Relative contribution of day-to-day and intra-specimen variation in faecal egg counts of Schistosoma mansoni before and after treatment with praziquantel

There is evidence that faecal egg counts of Schistosoma mansoni vary considerably from day to day, which results in poor sensitivity of single stool readings. Intra-specimen variation of S. mansoni egg counts may also be considerable, but has previously been considered as the less important component. We quantified the relative contribution of these two sources of variation among 96 schoolchildren from an area in Cĵte d'Ivoire highly endemic for S. mansoni. Stool specimens were collected over 5 consecutive days, and 5 egg-counts were made in each specimen by the Kato-Katz technique. The point prevalence of the first sample was 42.7% and the cumulative prevalence after the maximum sampling effort was 88.5%. Using generalized linear mixed models we found that the presence of S. mansoni eggs in a stool sample varied much more between days than within specimens, indicating that stool sample examination over multiple days is required for accurate prevalence estimates. However, using the same approach, we found that among infected children intra-specimen variation in egg counts was 4.3 times higher than day-to-day variation. After praziquantel administration, day-to-day variation was more important than before, since most infections were very light and thus likely to be missed altogether by stool examination on a single day. We conclude that diagnostic sensitivity in high transmission areas is maximized by making several stool readings on several days, but examining 1 stool specimen several times can make reasonable estimates of infection intensity.

The future shape of primary health care in New Zealand

The Minister of Health in New Zealand earlier this year released a discussion document titled "The Future Shape of Primary Health Care" which outlines some far-reaching proposals for the provision of primary health care services within New Zealand. This article sets the discussion document in the context of primary health care within New Zealand by examining current arrangements for primary health care, previous arrangements and the proposals outlined in the discussion document.

Associations of peak shifts in age--prevalence for human malarias with bednet coverage

Effects of bednet coverage (C) on prevalence of malaria were analysed using data from 1990-92 from 9 Papua New Guinean villages. Effects of coverage varied by age, resulting in a shift in age of peak prevalence from 4.7 (C = 0%) to 11.6 (C = 100%) years for Plasmodium falciparum, from 3.4 to 4.9 years for P. vivax and from 11.0 to 16.8 years for P. malariae. In small areas with no bednets the age distribution of P. falciparum parasitaemia was like that of a holoendemic area. Where coverage was complete the pattern corresponded to mesoendemicity. Thus, protracted use of bednets can result in profound changes in the endemicity of malaria even when coverage is incomplete and without insecticide treatment. Average entomological inoculation rates (EIRs) estimated from indoor landing rates on individuals without bednets were 35, 12 and 10 infectious bites per person per annum for P. falciparum, P. vivax and P. malariae, respectively. Logistic regression analyses indicated that the EIR estimate for P. falciparum was related to prevalence of this species independently of effects of bednet coverage. However, the recent EIR still accounted for much less variation than did the bednets. A similar pattern was seen for P. malariae, while there were no significant relationships between the recent EIR and the parasite positivity for P. vivax. It is concluded that short-term variations in inoculation rate are not important determinants of parasite prevalence in this population.

A randomised trial of an intervention to develop health promoting schools in Australia: the south western Sydney study

OBJECTIVE

This paper describes the evaluation of a health promoting schools intervention carried out in the south western region of Sydney, Australia. The evaluation sought to assess the project's impact on structures to support the health promoting school concept and changes in health-related policies and practices within 22 local schools.

METHODS

A randomised controlled study was employed. Intervention schools were offered seminars and training in the health promoting schools concept, encouraged to use a resource kit to help them establish their school as health promoting and invited to participate in a support network. Pre- and post measures of awareness, school structures and policies and practices to support the development of a health promoting school were taken and intervention and control schools compared.

RESULTS

There was an increased level of awareness of the health promoting school concept among intervention schools. However, there were no significant changes in health-related policies and practices at the school level, among both intervention and control schools.

CONCLUSIONS

A longer time frame and more structured support are required to influence school structures to support the development of a health promoting school.

