Wastewater-based epidemiology as a public health resource in low- and middle-income settings.

In the face of emerging and re-emerging diseases, novel and innovative approaches to population scale surveillance are necessary for the early detection and quantification of pathogens. The last decade has seen the rapid development of wastewater and environmental surveillance (WES) to address public health challenges, which has led to establishment of wastewater-based epidemiology (WBE) approaches being deployed to monitor a range of health hazards. WBE exploits the fact that excretions and secretions from urine, and from the gut are discharged in wastewater, particularly sewage, such that sampling sewage systems provides an early warning system for disease outbreaks by providing an early indication of pathogen circulation. While WBE has been mainly used in locations with networked wastewater systems, here we consider its value for less connected populations typical of lower-income settings, and in assess the opportunity afforded by pit latrines to sample communities and localities. We propose that where populations struggle to access health and diagnostic facilities, and despite several additional challenges, sampling unconnected wastewater systems remains an important means to monitor the health of large populations in a relatively cost-effective manner.

Traditional health practitioners and sustainable development: a case study in South Africa.

OBJECTIVES: To highlight legal and regulatory advances relating to South African traditional health practitioners (THPs) over the past 10 years and discuss the implications for the translation of health policies into guidelines for sustainable practice supporting public health. STUDY DESIGN: This is a rapid, structured literature review. METHODS: A rapid, structured literature review was undertaken to identify relevant studies related to South African THPs involving a search of peer-reviewed literature from three databases and a grey literature internet search. The identified citations were screened, critically appraised, and narratively synthesized. RESULTS: Efforts to regulate THPs in South Africa are underway; however, the lack of a regulatory framework for traditional practices is hampering progress. Several efforts to collaborate with THPs have been made over the years, many of which were not systematically evaluated and not based on principles of mutual respect. Existing collaborative examples need to be further supported by cost-effective evidence to suit the South African public health budget. Furthermore, small collaborative research efforts do not take into consideration the scale up of interventions. CONCLUSIONS: THPs in South Africa represent an important healthcare resource. However, the current policy environment does not support indicators to describe, monitor, and/or evaluate the role of THPs in the healthcare system.

Ethnopharmacological use of potassium permanganate in South African traditional medicine.

BACKGROUND: Potassium permanganate (KMnO4), which is widely available, is often used by traditional health practitioners (THPs) in South Africa (SA) without taking its potentially harmful properties into account. The crystalline KMnO4 salt is sold at traditional medicine markets and shops throughout SA. However, to date, traditional uses of KMnO4 remain undocumented. OBJECTIVE: To describe KMnO4 use by THPs in KwaZulu-Natal, SA. METHODS: This sub-study is part of a larger study investigating substances used in SA traditional medicine that are collectively known as imikhando in isiZulu - literally translated as 'ore'. THPs (N=201) were interviewed in the local language (isiZulu) by trained interviewers. Information on the reasons for using/not using KMnO4, the source of information on its use and modes of administration were collected. RESULTS: KMnO4 was used as a constituent of traditional medicine by 158 (79%) THPs. Their knowledge of KMnO4 use was acquired predominantly from fellow THPs (n=134; 85%). Reasons for use included skin rash or wounds (n=99, 63%) and to treat aches, pains and swelling (n=74; 47%). The main modes of administration were in the bath (n=94; 60%), orally (n=67; 42%) and in herbal compresses (n=66; 42%). The principal reason of the 43 THPs for not administering KMnO4 was not knowing how to use it (n=29; 71%). CONCLUSIONS: This study has identified traditional medicine users at risk of manganese toxicity owing to commonly used sociocultural practices. In particular, reports of oral ingestion and use in enemas are cause for concern. This public health issue needs regulatory measures and education programmes to enlighten the population against possible harm caused by KMnO4 exposure.

Bibliometric trends of South African environmental health articles between 1998 and 2015: Making local research visible and retrievable.

