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Chemical signals reveal information such as sender identity and receptivity to mating that benefit both the sender and the receiver. Although the use of chemical signals seems probable for chelonians, few studies have focused on this form of communication in turtles, and only in a limited number of species. We tested the response of male Painted Turtles Chrysemys picta to chemical signals exuded by conspecifics by examining whether male Painted Turtles spent more time near female or male Painted Turtles or a control (empty) section of a pool, based solely on chemical signals exuded by the stimulus animals. We completed 27 trials and recorded the time male turtles spent in each section of the pool (male, female or control). Male Painted Turtles spent the most time in the section of the pool that housed the female Painted Turtle and spent the least amount of time in the control section. A one-way ANOVA and Tukey's test showed a statistically significant difference between the time test males spent in the female section and control section. The time male Painted Turtles spent in the female and male sections did not differ significantly and no significant difference was found in the amount of time the test male spent in the male section and the control section. The results are consistent with the hypothesis that male Painted Turtles respond to chemical signals exuded by female Painted Turtles, potentially, to find mates. With many turtle populations declining, it is important to study aspects of their reproduction, including communication.

An experimental procedure was developed to incorporate the mechanisms of Gas-Cycling Enhanced Oil Recovery (GCEOR) phase behavior, IFT change, swelling, viscosity reduction and residual-liquid shrinkage in the presence of porous media possessing propped hydraulic fractures and matrix. Relatively large hydrocarbon pore volumes are possible using this technique whereby effluent compositions, densities and volumes are measured. The importance of rock and fluid properties is investigated along with operating pressure, injection gas composition and levels of primary depletion. Experimental oil flux is measured and scaled to forecast field production rates based on field frac data. The experimental design for core-flow testing has provided insight into GCEOR. Two dominant flow regimes are incorporated: matrix mass transfer into and from the fracture(s) and flow within the fracture(s). Reservoirs tested exhibited pressures from 3000 to over 5000 psi and temperatures from 140 to 220 F. Huff pressures were as high as 6000 psi. Over fortyseven separate primary depletions were accomplished followed by Huff and Puff (HnP) GCEOR on multiple rock and fluid types. Design parameters were changed from run to run allowing for insight into GCEOR operation and design. Simulation of experimental results with subsequent scale-up for field forecasting was performed. From the many primary depletion tests followed by GCEOR, using a variety of injection gases and reservoir fluids the effects of cycling pressure, injection gas composition, soak time, level of primary depletion before GCEOR, and other parameters were investigated. Measured results indicate that recovery of OOIP can be more than doubled compared to primary production, in some cases, by implementing GCEOR. From the broad, accumulated data base, the following have been observed: Cycling pressure should be optimized (highest pressure does not necessarily perform the best). Gas quality can, in some cases, play a major role but should be considered and quantified in GCEOR applications.oak time/Huff time in many cases may be optimized to maximize production cycles and minimize injection cycles.Gas utilization values, for well-designed GCEOR systems, are low compared to conventional continuous gas injection projects causing Huff and Puff GCEOR to approach gas storage performance. Gas utilization appears to be sensitive to the mechanisms at work in GCEOR.Less depletion before GCEOR initiation can accelerate recovery and can, in some cases, access residual oil that was not produced at higher levels of primary depletion.Contrary to expectation, the rock character may dominate GCEOR performance. In a subset of this testing, the rock heterogeneity had a more dominant role than fluid properties including miscibility.Simulation can be an important tool to upscale the experimental measurements to field design. It is shown that simulation tuned to measured, experimental Primary Depletion and GCEOR performance including phase behavior and rock-fluid interaction, provides more optimistic forecasts of field GCEOR performance than a simulator based on field-scale Primary Depletion data alone.