IMPLICATIONS

To facilitate organisational change in schools, health promoting school interventions need to provide structured support for schools and recognise that change takes time. A committee to initiate action, a plan to guide work and school support are likely to facilitate the adoption of the health promoting schools approach. Further work to refine the measurement of school-based action and its outcome and the development of indicators for a health promoting school is needed.

Leisure-time, occupational, and household physical activity among professional, skilled, and less-skilled workers and homemakers

BACKGROUND

Adults in lower status occupations are at higher risk of premature cardiovascular disease, for which physical inactivity is a major risk factor. While lower rates of leisure-time physical activity have been found to be associated consistently with lower income and education levels, the association between occupational and home-based physical activity with membership of different occupational categories is not well understood.

METHODS

An urban-representative population data set derived from a self-completion questionnaire was used to examine both self-reported leisure-time physical activity and a combined measure of occupational/home-based physical activity of adult less-skilled, skilled, and professional workers and homemakers (3795 males; 4140 females). chi(2) analyses, ANOVA, and logistic regressions were used to examine the associations between occupational group membership and physical activity.

RESULTS

After adjustment for age, body mass index, education, country of birth, marital status, and smoking, less-skilled workers were less likely to report any form of leisure-time physical activity. However, occupational category was not a strong predictor of participation in combined vigorous occupational/home physical activity. Homemakers and those in lower status occupations were less likely to report participation in vigorous leisure-time physical activity sufficient for cardiorespiratory fitness. With the inclusion of time spent in combined vigorous occupational/home physical activity, there was no longer an association of activity with occupational status for males. However, for females the association remained.

CONCLUSIONS

The assessment of occupational and household physical activity in addition to leisure-time activity may be important for understanding associations between occupational categories, physical activity, and increased levels of health risk and for the development of physical activity promotion strategies.

The prophylactic effects of artemether against Schistosoma japonicum infections

The fight against schistosomiasis in China has been very effective in reducing the number of infections across the country. However, the drug of choice, praziquantel, has no prophylactic effect, which reduces its efficacy in high transmission areas. This situation has prompted efforts to find prophylactic compounds, the most promising of which is the drug artemether. In this article, Xiao Shuhua, Mark Booth and Marcel Tanner review the results of laboratory tests and field trials of artemether against schistosomiasis in China.

Rapid screening for Schistosoma mansoni in western Côte d'Ivoire using a simple school questionnaire

The distribution of schistosomiasis is focal, so if the resources available for control are to be used most effectively, they need to be directed towards the individuals and/or communities at highest risk of morbidity from schistosomiasis. Rapid and inexpensive ways of doing this are needed, such as simple school questionnaires. The present study used such questionnaires in an area of western Côte d'Ivoire where Schistosoma mansoni is endemic; correctly completed questionnaires were returned from 121 out of 134 schools (90.3%), with 12,227 children interviewed individually. The presence of S. mansoni was verified by microscopic examination in 60 randomly selected schools, where 5047 schoolchildren provided two consecutive stool samples for Kato-Katz thick smears. For all samples it was found that 54.4% of individuals were infected with S. mansoni. Moreover, individuals infected with S. mansoni reported "bloody diarrhoea", "blood in stools" and "schistosomiasis" significantly more often than uninfected children. At the school level, Spearman rank correlation analysis showed that the prevalence of S. mansoni significantly correlated with the prevalence of reported bloody diarrhoea (P = 0.002), reported blood in stools (P = 0.014) and reported schistosomiasis (P = 0.011). Reported bloody diarrhoea and reported blood in stools had the best diagnostic performance (sensitivity: 88.2%, specificity: 57.7%, positive predictive value: 73.2%, negative predictive value: 78.9%). The study, which is probably the largest of its kind ever undertaken in Africa, revealed a moderate diagnostic performance of questionnaires for identifying individuals and/or communities at high risk from S. mansoni.

Geographical influences upon physical activity participation: evidence of a 'coastal effect'

OBJECTIVE

To examine the association between geographical proximity to the coast and physical activity participation levels.

