AeDES: a next-generation monitoring and forecasting system for environmental suitability of Aedes-borne disease transmission.

Aedes-borne diseases, such as dengue and chikungunya, are responsible for more than 50 million infections worldwide every year, with an overall increase of 30-fold in the last 50 years, mainly due to city population growth, more frequent travels and ecological changes. In the United States of America, the vast majority of Aedes-borne infections are imported from endemic regions by travelers, who can become new sources of mosquito infection upon their return home if the exposed population is susceptible to the disease, and if suitable environmental conditions for the mosquitoes and the virus are present. Since the susceptibility of the human population can be determined via periodic monitoring campaigns, the environmental suitability for the presence of mosquitoes and viruses becomes one of the most important pieces of information for decision makers in the health sector. We present a next-generation monitoring and forecasting system for [Formula: see text]-borne diseases' environmental suitability (AeDES) of transmission in the conterminous United States and transboundary regions, using calibrated ento-epidemiological models, climate models and temperature observations. After analyzing the seasonal predictive skill of AeDES, we briefly consider the recent Zika epidemic, and the compound effects of the current Central American dengue outbreak happening during the SARS-CoV-2 pandemic, to illustrate how a combination of tailored deterministic and probabilistic forecasts can inform key prevention and control strategies .

Radiotherapy-induced xerostomia: a randomised, double-blind, controlled trial of Visco-ease™ oral spray compared with placebo in patients with cancer of the head and neck.

Radiotherapy-induced xerostomia (RIX) is a common and untreatable side effect of radiotherapy to the head and neck. Visco-ease™ mouth spray (Lamellar Biomedical Ltd), a new product that is made from lamellar body mimetics, reduces the viscosity of saliva ex vivo. The purpose of this study was to evaluate its safety and effectiveness in the treatment of RIX in 43 patients with cancer of the head and neck. They were randomised into the Visco-ease™ or placebo groups, and asked to complete the Groningen radiotherapy-induced xerostomia (GRIX) questionnaire each week. The primary endpoint was a change in GRIX score from baseline to end of treatment. There was no difference in scores between the two groups, and none of the patients had device-related serious adverse events. Visco-ease™ oral spray was safe and tolerable but no better than placebo in reducing RIX in this group of patients.

Indwelling pleural catheters: an overview and real-life experience.

BACKGROUND: Indwelling pleural catheters (IPCs) are most frequently used in those with malignant pleural effusions, although their use is expanding to patients with non-malignant diseases. AIM: To provide an overview of IPCs and highlight how, when and why they can be used including our own real-life experience. DESIGN: Data were collected retrospectively from a large tertiary centre for all individuals who received an IPC between June 2010 and February 2018 inclusive. The data collected included gender, age, origin of malignancy, number of drains prior to IPC, whether they had received pleurodesis prior to IPC, presence of a trapped lung, date of insertion, documented complications, overall outcome and date of death. RESULTS: A total of 68 patients received an IPC, the majority were female (n = 38, 57%) with an overall median age of 68 years (range 40-90 years). The most common site of cancer origin was lung (n = 33, 49%) followed by pleura (n = 10, 15%) and breast (n = 9, 13%). The median survival of all patients was 141 days (IQR 26-181). Sixteen percent (n = 11) of patients underwent a spontaneous pleurodesis resulting in their IPC being removed. Only three individuals had a complication (4.4%). CONCLUSIONS: IPC insertion is a safe procedure and represents an exciting and expanding field in the management of pleural disease. Further longitudinal studies are required to fully delineate their place in the management of both malignant and benign effusions.

Effect of reactive vaccination on meningitis epidemics in Southern Ethiopia.

OBJECTIVES: To describe the duration and seasonality of meningitis epidemics in Southern Ethiopia and estimate the proportion of cases prevented by vaccination in order to assess the efficacy of current control strategies. METHODS: A descriptive study of epidemics occurring from 1999 to 2004. The number of cases reported in 24 districts undergoing vaccination campaigns was compared to 36 districts not receiving vaccines or where vaccines had been deployed in the zone. RESULTS: Sixty epidemics reporting a total of 5806 cases were identified. The duration of the epidemics ranged from 1 to 26 weeks with 45% lasting < or = 6 weeks. Forty-one epidemics reached the WHO epidemic threshold. Seventy-one percent of the cases reported from vaccinated areas occurred in the first 6 weeks compared to 62% in unvaccinated areas and 82% for districts where vaccines had been used in the zone. CONCLUSIONS: The majority of epidemics had a short duration limiting the potential to implement current vaccines effectively. Delivering vaccine to areas adjacent to an epidemic seems to increase their efficacy, however the size of this additional area needs to be better defined.

