Targeted elimination of species-rich larval habitats can rapidly collapse arbovirus vector mosquito populations at hotel compounds in Zanzibar.

Understanding the dynamics of larval habitat utilization by mosquito communities is crucial for the design of efficient environmental control strategies. The authors investigated the structure of mosquito communities found at hotel compounds in Zanzibar, networks of mosquito interactions with larval habitats and robustness of mosquito communities to elimination of larval habitats. A total of 23 698 mosquitoes comprising 26 species in six genera were found. Aedes aegypti (n = 16 207), Aedes bromeliae/Aedes lillie (n = 1340), Culex quinquefasciatus (n = 1300) and Eretmapodites quinquevitattus (n = 659) were the most dominant species. Ecological network analyses revealed the presence of dominant, larval habitat generalist species (e.g., A. aegypti), exploiting virtually all types of water holding containers and few larval habitat specialist species (e.g., Aedes natalensis, Orthopodomyia spp). Simulations of mosquito community robustness to systematic elimination of larval habitats indicate that mosquito populations are highly sensitive to elimination of larval habitats sustaining higher mosquito species diversity. This study provides insights on potential foci of future mosquito-borne arboviral disease outbreaks in Zanzibar and underscores the need for detailed knowledge on the ecological function of larval habitats for effective mosquito control by larval sources management.

The cost-effectiveness of banning highly hazardous pesticides to prevent suicides due to pesticide self-ingestion across 14 countries: an economic modelling study.

BACKGROUND: Reducing suicides is a key Sustainable Development Goal target for improving global health. Highly hazardous pesticides are among the leading causes of death by suicide in low-income and middle-income countries. National bans of acutely toxic highly hazardous pesticides have led to substantial reductions in pesticide-attributable suicides across several countries. This study evaluated the cost-effectiveness of implementing national bans of highly hazardous pesticides to reduce the burden of pesticide suicides. METHODS: A Markov model was developed to examine the costs and health effects of implementing a national ban of highly hazardous pesticides to prevent suicides due to pesticide self-poisoning, compared with a null comparator. We used WHO cost-effectiveness and strategic planning (WHO-CHOICE) methods to estimate pesticide-attributable suicide rates for 100 years from 2017. Country-specific costs were obtained from the WHO-CHOICE database and denominated in 2017 international dollars (I$), discounted at a 3% annual rate, and health effects were measured in healthy life-years gained (HLYGs). We used a demographic projection model beginning with the country population in the baseline year (2017), split by 1-year age group and sex. Country-specific data on overall suicide rates were obtained for 2017 by age and sex from the Global Burden of Disease Study 2017 Data Resources. The analysis involved 14 countries spanning low-income to high-income settings, and cost-effectiveness ratios were analysed at the country-specific level and aggregated according to country income group and the proportion of suicides due to pesticides. FINDINGS: Banning highly hazardous pesticides across the 14 countries studied could result in about 28 000 (95% uncertainty interval [UI] 24 000-32 000) fewer suicide deaths each year at an annual cost of I$0·007 per capita (95% UI 0·006-0·008). In the population-standardised results for the base case analysis, national bans produced cost-effectiveness ratios of $94 per HLYG (95% UI 73-123) across low-income and lower-middle-income countries and $237 per HLYG (95% UI 191-303) across upper-middle-income and high-income countries. Bans were more cost-effective in countries where a high proportion of suicides are attributable to pesticide self-poisoning, reaching a cost-effectiveness ratio of $75 per HLYG (95% UI 58-99) in two countries with proportions of more than 30%. INTERPRETATION: National bans of highly hazardous pesticides are a potentially cost-effective and affordable intervention for reducing suicide deaths in countries with a high burden of suicides attributable to pesticides. However, our study findings are limited by imperfect data and assumptions that could be improved upon by future studies. FUNDING: WHO.

Socioeconomic position and suicidal behaviour in rural Sri Lanka: a prospective cohort study of 168,000+ people.

