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Biomedical subjects

Christian Lengeler

Publications and source records attributed to Christian Lengeler.

32 records · Page 2Linked to original sources
PubMed2003

Cost-effectiveness of social marketing of insecticide-treated nets for malaria control in the United Republic of Tanzania.

OBJECTIVE: To assess the costs and consequences of a social marketing approach to malaria control in children by means of insecticide-treated nets in two rural districts of the United Republic of Tanzania, compared with no net use. METHODS: Project cost data were collected prospectively from accounting records. Community effectiveness was estimated on the basis of a nested case-control study and a cross-sectional cluster sample survey. FINDINGS: The social marketing approach to the distribution of insecticide-treated nets was estimated to cost 1560 US dollars per death averted and 57 US dollars per disability-adjusted life year averted. These figures fell to 1018 US dollars and 37 US dollars, respectively, when the costs and consequences of untreated nets were taken into account. CONCLUSION: The social marketing of insecticide-treated nets is an attractive intervention for preventing childhood deaths from malaria.

Bedding and Linens↗
PubMed2003

Targeted subsidy for malaria control with treated nets using a discount voucher system in Tanzania.

During the last decade insecticide-treated nets have become a key strategy for malaria control. Social marketing is an appealing tool for getting such nets to poor rural African communities who are most afflicted by malaria. This approach usually involves subsidized prices to make nets and insecticide more affordable and help establish a commercial market. We evaluated a voucher system for targeted subsidy of treated nets in young children and pregnant women in two rural districts of southern Tanzania. Qualitative work involved focus group discussions with community leaders, male and female parents of children under 5 years. In-depth interviews were held with maternal and child health clinic staff and retail agents. Quantitative data were collected through interviewing more than 750 mothers of children under 5 years during a cluster sample survey of child health. The voucher return rate was extremely high at 97% (7720/8000). However, 2 years after the start of the scheme awareness among target groups was only 43% (45/104), and only 12% of women (12/103; 95% CI 4-48%) had used a voucher towards the cost of a net. We found some evidence of increased voucher use among least poor households, compared with the poorest households. On the basis of these results we renewed our information, education and communication (IEC) campaign about vouchers. Discount vouchers are a feasible system for targeted subsidies, although a substantial amount of time and effort may be needed to achieve high awareness and uptake - by which we mean the proportion of eligible women who used the vouchers - among those targeted. Within a poor society, vouchers may not necessarily increase health equity unless they cover a high proportion of the total cost: since some cash is needed when using a voucher as part-payment, poorer women among the target group are likely to have lower uptake than richer women. The vouchers have two important additional functions: strengthening the role of public health services in the context of a social marketing programme and forming an IEC tool to demonstrate the group at most risk of severe malaria.

Animals↗
PubMed2003

Assessing the prevalence of hypertension in populations: are we doing it right?

BACKGROUND: Although it is well recognized that the diagnosis of hypertension should be based on blood pressure (BP) measurements taken on several occasions, notably to account for a transient elevation of BP on the first readings, the prevalence of hypertension in populations has often relied on measurements at a single visit. OBJECTIVE: To identify an efficient strategy for assessing reliably the prevalence of hypertension in the population with regards to the number of BP readings required. DESIGN: Population-based survey of BP and follow-up information. SETTING AND PARTICIPANTS: All residents aged 25-64 years in an area of Dar es Salaam (Tanzania). MAIN OUTCOME MEASURES: Three BP readings at four successive visits in all participants with high BP (n = 653) and in 662 participants without high BP, measured with an automated BP device.RESULTS BP decreased substantially from the first to third readings at each of the four visits. BP decreased substantially between the first two visits but only a little between the next visits. Consequently, the prevalence of high BP based on the third reading--or the average of the second and third readings--at the second visit was not largely different compared to estimates based on readings at the fourth visit. BP decreased similarly when the first three visits were separated by 3-day or 14-day intervals. CONCLUSIONS: Taking triplicate readings on two visits, possibly separated by just a few days, could be a minimal strategy for assessing adequately the mean BP and the prevalence of hypertension at the population level. A sound strategy is important for assessing reliably the burden of hypertension in populations.

Adult↗
PubMed2003

Randomized, double-blind, placebo-controlled trial of oral artemether for the prevention of patent Schistosoma haematobium infections.

