Open Water Source Research Articles

‘Tail-dipping’ to drink from an open water source in Cebus imitator (Primates: Cebidae) in a protected area of Costa Rica

Primate species demonstrate high levels of intelligence, innovation, and social learning. These characteristics give rise to a high likelihood of new behaviours occurring and being socially transmitted to other individuals within a group. Capuchin monkeys are group-living and are commonly considered to be among the most intelligent non-ape primates. They exhibit a large repertoire of complex behaviours and have been shown to be capable of innovating to problem solve. However, observations of new behaviours in wild populations are rare in comparison to captive populations. Here we describe Panamanian white-faced capuchins (Cebus imitator) carrying out a behaviour which has not been previously documented in capuchin species and may be related to predator avoidance. This behaviour was video-recorded and to our knowledge is the first record of a capuchin species using tail-dipping behaviour to access an open water source in the wild.

COVID 19 pandemic and behavioural change toward water hygiene and sanitation (WASH): A study in rural Odisha, India

COVID-19 Pandemic is not the first-ever pandemic which hit this globe, but it is the deadliest and possesses enough capability to shake the so-called developed global system. Additionally, the SARS-CoV-2 virus has been detected in feces of infected individuals, leading to the possibility that fecal-oral transmission could also play a role in virus transmission, particularly in low- and middle-income countries (LMICs) with high rates of open defecation, ineffective fecal sludge management, and poor access to safe drinking water. So people’s behaviour towards WASH is very important at this time.This study was done in two rural districts of Odisha, i.e. Sambalpur and Mayurbhanj. The district, blocks, villages were selected with simple random sampling. A sample size of 50 was taken through telephonic interviews.This study was done to understand the real life scenario of rural Odisha and how COVID 19 pandemic shape their behaviour toward the water hygiene and sanitation. So the research was designed in such a manner so that it can capture the important dimensions of WASH. The sample size includes a non-homogeneous group which represents the rural population in terms of social, economic, educational and gender perspectives. During the S1 situation if the source of drinking water is taken into consideration people were using those sources from many years and after lot of efforts from the government side people never changed their behaviour, people’s perspective on water treatment and hand washing were so strong that there was 32 percent people who never used to wash their hands they don’t even think it was important (38% people. At least 34 percent people used to thought there was no need of treating water before drinking when 46 percent of the sample population was using the open water source. But these scenarios changed after they lose their hope on their own immunity during the S2 situation. The numbers of washing hands increase, people started using soap and the perspective towards the water treatment also changed towards a positive aspect.This study clearly finds that 3As (Availability, Accessibility and Affordability) is not enough for behavioural change towards WASH but it needs 4As (Availability, Accessibility, Affordability and Accountability) and 1I (Intension). Because until people understand that they are accountable for their own vulnerability they will not able to think about the behavioural change and without their intension they cannot start the process.

Relation between organophosphate pesticide metabolite concentrations with pesticide exposures, socio-economic factors and lifestyles: A cross-sectional study among school boys in the rural Western Cape, South Africa.

Evidence on the relationship between lifestyle, socio-economic factors and pesticide exposure and urinary concentrations of organophosphate (OP) pesticide metabolites among children is generally incomplete. This study investigated the relationship between socio-economic factors and reported pesticide exposures and the sum of three urinary concentrations of dialkyl phosphate metabolites (DAP) among boys living in the rural areas of the Western Cape, South Africa. Data was collected during a cross-sectional study of 183 boys from three agricultural intense areas. Measurements included a questionnaire on socio-economic and pesticide exposures and urinary DAP concentrations. Most boys (70%) lived on farms with a median age of 12 years (range: 5.0-19.5 years). Children aged >14 years had lower DAP urine concentrations (median=39.9ng/ml; β=-68.1ng/ml; 95% CI:-136.8, 0.6) than children aged 9 years and younger (median=107.0ng/ml). DAP concentrations also varied significantly with area, with concentrations in the grape farming area, Hex River Valley (median=61.8ng/ml; β=-52.1; 95% CI:-97.9,-6.3ng/ml) and the wheat farming area, Piketberg (median=72.4ng/ml; β=-54.2; 95% CI: 98.8,-9.7ng/ml) lower than those in the pome farming area, Grabouw (median=79.9ng/ml). Other weaker and non-significant associations with increased DAP levels were found with increased household income, member of household working with pesticides, living on a farm, drinking water from an open water source and eating crops from the vineyard and or garden. The study found younger age and living in and around apple and grape farms to be associated with increased urinary DAP concentrations. Additionally, there were other pesticide exposures and socio-economic and lifestyle factors that were weakly associated with elevated urinary DAP levels requiring further study. The study provided more evidence on factors associated to urinary DAP concentrations especially in developing country settings.

