Taking it with a grain of salt: tolerance to increasing salinization in Culex pipiens (Diptera: Culicidae) across a low-lying delta.

BACKGROUND: Salinity, exacerbated by rising sea levels, is a critical environmental cue affecting freshwater ecosystems. Predicting ecosystem structure in response to such changes and their implications for the geographical distribution of arthropod disease vectors requires further insights into the plasticity and adaptability of lower trophic level species in freshwater systems. Our study investigated whether populations of the mosquito Culex pipiens, typically considered sensitive to salt, have adapted due to gradual exposure. METHODS: Mesocosm experiments were conducted to evaluate responses in life history traits to increasing levels of salinity in three populations along a gradient perpendicular to the North Sea coast. Salt concentrations up to the brackish-marine transition zone (8 g/l chloride) were used, upon which no survival was expected. To determine how this process affects oviposition, a colonization experiment was performed by exposing the coastal population to the same concentrations. RESULTS: While concentrations up to the currently described median lethal dose (LD50) (4 g/l) were surprisingly favored during egg laying, even the treatment with the highest salt concentration was incidentally colonized. Differences in development rates among populations were observed, but the influence of salinity was evident only at 4 g/l and higher, resulting in only a 1-day delay. Mortality rates were lower than expected, reaching only 20% for coastal and inland populations and 41% for the intermediate population at the highest salinity. Sex ratios remained unaffected across the tested range. CONCLUSIONS: The high tolerance to salinity for all key life history parameters across populations suggests that Cx. pipiens is unlikely to shift its distribution in the foreseeable future, with potential implications for the disease risk of associated pathogens.

Innovative actions in oceans and human health for Europe.

Innovative actions are local initiatives which leverage the interactions between the ocean and human health to reduce the risks and enhance the benefits for the stakeholders and the natural environment. These initiatives can have strong positive effects on human health and wellbeing as well as on the marine environment. We analysed 150 such innovative actions in Europe. Using a combined case study and survey approach, innovative actions were identified using interviews and content analysis of websites and compiled into a database. Quantitative data were analysed according to the Drivers, Pressures, State, Impact and Response (DPSIR) framework, guided by selected in-depth interviews. Overall, the innovative actions provided a positive impact on the health of both the ocean and humans through increasing food provision, water quality and tourism opportunities; and addressing environmental issues such as commercial fish stock depletion, pollution and climate change. Innovative actions contributed to meeting various targets of the Sustainable Development Goals (SDGs) 3, 13 and 14. These actions played a potential role ahead of and alongside policy. Some of the innovative actions may have potential to be put in place elsewhere. Such up-scaling would need to be adapted to local circumstances and could be facilitated by an innovative action exchange platform.

This study presents 150 innovative actions taken by citizens and organizations in Europe to promote the health of both the ocean and humans. These were analysed and categorized according to the environmental issues they responded to, the Sustainable Development Goals (SDGs) addressed, and the ecosystem services provided. Plastic pollution and loss of biodiversity were the most targeted environmental issues, while tourism, recreation and wellbeing were the services most addressed by the innovative actions. These innovative actions tended to target those SDGs that currently show a lack of progress. Such actions, with both an environmental and health promotion agenda, may have the potential to complement regular policymaking in achieving these SDGs. The impact could be further enhanced by sharing best practices among an international network of local stakeholder action innovators. An interactive map shows the locations and websites of the European innovative actions identified. The map can serve as a first step in providing a platform for the network to connect and inspire people interested in creating their own interventions.

Prevalence and environmental determinants of cutaneous leishmaniasis in rural communities in Tigray, northern Ethiopia.

BACKGROUND: In Ethiopia guidelines for diagnoses and treatment of leishmaniases are available, but only a few hundred people are diagnosed and receive treatment. A field study has been carried out to determine the status and environmental determinants of cutaneous leishmaniasis (CL) and assess the degree of awareness of the rural communities in affected areas in Tigray, northern Ethiopia. METHODOLOGY / PRINCIPAL FINDINGS: Following a reconnaissance survey that identified endemic foci, a cross sectional door-to-door survey was conducted in 2009 in five rural communities around the towns of Adigrat and Hagereselam in Tigray. In total 9,622 residents of 1,721 households were clinically screened and household heads interviewed regarding the determinants of infection. The χ2 test and logistic regression were used to determine differences in prevalence between localities, age and sex, and to identify environmental determinants of infection. The overall prevalence of localized CL was 2.3% (highest 4.7%), with marked inter-village differences. Another 20.9% had scars from previous infections. While risk was sex-independent, prevalence was significantly higher in the 0-9 (4.5%) and 10-19 (2.5%) age groups and predominantly involved the face (82.1%) and upper limbs (13.1%). Nearly 11% of the households had one or more cases of CL and this was associated with proximity to hyrax habitats. All interviewees were knowledgeable about the lesions but ignorant of the disease's mode of transmission and its association with hyraxes. CONCLUSIONS: The study established that CL is an important public health problem in the study communities, and has been so for a while, as demonstrated by the widespread presence of scars. CL in Tigray appeared to be predominantly of zoonotic nature, mainly transmitted in peri-domestic habitats in proximity to hyrax habitats. Integrated interventions, including awareness creation, are highly recommended.