METHOD

Using stratified random sampling, a telephone survey was carried out in 1994 with 1,000 adults in each of the 16 health service regions in New South Wales (N = 16,178). Physical activity levels were measured through self-report of the frequency and duration of walking, moderate and vigorous activities in the two weeks preceding the survey. Logistic regression modelling was carried out to examine the association between physical activity and 'coastal' location of residence, adjusting for age, sex, employment status, education level and country of birth.

RESULTS

After adjusting for other demographic factors, respondents who lived in a coastal postcode were 23% less likely to be classified as sedentary, 27% more likely to report levels of activity considered adequate for health, and 38% more likely to report high (vigorous) levels of physical activity than those who lived inland. Each of these associations was significant at the 0.05 level.

CONCLUSIONS

Characteristics of the physical environment in coastal postcodes are related to physical activity participation.

IMPLICATIONS

Physical environments may contribute to physical activity participation. Further efforts to conceptualise and measure these environmental influences is warranted. Public health efforts to promote physical activity should consider aspects of the physical environment as part of any intervention.

Firing rate distributions and efficiency of information transmission of inferior temporal cortex neurons to natural visual stimuli

The distribution of responses of sensory neurons to ecological stimulation has been proposed to be designed to maximize information transmission, which according to a simple model would imply an exponential distribution of spike counts in a given time window. We have used recordings from inferior temporal cortex neurons responding to quasi-natural visual stimulation (presented using a video of everyday lab scenes and a large number of static images of faces and natural scenes) to assess the validity of this exponential model and to develop an alternative simple model of spike count distributions. We find that the exponential model has to be rejected in 84% of cases (at the p < 0.01 level). A new model, which accounts for the firing rate distribution found in terms of slow and fast variability in the inputs that produce neuronal activation, is rejected statistically in only 16% of cases. Finally, we show that the neurons are moderately efficient at transmitting information but not optimally efficient.

Hormonal therapy for menopause and ovarian cancer in a collaborative re-analysis of European studies

The relationship between hormonal therapy for menopause (hormone replacement therapy, HRT) and the risk of epithelial ovarian cancer was evaluated in a collaborative re-analysis of 4 European case-control studies, 2 conducted in Greece and 1 each in Italy and the United Kingdom, including a total of 1,470 ovarian cancer cases and 3,271 hospital controls. Odds ratios (ORs) for HRT use were derived after allowance for study centre, age, socio-economic level, parity, menopausal status, type of menopause, age at menopause and oral contraceptive use. Overall, 109 (8.0%) ovarian cancer cases and 146 (4.7%) controls had ever used HRT, corresponding to an adjusted OR of 1.71 (95% confidence interval 1.30-2.25). The point estimates of the OR were 1.77 in the first Greek study, 1.40 in the second Greek study, 1.66 in the Italian study and 1.68 in the British study. Adjustment for possible confounders, including menopausal status, type of menopause, age at menopause and oral contraceptive use, slightly increased the OR. Limiting the analysis to women with information on relevant aspects of HRT use revealed a weak positive association with duration and some evidence that the excess relative risk for ovarian cancer declined with time since last use. These findings are compatible with a promoting effect of HRT in ovarian carcinogenesis. It is also possible, however, that the positive association reflects chance or selective administration of HRT to high-risk individuals, since until recently in Europe HRT was prescribed mainly for alleviation of peri-menopausal symptoms.

Field activity cost estimates for the first 3 years of the World Bank Loan Project for schistosomiasis control in China

The World Bank Loan Project for schistosomiasis in China commenced field activities in 1992. In this paper, we describe disease control strategies for levels of different endemicity, and estimate unit costs and total expenditure of screening, treatment (cattle and humans) and snail control for 8 provinces where Schistosoma japonicum infection is endemic. Overall, we estimate that more than 21 million US dollars were spent on field activities during the first three years of the project. Mollusciciding (43% of the total expenditure) and screening (28% of the total) are estimated to have the most expensive field activities. However, despite the expense of screening, a simple model predicts that selective chemotherapy could have been cheaper than mass chemotherapy in areas where infection prevalence was higher than 15%, which was the threshold for mass chemotherapy intervention. It is concluded that considerable cost savings could be made in the future by narrowing the scope of snail control activities, redefining the threshold infection prevalence for mass chemotherapy, defining smaller administrative units, and developing rapid assessment tools.