Relationship between urinary levels of organophosphate metabolites and pesticide exposures among rural school boys of the Western Cape

Background: Current evidence on the relationship between demographic, socio-economic and pesticide exposure risk factors and urinary levels of organophosphate pesticide metabolites among children is generally incomplete and conflicting in some cases. This study investigated the relationship between socio-economic, demographic and reported pesticide exposure related behaviours and characteristics in relation to urinary levels dialkyl phosphate (DAP) metabolites among boys from rural Western Cape, South Africa. Methods: A cross-sectional study of 183 school boys from three agricultural intense areas was conducted. Measurements included a questionnaire on demographic, socio-economic and pesticide exposure risk and analysis of urinary DAP metabolites (diethyl (DEP), dimethyl (DMP) and dimethyl triphosphate (DMTP)). Results: DAP, DEP, DMP and DMTP were detected with median concentrations of 68.3 ng/ml, 5.5 ng/ml, 32.6 ng/ml and 16.7 ng/ml, respectively. Most of the boys (70%) lived on farms with a median age of 12 years (range: 5 -19.5 years). The sum of DAP levels decreased in a dose dependant manner with age. Children older than 14 years had less DAP levels (β =-68.1, p=0.05) than children 9 years and younger. DAP levels also varied significantly with area, with the levels highest in Grabouw, followed by Piketberg (β=-54.2, p=0.01). Other weaker and non-significant predictors of increased DAP levels were household income, member of household work with pesticides, living on farm, drinking water from an open water source and eating crops from the vineyard and /or garden. Conclusion: The study provide evidence that lower age and residential area are predictors of increased urinary DAP concentrations among boys. Additionally, pesticide exposure factors such as member of household work with pesticide, living on the farm, drinking water from an open water source and eating crops from vineyard also determines increased DAP levels. Further studies with larger sample sizes and longitudinal designs are recommended.

Lack of access to an open water source for bathing inhibited the development of the preen gland and preening behavior in Sanshui White ducks

As a species of waterfowl, ducks rely on access to water to facilitate feeding behaviors. Further, wet preening behavior in ducks relies on access to water and is a key behavior for duck welfare. Traditionally, Chinese duck farms provide not only free access to drinking water in the duck house but also an open water pool outside of the house. However, recent restrictions prohibit the use of an open water pool for raising ducks in some areas of China. Little is known about the effects of not providing an open water pool on duck welfare, in particular, the development of the preen gland and wet preening behaviors. The preen gland secretes oil which is crucial for maintaining plumage conditions. A total of one hundred twenty 1-day-old Sanshui White ducks (SSWD) were randomly divided into 2 groups and fed for 6 wk with access to a water pool (WP) or without access to a water pool and provided drinking water only (LWP). The live body weights of ducks from the WP group were significantly increased compared with those of ducks in the LWP group starting from 3 wks of age (P < 0.05). Feed intake was increased in the WP group at 2 wk of age and from 4 to 6 wk of age (P < 0.05). The feed conversion ratio (FCR) was significantly different only at 4 and 5 wks of age, when the FCR was increased by 5.7% and 9.5%, respectively, in the LWP group compared with the WP group (P < 0.05). Lack of access to an open water pool significantly inhibited the growth of the preen gland based on its weight, size, and quantity of oil secretions (P < 0.05). In addition, the proportion of ducks exhibiting wet preening behavior was significantly reduced in the LWP group compared with the WP group (5.5 ± 0.2% vs. 24.8 ± 2.1%, P < 0.05). This study indicated that a lack of access to an open water source had negative impacts on the development of the preen gland and on the preening behavior of SSWD.

