scholarly journals Modeling the role of mortality-based response triggers on the effectiveness of African swine fever control strategies

2021 ◽  
Author(s):  
Gustavo Machado ◽  
Trevor Farthing ◽  
Mathieu Andraud ◽  
Francisco Paulo Nunes Lopes ◽  
Cristina Lanzas
Keyword(s):  
Spatial Distribution ◽  
Animal Movement ◽  
Control Strategies ◽  
Virulent Strain ◽  
Animal Health ◽  
African Swine Fever ◽  
Multiscale Model ◽  
Case Scenario ◽  
Modeling Framework ◽  
Highly Virulent

African swine fever (ASF) is considered the most impactful transboundary swine disease. In the absence of effective vaccines, control strategies are heavily dependent on mass depopulation and movement restrictions. Here we developed a nested multiscale model for the transmission of ASF, combining spatially explicit network model of animal movements with a deterministic compartmental model for the dynamics of two ASF strains within-pixels of 3 km x 3 km, amongst the pig population in one Brazilian state. The model outcomes are epidemic duration, number of secondary infected farms and pigs, and distance of ASF spread. The model also predicted the spatial distribution of ASF epidemics. We analyzed quarantine-based control interventions in the context of mortality trigger thresholds for the deployment of control strategies. The mean epidemic duration of a moderately virulent strain was 11.2 days assuming the first infection is detected (best-case scenario) and 15.9 days when detection is triggered at 10 % mortality. For a highly virulent strain, the epidemic duration was 6.5 days and 13.1 days, respectively. The distance from the source to infected locations and the spatial distribution was not dependent on strain virulence. Under the best-case scenario, we projected an average number of infected farms of 18.79 farms and 23.77 farms for the moderate and highly virulent strains, respectively. At 10% mortality-trigger, the predicted number of infected farms was on average 48.28 farms and 42.97 farms, respectively. We also demonstrated that the establishment of ring quarantine zones regardless of size (i.e., 5 km, 15 km) was outperformed by backward animal movement tracking. The proposed modeling framework provides an evaluation of ASF epidemic potential, providing a ranking of quarantine-based control strategies that could assist animal health authorities in planning the national preparedness and response plan.

scholarly journals Clinical Course and Gross Pathological Findings in Wild Boar Infected with a Highly Virulent Strain of African Swine Fever Virus Genotype II

Pathogens ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 688 ◽  
Author(s):  
Antonio Rodríguez-Bertos ◽  
Estefanía Cadenas-Fernández ◽  
Agustín Rebollada-Merino ◽  
Néstor Porras-González ◽  
Francisco J. Mayoral-Alegre ◽  
...  
Keyword(s):  
Wild Boar ◽  
Clinical Course ◽  
African Swine Fever Virus ◽  
Virulent Strain ◽  
African Swine Fever ◽  
Pathological Findings ◽  
Wild Boars ◽  
Gross Pathology ◽  
Highly Virulent ◽  
Genotype Ii

African swine fever (ASF) is a notifiable disease that in recent years has spread remarkably in Europe and Asia. Eurasian wild boar (Sus scrofa) plays a key role in the maintenance and spread of the pathogen. Here we examined gross pathology of infection in wild boar with a highly virulent, hemadsorbing genotype II ASF virus (ASFV) strain. To this end, six wild boars were intramuscularly inoculated with the 10 HAD50 Arm07 ASFV strain, and 11 wild boars were allowed to come into direct contact with the inoculated animals. No animals survived the infection. Clinical course, gross pathological findings and viral genome quantification by PCR in tissues did not differ between intramuscularly inoculated or contact-infected animals. Postmortem analysis showed enlargement of liver and spleen; serosanguinous effusion in body cavities; and multiple hemorrhages in lungs, endocardium, brain, kidneys, urinary bladder, pancreas, and alimentary system. These results provide detailed insights into the gross pathology of wild boar infected with a highly virulent genotype II ASFV strain. From a didactic point of view, this detailed clinical course and macroscopic description may be essential for early postmortem detection of outbreaks in wild boar in the field and contribute to disease surveillance and prevention efforts.

scholarly journals An Update on African Swine Fever Virology

Viruses ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 864 ◽  
Author(s):  
Axel Karger ◽  
Daniel Pérez-Núñez ◽  
Jesús Urquiza ◽  
Patricia Hinojar ◽  
Covadonga Alonso ◽  
...  
Keyword(s):  
Western Europe ◽  
Topoisomerase Ii ◽  
Virulent Strain ◽  
Animal Health ◽  
African Swine Fever ◽  
Sub Saharan Africa ◽  
Future Research ◽  
Special Focus ◽  
Health Food ◽  
Rna Helicases