PURPOSE: Lower socioeconomic position (SEP) is associated with an increased risk of suicidal behaviour in high income countries, but this association is not established in low- and middle-income countries (LMIC). METHODS: We investigated the association of SEP with suicidal behaviour in a prospective cohort study of 168,771 Sri Lankans followed up for episodes of attempted suicide and suicide. SEP data were collected at baseline at the household and individual level at the start of the follow-up period. We used multilevel Poisson regression models to investigate the association of SEP at community, household and individual levels with attempted suicide/suicide. RESULTS: Lower levels of asset ownership [IRR (95% CI) suicide 1.74 (0.92, 3.28); attempted suicide 1.67 (1.40, 2.00)] and education [suicide 3.16 (1.06, 9.45); attempted suicide 2.51 (1.70, 3.72)] were associated with an increased risk of suicidal behaviour. The association of these measures of SEP and attempted suicide was stronger in men than women. Individuals living in deprived areas [1.42 (1.16, 1.73)] and in households with a young female head of household [1.41 (1.04, 1.93)] or a temporary foreign migrant [1.47 (1.28, 1.68)] had an elevated risk of attempted suicide. Farmers and daily wage labourers had nearly a doubling in risk of attempted suicide compared to other occupations. CONCLUSIONS: Improved employment opportunities, welfare and mental health support services, as well as problem-solving skills development, may help support individuals with poorer education, farmers, daily wage labourers, individuals in young female-headed households and temporary foreign migrant households.

Attempted suicide in Sri Lanka - An epidemiological study of household and community factors.

BACKGROUND: An individual's suicide risk is determined by personal characteristics, but is also influenced by their environment. Previous studies indicate a role of contextual effects on suicidal behaviour, but there is a dearth of quantitative evidence from Asia. METHODS: Individual and community level data were collected on 165,233 people from 47,919 households in 171 communities in rural Sri Lanka. Data were collected on individual (age, sex, past suicide attempts and individual socioeconomic position (SEP)) and household (household SEP, pesticide access, alcohol use and multigenerational households) level factors. We used 3-level logit models to investigate compositional (individual) and contextual (household/community) effects. RESULTS: We found significant variation between households 21% (95% CI 18%, 24%) and communities 4% (95% CI 3%, 5%) in the risk of a suicide attempt. Contextual factors as measured by low household SEP (OR 2.37 95% CI 2.10, 2.67), low community SEP (OR 1.45 95% CI 1.21, 1.74), and community 'problem' alcohol use (OR 1.44 95% CI 1.19, 1.75) were associated with an increased risk of suicide attempt. Women living in households with alcohol misuse were at higher risk of attempted suicide. We observed a protective effect of living in multigenerational households (OR 0.53 95% CI 0.42, 0.65). LIMITATIONS: The outcome was respondent-reported and refers to lifetime reports of attempted suicide, therefore this study might be affected by socially desirable responding. CONCLUSIONS: Our study finds that contextual factors are associated with an individual's risk of attempted suicide in Sri Lanka, independent of an individual's personal characteristics.

Is socioeconomic position associated with risk of attempted suicide in rural Sri Lanka? A cross-sectional study of 165†000 individuals.

BACKGROUND: Lower socioeconomic position (SEP) is associated with an increased risk of suicidal behaviour in high-income countries, but this association is unclear in low-income and middle-income countries. METHODS: We investigated the association of SEP with attempted suicide in a cross-sectional survey of 165 233 Sri Lankans. SEP data were collected at the household (assets, social standing (highest occupation of a household member), foreign employment and young (≤40 years) female-headed households) and individual level (education and occupation). Respondent-reported data on suicide attempts in the past year were recorded. Random-effects logistic regression models, accounting for clustering, were used to investigate the association of SEP with attempted suicide. RESULTS: Households reported 398 attempted suicides in the preceding year (239 per 100 000). Fewer assets (OR 3.2, 95% CI 2.4 to 4.4) and having a daily wage labourer (ie, insecure/low-income job; OR 2.3, 95% CI 1.6 to 3.2) as the highest occupation increased the risk of an attempted suicide within households. At an individual level, daily wage labourers were at an increased risk of attempted suicide compared with farmers. The strongest associations were with low levels of education (OR 4.6, 95% CI 2.5 to 8.4), with a stronger association in men than women. CONCLUSIONS: We found that indicators of lower SEP are associated with increased risk of attempted suicide in rural Sri Lanka. Longitudinal studies with objective measures of suicide attempts are needed to confirm this association. TRIAL REGISTRATION NUMBER: NCT01146496; Pre-results.