Citizen science implements the first intensive acoustics-based survey of insectivorous bat species across the Murray–Darling Basin of South Australia

Effective land management and biodiversity conservation policy relies on good records of native species occurrence and habitat association, but for many animal groups these data are inadequate. In the Murray–Darling Basin (MDB), the most environmentally and economically important catchment in Australia, knowledge gaps exist on the occurrence and habitat associations of insectivorous bat species. We relied on the interest and effort of citizen scientists to assist with the most intensive insectivorous bat survey ever undertaken in the MDB region of South Australia. We used an existing network of Natural Resource Management groups to connect interested citizens and build on historical observations of bat species using a fleet of 30 Anabat Swift bat detectors. The survey effort more than doubled the number of bat occurrence records for the area in two years (3000 records; cf. 2693 records between 1890 and 2018; freely available through the Atlas of Living Australia). We used multinomial logistic regression to look at the relationship between three types of environmental covariates: flight space, nearest open water source and vegetation type. There were no differences in species richness among the environmental covariates. The records have been, and will continue to be, used to inform government land management policy, more accurately predict the impact of development proposals on bat populations, and update conservation assessments for microbat species. A social survey tool also showed that participation in the project led to positive behaviours, and planned positive behaviours, for improving bat habitat on private land.

The possibility of obtaining ultra-low-δ18O signature of precipitation near equatorial latitudes during the Snowball Earth glaciation episodes

Hydrothermally-altered rocks with ultra-low-δ18O and δD were discovered in Karelia, Russia, over 500km along the Belomorian Belt of the Baltic Shield. The ages of low δ18O and δD values are 2.41Ga and 2.29Ga, corresponding to the first and third Paleoproterozoic Snowball earth glacial episodes. Paleogeographic reconstruction suggests low latitudes for Baltica throughout Paleoproterozoic ice ages, requiring an effective distillation of water isotopes over short transport distances. Here we summarize how to use hydrothermally altered rocks to infer δ18O value of altering meteoric waters, then use an idealized General Circulation Model to test climate states with variable amount of ice cover and to check the hydrologic possibility of ultra-low-δ18O precipitation at low latitudes. Our model results suggest that the low δ18O values in precipitation is best achieved if the area of open water is quite narrow around the equator between latitudes 5°S and 5°N, or the Jormungand climate state. The δ18O of precipitation is high (>−15‰) over open water where high-δ18O vapor from ocean mixes with low-δ18O atmospheric water vapor. As such, a position of about 5–10° north or south of the equator is needed in order to achieve low δ18O of precipitation from an open water source. Our results suggest a slushball climate state with wide areas of open water is less likely to produce ultra-low-δ18O rocks for the low latitude position of Baltica.

Marine aerosol source regions to Prince of Wales Icefield, Ellesmere Island, and influence from the tropical Pacific, 1979–2001

AbstractUsing a coastal ice core collected from Prince of Wales (POW) Icefield on Ellesmere Island, we investigate source regions of sea ice‐modulated chemical species (methanesulfonic acid (MSA) and chloride (Cl−)) to POW Icefield and the influence of large‐scale atmospheric variability on the transport of these marine aerosols (1979–2001). Our key findings are (1) MSA in the POW Icefield core is derived primarily from productivity in the sea ice zone of Baffin Bay and the Labrador Sea, with influence from waters within the North Water (NOW) polynya, (2) sea ice formation processes within the NOW polynya may be a significant source of sea‐salt aerosols to the POW core site, in addition to offshore open water source regions primarily in Hudson Bay, and (3) the tropical Pacific influences the source and transport of marine aerosols to POW Icefield through its remote control on regional winds and sea ice variability. Regression analyses during times of MSA deposition reveal sea level pressure (SLP) anomalies favorable for opening of the NOW polynya and subsequent oceanic dimethyl sulfide production. Regression analyses during times of Cl− deposition reveal SLP anomalies that indicate a broader oceanic region of sea‐salt sources to the core site. These results are supported by Scanning Multichannel Microwave Radiometer‐ and Special Sensor Microwave/Imager‐based sea ice reconstructions and air mass transport density analyses and suggest that the marine biogenic record may capture local polynya variability, while sea‐salt transport to the site from larger offshore source regions in Baffin Bay is likely. Regression analyses show a link to tropical dynamics via an atmospheric Rossby wave.