Animal diseases constitute a continuing threat to animal health, food safety, national economy, and the environment. Among those, African swine fever (ASF) is one of the most devastating viruses affecting pigs and wild suids due to the lack of vaccine or effective treatment. ASF is endemic in countries in sub-Saharan Africa, but since its introduction to the Caucasus region in 2007, a highly virulent strain of ASF virus (ASFV) has continued to circulate and spread into Eastern Europe and Russia, and most recently into Western Europe, China, and various countries of Southeast Asia. Given the importance of this disease, this review will highlight recent discoveries in basic virology with special focus on proteomic analysis, replication cycle, and some recent data on genes involved in cycle progression and viral–host interactions, such as I215L (E2 ubiquitin-conjugating enzyme), EP402R (CD2v), A104R (histone-like protein), QP509L, and Q706L (RNA helicases) or P1192R (Topoisomerase II). Taking into consideration the large DNA genome of ASFV and its complex interactions with the host, more studies and new approaches are to be taken to understand the basic virus–host interaction for ASFV. Proteomic studies are just paving the way for future research.

scholarly journals Superficial Inguinal Lymph Nodes for Screening Dead Pigs for African Swine Fever

Viruses ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 83
Author(s):  
Kalhari Bandara Goonewardene ◽  
Chukwunonso Onyilagha ◽  
Melissa Goolia ◽  
Van Phan Le ◽  
Sandra Blome ◽  
...  
Keyword(s):  
Lymph Nodes ◽  
Animal Health ◽  
African Swine Fever ◽  
Inguinal Lymph Nodes ◽  
Copy Numbers ◽  
Routine Surveillance ◽  
World Organization ◽  
Opening Up ◽  
Highly Virulent ◽  
Level Monitoring

African swine fever (ASF) has spread across the globe and has reached closer to North America since being reported in the Dominican Republic and Haiti. As a result, surveillance measures have been heightened and the utility of alternative samples for herd-level monitoring and dead pig sampling have been investigated. Passive surveillance based on the investigation of dead pigs, both domestic and wild, plays a pivotal role in the early detection of an ASF incursion. The World Organization for Animal Health (OIE)-recommended samples for dead pigs are spleen, lymph nodes, bone marrow, lung, tonsil and kidney. However, obtaining these samples requires opening up the carcasses, which is time-consuming, requires skilled labour and often leads to contamination of the premises. As a result, we investigated the suitability of superficial inguinal lymph nodes (SILNs) for surveillance of dead animals. SILNs can be collected in minutes with no to minimum environmental contamination. Here, we demonstrate that the ASF virus (ASFV) genome copy numbers in SILNs highly correlate with those in the spleen and, by sampling SILN, we can detect all pigs that succumb to highly virulent and moderately virulent ASFV strains (100% sensitivity). ASFV was isolated from all positive SILN samples. Thus, sampling SILNs could be useful for routine surveillance of dead pigs on commercial and backyard farms, holding pens and dead on arrival at slaughter houses, as well as during massive die-offs of pigs due to unknown causes.

scholarly journals Mapping the Spatial Distribution of the Rumen Fluke Calicophoron daubneyi in a Mediterranean Area

Pathogens ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1122
Author(s):  
Antonio Bosco ◽  
Martina Nocerino ◽  
Mirella Santaniello ◽  
Maria Paola Maurelli ◽  
Giuseppe Cringoli ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Geographical Information Systems ◽  
Control Strategies ◽  
Animal Health ◽  
Small Ruminants ◽  
Mediterranean Area ◽  
Geographical Information ◽  
Cross Sectional ◽  
Calicophoron Daubneyi ◽  
Cattle Farms

Rumen flukes (Calicophoron daubneyi) represent a growing threat to the animal health, productivity and welfare of ruminants. The present study aimed to assess the spatial distribution of C. daubneyi infections in ruminants and to develop a predictive model of the environmental suitability for rumen flukes in a Mediterranean area. A cross-sectional coprological survey was conducted in 682 sheep, 73 goat and 307 cattle farms located in the Basilicata region (southern Italy). Faecal samples collected were analysed using the FLOTAC technique. Geographical Information Systems (GIS) and statistical models were developed to determine environmental risk factors and to delimitate the areas at highest risk of infections in small ruminants. The results showed 7.9% (95% CI 6.05–10.27) of sheep farms, 2.7% (95% CI 0.48–10.44) of goat farms and 55.0% (95% CI 49.62–60.99) of cattle farms were infected by C. daubneyi. The areas with high predicted risk were situated in the western part of the region. The soil texture, land use and the presence of streams and brooks were the variables statistically significant (p < 0.05) in explaining the C. daubneyi distribution in the study area. The study confirms the importance of geospatial technology in supporting parasite control strategies in livestock and demonstrates that a combined use of different geostatistical techniques can improve the prediction of the C. daubneyi infection risk in ruminants.

scholarly journals Quantifying the dynamics of pig movements improves targeted disease surveillance and control plans