Sanitation investments in Ghana: An ethnographic investigation of the role of tenure security, land ownership and livelihoods.

BACKGROUND: Ghana's low investment in household sanitation is evident from the low rates of improved sanitation. This study analysed how land ownership, tenancy security and livelihood patterns are related to sanitation investments in three adjacent rural and peri-urban communities in a district close to Accra, Ghana's capital. METHODS: Qualitative data was gathered for this comparative ethnographic study over seven months, (June, 2011-January, 2012) using an average of 43 (bi-weekly) participant observation per community and 56 in-depth interviews. Detailed observational data from study communities were triangulated with multiple interview material and contextual knowledge on social structures, history of settlement, land use, livelihoods, and access to and perceptions about sanitation. RESULTS: This study shows that the history of settlement and land ownership issues are highly correlated with people's willingness and ability to invest in household sanitation across all communities. The status of being a stranger i.e. migrant in the area left some populations without rights over the land they occupied and with low incentives to invest in sanitation, while indigenous communities were challenged by the increasing appropriation of their land for commercial enterprises and for governmental development projects. Interview responses suggest that increasing migrant population and the high demand for housing in the face of limited available space has resulted in general unwillingness and inability to establish private sanitation facilities in the communities. The increasing population has also created high demand for cheap accommodation, pushing tenants to accept informal tenancy agreements that provided for poor sanitation facilities. In addition, poor knowledge of tenancy rights leaves tenants in no position to demand sanitation improvements and therefore landlords feel no obligation or motivation to provide and maintain domestic sanitation facilities. CONCLUSIONS: The study states that poor land rights, the history of settlements, in-migration and insecure tenancy are key components that are associated with local livelihoods and investments in private sanitation in rapidly changing rural and peri-urban communities of Ghana. Sanitation policy makers and programme managers must acknowledge that these profound local, ethnic and economic forces are shaping people's abilities and motivations for sanitation investments.

Using on-farm sedimentation ponds to improve microbial quality of irrigation water in urban vegetable farming in Ghana.

This paper presents an assessment of the potential of using on-farm ponds to reduce levels of microbial contamination in wastewater--contaminated irrigation water. The study involved observations on the use of ponds in urban agriculture in Kumasi, Ghana, and more than 300 irrigation water samples were taken for physico-chemical and microbial laboratory analysis. The study shows that while on-farm ponds are commonly used, their potential to remove pathogens through sedimentation has not been fully optimized. Two-thirds of helminth eggs were in the sediments and careful collection of irrigation water without disturbing sediments reduced helminth eggs in irrigation water by about 70%. Helminth eggs reduced from about 5 to less than 1 egg per litre in three days in both dry and wet seasons while thermotolerant coliforms took six days in the dry season to reduce from about 8 to 4 log units per 100 ml, to meet the WHO guidelines. For optimal pathogen removal, better pond designs, farmers' training on collection of water with minimal disturbance and any other means to enhance sedimentation and pathogen die-off can be essential components of a multiple-barrier approach complementing farm-based measures like simple filtration techniques, better irrigation methods and post-harvest contamination.

The impact of pesticide regulations on suicide in Sri Lanka.