Spatial modelling and the prediction of Loa loa risk: decision making under uncertainty.

Health decision-makers working in Africa often need to act for millions of people over large geographical areas on little and uncertain information. Spatial statistical modelling and Bayesian inference have now been used to quantify the uncertainty in the predictions of a regional, environmental risk map for Loa loa (a map that is currently being used as an essential decision tool by the African Programme for Onchocerciasis Control). The methodology allows the expression of the probability that, given the data, a particular location does or does not exceed a predefined high-risk threshold for which a change in strategy for the delivery of the antihelmintic ivermectin is required.

A model to simulate the impact of timing, coverage and transmission intensity on the effectiveness of indoor residual spraying (IRS) for malaria control.

OBJECTIVE: (i) To develop a temperature- and rainfall-driven model of malaria transmission capable of prediction. (ii) To use the model to examine the relationship between the intervention timing and transmission intensity on the effectiveness of indoor residual spraying (IRS). METHODS: A dynamic model of malaria transmission was developed from existing models of malaria transmission dynamics. The model was used to retrospectively predict actual malaria cases from Hwange district in Zimbabwe using actual meteorological and IRS timing and coverage data. Simulations of alternative intervention scenarios (timing and coverage) examined the effectiveness of earlier and later interventions, at higher and lower coverage levels in epidemic and non-epidemic years. FINDINGS: The model was able to predict actual malaria cases in Hwange over a four-and-a-half-year period with a lead time of 4 months (e.g. January rainfall and temperature predicts April malaria) and a correlation coefficient of 0.825 (r(2) = 0.6814). The IRS simulations show that the marginal benefits of increasing IRS coverage are higher in high-transmission (HT) years relative to lower transmission years. This implies that over a period of years, maximum impact could be achieved with a given quantity of insecticide by increasing coverage in HT years. However, the model also shows that earlier spraying is more effective in all years, especially so in epidemic years, and that IRS has limited impact if it is carried out too late in relation to peak transmission. CONCLUSION: Temperature- and rainfall-driven models of malaria transmission have the potential to predict malaria epidemics. Early intervention based on prior knowledge of the magnitude of the malaria season can be more effective and efficient than carrying out routine activities every year. Malaria control planners need improved access to the technology that would allow them to better predict malaria epidemics and develop Malaria Early Warning Systems (MEWS). MEWS can then be linked to intervention planning to reduce the devastating impact of malaria epidemics on populations.

Evaluation of the meningitis epidemics risk model in Africa.

Meningitis epidemics have a strong environmental component in Africa with the most severe epidemics occurring in the Sahelian region known as the Meningitis Belt. The objective of this study is to evaluate an ecological model based on absolute humidity and land cover type to predict the location of these epidemics. The risk model is evaluated prospectively based on epidemics occurring in Africa from January 2000 to April 2004. Seventy-one epidemics occurred during this time period affecting 22% of continental African districts. The model predicted their location with a sensitivity of 88%. The evaluation also suggests that epidemics may be extending south of the Sahel, which is consistent with environmental changes in the region. This model could be used to select priority areas for the introduction of the newly developed conjugate meningococcal vaccines. Further studies are needed to enhance our understanding of the complex relationship between meningitis epidemics and the environment.

Malaria early warnings based on seasonal climate forecasts from multi-model ensembles.

The control of epidemic malaria is a priority for the international health community and specific targets for the early detection and effective control of epidemics have been agreed. Interannual climate variability is an important determinant of epidemics in parts of Africa where climate drives both mosquito vector dynamics and parasite development rates. Hence, skilful seasonal climate forecasts may provide early warning of changes of risk in epidemic-prone regions. Here we discuss the development of a system to forecast probabilities of anomalously high and low malaria incidence with dynamically based, seasonal-timescale, multi-model ensemble predictions of climate, using leading global coupled ocean-atmosphere climate models developed in Europe. This forecast system is successfully applied to the prediction of malaria risk in Botswana, where links between malaria and climate variability are well established, adding up to four months lead time over malaria warnings issued with observed precipitation and having a comparably high level of probabilistic prediction skill. In years in which the forecast probability distribution is different from that of climatology, malaria decision-makers can use this information for improved resource allocation.