2019 ◽  
Author(s):  
Gustavo Machado ◽  
Jason Ardila Galvis ◽  
Francisco Paulo Nunes Lopes ◽  
Joana Voges ◽  
Antônio Augusto Rosa Medeiros ◽  
...  
Keyword(s):  
Disease Control ◽  
Disease Surveillance ◽  
Control Strategies ◽  
Disease Spread ◽  
Growth Stages ◽  
Case Scenario ◽  
Modeling Framework ◽  
Worst Case ◽  
Movement Data ◽  
The Impact

SummaryTracking animal movements over time can fundamentally determine the success of disease control interventions throughout targeting farms that are tightly connected. In commercial pig production, animals are transported between farms based on growth stages, thus it generates time-varying contact networks that will influence the dynamics of disease spread. Still, risk-based surveillance strategies are mostly based on a static network. In this study, we reconstructed the static and temporal pig networks of one Brazilian state from 2017 to 2018, comprising 351,519 movements and 48 million transported pigs. The static networks failed to capture time-respecting movement pathways. Therefore, we propose a time-dependent network susceptible-infected (SI) model to simulate the temporal spread of an epidemic over the pig network globally through the temporal movement of animals among farms, and locally with a stochastic compartmental model in each farm, configured to calculate the minimum number of target farms needed to achieve effective disease control. In addition, we propagated disease on the pig temporal network to calculate the cumulative contacts as a proxy of epidemic sizes and evaluated the impact of network-based disease control strategies. The results show that targeting the first 1,000 farms ranked by degree would be sufficient and feasible to diminish disease spread considerably. Our finding also suggested that assuming a worst-case scenario in which every movement transmit disease, pursuing farms by degree would limit the transmission to up to 29 farms over the two years period, which is lower than the number of infected farms for random surveillance, with epidemic sizes of 2,593 farms. The top 1,000 farms could benefit from enhanced biosecurity plans and improved surveillance, which constitute important next steps in strategizing targeted disease control interventions. Overall, the proposed modeling framework provides a parsimonious solution for targeted disease surveillance when temporal movement data is available.

Protective effect of Trypanosoma rangeli against infections with a highly virulent strain of Trypanosoma cruzi

1997 ◽  
Vol 2 (5) ◽  
pp. 482-487 ◽  
Author(s):  
Claudio Zuniga ◽  
Teresa Palau ◽  
Pilar Penin ◽  
Carlos Gamallo ◽  
Jose Antonio de Diego
Keyword(s):  
Trypanosoma Cruzi ◽  
Protective Effect ◽  
Virulent Strain ◽  
Trypanosoma Rangeli ◽  
Highly Virulent

scholarly journals Risk factors associated with Ctenocephalides felis flea infestation of peri-urban goats: a neglected parasite in an under-appreciated host

2021 ◽  
Vol 53 (1) ◽  
Author(s):  
Julia Rose Dahm ◽  
Jordana Burdon Bailey ◽  
Robert F. Kelly ◽  
Patrick Chikungwa ◽  
Julius Chulu ◽  
...  
Keyword(s):  
Risk Factors ◽  
Urban Communities ◽  
Control Strategies ◽  
Animal Health ◽  
Animal Husbandry ◽  
Ctenocephalides Felis ◽  
Disease Spread ◽  
Health Concern ◽  
Cross Sectional ◽  
Flea Infestation

AbstractGoats are critical in mixed smallholder agricultural systems in lower and middle-income countries, while fleas are important human and animal health concerns around the world. Convenience sampling was used to describe and consider risk factors for flea infestations of peri-urban goats, with the aim of informing the iterative development of animal husbandry and management based control strategies. Seven hundred and ninety-two goats were examined in 228 households across 10 peri-urban communities surrounding Blantyre in southern Malawi. The prevalence of Ctenocephalides felis fleas was 18.3, 37.1 and 100% at the levels of individual goats, households and communities, respectively, highlighting a neglected human and animal health concern. Constant introduction of new livestock coupled to a lack of biosecurity within communities, the ubiquitous presence of dog and cat hosts for C. felis, the frequency and thoroughness of cleaning overnight goat accommodation, and goat age less than 12 months old were identified as risk factors for flea infestation. This focal cross-sectional study highlights the significance of fleas in peri-urban communities and uncovers trends and commonalities that are needed to inform sustainable disease management. The majority of the peri-urban goat keepers were female, had resided in the same community throughout their whole life and had primary level education. Advice on the planned management of fleas in livestock needs to be tailored towards this demographic group. This approach affords an opportunity to promote public health measures to address household flea infestations and zoonotic disease spread.

scholarly journals 168 The effects of fly control strategies on fly abundance, fly avoidance behaviors, and performance in feedlot bulls and steers