Mosquito Capture Rate Using CO2-Baited Traps in Relation to Distance From Water and Height: Implications for Avian Disease Transmission.

Accumulating evidence suggests that enzootic transmission of pathogens such as West Nile virus (WNV) by mosquitoes is governed by host-bird interactions, including mosquito preferences for specific species and developmental stages of host birds, host bird availability, and host defensive behavior. Here, we examined how the attack rate of five mosquito species in southern California was influenced by the position of CO2-baited traps in relation to distance from water and trap height. We identified 44,207 female mosquitoes representing five species: Aedes vexans Meigen, Anopheles franciscanus McCracken, Anopheles hermsi Barr & Guptavanij, and the two most abundant species which are also WNV vectors, Culex erythrothorax Dyar and Culex tarsalis Coquillett. Mosquito captures decreased markedly with trap height, and also decreased with distance from a riparian area but not with distance from an open water source lacking a vegetated border. The results of this study suggest that WNV-competent ornithophilic mosquitoes may amplify the virus especially in reservoir birds that roost or nest close to the ground and near riparian vegetation.

Non-fatal drowning in under-five rural children of Bangladesh

Drowning has been identified as a major cause of death in children in both developed and developing countries. Non-fatal drowning is several times higher than the fatal drowning. To describe the socio-demographic and environmental attributes of non-fatal drowning in rural children this community based descriptive study was conducted on 122 children having non-fatal drowning events within one year of study period. This study was undertaken in Raigonj sub-district of Sirajgonj district in Bangladesh. Mothers of those children were interviewed using a structured questionnaire. Out of all participants 56.6% children were 2-4 years of age and male-female ratio was almost equal. Of the total respondent mothers 55% were illiterate and 41.8% were below the age of 25 years. Seasonal variation was observed in non-fatal drowning. Rainy season (50.8%) appeared as the most risky period followed by summer (29.5%). Higher incidence occurred (53.3%) between 10 am to 2 pm of the day. Although most of the drowning occurred outside the home, 9% drowning occurred in water container (like drum, tub) within the home. Pond (50.5%) was found as the most common place among open water source. During the occurrence, 23% child was not accompanied by parents or any caregivers. At the time of drowning, 47.5% mothers were engaged with usual household work and were not present at the place of occurrence whereas 13% mothers were present around the place of occurance. Before drowning, 45.1% victim was either playing, bathing or swimming in the water. Only 10.7% needed resuscitation, 25% were taken to health centre and reached the health centre within an hour, about a fifth (22.6%) of them were admitted. Restriction in dangerous water activities, strengthening supervision of children might decrease the incidence of drowning while quick and effective medical response might prevent its fatal consequences.Ibrahim Med. Coll. J. 2015; 9(2): 37-41

High prevalence of toxoplasmosis in free-range chicken of the Fernando de Noronha Archipelago, Brazil

The present study aimed to determine the prevalence of toxoplasmosis in free-range chickens of the Fernando de Noronha Archipelago, Brazil and to identify risk factors associated with Toxoplasma gondii infection. Blood samples were collected from all the adult chickens raised in the Archipelago and screened by Indirect Fluorescent Antibody Test (430 samples, in total). Univariate analysis (Chi-square) and logistic regression were used to investigate the relationship between various variables possibly predictive of an increased likelihood of T. gondii infection. The overall prevalence of T. gondii infection in chickens of the Fernando de Noronha Archipelago was 88.4% (380/430; 84.6%–91.0%; 95% CI), ranging from 57.1% to 100.0% among the studied properties. The risk factors associated with T. gondii infection were the number of domestic cats in the properties (p=0.022), the presence of feral cats (p=0.006) and the presence of an open water source (p=0.046). Domestic and feral cats should be prevented from accessing the water and food supplied to chickens.