Water and health: From environmental pressures to integrated responses.

The water-related exposome is a significant determinant of human health. The disease burden through water results from water-associated communicable and non-communicable diseases and is influenced by water pollution with chemicals, solid waste (mainly plastics), pathogens, insects and other disease vectors. This paper analyses a range of water practitioner-driven health issues, including infectious diseases and chemical intoxication, using the conceptual framework of Drivers, Pressures, State, Impacts, and Responses (DPSIR), complemented with a selective literature review. Pressures in the environment result in changes in the State of the water body: chemical pollution, microbiological contamination and the presence of vectors. These and other health hazards affect the State of human health. The resulting Impacts in an exposed population or affected ecosystem, in turn incite Responses. Pathways from Drivers to Impacts are quite divergent for chemical pollution, microbiological contamination and the spread of antimicrobial resistance, in vectors of disease and for the combined effects of plastics. Potential Responses from the water sector, however, show remarkable similarities. Integrated water management interventions have the potential to address Drivers, Pressures, Impacts, and State of several health issues at the same time. Systematic and integrated planning and management of water resources, with an eye for human health, could contribute to reducing or preventing negative health impacts and enhancing the health benefits.

How does an Ethiopian dam increase malaria? Entomological determinants around the Koka reservoir.

OBJECTIVES: To identify entomological determinants of increased malaria transmission in the vicinity of the Koka reservoir in Central Ethiopia. METHODS: Larval and adult mosquitoes were collected between August 2006 and December 2007 in villages close to (<1km) and farther away from (>6 km) the Koka reservoir. Adult mosquitoes were tested for the source of blood meal and sporozoites. RESULTS: In reservoir villages, shoreline puddles and seepage at the base of the dam were the most productive Anopheles-breeding habitats. In villages farther from the dam (control villages), rain pools were important breeding habitats. About five times more mature anopheline larvae and six times more adult anophelines were found in the villages near the reservoir. Anopheles arabiensis and Anopheles pharoensis were the most abundant species in the reservoir villages throughout the study period. The majority of adult and larval anophelines were collected during the peak malaria transmission season (September-October). Blood meal tests suggested that A. arabiensis fed on humans more commonly (74.6%) than A. pharoensis (62.3%). Plasmodium falciparum-infected A. arabiensis (0.97-1.32%) and A. pharoensis (0.47-0.70%) were present in the reservoir villages. No P. falciparum-infected anophelines were present in the control villages. CONCLUSIONS: The Koka reservoir contributes to increased numbers of productive Anopheles-breeding sites. This is the likely the cause for the greater abundance of malaria vectors and higher number of malaria cases evidenced in the reservoir villages. Complementing current malaria control strategies with source reduction interventions should be considered to reduce malaria in the vicinity of the reservoir.

The impact of a small-scale irrigation scheme on malaria transmission in Ziway area, Central Ethiopia.

