Impact of spatial clustering on disease transmission and optimal control.

Spatial heterogeneities and spatial separation of hosts are often seen as key factors when developing accurate predictive models of the spread of pathogens. The question we address in this paper is how coarse the resolution of the spatial data can be for a model to be a useful tool for informing control policies. We examine this problem using the specific case of foot-and-mouth disease spreading between farms using the formulation developed during the 2001 epidemic in the United Kingdom. We show that, if our model is carefully parameterized to match epidemic behavior, then using aggregate county-scale data from the United States is sufficient to closely determine optimal control measures (specifically ring culling). This result also holds when the approach is extended to theoretical distributions of farms where the spatial clustering can be manipulated to extremes. We have therefore shown that, although spatial structure can be critically important in allowing us to predict the emergent population-scale behavior from a knowledge of the individual-level dynamics, for this specific applied question, such structure is mostly subsumed in the parameterization allowing us to make policy predictions in the absence of high-quality spatial information. We believe that this approach will be of considerable benefit across a range of disciplines where data are only available at intermediate spatial scales.

Analysis of the Costs and Economic Feasibility of Requiring Postharvest Processing for Raw Oysters.

Because of concerns about Vibrio vulnificus, the U.S. Food and Drug Administration is considering requirements for postharvest processing (PHP) of oysters harvested from the Gulf of Mexico during warm-weather months and intended for raw consumption. As described in the paper, feasible PHP methods for warm-weather-harvested oysters include cool pasteurization, high hydrostatic pressure, and low-dose gamma-irradiation. We estimate that the costs of applying PHP are approximately 5 to 6 cents per half-shell oyster intended for raw consumption. However, most oyster processors have insufficient volumes to cost-effectively install PHP equipment. To assist these smaller operations, central PHP facilities operated by a 3rd party would be needed. A geographic information system analysis that minimized volume-weighted travel distances from each Gulf oyster operation identified 6 optimal PHP facility locations in the Gulf region. Even with the establishment of central PHP facilities, some oyster operations will become unprofitable and be at risk for closure.

Prevalence of Trachoma in Senegal: Results of Baseline Surveys in 17 Districts.

PURPOSE: Senegal is endemic for trachoma, an infectious and potentially blinding eye disease. To complete the country's district-level baseline map of trachoma, we conducted population-based surveys in 17 health districts that were suspected-endemic but had yet to be surveyed. METHODS: We randomly selected 30 clusters (villages) per district and 30 households per village, and estimated the district-level prevalences of trachomatous inflammation-follicular (TF) in children aged 1-9 years, and trichiasis in persons aged ≥15 years. Data on household-level water, sanitation, and hygiene variables were also collected. Global Trachoma Mapping Project methods were followed in training, fieldwork, and data handling. RESULTS: 25,704 children aged 1-9 years and 30,345 adults aged 15 years and above were examined. In children aged 1-9 years, the prevalence of TF was <5% in all 17 districts, with the exception of Saint-Louis (5.1%, 95% CI 3.2-7.5). Trichiasis prevalence in participants aged 15 years and above ranged by district from 0%-1.1% (95% CI 0.7-1.5), with 9 districts having trichiasis prevalences above the elimination threshold of 0.2%. Trichiasis was seen to be significantly less frequent in males than in females (0.17% [95% CI 0.12-0.24] versus 0.49% [95% CI 0.38-0.61], p < 0.001). The prevalence of trichiasis rose steeply with age; 62% of cases were observed in people aged 55 years or above. CONCLUSIONS: Active trachoma is not a public health problem in 16 of the 17 surveyed districts, and implementation of the full Surgery (S) - Antibiotics (A) - Facial cleanliness (F) - Environmental improvement (E) strategy is not a programmatic priority. Increased provision of trichiasis surgery is warranted in nine districts.

Ethiopia and its steps to mobilize resources to achieve 2020 elimination and control goals for neglected tropical diseases webs joined can tie a lion.

In June 2013, at the launch of its National Neglected Tropical Disease (NTD) Master Plan, the Ethiopian government pledged to achieve WHO NTD elimination and control targets by 2020. With an estimated 80 million people living in areas where one or more NTDs are endemic, this goal presented an enormous challenge for the Federal Ministry of Health. However, as of September 2015, the Federal Ministry of Health has managed to mobilize support to implement mass drug administration in 84% of the trachoma endemic districts and 100% of the endemic districts for onchocerciasis, lymphatic filariasis, soil-transmitted helminthes and schistosomiasis. The national program still is facing large gaps in its podoconiosis and leishmaniasis programs, and it faces significant other challenges to stay on track for 2020 targets. However, this unprecedented scale-up in support was achieved through significant government investment in NTD interventions and creative coordination between donors and implementing partners, which may provide valuable lessons for other national NTD programs trying to achieve nationwide coverage.