BACKGROUND: Between 1950 and 1995 suicide rates in Sri Lanka increased 8-fold to a peak of 47 per 100,000 in 1995. By 2005, rates had halved. We investigated whether Sri Lanka's regulatory controls on the import and sale of pesticides that are particularly toxic to humans were responsible for these changes in the incidence of suicide. METHODS: Ecological analysis using graphical and descriptive approaches to identify time trends in suicide and risk factors for suicide in Sri Lanka, 1975-2005. RESULTS: Restrictions on the import and sales of WHO Class I toxicity pesticides in 1995 and endosulfan in 1998, coincided with reductions in suicide in both men and women of all ages. 19,769 fewer suicides occurred in 1996-2005 as compared with 1986-95. Secular trends in unemployment, alcohol misuse, divorce, pesticide use and the years associated with Sri Lanka's Civil war did not appear to be associated with these declines. CONCLUSION: These data indicate that in countries where pesticides are commonly used in acts of self-poisoning, import controls on the most toxic pesticides may have a favourable impact on suicide. In Asia, there are an estimated 300,000 deaths from pesticide self-poisoning annually. National and international policies restricting the sale of pesticides that are most toxic to humans may have a major impact on suicides in the region.

Identification of strategies to prevent death after pesticide self-poisoning using a Haddon matrix.

Despite pesticide self-poisoning causing around 300 000 deaths each year in the rural Asia Pacific region, no comprehensive public health response has yet been formulated. The authors have developed a Haddon matrix to identify factors that increase the risk of fatal rather than non-fatal pesticide self-poisoning in Sri Lanka. Many important host factors such as age, gender, and genetics are not alterable; factors that could be changed-alcohol use and mental health-have previously proved difficult to change. Interventions affecting agent or environmental factors may be easier to implement and more effective, in particular those limiting the human toxicity and accessibility of the pesticides, and the quality, affordability, and accessibility of health care in the community. Controlled studies are required to identify effective strategies for prevention and harm minimization and to garner political support for making the changes necessary to reduce this waste of life. Lessons learnt from Sri Lanka are likely to be highly relevant for much of rural Asia.

The role of private drug vendors as malaria treatment providers in selected malaria endemic areas of Sri Lanka.

BACKGROUND AND OBJECTIVES: The involvement of private drug vendors in malaria treatment is particularly high in developing countries and understanding their practices and knowledge about antimalarials and malaria treatment will aid in devising strategies to increase the correct use of antimalarials and improve adherence to the government's malaria drug policy. Results of a study on the knowledge and practices of the private drug vendors conducted in seven districts in Sri Lanka, mostly in malarious areas are presented. METHODS: Data on awareness of government's malaria drug policy, practice of issuing antimalarials, knowledge about malaria and antimalarial drugs were collected from the drug vendors using pre-tested questionnaire in vernacular language. Data were statistically analysed using Stata 8.2. Chi-square test was carried out for individual explanatory variables and a logistic regression model was applied taking all response variables as binary outcome. RESULTS: Vendors' knowledge on antimalarials was poor with 58% of the vendors being unaware of the government malaria drug policy in the country. Also, the advice provided to customers buying antimalarials was limited. However, the majority of the private vendors emphasised that they were aware of the importance of case confirmation before treatment as stressed in the national policy. Although, the vendors did not have a high awareness of national drug policies they were only found selling chloroquine and primaquine as recommended by the Ministry of Health. INTERPRETATION AND CONCLUSION: In recent years Sri Lanka, as a whole, has experienced very little malaria. The reduction in demand for antimalarials due to low incidence levels may have influenced the knowledge and awareness on antimalarials and government drug policies. However, since low levels of malaria do not guarantee that epidemics will not occur, attempts to educate private drug vendors as a part of an organised control programmes are of major importance.

Practice of using human excreta as fertilizer and implications for health in Nghean Province, Vietnam.

