objective was to assess whether ethnic group, culture, level of deprivation or children's caries experience impact upon the relationships between oral health related behaviours, attitudes to these respective behaviours and to dental caries. CLINICAL SETTING: Nurseries, health centres and dental clinics in 17 countries. PARTICIPANTS: 2822 children aged 3 to 4 years and their parents. MAIN OUTCOME MEASURES: Dental examination of children and questionnaire to parents. RESULTS: Factor analysis identified 8 coherent attitudes towards toothbrushing, sugar snacking and childhood caries. Attitudes were significantly different in families from deprived and non-deprived backgrounds and in families of children with and without caries. Parents perception of their ability to control their children's toothbrushing and sugar snacking habits were the most significant predictor of whether or not favourable habits were reported. Some differences were found by site and ethnic group. CONCLUSIONS: This study supports the hypothesis that parental attitudes significantly impact on the establishment of habits favourable to oral health. An appreciation of the impact of cultural and ethnic diversity is important in understanding how parental attitudes to oral health vary. Further research should examine in a prospective intervention whether enhancing parenting skills is an effective route to preventing childhood caries.

Barriers to the treatment of childhood caries perceived by dentists working in different countries.

OBJECTIVE: To explore whether dentists' beliefs and attitudes to providing preventive and restorative dental care for young children can form a barrier to the provision of care. BASIC RESEARCH DESIGN: The Barriers to Childhood Caries Treatment (BaCCT) Questionnaire, a standardised international measure was developed and applied. PARTICIPANTS: Through a research consortium, each site was asked to recruit 100 dentists. The sample participating was not intended to be nationally representative. Dentists were mainly randomly selected and contacted by mail with one or more mailings depending on site. RESULTS: 2,333 dentists in 14 countries and 17 sites participated. Factor analysis identified four factors as potential barriers. Two factors were found to be barriers in many sites. First, in most countries, dentists agreed that young children's coping skills limit their ability to accept dental care. Secondly, dentists with negative personal feelings, for example, that providing care can be stressful and troublesome and that they feel time constrained. Differences in dentists' beliefs can be partly explained by their work profile, with those treating children often, and those working under systems where they feel they can provide quality care being least likely to identify barriers to providing care for children. CONCLUSIONS: The BaCCT Questionnaire was determined to be a valid psychometric measure. Separately, it was found that health systems do impact on dentists' ability to deliver preventive and restorative care for children but that these effects vary across countries and further work is needed to determine how best these should be examined.

Oral health related knowledge, behaviours, attitude and self-assessed status of primary school teachers in Tanzania.

AIM: To assess the oral health related knowledge, attitudes, behaviours and self-assessed status of primary school teachers in Rungwe, Tanzania. SUBJECTS: 195 final year teacher trainees and 239 in-service teachers. METHOD: A structured questionnaire. RESULTS: School teachers were generally well informed and had moderate attitudes and behaviours to oral health related issues. However, a few but important deficiencies in this regard have been identified on which recommendations are presented. A substantial proportion of teachers reported having dental problems. However, the teachers had positive attitudes towards oral health education to pupils as part of a teaching curriculum. A professional support is called upon for teachers from the oral health personnel in terms of oral health education training at teachers' colleges, to prepare the teacher trainees for their future task. CONCLUSION: In-service teachers need to be motivated to improve their awareness on sound oral health information, attitudes and behaviours. This will facilitate their role as school oral health education providers in Tanzanian primary schools.