BACKGROUND: South Africa (SA) has to grapple with multiple burdens of disease for which environmental factors have a role to play in both causation and prevention. This article describes a bibliometric review of environmental health indexed literature for SA over an 18-year period. OBJECTIVES: To provide an overview of the nature of SA-based published environmental health indexed research and to identify search challenges, frequently researched topics, and gaps and opportunities for future research. METHODS: The Web of Science, PubMed and Science Direct were used to search for original, peer-reviewed and review articles with the inclusion criteria 'environmental health' and 'South Africa' available online and published between 1998 and 2015, inclusively. RESULTS: A total of 230 journal articles were included in the bibliometric analysis. The highest number of articles (n=54) was published in 2015. The majority of the first authors were affiliated with SA institutions (n=160, 69.5%). For the articles where funding was explicitly declared (n=148), the three most frequently occurring agencies that funded the published research were the National Research Foundation in SA (n=17), the South African Medical Research Council (n=13) and the Water Research Commission (n=9). There was little inter-annual/environmental health category variation over time owing to the relatively small sample size. The largest number of retrieved journal articles was in the area of environmental pollution control (n=76), followed by environmental health lifestyle and behaviour-related topics (n=42) and then water monitoring (n=26). CONCLUSIONS: Despite the research needed to solve large environmental health challenges in SA, environmental health was only used as a keyword in title, author keywords or abstract for 230 SA-based studies over an 18-year period. This makes it extremely difficult for environmental health research to be located and used to inform the profession as well as the research agenda. Several issues that environmental health practitioners are typically tasked to implement and monitor are not indexed as environmental health topics. The need for authors to use 'environmental health' as a keyword is emphasised, particularly if research is to inform decision-making and policy support, as well as guide future research in the country.

Commonly used metal and crystalline salts in South African traditional medicine.

ETHNOPHARMACOLOGICAL RELEVANCE: Traditional medicines in the form of plants, animals and/or minerals are used by millions of South Africans. There is currently no data regarding the commonly used mineral elements thus the potential benefits or hazards of such products remain unclear. MATERIALS AND METHODS: Metal and crystalline salts were purchased from a rural market (Nongoma, Zululand, South Africa). Information regarding the colloquial name, price and weight was recorded. Energy dispersive X-ray spectroscopy (EDX) was used to quantatively determine the unknown salts. RESULTS: Six widely available salts were analyzed. Ndonya, as it is colloquially known, refers to two products which look identical to the untrained eye-one is dyed table salt and the other is hexavalent chromium. A further product used medicinally, although not widely available, was identified as iron chromite ore. CONCLUSIONS: The array of substances documented, ranging from benign to carcinogenic, stresses the importance of documenting components used in traditional medicine and confirms the necessity to regulate South Africa traditional medicine. Healthcare workers should be aware of the complexities of using such metal salt.

South African traditional medicinal plant trade-Challenges in regulating quality, safety and efficacy.

Based on the long history of medicinal plant use, users of traditional medicines accept that they are safe for human consumption. However, the absence of regulation of the medicinal plant trade in aspects such as collection, processing and storage provides no such guarantee. Environmental pollution, misidentification and adulteration provides further grounds for concern. The potential adverse effects of South African traditional medicines are not well documented. There are only a few investigations of mutagenic properties and heavy metal contamination. In the absence of regulatory controls, the safety and quality of medicinal plants vary considerably. The current comprehension and future challenges regarding quality, safety and efficacy of South African traditional medicine are discussed.

Variation in heavy metals and microelements in South African medicinal plants obtained from street markets.

South African medicinal plants are traditionally harvested from a wide range of undisclosed locations by plant gatherers. Thus, there is a risk that plant material may be exposed to a variety of pollutants. The variation in five heavy metals (arsenic, cadmium, cobalt, nickel, and lead) and six essential elements (boron, copper, iron, manganese, molybdenum, and zinc) was determined in commonly used South African medicinal plants obtained from street markets. Elemental content was determined using inductively coupled plasma optical emission spectrophotometry. The reliability of the procedure was ensured by analysing a certified reference material. Medicinal plant samples contained arsenic and cadmium at levels exceeding the World Health Organization limits of 1 and 0.3 mg kg(-1) respectively. Lead and nickel were detected in all samples. Elevated iron and manganese levels were recorded in certain plant species. Multiple metal contamination of parts of medicinal plants gives grounds for concern. This study emphasizes the unsafe consequences of the South African practice of collecting medicinal plants from undisclosed locations and making these readily available to the public.