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 15-16
Author(s):  
Courtney McNeff ◽  
Justin Talley ◽  
Colton A Robison ◽  
Blake K Wilson
Keyword(s):  
Treatment Time ◽  
Control Strategies ◽  
Block Design ◽  
Animal Health ◽  
Piperonyl Butoxide ◽  
Stable Fly ◽  
Animal Performance ◽  
Time Interaction ◽  
Avoidance Behaviors ◽  
Fly Control

Abstract The objective of this experiment was to examine the effects of fly control strategies on fly abundance, fly avoidance behaviors, and animal performance in a feedlot setting. Angus bulls (n = 64; BW = 281 ± 36.2 kg) and steers (n = 36; BW = 475 ± 40.4 kg) were blocked by sex and BW and assigned to 1 of 4 experimental treatments in a randomized complete block design (7 pens/treatment; 4 bulls/pen; 3 steers/pen). Treatments included: control (CON; no fly control), abamectin, piperonyl butoxide, and zetacypermethrin insecticide tags (FT; Tri-Zap®, Y-Tex Corporation, Cody, WY), permethrin and piperonyl butoxide pour on (PO; Permectrin® CDS, Bayer Animal Health, Shawnee Mission, KS), or a garlic-powder top dress (GR) administered at 0.28 g •-1 animal •-1d. The experiment was conducted between June and September. Horn and stable fly abundance (FA) and fly avoidance behaviors (FAB; i.e. tail-flicks, stomping, head-tossing) were recorded by trained personnel. Both FA and FAB were recorded once/wk on days with similar temperatures, humidity, wind speed, and without precipitation based on Oklahoma Mesonet data (Stillwater site). There was a tendency for a treatment × time interaction for horn FA with differences in treatments occurring at wk 1, 2, 8, and 14. There was no treatment × time interaction for stable FA or FAB, however both were affected by time (P &lt; 0.001). There were no differences in final BW (P = 0.34), overall ADG (P = 0.30), overall DMI (P = 0.53), or overall G:F (P = 0.39). There was a tendency (P ≤ 0.10) for GR to have decreased BW on d 28 and decreased ADG from d 0 to 28 compared to FT and PO. There was also a tendency (P = 0.09) for decreased DMI from d 0 to 56 for GR compared to CON and FT. Overall FA was less than expected (mean = 1 to 17 flies/animal) throughout the experiment and overall animal performance was unaffected by fly control strategy.

scholarly journals Modelling the Spatial Distribution of ASF-Positive Wild Boar Carcasses in South Korea Using 2019–2020 National Surveillance Data

Animals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1208
Author(s):  
Jun-Sik Lim ◽  
Timothée Vergne ◽  
Son-Il Pak ◽  
Eutteum Kim
Keyword(s):  
Spatial Distribution ◽  
Risk Factor ◽  
South Korea ◽  
Wild Boar ◽  
African Swine Fever Virus ◽  
Significant Risk ◽  
African Swine Fever ◽  
Credible Interval ◽  
Imperfect Detection ◽  
Wild Boars

In September 2019, African swine fever (ASF) was reported in South Korea for the first time. Since then, more than 651 ASF cases in wild boars and 14 farm outbreaks have been notified in the country. Despite the efforts to eradicate ASF among wild boar populations, the number of reported ASF-positive wild boar carcasses have increased recently. The purpose of this study was to characterize the spatial distribution of ASF-positive wild boar carcasses to identify the risk factors associated with the presence and number of ASF-positive wild boar carcasses in the affected areas. Because surveillance efforts have substantially increased in early 2020, we divided the study into two periods (2 October 2019 to 19 January 2020, and 19 January to 28 April 2020) based on the number of reported cases and aggregated the number of reported ASF-positive carcasses into a regular grid of hexagons of 3-km diameter. To account for imperfect detection of positive carcasses, we adjusted spatial zero-inflated Poisson regression models to the number of ASF-positive wild boar carcasses per hexagon. During the first study period, proximity to North Korea was identified as the major risk factor for the presence of African swine fever virus. In addition, there were more positive carcasses reported in affected hexagons with high habitat suitability for wild boars, low heat load index (HLI), and high human density. During the second study period, proximity to an ASF-positive carcass reported during the first period was the only significant risk factor for the presence of ASF-positive carcasses. Additionally, low HLI and elevation were associated with an increased number of ASF-positive carcasses reported in the affected hexagons. Although the proportion of ASF-affected hexagons increased from 0.06 (95% credible interval (CrI): 0.05–0.07) to 0.09 (95% CrI: 0.08–0.10), the probability of reporting at least one positive carcass in ASF-affected hexagons increased from 0.49 (95% CrI: 0.41–0.57) to 0.73 (95% CrI: 0.66–0.81) between the two study periods. These results can be used to further advance risk-based surveillance strategies in the Republic of Korea.

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