scholarly journals Livestock movement informs the risk of disease spread in traditional production systems in East Africa

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Divine Ekwem ◽  
Thomas A. Morrison ◽  
Richard Reeve ◽  
Jessica Enright ◽  
Joram Buza ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Production Systems ◽  
Control Strategies ◽  
Herd Size ◽  
Transmission Risk ◽  
Disease Spread ◽  
Transmission Potential ◽  
Spatial And Temporal Scales ◽  
Transmission Distance ◽  
Risk Of Disease

AbstractIn Africa, livestock are important to local and national economies, but their productivity is constrained by infectious diseases. Comprehensive information on livestock movements and contacts is required to devise appropriate disease control strategies; yet, understanding contact risk in systems where herds mix extensively, and where different pathogens can be transmitted at different spatial and temporal scales, remains a major challenge. We deployed Global Positioning System collars on cattle in 52 herds in a traditional agropastoral system in western Serengeti, Tanzania, to understand fine-scale movements and between-herd contacts, and to identify locations of greatest interaction between herds. We examined contact across spatiotemporal scales relevant to different disease transmission scenarios. Daily cattle movements increased with herd size and rainfall. Generally, contact between herds was greatest away from households, during periods with low rainfall and in locations close to dipping points. We demonstrate how movements and contacts affect the risk of disease spread. For example, transmission risk is relatively sensitive to the survival time of different pathogens in the environment, and less sensitive to transmission distance, at least over the range of the spatiotemporal definitions of contacts that we explored. We identify times and locations of greatest disease transmission potential and that could be targeted through tailored control strategies.

scholarly journals Livestock Movement Informs the Risk of Disease Spread in Traditional Production Systems in East Africa

2021 ◽  
Author(s):  
Divine Ekwem ◽  
Thomas A. Morrison ◽  
Richard Reeve ◽  
Jessica Enright ◽  
Joram Buza ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Production Systems ◽  
Control Strategies ◽  
Herd Size ◽  
Disease Spread ◽  
Transmission Potential ◽  
Spatial And Temporal Scales ◽  
Transmission Distance ◽  
Cattle Movements ◽  
Risk Of Disease

Abstract In Africa, livestock are important to local and national economies, but their productivity is constrained by infectious diseases. Comprehensive information on livestock movements and contacts is required to devise appropriate disease control strategies; yet, understanding contact risk in systems where herds mix extensively, and where different pathogens can be transmitted at different spatial and temporal scales, remains a major challenge. We deployed Global Positioning System collars on cattle in 52 herds in a traditional agropastoral system in western Serengeti, Tanzania, to understand fine-scale movements and between-herd contacts, and to identify locations of greatest interaction between herds. We examined contact across spatiotemporal scales relevant to different disease transmission scenarios. Daily cattle movements increased with herd size and rainfall. Generally, contact was greatest away from households, during periods with low rainfall and in locations close to dipping points. We demonstrate how movements and contacts affect the risk of disease spread. For example, contact rate was relatively sensitive to the survival time of different pathogens in the environment, and less sensitive to transmission distance, at least over the range of values that we explored. We identify times and locations of greatest disease transmission potential and that could be targeted through tailored control strategies.

Mapping the Potential for Infectious Disease Transmission in a Wide-Body Aircraft Cabin

2019 ◽  
Author(s):  
Seif Mahmoud ◽  
James S. Bennett ◽  
Mohammad H. Hosni ◽  
Byron Jones
Keyword(s):  
Infectious Diseases ◽  
Disease Transmission ◽  
Radial Distance ◽  
Transmission Risk ◽  
Disease Spread ◽  
Health Concern ◽  
Tracer Gas ◽  
Infectious Disease Transmission ◽  
Gas Concentration ◽  
Aircraft Cabin

Abstract With more than two billion passengers annually, in-flight transmission of infectious diseases is a major global health concern. It is widely believed that principal transmission risk associated with air travel for most respiratory infectious diseases is limited to within two rows of an infectious passenger. However, several passengers became infected despite sitting several rows away from the contagious passenger. This work thoroughly investigated the potential for disease spread inside airplane cabins using tracer gas to quantify airborne dispersion. Measurements were conducted in a full-scale, 11-row mock-up of a wide-body aircraft cabin. Heated mannequins to simulate passengers’ thermal load were placed on the cabin seats. Tracer gas was injected at the breathing level at four different hypothetical contagious passenger locations. The tracer gas concentration was measured radially up to 3.35 m away from the injection location representing four rows of a standard aircraft. A four-port sampling tree was used to collect samples at the breathing level at four different radial locations simultaneously. Each port was sampled for 30 minutes. A total of 42 tests were conducted in matching pairs to alleviate potential statistical or measurements bias. The results showed that the airflow pattern inside the mock-up airplane cabin plays a major role in determining tracer gas concentration meaning that the concentration at the same radial distance in different directions are not necessarily the same. Also, due to the air distribution pattern and cabin walls, concentrations at some seats may be higher than the source seat.