The ancient practice of applying latrine wastes to agricultural land has maintained soil fertility in Vietnam for several centuries but may be associated with health risks if the wastes are inadequately treated before usage. This study aimed at investigating the perceptions and handling practices using latrine wastes as fertilizers in a community in central Vietnam. Information was collected through structured questionnaire interviews administered to 75 farming households, focus group discussions, and key informant interviews. The majority (64%) of households had a single vault latrine, a possession that was associated with low income (chi2= 12.45; p < 0.05). Most households (85%) used latrine waste in agriculture that was composted before usage (98%). Households often mixed the composted excreta with kitchen ashes and powdered lime likely to increase pH and pathogen die-off. About 28% of households that were applying latrine waste as fertilizer composted three to six months, and only 11 (18%) households composted human excreta for more than the recommended six months. Households with double vault latrines were 7.8 (chi2= 9.4; p<0.05) times more likely to compost human excreta more than six months as compared with households having single vault latrine. Most farmers distributed the latrine wastes with bare hands (66%) because of convenience during application. Respondents with a high educational level used protective gloves more often when distributing latrine wastes in the fields compared to respondents with a low educational level (chi2 = 7.6; p<0.05). If any negative health impacts of latrine waste use in agriculture are to be reduced, then it is suggested that sustainable interventions should take into consideration farmers current excreta-use practices.

Physico-chemical characteristics of Anopheles culicifacies and Anopheles varuna breeding water in a dry zone stream in Sri Lanka.

BACKGROUND & OBJECTIVES: Selected physico-chemical characteristics of flowing and pooled water in a stream that generated two malaria vectors, Anopheles culicifacies s.l. Giles and Anopheles varuna Iyengar, were investigated during August-September 1997 and July 1998 at the Upper Yan Oya watershed in north-central Sri Lanka. METHODS: The physico-chemical parameters measured were: temperature, dissolved oxygen, pH, conductivity, total dissolved solids, alkalinity, ammonia nitrogen, nitrate nitrogen, calcium, magnesium, carbondioxide, ferrous iron, phosphate, colour and turbidity. In total, 75.5% of 151 samples analysed were mosquito-positive. Logistic regression was used for statistical analysis. RESULTS: Among physico-chemical parameters, An. culicifacies (the major malaria vector in the country) was positively related only to temperature, and An. varuna (a secondary malaria vector) to calcium. Among habitat characteristics, An. culicifacies was associated with light and vegetation, and negatively associated with the presence of potential predators. An. varuna was positively associated with other aquatic fauna. INTERPRETATION & CONCLUSION: Surprisingly this detailed study did not find an association between An. culicifacies and dissolved oxygen as previously found in the few studies that have looked at physico-chemical characteristics of malaria vector breeding habitats in south Asia. This study, along with existing information from other studies indicate that most of the physico-chemical parameters measured under natural conditions within the same habitat type is insufficient to explain the distribution of vectors within such habitats. However, it seems likely that both An. culicifacies and An. varuna follow a strategy whereby ovipositing females scatter their eggs over most of or all of a highly temporary and only transiently available stream bed pool habitat, in order to optimise breeding success.

Food of larval Anopheles culicifacies and Anopheles varuna in a stream habitat in Sri Lanka.

No previous studies have been conducted on the natural food of larval Anopheles culicifacies s.l. (the major malaria vector) and An. varuna (a secondary vector) in Sri Lanka. The present study analyzed the contents of guts dissected from larvae collected from pools in a natural stream-cum-irrigation conveyance channel in the Upper Yan Oya watershed in the North Central Province of the country during August-September 1997 and July 1998. Determinations of physicochemical and biological parameters of the pools and their water were done at the same time. A fluorochromatic stain, 4',6-diamidino-2-phenylindole, was used to stain larval gut contents. Quantitative estimates of different categories of food types were made by analyzing the gut contents of 95 An. culicifacies (26 second instars and 69 fourth instars) and 52 An. varuna (21 second instars and 31 fourth instars). Detritus was the most frequent food type, comprising >74% of the gut contents in both species. Other food types included bacteria (cocci and rods), filamentous algae, diatoms, and desmids. Overall, bacteria constituted a significantly higher proportion of the gut contents in An. culicifacies than in An varuna. Significantly more detritus, bacteria, and total particulate matter occurred in 4th instars of An. culicifacies than in An. varuna, indicating a greater food intake in the former species. Second instars of An. culicifacies and An. varuna did not differ significantly in any parameter. A significant increase in food intake between 2nd and 4th instars was seen for An. culicifacies, but not An. varuna. Food indices were lower in An. varuna than in An. culicifacies when the 2 species co-occurred, indicating competition for food, and the implications of this to adult body size, survival, and fecundity are discussed.