Five year impact of chemotherapy on morbidity attributable to Schistosoma japonicum infection in the Dongting Lake region

OBJECTIVE

To determine changes in the last 5 years of the fraction of acute and chronic symptoms attributable to schistosomiasis japonica in fishing communities with moderate endemicity in the Dongting Lake region of China.

METHOD

Complete medical histories, physical examinations, and stool samples were obtained from 1909 individuals (53% male) ranging in age from 4 to 81 years. Age, sex, occupation, frequency of water contact, number of times treated for schistosomiasis, and last year of treatment were tested as potential effect modifiers and confounders.

RESULTS

Overall, there were very few infected cases and very little variation in any prevalence ratio with infection intensity, sex, age, year of last treatment, number of times treated or frequency of water contact. The attributable fraction of liver enlargement in one village was estimated at 0.114 (11.4%), although this was not significantly > 0(95% CI; -0.008-0.237).

CONCLUSION

The chemotherapy-based schistosomiasis control programme in this locality has succeeded in reducing attributable morbidity to undetectable levels, but many uncertainties remain about sustaining control efforts in the future. Both old and new control strategies will have to be examined if the health and well-being of these people are to be maintained into the next millennium, given that periodic chemotherapy will not be accepted indefinitely.

Extramedullary T lymphoblastic transformation of chronic myeloid leukaemia occurring after double allogeneic transplantation

The clinical course of chronic myeloid leukaemia (CML) is characterised by a chronic phase followed by an acute phase or blast crisis. Lymphoid transformation accounts for 20-30% of such events, with the majority of cases being of B cell origin. Extramedullary transformation occurs in approximately 10% of cases. We report a case of T cell lymphoblastic transformation in CML presenting as an extramedullary mass after allogeneic stem cell transplant. This case supports the growing evidence that CML arises in the pluripotent stem cell.

Comparative experience of a simple technique for laparoscopic chronic ambulatory peritoneal dialysis catheter placement

BACKGROUND

Chronic ambulatory peritoneal dialysis (CAPD) is now an established technique for renal dialysis. Patients with renal failure cope poorly with major surgery and it is vital that the dialysis catheter tip is sited accurately in the pelvis if long-term catheter function is to be achieved. Laparoscopic placement of CAPD catheters may have potential advantages for renal patients by avoiding the morbidity of a laparotomy.

METHODS

A retrospective audit was performed of all CAPD catheters inserted at the John Hunter Hospital over a 2-year period. Results of laparoscopically inserted catheters and those placed at laparotomy were compared.

RESULTS

Sixty catheters were inserted, 30 laparoscopically and 30 at laparotomy. The mean operative time was 41 min in the laparoscopic patients and 57 min in the laparotomy patients (P = 0.0001). The mean total dose of narcotic administered postoperatively was significantly less in the laparoscopic group (5 mg vs 65 mg, P = 0.00002). There were three minor peri-operative complications in the laparoscopic group and seven peri-operative complications in the laparotomy group, three required reoperation and one resulted in the patient's death. There were no significant differences in the incidence of exit-site infection, catheter blockage, peritonitis, and overall catheter survival, although the laparoscopically placed catheters had been followed up for a shorter period (10 vs 16 months).

CONCLUSIONS

This laparoscopic technique is safe and effective. Postoperative pain was less than for open placement. Laparoscopically placed catheters had a low incidence of peri-operative complications. Medium-term patency is similar to conventionally placed catheters. This procedure requires no additional equipment to that available for laparoscopic cholecystectomy and takes less time than the open operation.