scholarly journals Potential Distribution Map of Culicoides insignis (Diptera: Ceratopogonidae), Vector of Bluetongue Virus, in Northwestern Argentina

2016 ◽  
Vol 16 (1) ◽  
Author(s):  
Cecilia A. Veggiani Aybar ◽  
Romina A. Díaz Gomez ◽  
María J. Dantur Juri ◽  
Mercedes S. Lizarralde de Grosso ◽  
Gustavo R. Spinelli
Keyword(s):  
Disease Transmission ◽  
Bluetongue Virus ◽  
Potential Distribution ◽  
Control Strategies ◽  
Area Under The Curve ◽  
Transmission Risk ◽  
Distribution Map ◽  
Northwestern Argentina ◽  
Jackknife Test ◽  
Maxent Model

Abstract Culicoides insignis Lutz is incriminated as a vector of bluetongue virus (BTV) to ruminants in America. In South America, almost all countries have serological evidence of BTV infections, but only four outbreaks of the disease have been reported. Although clinical diseases have never been cited in Argentina, viral activity has been detected in cattle. In this study, we developed a potential distribution map of Culicoides insignis populations in northwestern Argentina using Maximum Entropy Modeling (Maxent). For the analyses, information regarding both data of specimen collections between 2003 and 2013, and climatic and environmental variables was used. Variables selection was based on the ecological relevance in relation to Culicoides spp. biology and distribution in the area. The best Maxent model according to the Jackknife test included 53 C. insignis presence records and precipitation of the warmest quarter, altitude, and precipitation of the wettest month. Accuracy was evaluated by the area under the curve (AUC = 0.97). These results provide an important analytical resource of high potential for both the development of suitable control strategies and the assessment of disease transmission risk in the region.

scholarly journals Assessment of Airborne Disease Transmission Risk and Energy Impact of HVAC Mitigation Strategies

2021 ◽  
Author(s):  
Michael J. Risbeck ◽  
Martin Z. Bazant ◽  
Zhanhong Jiang ◽  
Young M. Lee ◽  
Kirk H. Drees ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Significant Risk ◽  
Mitigation Strategies ◽  
Transmission Risk ◽  
Disease Spread ◽  
Particle Removal ◽  
Outdoor Air ◽  
Common Basis ◽  
Air Ventilation ◽  
Airborne Disease

The COVID-19 pandemic has focused renewed attention on the ways in which building HVAC systems may be operated to mitigate the risk of airborne disease transmission. The most common suggestion is to increase outdoor-air ventilation rates so as to dilute the concentrations of infectious aerosol particles indoors. Although this strategy does reduce the likelihood of disease spread, it is often much more costly than other strategies that provide equivalent particle removal or deactivation. To address this tradeoff and arrive at practical recommendations, we explain how different mitigation strategies can be expressed in terms of equivalent outdoor air (EOA) to provide a common basis for energy analysis. We then show the effects of each strategy on EOA delivery and energy cost in simulations of realistic buildings in a variety of climates. Key findings are that in-duct filtration is often the most efficient mitigation strategy, while significant risk reduction generally requires increasing total airflow to the system, either through adjusted HVAC setpoints or standalone disinfection devices.

scholarly journals Ascaris suum in pigs of the Zona da Mata, Minas Gerais State, Brazil

2015 ◽  
Vol 24 (3) ◽  
pp. 375-378 ◽  
Author(s):  
Mariana Costa Fausto ◽  
Isabela de Castro Oliveira ◽  
Guilherme Costa Fausto ◽  
Lorendane Millena de Carvalho ◽  
Fabrício Luciani Valente ◽  
...  
Keyword(s):  
Production Systems ◽  
Control Strategies ◽  
Ascaris Suum ◽  
Herd Size ◽  
Livestock Production ◽  
Minas Gerais ◽  
Pig Production ◽  
Minas Gerais State ◽  
Time Of Year ◽  
Inspection Service

Among the parasites that affect pigs, Ascaris suum stands out for causing the greatest losses to livestock production systems. This parasite can be monitored during the slaughter of animals through the identification of “milk spots” or white patches on the liver caused by its larval migration. However, infection in the herd is usually subclinical, which is why the presence of this parasite in industrial pig production has been overlooked. The aim of the study was therefore to evaluate the occurrence of milk spots on the liver of animals slaughtered in the micro-region of Ponte Nova in the Zona da Mata - Minas Gerais, Brazil, and to associate these lesions with the time of year, herd size and source of origin of the animals. An evaluation was made of 1,069 lots, totaling 108,073 animals, based on data extracted from the Federal Inspection Service. The animals were slaughtered during the period of January 2011 to June 2013. Out of the total number of slaughtered animals, 10,535 (9.75%) tested positive for these lesions. Therefore, veterinarians and producers should be warned about the inefficiency of the deworming protocols that are used, and the need to develop and/or review control strategies for this parasite in production systems.