Study on transport of powdered activated carbon using a rotating circular flume

This study employed a rotating flume to examine the Powdered Activated Carbon (PAC) transport with water flow. The initial PAC concentration was 10 mg/L-30 mg/L, and PAC concentration versus time under a specified cross-sectional averaging fluid shear was observed. Results show that compared with PAC deposition in still water, PAC is depleted to zero faster under a fluid shear of 0.02 Pa, due to PAC agglomeration with the fluid shear. However, since PAC floc size only ranges from a single particle (2 μm) to approximate 6 μm, an increasing of instantaneous turbulent fluctuations could counteract the force of PAC floc settling downward, and as a result the steady PAC concentration increases with the increase of shear stress. It is found that the critical shear stress for PAC deposition is about 0.60 Pa, and further the PAC deposition probability is presented according to the experimental scenarios between 0.02 Pa and 0.60 Pa. Combining the PAC transport and deposition formula with PAC-pollutant removal model provides an insight into PAC deployment in raw water aqueduct for sudden open water source pollution.

Household-level risk factors for Newcastle disease seropositivity and incidence of Newcastle disease virus exposure in backyard chicken flocks in Eastern Shewa zone, Ethiopia

A cross-sectional study with repeated sampling was conducted to investigate potential risk factors for Newcastle disease (ND) seropositivity and for incidence of ND virus (NDV) exposure in household flocks of backyard chickens in Eastern Shewa zone, Ethiopia. Data were collected from 260 randomly selected households in 52 villages in Adami Tulu Jido Kombolcha and Ada’a woredas (districts) using a structured questionnaire, and serum samples from chickens were tested for NDV antibodies using a blocking enzyme-linked immunosorbent assay (ELISA). Sampling took place during September 2009 and the same households were again sampled in May 2010. Household-level seroprevalence and incidence of NDV exposure were estimated in various ways using serological results from the two samplings, flock dynamics, and farmers’ reports of ND in their flocks. The risk factors were assessed using multivariable mixed-effects logistic regression models. Household-level seroprevalence at the two sampling times was 17.4% and 27.4%, respectively, and the estimated incidence of household-level NDV exposure during the intervening period ranged between 19.7% and 25.5%. At the first sampling, reduced frequency of cleaning of poultry waste was associated with increased odds of seropositivity (OR=4.78; 95% CI: 1.42, 16.11; P=0.01) while hatching at home vs. other sources (buying in replacement birds, receiving as gift or buying fertile eggs) was associated with lower odds of seropositivity, both at the first sampling (OR=0.30; 95% CI: 0.11, 0.82; P=0.02) and the second sampling (OR=0.23; 95% CI: 0.10, 0.52; P<0.001). The risk of NDV exposure was shown to be higher with larger flock size at the beginning of the observation period (OR=3.6; 95% CI: 1.25, 10.39; P=0.02). Using an open water source (pond or river) for poultry compared to closed sources (tap or borehole) was associated with increased risk of NDV exposure (OR=3.14; 95% CI: 1.12, 8.8; P=0.03). The use of a grain supplement (OR=0.14; 95% CI: 0.03, 0.69; P=0.03) and hatching at home for flock replacement (OR=0.23; 95% CI: 0.10, 0.52; P=0.005) were associated with a lower risk of NDV exposure. Newcastle disease seroprevalence and incidence of NDV exposure were more heterogeneous between villages than between kebeles (aggregations of villages) and woredas in the study area. Further investigation of village-level risk factors would likely improve our understanding of ND epidemiology in backyard chickens.

Current Status of Schistosoma mansoni Infections and Associated Risk Factors among Students in Gorgora Town, Northwest Ethiopia

Background and Objective. Schistosomiasis is highly prevalent in tropics and causes morbidity and mortality in developing countries including Ethiopia. This study is aimed to assess the current status of S. mansoni infections and associated risk factors among students in Gorgora town, Northwest Ethiopia. Method. A cross-sectional study was conducted from October 2010 to November 2010 at Gorgora, Northwest Ethiopia. All students (579) present during the study period were enrolled. Pretested questionnaires were used to collect sociodemographic data and predisposing factors. Stool examination was performed using wet mount and Kato-Katz techniques. Data were entered and analysed using SPSS version 20.0 statistical software. Result. Among 579 students enrolled, 291 (50.3%) were positive for one or more intestinal parasites. Prevalence of S. mansoni was found to be 20.6% with mean intensity of infection (125 eggs per gram of feces). Lack of awareness and water contact habits such as frequent swimming in the open water source, agricultural activities on bare foot, and washing clothes were also associated with high risk of S. mansoni infection. Conclusion. Even though there seems to be a decline in the prevalence of S. mansoni infections in the study area, the problem still persists and affects students significantly. Therefore, therapeutic intervention and health education are needed.