Artemether is an efficacious antimalarial drug that also displays antischistosomal properties. Laboratory studies have found that artemether curtails the development of adult worms of Schistosoma japonicum, S. mansoni and S. haematobium, and thus prevents morbidity. These findings have been confirmed in clinical trials for the former two parasites; administered orally once every 2-3 weeks, artemether significantly reduced the incidence and intensity of patent infections. Here, we present the first randomized, double-blind, placebo-controlled trial of artemether against S. haematobium, done in a highly endemic area of Côte d'Ivoire. Urine specimens from 440 schoolchildren were examined over 4 consecutive days, followed by two systematic praziquantel treatments 4 weeks apart. S. haematobium-negative children were randomized to receive 6 mg/kg artemether (N = 161) or placebo (N = 161). Medication was administered orally for a total of six doses once every 4 weeks. Adverse events were assessed 72 hours after medication, and perceived illness episodes were monitored throughout the study period. Incidence and intensity of S. haematobium infections, and microhematuria and macrohematuria were assessed 3 weeks after the final dosing. We also monitored malaria parasitemia and treated positive cases with sulfadoxine-pyrimethamine (SP). Oral artemether was well tolerated. The incidence of patent S. haematobium infections in artemether recipients was significantly lower than in placebo recipients (49% versus 65%, protective efficacy: 0.25, 95% CI: 0.08-0.38, P = 0.007). The geometric mean infection intensity in the artemether group was less than half that of the placebo recipients (3.4 versus 7.4 eggs/10 mL urine, P < 0.001). Heavy S. haematobium infections, microhematuria and macrohematuria, and the incidence of malaria parasitemia were all significantly lower in artemether recipients. In conclusion, previous findings of efficacy of artemether against S. japonicum and S. mansoni were confirmed for S. haematobium, although the protective efficacy was considerably lower. These findings enlarge the scope and potential of artemether and further contribute to discussions of its role as an additional tool for integrated schistosomiasis control.

Administration, Oral↗
PubMed2002

Association between Schistosoma mansoni and hookworm infections among schoolchildren in Côte d'Ivoire.

Infections with Schistosoma mansoni and hookworms are widespread in sub-Saharan Africa and the burden of disease associated with both parasites is enormous. Although there is a large overlap in their geographic distribution, little is known about the association between S. mansoni and hookworm infections and the underlying mechanisms. We explored this association among 325 schoolchildren from Côte d'Ivoire, by screening multiple stool specimens over consecutive days. We found a highly significant positive association between S. mansoni and hookworm infections with an adjusted odds ratio of 2.25 (95% confidence interval: 1.31-3.85; P=0.003). Increasing infection intensity of S. mansoni was significantly correlated with an increased likelihood of concomitant hookworm infections (chi(2)=20.72; P<0.001). Egg counts in stool specimens derived from a single day did not consistently reveal the positive association between the two parasites, which underlines the importance of repeated stool examinations. Several self-reported water contact patterns were significantly associated either with S. mansoni, hookworm or concomitant infections. Our findings are of considerable importance for tailoring effective health education messages that are readily adapted to the local epidemiological setting. Complemented with other control interventions, these measures might significantly reduce the burden caused by S. mansoni and hookworm infections.

Adolescent↗
PubMed2002

Screening for schistosomiasis with questionnaires.

New schistosomiasis control initiatives have been launched to reduce significantly the current global burden of this disease, mainly through regular administration of praziquantel to schoolchildren living in endemic areas. Because schistosomiasis is distributed focally, epidemiological tools for rapid and inexpensive identification of communities at highest risk of morbidity are required to target praziquantel most efficiently. This article outlines the development and validation of simple questionnaires for screening of Schistosoma haematobium and Schistosoma mansoni in sub-Saharan Africa.

Africa South of the Sahara↗
PubMed2002

Socially marketed insecticide-treated nets improve malaria and anaemia in pregnancy in southern Tanzania.