scholarly journals Estimation and Mitigation of Epidemic Risk on a Public Transit Route using Automatic Passenger Count Data

2021 ◽  
pp. 036119812098513
Author(s):  
Pramesh Kumar ◽  
Alireza Khani ◽  
Eric Lind ◽  
John Levin
Keyword(s):  
Relative Risk ◽  
Disease Transmission ◽  
Public Transit ◽  
Disease Spread ◽  
Contact Network ◽  
Transit System ◽  
Underdetermined System ◽  
Risk Of Disease ◽  
Two Measures ◽  
Transit Route

This paper studies the potential spread of infectious disease through passenger encounters in a public transit system using automatic passenger count (APC) data. An algorithmic procedure is proposed to evaluate three different measures to quantify these encounters. The first two measures quantify the increased possibility of disease spread from passenger interaction when traveling between different origin–destination pairs. The third measure evaluates an aggregate measure quantifying the relative risk of boarding at a particular stop of the transit route. For calculating these measures, compressed sensing is employed to estimate a sparse passenger flow matrix planted in the underdetermined system of equations obtained from the APC data. Using the APC data of Route 5 in Minneapolis/St. Paul region during the COVID-19 pandemic, it was found that all three measures grow abruptly with the number of passengers on board. The passenger contact network is densely connected, which further increases the potential risk of disease transmission. To reduce the relative risk, it is proposed to restrict the number of passengers on-board and analyze the effect of this using a simulation framework. It was found that a considerable reduction in the relative risk can be achieved when the maximum number of passengers on-board is restricted below 15. To account for the reduced capacity and still maintain reasonable passenger wait times, it would then be necessary to increase the frequency of the route.

scholarly journals Opposing effects of allogrooming on disease transmission in ant societies

2015 ◽  
Vol 370 (1669) ◽  
pp. 20140108 ◽  
Author(s):  
Fabian J. Theis ◽  
Line V. Ugelvig ◽  
Carsten Marr ◽  
Sylvia Cremer
Keyword(s):  
Disease Transmission ◽  
Disease Risk ◽  
The Body ◽  
Disease Spread ◽  
Sis Model ◽  
Lasius Neglectus ◽  
Host Pathogen ◽  
Group Members ◽  
Risk Of Disease ◽  
Opposing Effects

To prevent epidemics, insect societies have evolved collective disease defences that are highly effective at curing exposed individuals and limiting disease transmission to healthy group members. Grooming is an important sanitary behaviour—either performed towards oneself (self-grooming) or towards others (allogrooming)—to remove infectious agents from the body surface of exposed individuals, but at the risk of disease contraction by the groomer. We use garden ants ( Lasius neglectus ) and the fungal pathogen Metarhizium as a model system to study how pathogen presence affects self-grooming and allogrooming between exposed and healthy individuals. We develop an epidemiological SIS model to explore how experimentally observed grooming patterns affect disease spread within the colony, thereby providing a direct link between the expression and direction of sanitary behaviours, and their effects on colony-level epidemiology. We find that fungus-exposed ants increase self-grooming, while simultaneously decreasing allogrooming. This behavioural modulation seems universally adaptive and is predicted to contain disease spread in a great variety of host–pathogen systems. In contrast, allogrooming directed towards pathogen-exposed individuals might both increase and decrease disease risk. Our model reveals that the effect of allogrooming depends on the balance between pathogen infectiousness and efficiency of social host defences, which are likely to vary across host–pathogen systems.

scholarly journals Cattle movement network, herd size, and bovine brucellosis in the State of Mato Grosso, Brazil

2016 ◽  
Vol 37 (5Supl2) ◽  
pp. 3777 ◽  
Author(s):  
Rafael Ishibashi Cipullo ◽  
José Henrique Hildebrand Grisi-Filho ◽  
Ricardo Augusto Dias ◽  
Fernando Ferreira ◽  
José Soares Ferreira Neto ◽  
...  
Keyword(s):  
Herd Size ◽  
The State ◽  
Disease Spread ◽  
Total Degree ◽  
Bovine Brucellosis ◽  
Mato Grosso ◽  
Cattle Movement ◽  
Tenfold Increase ◽  
Risk Of Disease ◽  
Animal Trade