Adult anopheline ecology and malaria transmission in irrigated areas of South Punjab, Pakistan.

Surface irrigation in the Punjab province of Pakistan has been carried out on a large scale since the development of the Indus Basin Irrigation System in the late 19th century. The objective of our study was to understand how the population dynamics of adult anopheline mosquitoes (Diptera: Culicidae) could be related to malaria transmission in rural areas with intensive irrigation and a history of malaria epidemics. In this paper we present our observations from three villages located along an irrigation canal in South Punjab. The study was carried out from 1 April 1999 to 31 March 2000. Mosquitoes were collected from bedrooms using the pyrethroid spraycatch method and from vegetation and animal sheds using backpack aspirators. Overall, Anopheles subpictus Grassi sensu lato predominated (55.6%), followed by An. stephensi Liston s.l. (41.4%), An. culicifacies Giles s.l. (2.0%), An. pulcherrimus Theobald (1.0%) and An. peditaeniatus Leicester (0.1%). Most mosquitoes (98.8%) were collected from indoor resting-sites whereas collections from potential resting-sites outdoors accounted for only 1.2% of total anopheline densities, confirming the endophilic behaviour of anophelines in Pakistan. Anopheles stephensi, An. culicifacies and An. subpictus populations peaked in August, September and October, respectively. High temperatures and low rainfall negatively affected seasonal abundance in our area. There were interesting differences in anopheline fauna between villages, with An. culicifacies occurring almost exclusively in the village at the head of the irrigation canal, where waterlogged and irrigated fields prevailed. Monthly house-to-house fever surveys showed that malaria transmission remained low with an overall slide positivity rate of 2.4% and all cases were due to infection with Plasmodium vivax. The most plausible explanation for low transmission in our study area seems to be the low density of Pakistan's primary malaria vector, An. culicifacies. The role of other species such as An. stephensi is not clear. Our observations indicate that, in South Punjab, irrigation-related sites support the breeding of anopheline mosquitoes, including the vectors of malaria. As our study was carried out during a year with exceptionally hot and dry climatic conditions, densities and longevity of mosquitoes would probably be higher in other years and could result in more significant malaria transmission than we observed. To assess the overall importance of irrigation-related sites in the epidemiology of malaria in the Punjab, more studies are needed to compare irrigated and non-irrigated areas.

Ammonium sulphate fertiliser increases larval populations of Anopheles arabiensis and culicine mosquitoes in rice fields.

Field experiments were conducted in central Kenya, to study the effect of ammonium sulphate fertiliser ((NH(4))(2)SO(4)) on mosquito larval populations in rice fields. The experiments used a complete randomised block design having four blocks with two experimental ponds per block, and the fertiliser and control treatments allocated randomly among the ponds. Student's two-sample unpaired t-test was used to test for the significance of differences between the relative counts of larvae in fertiliser and control treatments. The results showed a significant overall increase in the larval populations of An. arabiensis (P<0.01) and culicine mosquitoes (P<0.05), after ponds were treated with the fertiliser. Significantly more fourth instar larvae of An. arabiensis were collected in fertiliser than control plots (P<0.001). An. arabiensis data indicated that the first fertiliser application had the most impact, compared to the second and third applications. This was evident in a significant peak of combined first and second instar An. arabiensis larvae observed 5 days after the first fertiliser application (P<0.05). The studies suggest that ammonium sulphate fertiliser reduces turbidity of water in rice fields, thereby making them visually more attractive for egg-laying by An. arabiensis and culicine mosquitoes.