OBJECTIVES: To study the uptake of socially marketed insecticide-treated nets (ITNs) and their impact on malaria and anaemia in pregnancy; and to report on a discount voucher system which aimed to increase coverage in pregnancy. METHODS: A 12-month cross-sectional study of women in the second or third trimester of pregnancy. ITN use and other factors were assessed by questionnaire and a blood sample taken for malaria parasitaemia and anaemia. 'Non-users' of ITNs included both women not using any net and women using untreated nets. RESULTS: Fifty three per cent of pregnant women used ITNs. Women aged 15-19, primigravidae, unmarried women, and those with no access to cash had the lowest ITN use. Fewer ITN users were positive for malaria than ITN non-users (25 vs. 33%: P=0.06), and the protective efficacy (PE) for parasitaemia was 23% (CI 2-41). Multiparous ITN users had a twofold decrease in parasite density compared with multiparous non-ITN users (625 parasites/microl vs. 1173 parasited/microl: P=0.01). Fewer ITN users were anaemic (Hb < 11 g/dl) than ITN non-users (72 vs. 82%: P=0.01). ITNs had a PE of 12% (CI 2-21) against mild anaemia and a PE of 38% (CI 4-60) against severe anaemia (Hb < 8 g/dl). There was a trend in the prevalence of severe, mild and no anaemia, and of high density, low density and no malaria infection by ITN status. Recently treated nets were most effective at preventing malaria and anaemia (prevalence of mild anaemia was 68% compared with 82% for those without nets (P=0.002); prevalence of malaria was 22% compared with 33% for those without nets (P=0.02). Knowledge and reported use of the discount voucher system were low. Further qualitative research is ongoing. CONCLUSIONS: A modest impact of ITNs on pregnancy malaria and anaemia was shown in our high malaria transmission setting. The development of ITN programmes for malaria control should include pregnant women as a specific target group.

Adolescent↗
PubMed2002

Risk factors for child mortality in rural Tanzania.

We conducted a community-based nested case-control study of post-neonatal deaths in children under 5 years, with frequency-matched controls chosen from a full sampling frame provided by a demographic surveillance system. Using a questionnaire, we studied treatment-seeking behaviour in fatal illness. In cases and controls we investigated demographic and socio-economic factors, health-seeking behaviour, the household environment including accessibility of health care, and individual child care factors. Half of the deaths (215/427) occurred at home, and one-third (146/427) at a health facility. Three-quarters (330/427) of the children who died had received treatment from a health facility in their fatal illness. Four independent risk factors for death were identified which were each associated with more than 5% of child mortality: not being carried on the back while the mother cooked [odds ratio (OR) 1.6: 1.3, 2.0], poor maternal education (OR 1.4: 95% CI 1.0, 1.9 for those with no education compared with those with complete primary education), lack of exclusive breastfeeding in the first 3 months of life (OR 1.4: 1.1, 1.8), and low socio-economic status (OR 1.3: 1.0, 1.6). The majority of children who died had sought treatment at a health facility during the fatal illness, which would lend support to interventions to improve case-management. The association between mothers carrying their children and child survival was unexpected and deserves further investigation.

Case-Control Studies↗
PubMed2002

Distribution of blood pressure, body mass index and smoking habits in the urban population of Dar es Salaam, Tanzania, and associations with socioeconomic status.

OBJECTIVE: To estimate the distribution of blood pressure (BP), body mass index (BMI), smoking habits and their associations with socioeconomic status (SES) in an urban population in early epidemiological transition. METHODS: Cross-sectional survey of the entire population aged 25-64 years in five branches of Dar es Salaam (Tanzania) through visits to all homes in the study area. Blood pressure was based on the mean of the second and third readings with an automated device. Socioeconomic status was estimated with indicators of education, occupation and wealth. RESULTS: In all 9254 people were examined. Age-adjusted prevalence (%) among men/ women aged 35-64 years was 27.1/30.2 for BP > or = 140/90 mmHg or antihypertensive medication, 13.1/17.7 for BP > or = 160/95 mmHg or antihypertensive medication, 28.0/27.4 for BMI of 25.0-29.9 kg/m(2), 6.9/17.4 for BMI > or = 30 kg/m(2), and 22.0/2.6 for smoking (> or = 1 cigarette per day). Prevalence of categories of drinking frequency and history of diabetes are also reported. After adjustment for covariates, SES was associated inversely with BP and smoking and directly with BMI. Body mass index was associated positively with BP (1.01 and 0.91 mmHg systolic BP per 1 kg/m(2) BMI in men and women, respectively) and inversely with smoking (-1.14 kg/m(2) in male smokers versus non-smokers). Hypertension treatment rates were low, particularly in people of low SES. CONCLUSIONS: High prevalence of several cardiovascular risk factors in the urban population of a low-income country stresses the need for early public health interventions and adaptation of the health care infrastructure to meet the emerging challenge of cardiovascular disease. The direct SES-BMI association may drive increasing BMI and BP while the population becomes more affluent.