The aims of the present study were to compare centrality and other measures of bovine movement networks in the state of Mato Grosso, Brazil, in 2007, by examination of the positive and negative herds identified in the brucellosis survey conducted in 2003. In addition, we aimed to examine the association between herd size (measured by the number of females older than 24 months, denoted FEM24+) and animal trade between herds. We found a statistical association between brucellosis occurrence and both the total degree (number of traded animals) and out-degree (for the number of animals sold and the number of neighboring herds). This finding suggests that positive herds in the 2003 survey were trading (particularly selling) more frequently in 2007 than negative herds, thereby presumably increasing the risk of disease spread. Statistical differences observed (p-values) in the network of movements for reproduction purposes were more significant than those observed in other networks for average herd size; degrees of animals, batches, and neighbors; outdegree of neighbors; and betweenness. We found positive associations (p < 0.001) between the following variables: number of traded animals and the FEM24+ herd size; FEM24+ herd size and FEM24+ herd size of neighbors within the network of cattle movement; FEM24+ herd size of neighbors and number of traded animals; and weighted degree (animals) of neighbors and degree (animals) of the herd of origin. A comparison of positive and negative herds stratified by herd size (? 10 FEM24+; 11-50 FEM24+; and > 50 FEM24+), within the network of movements for reproduction purposes, revealed significant differences (p < 0.05) in the > 50 FEM24+ category only, for average herd size, total degree (animals, batches, and neighbors), outdegree (animals, batches, and neighbors), and outcloseness. Logistic regression analysis, in which average herd size and degree (animals) were both factors, showed that a tenfold increase in herd size and the number of animals traded would lead to an increased chance of a herd being positive by 41% (OR = 1.41 [1.01; 1.99]) and 39% (OR = 1.39 [1.05; 1.85]), respectively. We concluded that the presence of bovine brucellosis is associated with a larger herd size, which is consistent with other reports. We also found an association between the increased trade of bovines and the presence of bovine brucellosis. Furthermore, an association was noted between herd size and animal trade, both of which could contribute to the spread of brucellosis.

scholarly journals Methods to infer transmission risk factors in complex outbreak data

2011 ◽  
Vol 9 (68) ◽  
pp. 456-469 ◽  
Author(s):  
Simon Cauchemez ◽  
Neil M. Ferguson
Keyword(s):  
Risk Factors ◽  
Missing Data ◽  
Disease Transmission ◽  
Control Strategies ◽  
Model Fitting ◽  
Structured Populations ◽  
Transmission Risk ◽  
Effective Control ◽  
Reconstruction Methods ◽  
History Of

Data collected during outbreaks are essential to better understand infectious disease transmission and design effective control strategies. But analysis of such data is challenging owing to the dependency between observations that is typically observed in an outbreak and to missing data. In this paper, we discuss strategies to tackle some of the ongoing challenges in the analysis of outbreak data. We present a relatively generic statistical model for the estimation of transmission risk factors, and discuss algorithms to estimate its parameters for different levels of missing data. We look at the problem of computational times for relatively large datasets and show how they can be reduced by appropriate use of discretization, sufficient statistics and some simple assumptions on the natural history of the disease. We also discuss approaches to integrate parametric model fitting and tree reconstruction methods in coherent statistical analyses. The methods are tested on both real and simulated datasets of large outbreaks in structured populations.

scholarly journals Recommended Precautions for Patients Undergoing Hemodialysis Who Have AIDS or Non-A, Non-B Hepatitis

1985 ◽  
Vol 6 (8) ◽  
pp. 301-305 ◽  
Author(s):  
Martin S. Favero
Keyword(s):  
Hepatitis B ◽  
Disease Transmission ◽  
Environmental Control ◽  
Control Strategies ◽  
Free Standing ◽  
Staff Members ◽  
Risk Of Disease ◽  
Control Procedures ◽  
Acquired Immunodeficiency ◽  
Immunodeficiency Syndrome

AbstractPrecautions used for dialysis patients who have acquired immunodeficiency syndrome or non-A, non-B hepatitis are based on infection control strategies developed for the control of hepatitis B in dialysis centers. Specificially, these recommendations include identifying infected patients; isolating (except for non-A, non-B hepatitis patients) patients, and separating staff, and equipment; applying blood precautions and aseptic techniques; and using good environmental control procedures. AIDS patients can be safely dialyzed by either hemodialysis or peritoneal dialysis in hospital-based or free-standing centers, or at home without risk of AIDS transmission to other patients or to staff members, if precautions that have been developed for the control of hepatitis B infection in dialysis units are employed. Further, the type of dialysis treatment, or modality, should be based on the needs of the patient and not on a fear of risk of disease transmission.

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