Application of Geographical Information Systems and Remote Sensing technologies for assessing and monitoring malaria risk.

Despite over 30 years of scientific research, algorithm development and multitudes of publications relating Remote Sensing (RS) information with the spatial and temporal distribution of malaria, it is only in recent years that operational products have been adopted by malaria control decision-makers. The time is ripe for the wealth of research knowledge and products from developed countries be made available to the decision-makers in malarious regions of the globe where this information is urgently needed. This paper reviews the capability of RS to provide useful information for operational malaria early warning systems. It also reviews the requirements for monitoring the major components influencing emergence of malaria and provides examples of applications that have been made. Discussion of the issues that have impeded implementation on a global scale and how those barriers are disappearing with recent economic, technological and political developments are explored; and help pave the way for implementation of an integrated Malaria Early Warning System framework using RS technologies.

The use of spatial analysis in mapping the distribution of bancroftian filariasis in four West African countries.

The geographical distribution of human infection with Wuchereria bancrofti was investigated in four West African countries (Benin, Burkina Faso, Ghana and Togo), using a commercial immunochromatographic test for filarial antigen. Efforts were made to cover each health-system implementation unit and to ensure no sampling point was >50 km from another, but otherwise the 401 study communities were selected at random. The aim was to enable spatial analysis of the data, to provide a prediction of the overall spatial relationships of the infection. The results, which were subjected to an independent random validation in Burkina Faso and Ghana, revealed that prevalence in the adult population of some communities exceeded 70% and that, over large areas of Burkina Faso, community prevalences were between 30% and 50%. Most of Togo, southern Benin and much of southern Ghana appeared completely free of the infection. Although there were foci on the Ghanaian coast with prevalences of 10%-30%, such high prevalences did not extend into coastal Togo or costal Benin. The prevalence map produced should be useful in prioritizing areas for filariasis control, identifying potential overlap with ivermectin-distribution activities undertaken by onchocerciasis-control programmes, and enabling inter-country and sub-regional planning to be initiated. The results indicate that bancroftian filariasis is more widely distributed in arid areas of Burkina Faso than hitherto recognized and that the prevalences of infection have remained fairly stable for at least 30 years. The campaign to eliminate lymphatic filariasis as a public-health problem in Africa will require significantly more resources (human, financial, and logistic) than previously anticipated.

The development of Malaria Early Warning Systems for Africa.

Current efforts to predict malaria epidemics focus on the role weather anomalies can play in epidemic prediction. Alongside weather monitoring and seasonal climate forecasts, epidemiological, social and environmental factors can also play a role in predicting the timing and severity of malaria epidemics. Such factors can be incorporated into a framework for malaria early warning.

Environmental information systems for the control of arthropod vectors of disease.

Over the last decade, remote sensing technologies and geographical information systems have moved from the research arena into the hands of vector control specialists. This review explains remote sensing approaches and spatial information technologies used for investigations of arthropod pests and vectors of diseases affecting humans and livestock. Relevant applications are summarized with examples of studies on African horse sickness vector Culicoides midges (Diptera: Ceratopogonidae), malaria vector Anopheles and arbovirus vector culicine mosquitoes (Diptera: Culicidae), leishmaniasis vector Phlebotomus sandflies (Diptera: Psychodidae), trypanosomiasis vector tsetse (Diptera: Glossinidae), loaiasis vector Chrysops (Diptera: Tabanidae), Lyme disease vector Ixodes and other ticks (Acari: Ixodidae). Methods and their uses are tabulated and discussed with recommendations for efficiency, caution and progress in this burgeoning field.

Satellite mapping of Loa loa prevalence in relation to ivermectin use in west and central Africa.

For many years, ivermectin has been widely distributed throughout west Africa for the safe and effective control of onchocerclasis. However, recent events in Loa-loa-endemic areas of Cameroon, where severe adverse reactions have occurred, now constrain the public-health use of this drug in the forest habitat of the L. loa vector. We have created a model of L. loa prevalence to identify areas where high endemicity may be associated with the occurrence of such reactions. The model results have been mapped and the areas of overlap between high L. loa prevalence and planned ivermectin distribution for onchocerciasis control identified.

Predicting malaria infection in Gambian children from satellite data and bed net use surveys: the importance of spatial correlation in the interpretation of results.