Fabrication of high aspect-ratio polymer microstructures for large-area electronic portal x-ray imagers.

Megavoltage x-ray imaging performed during radiotherapy is the method of choice for geometric verification of patient localization and dose delivery. Presently, such imaging is increasingly performed using electronic portal imaging devices (EPIDs) based on indirect detection active matrix flat panel imagers (AMFPIs). These devices use a scintillating phosphor screen in order to convert incident x-rays into optical photons, which are then detected by the underlying active matrix photodiode array. The use of a continuous phosphor introduces a trade-off between x-ray quantum efficiency and spatial resolution, which limits current devices to use only ∼2% of the incident x-rays. This trade-off can be circumvented by "segmented phosphor screens", comprising a two-dimensional matrix of optically-isolated cell structures filled with scintillating phosphor. In this work we describe the fabrication of millimeter-thick segmented phosphor screens using the MEMS (micro-electro-mechanical-system) polymer SU-8. This method is capable of being extended to large-area substrates.

Toxicity of metal elements on germination and seedling growth of widely used medicinal plants belonging to Hyacinthaceae.

In South Africa, pollution of agricultural soils is on the increase primarily due to excessive application of fertilizers, sewage disposal and mining activities. This study was done to determine the effect of trace elements (Cu, Zn) and heavy metals (Cd, Pb, Hg) on germination and seedling development of Bowiea volubilis, Eucomis autumnalis and Merwilla natalensis. These medicinal plant species are highly recommended for cultivation in South Africa to reduce the pressure on wild populations. Copper and Zn at 1 mg L(-1) significantly (p < 0.05) reduced the percentage germination of E. autumnalis. Low concentrations (>or=1 mg L(-1)) of Cu and Zn negatively affected the roots of all three species. Mercury concentrations of 0.5 and 1 mg L(-1) significantly (p < 0.05) decreased the percentage germination of B. volubilis and E. autumnalis respectively. Cadmium and Hg at 2 mg L(-1) showed a detrimental effect on the root growth of B. volubilis. Concentrations of 0.5 mg L(-1) of all heavy metals tested significantly (p < 0.05) decreased shoot length of M. natalensis.

Microfluidic genetic analysis with an integrated a-Si:H detector.

We have developed an integrated hydrogenated amorphous silicon (a-Si:H) fluorescence detector for microfluidic genetic analysis. It consists of a half-ball lens, a ZnS/YF3 multilayer optical interference filter with a pinhole, and an annular a-Si:H PIN photodiode allowing the laser excitation to pass up through the central aperture in the photodiode and the filter. Microfluidic separations of multiplex PCR products generated from methicillin-resistant/sensitive Staphylococcus aureus (MRSA/MSSA) DNA on microfluidic capillary electrophoresis (CE) devices are successfully detected with the integrated detector. Similarly, multiplex PCR amplicons from the kanamycin resistant and K12 serotype-specific genes of E. coli cells are detected. The direct detection of multiplex PCR amplicons indicates that the fluorescence detector can be successfully coupled with current microfluidic PCR-CE platforms. This work establishes that the integrated a-Si:H detector provides relevant limits of detection for point-of-care genetic and pathogen analysis with microfluidic devices.

Strategies to improve the signal and noise performance of active matrix, flat-panel imagers for diagnostic x-ray applications.