A radial-flow, matrix-frac experimental procedure was developed to incorporate the mechanisms of Gas-Cycling Enhanced Oil Recovery (GCEOR) phase behavior, IFT change, swelling, viscosity reduction and residual-liquid shrinkage in the presence of porous media possessing propped hydraulic fractures and matrix. Relatively large hydrocarbon pore volumes are possible using this technique whereby effluent compositions, densities and volumes are measured. The importance of rock and fluid properties is investigated along with operating pressure, injection gas composition and levels of primary depletion. More than fifty primary depletions followed by GCEOR Huff and Puff operations have been conducted and some of the more interesting results have been assembled for discussion. Two dominant flow regimes are incorporated: matrix mass transfer into and from the fracture(s) and flow within the fracture(s). Reservoirs tested exhibited pressures from 3000 to over 5000 psi and temperatures from 140 to 220 F. Design parameters were changed from run to run allowing for insight into GCEOR operation and design. Of particular note is the ability to run different fluid systems in the same porous media in order to breathe insight into the relative importance of geology and phase behavior. Simulation of some experimental results with subsequent scale-up for field forecasting was performed, although not all systems were simulated as yet. Measured results indicate that recovery of OOIP can be more than doubled compared to primary production, in some cases, by implementing GCEOR. The role of injection gas composition, operating pressure, soak/ Huff time is commented on and appears to change from system to system. Analyzing measured oil flux in the experiments allowed the calculation of experimental Peclet numbers, indicating the relative importance of convection compared to diffusion. From the accumulated data base, the following have been observed: Cycling pressure should be optimized (highest pressure does not necessarily perform the best). Gas quality can, in some cases, play a major role but should be considered and quantified in GCEOR applications. Soak time/ Huff time may be optimized to maximize production cycles and minimize injection cycles. Gas utilization values, for well-designed GCEOR systems, are low compared to conventional continuous gas injection projects causing Huff and Puff GCEOR to approach gas storage performance. Gas utilization appears to be sensitive to the mechanisms at work in GCEOR. Less depletion before GCEOR initiation may accelerate recovery and may, in some cases, access residual oil that was not produced at higher levels of primary depletion. However, significant increases in recovery factor have not been observed with decreased degree of depletion on primary production. Contrary to expectation, the rock character may dominate GCEOR performance. In a subset of this testing, the rock heterogeneity had a more dominant role than fluid properties including miscibility. It appears from this ongoing testing that design of GCEOR projects may be dominated by different parameters from field to field, and possibly well to well. Simulation would provide a good approach in order to bridge the experimental measurements to field design. Experimental GCEOR measurements provide an objective means in order to calibrate the mathematical models in order to forecast field GCEOR upside.

Gas cycling enhanced oil recovery (GCEOR) is under intense investigation. A novel experimental procedure was developed to quantify the parameters that affect GCEOR performance. Porous media, exhibiting in-situ liquid permeability from 200 nD to 2 µD, were evaluated for GCEOR upside. The influence of cycling pressure, injection gas composition, soak time and level of primary depletion before initiation of GCEOR were measured. The innovative experimental design for core-flow testing permitted the quantification of GCEOR using large lab-scale hydrocarbon pore volumes (HCPV). The unique experimental design allowed nano-darcy media to be tested using a time line comparable to conventional millidarcy media. Two dominant flow regimes were incorporated: matrix mass transfer into the fracture and flow within the fracture. Three mechanisms for EOR are described: extraction, swelling, and reduction of interfacial tension. Full reservoir conditions were reproduced and primary depletion followed by huff and puff GCEOR were evaluated, while changing the design parameters listed above. This work was performed on diverse oil and rock properties. More than 30 primary depletion tests followed by GCEOR have been conducted. The effects of cycling pressure, injection gas composition, soak time, level of primary depletion before GCEOR, and other parameters were investigated. Due to large HCPV, good mass balance was maintained and sufficient fluids were produced, as a function of cycle number (huff and puff), in order to be able to measure effluent gas and liquid compositions and densities from each cycle along with the recovery of original oil in place (OOIP). All testing was done in order to quantify the relative benefit of huff and puff GCEOR compared to primary depletion recovery. Results indicate that recovery of OOIP can be more than doubled by implementing GCEOR: cycling pressure should be optimized (highest pressure does not necessarily perform the best); soak time/ huff time may compensate for non-optimal pressure operation; injection-gas composition can impact performance; gas utilization values are low compared to conventional continuous gas injection projects; less depletion before GCEOR initiation can accelerate recovery and can access residual oil that was not produced at higher levels of primary depletion.