Breeding of Anopheles mosquitoes in irrigated areas of South Punjab, Pakistan.

As part of investigations on potential linkages between irrigation and malaria transmission, all surface water bodies in and around three villages along an irrigation distributary in South Punjab, Pakistan, were surveyed for anopheline mosquito larvae (Diptera: Culicidae) from April 1999 to March 2000. Samples were characterized according to exposure to sunlight, substratum, presence of vegetation, fauna, inorganic matter and physical water condition (clear/turbid/foul). Also water temperature, dissolved oxygen (DO), electroconductivity (EC) and pH of sites were recorded. A total of 37982 Anopheles larvae of six morphological types were collected from 2992 samples taken from irrigation/agricultural and village/domestic aquatic habitats. Anopheles subpictus Grassi sensu lato was by far the most abundant (74.3%), followed by An. culicifacies Giles s.l. (4.1%), An. stephensi Liston s.l. (2.6%), An. pulcherrimus Theobald (1.8%), An. peditaeniatus Leicester (0.3%) and An. nigerrimus Giles (0.1%). The four most abundant species were significantly associated with waterlogged fields and communal village drinking-water tanks. Habitat characteristics most correlated with occurrence of anophelines were the physical water condition and the absence/presence of fauna, particularly predators. Occurrence and abundance of Anopheles immatures were not significantly correlated with water temperature, DO, EC or pH. Malaria vectors of the Anopheles culicifacies complex occurred at relatively low densities, mainly in irrigated and waterlogged fields. In South Punjab, where rainfall is very low, it should be possible to reduce anopheline breeding through water management, as larvae develop mainly in water bodies that are directly or indirectly related to the extensive canal-irrigation system.

Irrigation water as a source of drinking water: is safe use possible?

BACKGROUND: In arid and semi-arid countries there are often large areas where groundwater is brackish and where people have to obtain water from irrigation canals for all uses, including domestic ones. An alternative to drawing drinking water directly from irrigation canals or village water reservoirs is to use the water that has seeped from the irrigation canals and irrigated fields and that has formed a small layer of fresh water on top of the brackish groundwater. The objective of this study was to assess whether use of irrigation seepage water for drinking results in less diarrhoea than direct use of irrigation water and how irrigation water management would impact on health. METHODS: The study was undertaken in an irrigated area in the southern Punjab, Pakistan. Over a one-year period, drinking water sources used and diarrhoea episodes were recorded each day for all individuals of 200 households in 10 villages. Separate surveys were undertaken to collect information on hygiene behaviour, sanitary facilities, and socio-economic status. RESULTS: Seepage water was of much better quality than surface water, but this did not translate into less diarrhoea. This could only be partially explained by the generally poor quality of water in the in-house storage vessels, reflecting considerable in-house contamination of drinking water. Risk factors for diarrhoea were absence of a water connection and water storage facility, lack of a toilet, low standard of hygiene, and low socio-economic status. The association between water quality and diarrhoea varied by the level of water availability and the presence or absence of a toilet. Among people having a high quantity of water available and a toilet, the incidence rate of diarrhoea was higher when surface water was used for drinking than when seepage water was used (relative risk 1.68; 95% CI 1.31-2.15). For people with less water available the direction of the association between water quality and diarrhoea was different (relative risk 0.80; 95% CI 0.69-0.93). This indicates that good quality drinking water provides additional health benefits only when sufficient quantities of water and a toilet are available. In a multivariate analysis no association was found between water quality and diarrhoea but there was a significant effect of water quantity on diarrhoea which was to a large extent mediated through sanitation and hygiene behaviour. CONCLUSIONS: Increasing the availability of water in the house by having a household connection and a storage facility is the most important factor associated with reduced diarrhoea in this area. Safe use of canal irrigation water seems possible if households can pump seepage water to a large storage tank in their house and have a continuous water supply for sanitation and hygiene. Irrigation water management clearly has an impact on health and bridging the gap between the irrigation and drinking water supply sectors could provide important health benefits by taking into account the domestic water availability when managing irrigation water.