Schistosomiasis and soil-transmitted helminths among an adult population in a war affected area, Southern Kordofan state, Sudan

BackgroundSchistosomiasis remains a major health problem at global and national levels, contributing to the vulnerability of the poor people in Sudan. Southern Kordofan is affected by Schistosomiasis but the disease prevalence was unknown.Methods1826 adults were recruited in a community-based survey. Each recruited subject submitted at least 10 ml urine and one stool sample; they were also interviewed and filled in a questionnaire.Results1826 adults were recruited in a community-based survey. Each recruited subject submitted at least 10 ml urine and one stool sample; they were also interviewed and filled in a questionnaire. The prevalence of S. haematobium was 6.9 % among the adult population. We estimated S. mansoni prevalence as 0.0 %. S. haematobium infection was focally distributed at the village level. The infection was associated with non preference of latrine use – if available, use of open water source for household affairs such as cleaning and also with the history of schistosomiasis treatment. The prevalence of soil transmitted helminths (STH) was also reported as high at 7.8 %, and two species were identified; Hymenolepis nana and Giardia lamblia.ConclusionSchistosomiasis is a significant health problem among the adult population in Southern Kordofan. The estimated prevalence will serve as a guide in developing a Schistosomiasis Control Program and applying treatment plans.

Epidemiology and Molecular Relationships of Cryptosporidium spp. in People, Primates, and Livestock from Western Uganda

Background Cryptosporidium is one of the most common parasitic diarrheal agents in the world and is a known zoonosis. We studied Cryptosporidium in people, livestock, and non-human primates in the region of Kibale National Park, Uganda. Land use change near the park has resulted in fragmented forest patches containing small, remnant populations of wild primates that interact intensively with local people and livestock. Our goal was to investigate risk factors for Cryptosporidium infection and to assess cross-species transmission using molecular methods.Methodology/Principal FindingsDiagnostic PCR revealed a prevalence of Cryptosporidium of 32.4% in humans, 11.1% in non-human primates, and 2.2% in livestock. In the case of humans, residence in one particular community was associated with increased risk of infection, as was fetching water from an open water source. Although 48.5% of infected people reported gastrointestinal symptoms, this frequency was not significantly different in people who tested negative (44.7%) for Cryptosporidium, nor was co-infection with Giardia duodenalis associated with increased reporting of gastrointestinal symptoms. Fecal consistency was no different in infected versus uninfected people or animals. DNA sequences of the Cryptosporidium oocyst wall protein gene placed all infections within a well-supported C. parvum/C. hominis clade. However, the only two sequences recovered from primates in the core of the park's protected area fell into a divergent sub-clade and were identical to published sequences from C. parvum, C. hominis, and C. cuniculus, suggesting the possibility of a separate sylvatic transmission cycle.Conclusions/Significance Cryptosporidium may be transmitted frequently among species in western Uganda where people, livestock, and wildlife interact intensively as a result of anthropogenic changes to forests, but the parasite may undergo more host-specific transmission where such interactions do not occur. The parasite does not appear to have strong effects on human or animal health, perhaps because of persistent low-level shedding and immunity.

Changing individual-level risk factors for malaria with declining transmission in southern Zambia: a cross-sectional study