This paper presents a hydrocarbon volumetric assessment approach for multiphase reservoirs. The methodology is based upon mass material balance in both gas condensate and wet gas systems and permits for oil/condensate volumetric determination utilizing a novel concept referred to as pseudo formation volume factor (Bo*). This method allows for a continuous oil/condensate volumetric assessment across all four hydrocarbon phases: black oil, volatile oil, gas condensate, and wet gas. A Duvernay field application example is presented. In conventional oil/condensate volumetric methods, a discontinuity is observed at the boundary between undersaturated gas and oil systems when you move across the mapped phases. The discontinuity results from an inconsistent oil/condensate volumetric approach between oil and gas primary phases. Oil/condensate volumetrics is a function of an oil formation volume factor (Bo) in oil systems while, in comparison, a function of a condensate-gas ratio (CGR) in gas systems. This volumetric assessment inconsistency is exemplified in areas of multiple phases, where operators are mapping oil/condensate from wet gas to black oil over a localized area. Realistically, a distinct boundary between in-situ fluid phases does not exist; rather, this change in phase is gradual. The traditional Bo is a volumetric comparison of the live-oil volume to the dead-oil volume of an equivalent unit mass of oil. Evolved gas from the live-oil volume creates the volumetric shrinkage observed within the dead-oil volume. The fundamental basis of the Bo is a mass material balance and can be expressed as a ratio of the dead-oil density to the live-oil density if the mass of evolved gas is accounted for. The Bo* approach applies the same mass material balance concept to the recovered standard condition condensate within the gas-condensate and wet gas system. This condensate shrinkage concept, however, is not based upon the evolved gas from the oil, since the primary phase is gas in the gas-condensate and wet gas systems. In contrast, the Bo* concept is a density comparison of the standard condition condensate recovered at the surface to its associated density in the gas phase at downhole pressure and temperature conditions. The fundamental assumption in the Bo* mass balance solution is ideal gas behavior. The gross live-fluid gas density is corrected to the live-fluid gas density of the standard condition condensate only. This is based upon a liquid component mass balance ratio within the recombined fluid, applied to the gross live-fluid density. The Bo* however, can also be algebraically solved for, which is the recommended approach. Like the traditional Bo, the Bo* is a strong predictive function of the mapped initial gas-oil ratio (GOR). An apparent boundary transition between the Bo and Bo* correlations is observed in the expected 3,200 SCF/STB range of GOR. Both the Bo and the Bo* can also be predictively linked to the hydrocarbon maturity, pressure, and temperature mapping. Hydrocarbon volumetric assessment utilizing the Bo* approach determines oil/condensate volumes by applying a Bo (oil phase) or Bo* (gas phase), correlated to a mapped predictive variable such as GOR. Gas volumes are subsequently a function of the calculated oil/condensate in-place and the mapped GOR. The Bo* approach is volumetrically equivalent to a traditional volumetric approach in gas systems and is based upon fundamental mass balance concepts. The advantage of the Bo* methodology is the ability to consistently and continuously assess oil/condensate volumetrics across contiguous oil and gas phase windows.

Unmanned aerial vehicles, or UAVs, flown for medical resupply missions by the military can bring meaningful benefits to a blood supply network that is large and complex. The authors assess the utility and design of autonomous UAVs — specifically, small fixed-wing aircraft — and search for an optimal fleet design by examining payloads and cost models for two missions: logistical resupply and emergency delivery of blood.

Background Long-lasting insecticidal nets (LLINs) (with pyrethroids) and indoor residual spraying (IRS) are the cornerstones of the Sudanese malaria control program. Insecticide resistance to the principal insecticides in LLINs and IRS is a major concern. This study was designed to monitor insecticide resistance in Anopheles arabiensis from 140 clusters in four malaria-endemic areas of Sudan from 2011 to 2014. All clusters received LLINs, while half (n = 70), distributed across the four regions, had additional IRS campaigns. Methods Anopheles gambiae (s.l.) mosquitoes were identified to species level using PCR techniques. Standard WHO insecticide susceptibility bioassays were carried out to detect resistance to deltamethrin (0.05%), DDT (4%) and bendiocarb (0.1%). TaqMan assays were performed on random samples of deltamethrin-resistant phenotyped and pyrethrum spray collected individuals to determine Vgsc-1014 knockdown resistance mutations. Results Anopheles arabiensis accounted for 99.9% of any anopheline species collected across all sites. Bioassay screening indicated that mosquitoes remained susceptible to bendiocarb but were resistance to deltamethrin and DDT in all areas. There were significant increases in deltamethrin resistance over the four years, with overall mean percent mortality to deltamethrin declining from 81.0% (95% CI: 77.6–84.3%) in 2011 to 47.7% (95% CI: 43.5–51.8%) in 2014. The rate of increase in phenotypic deltamethrin-resistance was significantly slower in the LLIN + IRS arm than in the LLIN-only arm (Odds ratio 1.34; 95% CI: 1.02–1.77). The frequency of Vgsc-1014F mutation varied spatiotemporally with highest frequencies in Galabat (range 0.375–0.616) and New Halfa (range 0.241–0.447). Deltamethrin phenotypic-resistance correlated with Vgsc-1014F frequency. Conclusion Combining LLIN and IRS, with different classes of insecticide, may delay pyrethroid resistance development, but the speed at which resistance develops may be area-specific. Continued monitoring is vital to ensure optimal management and control. Electronic supplementary material The online version of this article (10.1186/s13071-018-2732-9) contains supplementary material, which is available to authorized users.