Water management for controlling the breeding of Anopheles mosquitoes in rice irrigation schemes in Kenya.

An experiment to assess the impact of intermittent irrigation on Anopheles larval populations, rice yields and water use was conducted in the Mwea rice irrigation scheme in Kenya. Four water regimes including intermittent irrigation were tested in a complete randomized block experimental design. Intermittent irrigation was carried out on a weekly schedule, with flooded conditions from Saturday through Tuesday morning. Larval sampling at each plot was conducted every Monday and prior to draining of intermittently irrigated subplots on Tuesday. All the adult anopheline mosquitoes emerging from larvae collected in the experimental plots were identified as being An. arabiensis. By far the highest numbers of An. arabiensis 1st instar larvae were found in the intermittently irrigated subplots, indicating that the water regime provided the most attractive environment for egg laying. However, the ratio between the 4th and 1st instar larvae in the subplots was only 0.08, indicating very low survival rates. In contrast, the 4th/1st instar ratio for subplots with other water management regimes ranged between 0.27 and 0.68, suggesting a correspondingly higher survival than observed with intermittent irrigation. The total number of 4th instars was almost the same in the intermittently irrigated subplots and the irrigation system normally practised by the farmers. The failure to eliminate larval development up to the 4th instar in the former method was attributed to residual pools of water. Larval abundance fluctuated throughout the 12-week sampling period. The highest larval densities were recorded in the 3 weeks after transplanting the rice seedlings. Afterwards, larval numbers dropped dramatically as the height of rice plants increased. Rice yields at harvest did not show statistically significant differences among subplots with different water regimes. The average yield per hectare ranged from 4.8-5.3 metric tonnes. The average daily water percolation/seepage rate was 3.6 mm and did not significantly differ among different water management regimes. Further research is necessary to, among other things, determine whether rice yields could be increased by having flooded and drained intervals that were different from those used in this study. It would likewise be important to assess on a wider scale the feasibility of implementing intermittent irrigation with respect to farmer acceptance and required changes in irrigation system design and management.

A village treatment center for malaria: community response in Sri Lanka.

Early diagnosis and treatment of malaria cases is one of the basic elements of the current global malaria control strategy. In order to provide this service to people in rural areas there is a need for new cost-effective approaches. To ensure that such new approaches are acceptable to the target communities, it is important to know the rationale for people's malaria treatment-seeking behavior. The present study provides insights into the reasons for people's preferences for different types of healthcare facilities and describes variation of these preferences within a rural community in Sri Lanka. The study reports on the experiences with the establishment of a village health facility and its effect on the treatment-seeking behavior of the population. After the introduction of the village treatment center it quickly took over the role of main provider for diagnosis and treatment of malaria from the government facilities. The treatment center did not improve the response time in seeking treatment for young children, but the delay for adults was reduced by 1-2 days. Mothers with small children often preferred the government facilities since they wanted a more qualified opinion than available from the locally recruited staff of the village treatment center. The treatment center significantly reduced the stress and discomfort experienced by the elderly and handicapped segment of the community. The study indicated that the effective catchment area of a village treatment center will be influenced by the degree of initial support from key individuals in the communities, the selection procedure and training of assistants, and the history of the relationships between different villages to be served by the center. The government health services and communities across the dry zone of Sri Lanka could benefit substantially from the establishment of more village treatment centers. To ensure the long-term sustainability of these type of facilities it is necessary to assess the feasibility of charging a user fee and establishing multi-purpose clinics. Government policies and administrative procedures will need to be adjusted to make the successful operation of village treatment centers possible.