Adult↗
PubMed2002

National laboratory reports of Chlamydia trachomatis seriously underestimate the frequency of genital chlamydial infections among women in Switzerland.

BACKGROUND: Public health authorities want to evaluate their sexually transmitted disease (STD) surveillance systems to promote the most effective use of health resources. GOAL: The goal of this study was to estimate the sensitivity of national laboratory reports of in Switzerland (the proportion of cases detected by national laboratory reports). STUDY DESIGN: A cross sectional prevalence study was conducted by the Swiss Sentinel Surveillance Network of Gynecologists in 1998. Two groups of women aged less than 35 years were included in the study: those having a first consultation for pregnancy and those having a routine check-up. RESULTS: A total of 1589 women were tested for. The prevalence among pregnant women (n = 817) was 1.3%, and that among sexually active women (n = 772) was 2.8%. Using the prevalences observed among check-up women, we estimate that there were at least 24,400 infections in Switzerland among women aged 20 to 34 years in 1998 (95% CI: 14,300-34,300). The number of laboratory reports of in this age group was 1,150 in 1998. CONCLUSION: Our study suggests that the sensitivity of national laboratory reports of in 1998 was less than 5% for women aged 20 to 34 years.

Adult↗
PubMed2002

Polyparasitism with Schistosoma mansoni, geohelminths, and intestinal protozoa in rural Côte d'Ivoire.

Single species infections with schistosomes, geohelminths, and intestinal protozoans are common over large parts of sub-Saharan Africa, and it is expected that polyparasitism affects a considerable proportion of the population, hence posing a great toll on public health. However, few investigations have been carried out to quantify the extent of polyparasitism. Here, a detailed assessment is reported for the epidemiology of Schistosoma mansoni, geohelminths, and intestinal protozoan infections, with particular emphasis on polyparasitism among 260 community members in rural Cĵte d'Ivoire. Schistosoma mansoni, Entamoeba coli, and hookworm were the predominant species with prevalences of 71.5, 64.6, and 51.9%, respectively. Only 8 individuals displayed no infection, whereas two-thirds of the population harbored 3 or more parasites concurrently. There were a series of significant pairwise parasite co-occurrences, e.g., between S. mansoni and hookworms and between S. mansoni and E. coli. It is concluded that polyparasitism in the population studied here was very common, which is probably the case also in other areas of rural Cĵte d'Ivoire and elsewhere in sub-Saharan Africa. These findings call for integrated approaches to effectively control multiple parasitic and protozoan infections.

Adolescent↗
PubMed2002

Questionnaires for rapid screening of schistosomiasis in sub-Saharan Africa.

New initiatives are aiming to reduce the global burden of schistosomiasis, mainly through the large-scale application of chemotherapy. To target chemotherapy effectively, rapid assessment procedures are needed for identifying high-risk communities that are foci for the disease. In this review, we examine the development and validation of simple school questionnaires for screening communities for Schistosoma haematobium and S. mansoni rapidly and inexpensively. The focus is on sub-Saharan Africa, where 85% of the current schistosomiasis burden is concentrated. For more than a decade, the questionnaire approach has been validated in 10 countries, with 133 880 children interviewed in 1282 schools, and with 54 996 children examined for S. haematobium. The questionnaires were well accepted, highly reliable, and of low cost. The success of the questionnaires is explained by the fact that S. haematobium infections were easily perceived through the presence of blood in urine. Evidence from 48 258 children interviewed in 545 schools indicated that reported blood in stools and bloody diarrhoea are valuable indicators for community diagnosis of S. mansoni. However, the diagnostic performance of the questionnaires for S. mansoni was weaker than for S. haematobium, and although these results are encouraging, the questionnaires need additional validation. Recently, questionnaires were extended from community to individual diagnosis and showed considerable promise. Questionnaires are now available for promptly defining the magnitude of schistosomiasis in a large area, which will allow limited resources for morbidity control to be allocated optimally.

Africa South of the Sahara↗