The Joint military community provides a wide array of medical support services to its personnel, including the transfusion of blood and blood products. Ensuring that blood remains available and safe for transfusion requires sophisticated logistical support, especially for the military community's provision of blood to medical operations around the globe. However, that supply chain may become brittle in future potential operating environments, such as large-scale combat operations where adversaries may contest the U.S. military's freedom of movement. This study describes the elements in the military's current blood supply chain and outlines a framework for assessing its performance. Through that lens, the authors then explore an array of approaches offering promise in improving the resiliency of the blood supply chain, including alternative concepts of operation and technologies. By understanding the mechanisms that underlie blood supply chain resilience, the Joint medical community can be better positioned to tailor a robust portfolio of resiliency investments. Such a portfolio would better ensure the availability and safety of blood and blood products under a wide array of stressors and threats to the system.

Significance Emerging insecticide resistance in malaria vectors could presage a catastrophic rebound in malaria morbidity and mortality. In areas of moderate levels of resistance to pyrethroids, long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) with a carbamate insecticide were significantly more effective than IRS with pyrethroid insecticide. The impact on the effectiveness of LLINs could not be quantified. The incremental cost of using a carbamate insecticide to which vectors are susceptible was US $0.65 per person protected per year, which is considered acceptable by international standards. While the WHO recommends that different interventions, where possible, should use different insecticide classes, these data alone should not be used as the basis for a policy change in vector control interventions., Insecticide-based interventions have contributed to ∼78% of the reduction in the malaria burden in sub-Saharan Africa since 2000. Insecticide resistance in malaria vectors could presage a catastrophic rebound in disease incidence and mortality. A major impediment to the implementation of insecticide resistance management strategies is that evidence of the impact of resistance on malaria disease burden is limited. A cluster randomized trial was conducted in Sudan with pyrethroid-resistant and carbamate-susceptible malaria vectors. Clusters were randomly allocated to receive either long-lasting insecticidal nets (LLINs) alone or LLINs in combination with indoor residual spraying (IRS) with a pyrethroid (deltamethrin) insecticide in the first year and a carbamate (bendiocarb) insecticide in the two subsequent years. Malaria incidence was monitored for 3 y through active case detection in cohorts of children aged 1 to

Insecticide-based interventions have contributed to ∼78% of the reduction in the malaria burden in sub-Saharan Africa since 2000. Insecticide resistance in malaria vectors could presage a catastrophic rebound in disease incidence and mortality. A major impediment to the implementation of insecticide resistance management strategies is that evidence of the impact of resistance on malaria disease burden is limited. A cluster randomized trial was conducted in Sudan with pyrethroid-resistant and carbamate-susceptible malaria vectors. Clusters were randomly allocated to receive either long-lasting insecticidal nets (LLINs) alone or LLINs in combination with indoor residual spraying (IRS) with a pyrethroid (deltamethrin) insecticide in the first year and a carbamate (bendiocarb) insecticide in the two subsequent years. Malaria incidence was monitored for 3 y through active case detection in cohorts of children aged 1 to