OBJECTIVE: To assess the impact of a small-scale irrigation scheme in Ziway area, a semi-arid area in the Central Ethiopian Rift Valley, on malaria transmission. METHOD: Parasitological, entomological and socio-economic studies were conducted in a village with and a village without irrigation. Blood smear samples were taken from individuals during the dry and wet seasons of 2005/2006. Socio-economic data were collected from household heads and key agricultural and health informants through interviews and questionnaires. Larval and adult mosquitoes were sampled during the dry and short wet seasons of 2006. Female anopheline mosquitoes were tested by enzyme-linked immunosorbent assay for blood meal sources and sporozoite infections. RESULTS: Malaria prevalence was higher in the irrigated village (19%, P < 0.05) than the non-irrigated village (16%). In the irrigated village, malaria prevalence was higher in the dry season than in the wet season while the reverse occurred in the non-irrigated village. Households with access to irrigation had larger farm land sizes and higher incomes, but also higher prevalence of malaria. Larval and adult abundance of the malaria vectors, Anopheles arabiensis and Anopheles pharoensis, was higher in the irrigated than in the non-irrigated village throughout the study period. Furthermore, the abundance of An. pharoensis was significantly higher than that of An. arabiensis during the dry irrigated period of the year. Canal leakage pools, irrigated fields and irrigation canals were the major breeding habitats of the two vector mosquitoes. Plasmodium falciparum sporozoite infection rates of 1.18% and 0.66% were determined for An. arabiensis and An. pharoensis in the irrigated village. Peak biting activities of the vectors occurred before 22:00 h, which is a source of concern that the effectiveness of ITNs may be compromised as the mosquitoes feed on blood before people go to bed. CONCLUSION: Irrigation schemes along the Ethiopian Rift Valley may intensify malaria by increasing the level of prevalence during the dry season. To reduce the intensity of malaria transmission in the small-scale irrigation schemes currently in operation in Ethiopia, year-round source reduction by using proper irrigation water management, coupled with health education, needs to be incorporated into the existing malaria control strategies.

Cryptosporidium and Giardia as determinants for selection of an appropriate source of drinking-water in southern Sri Lanka.

Four different water sources (irrigation canals, small reservoirs, shallow wells, and tubewells), used for domestic purposes, in an irrigated area in southern Sri Lanka, were tested for Giardia spp. cysts and Cryptosporidium spp. oocysts. Identification of these parasites in water sources is important as these are increasingly recognized as causative agents of waterborne diarrhoeal disease. All the four sources of water were contaminated with cysts and oocysts. The sources of surface-water contained a greater number of protozoa compared to tubewells and shallow wells (p < 0.05). The results indicate a reduction of high parasite loads by natural filtration as the water moves from canals to shallow wells through the soil profile. This could present an opportunity to reduce the burden of diarrhoeal disease due to protozoa by selecting an appropriate source of drinking-water and identifying those water sources that require treatment solutions.

Environmental control of schistosomiasis through community participation in a Moroccan oasis.

Summary Akka oasis, in the province of Tata, southern Morocco, is one of the oldest foci of urinary schistosomiasis in Morocco where transmission is still taking place. We report the results of two studies: a cross-sectional snail survey investigated the distribution of Bulinus truncatus in relation to habitat factors in the Akka traditional irrigation system. The presence of aquatic vegetation, especially Potamogeton sp. was identified as a key factor determining snail occurrence and abundance in canals, impoundments and isolated small puddles and streamlets in the Akka riverbed. In a participatory rapid appraisal, the community identified snail control as a way to reduce transmission of schistosomiasis. Without any further outside incentives, the local irrigation committee implemented repeated cleaning and vegetation removal in canals. A longitudinal study evaluated the effect of these measures on populations of B. truncatus. Snail and egg mass densities showed significant reductions after repeated vegetation clearing in the study sites. The participatory approach led to low-cost, environment-friendly schistosomiasis control measures that were effective and sustainable.

Engineering and malaria control: learning from the past 100 years.

Traditionally, engineering and environment-based interventions have contributed to the prevention of malaria in Asia. However, with the introduction of DDT and other potent insecticides, chemical control became the dominating strategy. The renewed interest in environmental-management-based approaches for the control of malaria vectors follows the rapid development of resistance by mosquitoes to the widely used insecticides, the increasing cost of developing new chemicals, logistical constraints involved in the implementation of residual-spraying programs and the environmental concerns linked to the use of persistent organic pollutants. To guide future research and operational agendas focusing on environmental-control interventions, it is necessary to learn from the successes and failures from the time before the introduction of insecticides. The objective of this paper is to describe the experiences gained in Asia with early vector control interventions focusing on cases from the former Indian Punjab, Malaysia and Sri Lanka. The paper deals primarily with the agricultural engineering and land and water management vector control interventions implemented in the period 1900-1950. The selected cases are discussed in the wider context of environment-based approaches for the control of malaria vectors, including current relevance. Clearly, some of the interventions piloted and implemented early in the last century still have relevance today but generally in a very site-specific manner and in combination with other preventive and curative activities. Some of the approaches followed earlier on to support implementation would not be acceptable or feasible today, from a social or environmental point of view.