BackgroundMalaria elimination will require that both symptomatic- and asymptomatic-infected persons be identified and treated. However, well-characterized, individual-level risk factors for malaria may not be valid in regions with declining malaria transmission. Changes in individual-level correlates of malaria infection were evaluated over three years in a region of declining malaria transmission in southern Zambia.MethodsMalaria surveys were conducted in two study areas within the catchment area of Macha Hospital, Zambia in 2007 and 2008/2009. A random sample of households was identified from a digitized satellite image of the study areas. Cross-sectional surveys were conducted approximately five times throughout the year in each of the two study areas. During study visits, adults and caretakers of children were administered questionnaires and a blood sample was obtained for a rapid diagnostic test (RDT) for malaria.ResultsIn the 2007 study area, 330 individuals were surveyed. 40.9% of participants lived in a household with at least one insecticide-treated bed net (ITN); however, only 45.2% reported sleeping under the ITN. 23.9% of participants were RDT positive. Correlates of RDT positivity included younger age, the presence of symptoms, testing during the rainy season, using an open water source, and not sleeping under an ITN. In the 2008 study area, 435 individuals were surveyed. 77.0% of participants lived in a household with at least one ITN; however, only 56.4% reported sleeping under the ITN. 8.1% of participants were RDT positive. RDT positivity was negatively correlated with the presence of symptoms within the last two weeks but positively correlated with documented fever. In 2009, 716 individuals were surveyed in the same area as 2008. 63.7% of participants lived in a household with at least one ITN; however, only 57.7% reported sleeping under the ITN. 1.5% of participants were RDT positive. Only self-reported fever was significantly correlated with RDT positivity.ConclusionsWith declining malaria prevalence, few individual-level characteristics were correlated with RDT positivity. This lack of correlation with individual characteristics hampers identification of individuals infected with malaria. Strategies based on ecological or environmental risk factors may be needed to target control efforts and achieve further reductions and elimination.

Prevalence distribution and risk factors for Schistosoma hematobium infection among school children in Blantyre, Malawi.

BackgroundSchistosomiasis is a public health problem in Malawi but estimates of its prevalence vary widely. There is need for updated information on the extent of disease burden, communities at risk and factors associated with infection at the district and sub-district level to facilitate effective prioritization and monitoring while ensuring ownership and sustainability of prevention and control programs at the local level.Methods and FindingsWe conducted a cross-sectional study between May and July 2006 among pupils in Blantyre district from a stratified random sample of 23 primary schools. Information on socio-demographic factors, schistosomiasis symptoms and other risk factors was obtained using questionnaires. Urine samples were examined for Schistosoma hematobium ova using filtration method. Bivariate and multiple logistic regressions with robust estimates were used to assess risk factors for S. hematobium. One thousand one hundred and fifty (1,150) pupils were enrolled with a mean age of 10.5 years and 51.5% of them were boys. One thousand one hundred and thirty-nine (1,139) pupils submitted urine and S. hematobium ova were detected in 10.4% (95%CI 5.43–15.41%). Male gender (OR 1.81; 95% CI 1.06–3.07), child's knowledge of an existing open water source (includes river, dam, springs, lake, etc.) in the area (OR 1.90; 95% CI 1.14–3.46), history of urinary schistosomiasis in the past month (OR 3.65; 95% CI 2.22–6.00), distance of less than 1 km from school to the nearest open water source (OR 5.39; 95% CI 1.67–17.42) and age 8–10 years (OR 4.55; 95% CI 1.53–13.50) compared to those 14 years or older were associated with infection. Using urine microscopy as a gold standard, the sensitivity and specificity of self-reported hematuria was 68.3% and 73.6%, respectively. However, the positive predictive value was low at 23.9% and was associated with age.ConclusionThe study provides an important update on the status of infection in this part of sub-Saharan Africa and exemplifies the success of deliberate national efforts to advance active participation in schistosomiasis prevention and control activities at the sub-national or sub-district levels. In this population, children who attend schools close to open water sources are at an increased risk of infection and self-reported hematuria may still be useful in older children in this region.

Frost flowers as a source of fractionated sea salt aerosol in the polar regions

Frost flowers collected from the surface of new sea ice near the Brunt Ice Shelf, Antarctica, show depletion in sulphate and sodium relative to other sea water ions. This is consistent with loss of mirabilite (Na2SO4) during formation of the brine from which the frost flowers grow. Aerosol generated from frost flowers would have higher sodium:sulphate ratios than aerosol generated from sea water. This would explain low values of non‐sea‐salt sulphate encountered in winter aerosol, and winter layers in ice cores, at coastal Antarctic sites. Calculations confirm that the frost flower source should be significant compared to an open water source for coastal regions.