A theoretical investigation of factors limiting the detective quantum efficiency (DQE) of active matrix flat-panel imagers (AMFPIs), and of methods to overcome these limitations, is reported. At the higher exposure levels associated with radiography, the present generation of AMFPIs is capable of exhibiting DQE performance equivalent, or superior, to that of existing film-screen and computed radiography systems. However, at exposure levels commonly encountered in fluoroscopy, AMFPIs exhibit significantly reduced DQE and this problem is accentuated at higher spatial frequencies. The problem applies both to AMFPIs that rely on indirect detection as well as direct detection of the incident radiation. This reduced performance derives from the relatively large magnitude of the square of the total additive noise compared to the system gain for existing AMFPIs. In order to circumvent these restrictions, a variety of strategies to decrease additive noise and enhance system gain are proposed. Additive noise could be reduced through improved preamplifier, pixel and array design, including the incorporation of compensation lines to sample external line noise. System gain could be enhanced through the use of continuous photodiodes, pixel amplifiers, or higher gain x-ray converters such as lead iodide. The feasibility of these and other strategies is discussed and potential improvements to DQE performance are quantified through a theoretical investigation of a variety of hypothetical 200 microm pitch designs. At low exposures, such improvements could greatly increase the magnitude of the low spatial frequency component of the DQE, rendering it practically independent of exposure while simultaneously reducing the falloff in DQE at higher spatial frequencies. Furthermore, such noise reduction and gain enhancement could lead to the development of AMFPIs with high DQE performance which are capable of providing both high resolution radiographic images, at approximately 100 microm pixel resolution, as well as variable resolution fluoroscopic images at 30 fps.

Empirical investigation of the signal performance of a high-resolution, indirect detection, active matrix flat-panel imager (AMFPI) for fluoroscopic and radiographic operation.

Signal properties of the first large-area, high resolution, active matrix, flat-panel imager are reported. The imager is based on an array of 1536 x 1920 pixels with a pixel-to-pixel pitch of 127 microns. Each pixel consists of a discrete amorphous silicon n-i-p photodiode coupled to an amorphous silicon thin-film transistor. The imager detects incident x rays indirectly by means of an intensifying screen placed over the array. External acquisition electronics send control signals to the array and process analog imaging signals from the pixels. Considerations for operation of the imager in both fluoroscopic and radiographic modes are detailed and empirical signal performance data are presented with an emphasis on exploring similarities and differences between the two modes. Measurements which characterize the performance of the imager were performed as a function of operational parameters in the absence or presence of illumination from a light-emitting diode or x rays. These measurements include characterization of the drift and magnitude of the pixel dark signal, the size of the pixel switching transient, the temporal behavior of pixel sampling and the implied maximum frame rate, the dependence of relative pixel efficiency and pixel response on photodiode reverse bias voltage and operational mode, the degree of linearity of pixel response, and the trapping and release of charge from metastable states in the photodiodes. In addition, X-ray sensitivity as a function of energy for a variety of phosphor screens for both fluoroscopic and radiographic operation is reported. Example images of a line-pair pattern and an anthropomorphic phantom in each mode are presented along with a radiographic image of a human hand. General and specific improvements in imager design are described and anticipated developments are discussed. This represents the first systematic investigation of the operation and properties in both radiographic and fluoroscopic modes of an imager incorporating such an array.

Demonstration of megavoltage and diagnostic x-ray imaging with hydrogenated amorphous silicon arrays.

Flat-panel imagers consisting of the first large area, self-scanning, pixelated, solid-state arrays made with hydrogenated amorphous silicon (a-Si:H) are under development by the authors for applications in diagnostic x-ray and megavoltage radiotherapy imaging. The arrays, designated by the acronym MASDA for multi-element amorphous silicon detector array, consist of a two-dimensional array of a-Si:H photodiodes and thin-film transistors and are used in conjunction with scintillating materials. Imagers utilizing MASDA arrays offer a variety of advantages over existing technologies. This article presents initial megavoltage and diagnostic-quality x-ray images taken with several such arrays including the first examples of anatomical-phantom images. The external readout electronics and imaging techniques required to obtain such images are outlined, the construction, operation, and advantages of the arrays briefly reviewed, and the future potential of this new technology discussed.