Background The cornerstone of current schistosomiasis control programmes is delivery of praziquantel to at-risk populations. Such preventive chemotherapy requires accurate information on the geographic distribution of infection, yet the performance of alternative survey designs for estimating prevalence and converting this into treatment decisions has not been thoroughly evaluated. Methodology/Principal findings We used baseline schistosomiasis mapping surveys from three countries (Malawi, Côte d’Ivoire and Liberia) to generate spatially realistic gold standard datasets, against which we tested alternative two-stage cluster survey designs. We assessed how sampling different numbers of schools per district (2–20) and children per school (10–50) influences the accuracy of prevalence estimates and treatment class assignment, and we compared survey cost-efficiency using data from Malawi. Due to the focal nature of schistosomiasis, up to 53% simulated surveys involving 2–5 schools per district failed to detect schistosomiasis in low endemicity areas (1–10% prevalence). Increasing the number of schools surveyed per district improved treatment class assignment far more than increasing the number of children sampled per school. For Malawi, surveys of 15 schools per district and 20–30 children per school reliably detected endemic schistosomiasis and maximised cost-efficiency. In sensitivity analyses where treatment costs and the country considered were varied, optimal survey size was remarkably consistent, with cost-efficiency maximised at 15–20 schools per district. Conclusions/Significance Among two-stage cluster surveys for schistosomiasis, our simulations indicated that surveying 15–20 schools per district and 20–30 children per school optimised cost-efficiency and minimised the risk of under-treatment, with surveys involving more schools of greater cost-efficiency as treatment costs rose., Author summary Many countries are currently scaling up efforts to control schistosomiasis, a helminthic disease for which preventive chemotherapy with praziquantel is the main control tool. In order to apply WHO guidelines on how frequently to treat a given district or similar geographic unit for schistosomiasis, survey-based estimates of infection prevalence are required. However, the optimal size and design of survey for generating such data is not clear, and there is a clear trade-off between accuracy and cost–larger surveys provide more accurate information with which to target treatment, but cost more to carry out. Here, we systematically assess what size and design of simple 2-stage cluster survey (where primary school children are tested for infection), might best enable control programmes to implement WHO treatment guidelines. We use empirical data on schistosomiasis distribution from three African countries together with computer simulations to compare survey performance, in terms of accuracy and cost-efficiency–the ability of a survey to accurately determine treatment frequency, per unit cost. We show that although small surveys of around 5 schools per district are frequently adopted for mapping schistosomiasis, such small surveys are prone to miss endemic schistosomiasis fairly often, and are also not cost efficient. Our results suggest that among the designs tested, surveys involving 15–20 schools per district optimise cost-efficiency, providing the most accurate treatment decisions per dollar spent. These findings have important implications for the schistosomiasis control community, and provide the first evidence-based suggestion of a simple survey design for mapping schistosomiasis in endemic countries.

It is widely known that the recent Ebola Virus Disease (EVD) in West Africa caused a serious disruption to the national health system, with many of ongoing disease focused programmes, such as mass drug administration (MDA) for onchocerciasis (ONC), lymphatic filariasis (LF) and schistosomiasis (SCH), being suspended or scaled-down. As these MDA programmes attempt to restart post-EVD it is important to understand the challenges that may be encountered. This commentary addresses the opinions of the major health sectors involved, as well as those of community members, regarding logistic needs and challenges faced as these important public health programmes consider restarting. There appears to be a strong desire by the communities to resume NTD programme activities, although it is clear that some important challenges remain, the most prominent being those resulting from the severe loss of trained staff. Electronic supplementary material The online version of this article (doi:10.1186/s40249-017-0272-8) contains supplementary material, which is available to authorized users.