In line with the renewed World Health Organization Global Malaria Control Strategy, we have advocated the use of satellite imagery by control services to provide environmental information for malaria stratification, monitoring, and early warning. To achieve this operationally, appropriate methodologies must be developed for integrating environmental and epidemiologic data into models that can be used by decision-makers for improved resource allocation. Using methodologies developed for the Famine Early Warning Systems and spatial statistics, we show a significant association between age related malaria infection in Gambian children and the amount of seasonal environmental greenness as measured using the normalized difference vegetation index derived from satellite data. The resulting model is used to predict changes in malaria prevalence rates in children resulting from different bed net control scenarios.

Towards a kala azar risk map for Sudan: mapping the potential distribution of Phlebotomus orientalis using digital data of environmental variables.

The need to define the geographical distribution of Phlebotomus orientalis results from its importance as the dominant vector of kala azar (visceral Iceishmaniasis) in Sudan. Recent epidermics of this disease in southern and eastern Sudan caused an estimated 100000 deaths and have renewed the impetus for defining the ecological boundaries of the vector. This information is an essential prerequisite to the production of a risk map for kala azar. This study uses data on the presence and absence of P. orientalis from 44 collecting sites across the central belt of Sudan. A logistic regression model was used to estimate the probability of the presence of P. orientalis at each collecting site as a function of climatic and environmental variables (rainfall; temperature; altitude; soil type and the satellite-derived environmental proxies - Normalized Difference Vegetation Index and Land Surface Temperature). The logistic regression model indicates mean annual maximum daily temperature and soil type as the most important ecological determinants of P. orientalis distribution. An initial risk map was created in a raster-based geographical information system which delineates the area where P. orientalis may occur. This map was then refined using a mask layer indicating the known rainfall-based boundaries of the distribution of Acacia-Balanites woodland - a woodland type known to be associated with the distribution of this vector. The predictive performance of the risk map is discussed.

Forecasting and prevention of epidemic malaria: new perspectives on an old problem.

There is a clear need for improved epidemic malaria surveillance mechanisms in areas prone to the disease. Epidemiological surveillance systems are rarely able to provide information in a sufficiently timely manner for adequate epidemic response. This is especially true in African countries where surveillance is poorly developed, and particularly so in remote regions of unstable malaria such as desert fringes. There is long standing evidence linking climatic variability and epidemic risk. The last ten years have seen significant developments in Environmental Information System (EIS) for a range of natural resource management purposes. The routine information products from these systems have been shown to be both spatially and temporally related to malaria transmission indicators across the African continent. EIS may therefore provide a useful and cost effective input to epidemic malaria control planning and response.

Permethrin-treated bed nets do not have a 'mass-killing effect' on village populations of Anopheles gambiae s.l. in The Gambia.

In The Gambia, the use of permethrin-treated bed nets has led to a reduction in morbidity and mortality from malaria in children. However, no clear evidence has been found for a 'mass-killing effect' on the mosquito vectors as a result of this intervention. Two further entomological studies to investigate this phenomenon have been carried out. In one study, 20 villages were paired so that bed nets in one member of each pair were treated with permethrin. In the other, a cross-over design was used in which treated and untreated bed nets were exchanged between 2 villages. Longevity, biting rate and resting density of the malaria vector population and sporozoite rates were assessed in both studies. Malaria vectors were equally abundant and long-lived, and as likely to be infective, in villages with treated bed nets as in those with untreated nets. However, a clear reduction in the density of the indoor-resting population of mosquitoes in rooms with treated bed nets was found, probably reflecting the excito-repellency of the insecticide. This study confirmed that, in The Gambia, the protection against death and morbidity from malaria seen in children using treated bed nets must be due primarily to personal protection rather than to a 'mass-killing effect' on the mosquito vector population at a village level.

Environmental information systems in malaria risk mapping and epidemic forecasting.

Every year between one and two million African children under five die of malaria. If one adds to this the contribution of malaria to all-cause infant mortality then clearly the burden of the disease is catastrophic--a disaster quietly happening each and every year. New tools are needed urgently to support those currently available for control of the disease. An effective vaccine remains elusive. This article outlines the potential contribution to malaria control services of satellite information, which is being used by resource managers in other sectors. In particular, it highlights the lessons which can be learned from early warning systems in other areas, especially those designed to respond to famine. An appendix provides a brief introduction to satellite data and their interpretation.