Background Loiasis is a filarial disease caused Loa loa. The main vectors are Chrysops silacea and C. dimidiata which are confined to the tropical rainforests of Central and West Africa. Loiasis is a mild disease, but individuals with high microfilaria loads may suffer from severe adverse events if treated with ivermectin during mass drug administration campaigns for the elimination of lymphatic filariasis and onchocerciasis. This poses significant challenges for elimination programmes and alternative interventions are required in L. loa co-endemic areas. The control of Chrysops has not been considered as a viable cost-effective intervention; we reviewed the current knowledge of Chrysops vectors to assess the potential for control as well as identified areas for future research. Results We identified 89 primary published documents on the two main L. loa vectors C. silacea and C dimidiata. These were collated into a database summarising the publication, field and laboratory procedures, species distributions, ecology, habitats and methods of vector control. The majority of articles were from the 1950–1960s. Field studies conducted in Cameroon, Democratic Republic of Congo, Equatorial Guinea, Nigeria and Sudan highlighted that C. silacea is the most important and widespread vector. This species breeds in muddy streams or swampy areas of forests or plantations, descends from forest canopies to feed on humans during the day, is more readily adapted to human dwellings and attracted to wood fires. Main vector targeted measures proposed to impact on L. loa transmission included personal repellents, household screening, indoor residual spraying, community-based environmental management, adulticiding and larviciding. Conclusions This is the first comprehensive review of the major L. loa vectors for several decades. It highlights key vector transmission characteristics that may be targeted for vector control providing insights into the potential for integrated vector management, with multiple diseases being targeted simultaneously, with shared human and financial resources and multiple impact. Integrated vector management programmes for filarial infections, especially in low transmission areas of onchocerciasis, require innovative approaches and alternative strategies if the elimination targets established by the World Health Organization are to be achieved. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2103-y) contains supplementary material, which is available to authorized users.

Free-ranging Red-eared Sliders (Trachemys scripta elegans) were captured from farm ponds located in the Flint Hills of Kansas and a zoo pond in Emporia, Kansas, USA, to evaluate their enteric bacterial flora and associated antibiotic resistance. Bacteria obtained from cloacal swabs were composed of six different Gram-negative genera. Although antibiotic resistance was present in turtles captured from both locations, 40 and 49% of bacteria demonstrated multiple antibiotic resistance to four of the antibiotics tested from the zoo captured and Flint Hills ponds turtles, respectively. These data illustrate environmental antibiotic resistance is widespread in the bacterial flora obtained from Red-eared Sliders in east central Kansas.

Ponds are common in many agricultural landscapes and provide aquatic habitat for wildlife. Most studies of semi-aquatic turtle assemblages have been conducted in lotic environments or large lentic habitats (e.g., lakes, reservoirs), but few studies have described pond communities. We used Frame nets and basking traps to sample turtle assemblages within eight ponds located in east-central Kansas (Lyon Co.) from 15 May 2007 – 1 October 2007. Our objective was to describe selected aspects of the semi-aquatic turtle assemblages in these ponds: species richness, relative abundance, catch per unit effort, and density. A total of 655 unique individuals were captured and four species were detected (Chrysemys picta bellii, N = 387; Trachemys scripta elegans, N= 188; Chelydra serpentina, N = 79; Pseudemys concinna, N = 1). Chrysemys picta bellii was usually the most abundant species, with T. s. elegans and C. serpentina ranked second and third, respectively. Likewise, catch per unit effort (an index of abundance) w...

The general paradigm associated with overland movements of semi-aquatic turtles between aquatic habitats predicts that males move more frequently and for greater distances than females and juveniles, and that larger individuals move more frequently than smaller individuals. We used capture-mark-recapture techniques to examine interpond movement patterns of western painted turtles (Chrysemys picta) among a complex of eight ponds in east-central Kansas in 2007. We assessed the broad applicability of predictions of the general paradigm by testing the following hypotheses: 1) males make interpond movements more frequently than females, 2) larger adult-sized individuals make interpond movements more frequently than juveniles, 3) propensity for pond-to-pond movement varies as a function of size within categories (i.e., males, females, and juveniles), and 4) mean minimum distance traveled between ponds is greatest for males. The proportion of males that moved between ponds was not significantly different from that of females, and we did not observe a significant difference in proportion of adults and juveniles categorized as movers. Mean length of plastron of individuals classified as movers and non-movers was not significantly different within either females or juveniles. Males categorized as non-movers were significantly larger than those that made interpond movements. Mean minimum distance traveled between ponds was not significantly different among males, females, and juveniles. Thus, our results were not consistent with any of the predictions of the general paradigm. Costs and benefits associated with overland movements of turtles are likely to vary both spatially and temporally. We suggest that as cost-benefit ratios vary, so should predictions about the propensity for interpond movements among turtles of different sexes, sizes, and ontogenetic stages.

Cytochrome c oxidase is the terminal electron acceptor in the electron transport chain in many aerobic organisms. This multi-protein complex can be composed of a varying number of subunits depending on species. In the budding yeast, Saccharomyces cerevisiae, cytochrome c oxidase is made up of 11 subunits, 8 are derived from the nuclear genome and 3 are derived from the mitochondrial genome. To ensure these subunits come together at the correct time and place a family of assembly factors is required. In the case of the mitochondrial DNA encoded subunit 1 there is a linear pathway of biosynthesis where these assembly factors and other structural subunits associate at specific times to regulate specific maturation events. In the absence of some assembly factors subunit 1 is subject to degradation by the protease Oma1p. In yeast, this results in a deficiency in cytochrome c oxidase activity and the inability to grow using substrates requiring intact oxidative phosphorylation. We have performed a mutagenic screen of mitochondrial DNA to identify mutations in the subunit 1 gene that can suppress the oxidative phosphorylation deficient phenotype caused by the absence of the assembly factors, COA2 and SHY1. Through analysis of the COX1 gene we will identify putative regions required for the proteolytic processing of subunit 1 by the Oma1p protease. The information gathered from this research will guide us in identifying putative regions required for cytochrome c oxidase subunit 1 degradation and also provide more information regarding the proteolytic requirements of the Oma1p protease.

Background The prevalence of Wuchereria bancrofti, which causes lymphatic filariasis (LF) in The Gambia was among the highest in Africa in the 1950s. However, surveys conducted in 1975 and 1976 revealed a dramatic decline in LF endemicity in the absence of mass drug administration (MDA). The decline in prevalence was partly attributed to a significant reduction in mosquito density through the widespread use of insecticidal nets. Based on findings elsewhere that vector control alone can interrupt LF, we asked the question in 2013 whether the rapid scale up in the use of insecticidal nets in The Gambia had interrupted LF transmission. Methodology/Principal Finding We present here the results of three independently designed filariasis surveys conducted over a period of 17 years (1997–2013), and involving over 6000 subjects in 21 districts across all administrative divisions in The Gambia. An immunochromatographic (ICT) test was used to detect W. bancrofti antigen during all three surveys. In 2001, tests performed on stored samples collected between 1997 and 2000, in three divisions, failed to show positive individuals from two divisions that were previously highly endemic for LF, suggesting a decline towards extinction in some areas. Results of the second survey conducted in 2003 showed that LF was no longer endemic in 16 of 21 districts surveyed. The 2013 survey used a WHO recommended LF transmission verification tool involving 3180 6–7 year-olds attending 60 schools across the country. We demonstrated that transmission of W. bancrofti has been interrupted in all 21 districts. Conclusions We conclude that LF transmission may have been interrupted in The Gambia through the extensive use of insecticidal nets for malaria control for decades. The growing evidence for the impact of malaria vector control activities on parasite transmission has been endorsed by WHO through a position statement in 2011 on integrated vector management to control malaria and LF., Author Summary The prevalence of lymphatic filariasis (LF), in The Gambia was among the highest in Africa in the 1950s when about 50% of the adult population was positive for microfilaraemia. However, surveys conducted in 1975 and 1976 revealed a dramatic decline in LF endemicity in the absence of systematic treatment with anti-filaria medicines. This decline in LF prevalence in all villages was partly attributed to a significant drop in human-mosquito contact through a sustained reduction in rainfall in the 1960s and 1970s and the widespread use of insecticidal nets to protect against malaria. We asked the question in 2013 whether the rapid scale up in the use of insecticidal nets for malaria control in Gambia had resulted in the interruption of LF transmission. In this paper we present the results of three independently designed filariasis surveys conducted over a period of 17 years (1997–2013), and involving over 6000 subjects in 21 districts across all administrative divisions in the country. In 2001, tests performed to detect circulating filarial antigens (CFA) in serum samples collected between 1997 and 2000, in three divisions, failed to show positive individuals from two that were previously highly endemic for the LF. Results of the second survey conducted in 2003 indicated that five of the 21 districts were slightly endemic for LF with CFA rates of 1% or 2% but MDA was never implemented in The Gambia. The results of our final survey conducted in 2013 were unequivocal in confirming the absence of transmission of LF in all 21 districts surveyed using WHO recommended statistically robust and validated tool known as transmission assessment survey (TAS). The Gambia achieving a non-endemic status for LF represents a significant step in the efforts to shrink the filariasis endemicity map and demonstrates the value of cross sector approaches in disease control.