The impact of African Swine Fever Virus on smallholder village pig production: an outbreak investigation in Lao PDR

African Swine Fever Virus (ASFV) causes a deadly disease of pigs which spread through southeast Asia in 2019. We investigated one of the first outbreaks of ASFV in Lao Peoples Democratic Republic amongst smallholder villages of Thapangtong District, Savannakhet Province. In this study, two ASFV affected villages were compared to two unaffected villages. Evidence of ASFV-like clinical signs appeared in pig herds as early as May 2019, with median epidemic days on 1 and 18 June in the two villages, respectively. Using participatory epidemiology mapping techniques, we found statistically significant spatial clustering in both outbreaks (P < 0.001). Villagers reported known risk factors for ASFV transmission − such as free-ranging management systems and wild boar access − in all four villages. The villagers reported increased pig trader activity from Vietnam before the outbreaks; however, the survey did not determine a single outbreak source. The outbreak caused substantial household financial losses with an average of 9 pigs lost to the disease, and Monte Carlo analysis estimated this to be USD 215 per household. ASFV poses a significant threat to food and financial security in smallholder communities such as Thapangtong, where 40.6% of the district’s population are affected by poverty. This study shows ASFV management in the region will require increased local government resources, knowledge of informal trader activity and wild boar monitoring alongside education and support to address intra-village risk factors such as free-ranging, incorrect waste disposal and swill feeding.

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The impact of African Swine Fever Virus on smallholder village pig production: an outbreak investigation in Lao PDR

10.22541/au.161225061.17768930/v1 ◽

2021 ◽

Author(s):

Nina Matsumoto ◽

J Siengsanan-Lamont ◽

Tariq Halasa ◽

James Young ◽

Michael Ward ◽

...

Keyword(s):

Risk Factors ◽

Wild Boar ◽

Spatial Clustering ◽

African Swine Fever Virus ◽

Lao Pdr ◽

Clinical Signs ◽

African Swine Fever ◽

Fever Virus ◽

Free Ranging ◽

The Impact

African Swine Fever Virus (ASFV) causes a deadly disease of pigs which spread through southeast Asia in 2019. We investigated one of the first outbreaks of ASFV in Lao Peoples Democratic Republic amongst smallholder villages of Thapangtong District, Savannakhet Province. In this study, two ASFV affected villages were compared to two unaffected villages. Evidence of ASFV-like clinical signs appeared in pig herds as early as May 2019, with median epidemic days on 1 and 18 June in the two villages, respectively. Using participatory epidemiology mapping techniques, we found statistically significant spatial clustering in both outbreaks (P < 0.001). Villagers reported known risk factors for ASFV transmission  such as free-ranging management systems and wild boar access  in all four villages. The villagers reported increased pig trader activity from Vietnam before the outbreaks; however, the survey did not determine a single outbreak source. The outbreak caused substantial household financial losses with an average of 9 pigs lost to the disease, and Monte Carlo analysis estimated this to be USD 215 per household. ASFV poses a significant threat to food and financial security in smallholder communities such as Thapangtong, where 40.6% of the district’s population are affected by poverty. This study shows ASFV management in the region will require increased local government resources, knowledge of informal trader activity and wild boar monitoring alongside education and support to address intra-village risk factors such as free-ranging, correct waste disposal and swill feeding.

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Detection of African swine fever virus in free‐ranging wild boar in Southeast Asia

Transboundary and Emerging Diseases ◽

10.1111/tbed.13964 ◽

2020 ◽

Author(s):

Emily Denstedt ◽

Alice Porco ◽

Jusun Hwang ◽

Nguyen Thi Thanh Nga ◽

Pham Thi Bich Ngoc ◽

...

Keyword(s):

Southeast Asia ◽

Wild Boar ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

Free Ranging

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No evidence for African swine fever virus DNA in haematophagous arthropods collected at wild boar baiting sites in Estonia

Transboundary and Emerging Diseases ◽

10.1111/tbed.14013 ◽

2021 ◽

Author(s):

Reet Herm ◽

Heli Kirik ◽

Annika Vilem ◽

Laura Zani ◽

Jan Hendrik Forth ◽

...

Keyword(s):

Wild Boar ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus

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The Role of Interleukine-10 and Interferon-γ as Potential Markers of the Evolution of African Swine Fever Virus Infection in Wild Boar

Pathogens ◽

10.3390/pathogens10060757 ◽

2021 ◽

Vol 10 (6) ◽

pp. 757

Author(s):

Sandra Barroso-Arévalo ◽

Jose A. Barasona ◽

Estefanía Cadenas-Fernández ◽

José M. Sánchez-Vizcaíno

Keyword(s):

Wild Boar ◽

Vaccine Candidate ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Interferon Γ ◽

Fever Virus ◽

Control Group ◽

Challenge Virus ◽

Ifn Γ

African swine fever virus (ASFv) is one of the most challenging pathogens to affect both domestic and wild pigs. The disease has now spread to Europe and Asia, causing great damage to the pig industry. Although no commercial vaccine with which to control the disease is, as yet, available, some potential vaccine candidates have shown good results in terms of protection. However, little is known about the host immune mechanisms underlying that protection, especially in wild boar, which is the main reservoir of the disease in Europe. Here, we study the role played by two cytokines (IL-10 and IFN-γ) in wild boar orally inoculated with the attenuated vaccine candidate Lv17/WB/Rie1 and challenged with a virulent ASFv genotype II isolate. A group of naïve wild boar challenged with the latter isolate was also established as a control group. Our results showed that both cytokines play a key role in protecting the host against the challenge virus. While high levels of IL-10 in serum may trigger an immune system malfunctioning in challenged animals, the provision of stable levels of this cytokine over time may help to control the disease. This, together with high and timely induction of IFN-γ by the vaccine candidate, could help protect animals from fatal outcomes. Further studies should be conducted in order to support these preliminary results and confirm the role of these two cytokines as potential markers of the evolution of ASFV infection.

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African Swine Fever Laboratory Diagnosis—Lessons Learned from Recent Animal Trials

Pathogens ◽

10.3390/pathogens10020177 ◽

2021 ◽

Vol 10 (2) ◽

pp. 177

Author(s):

Jutta Pikalo ◽

Paul Deutschmann ◽

Melina Fischer ◽

Hanna Roszyk ◽

Martin Beer ◽

...

Keyword(s):

African Swine Fever Virus ◽

Clinical Signs ◽

African Swine Fever ◽

Laboratory Diagnosis ◽

Lessons Learned ◽

Hemorrhagic Disease ◽

Passive Surveillance ◽

Animal Trials ◽

Fit For Purpose ◽

The Impact

African swine fever virus (ASFV) causes a hemorrhagic disease in pigs with high socio-economic consequences. To lower the impact of disease incursions, early detection is crucial. In the context of experimental animal trials, we evaluated diagnostic workflows for a high sample throughput in active surveillance, alternative sample matrices for passive surveillance, and lateral flow devices (LFD) for rapid testing. We could demonstrate that EDTA blood is significantly better suited for early ASFV detection than serum. Tissues recommended by the respective diagnostic manuals were in general comparable in their performance, with spleen samples giving best results. Superficial lymph nodes, ear punches, and different blood swabs were also evaluated as potential alternatives. In summary, all matrices yielded positive results at the peak of clinical signs and could be fit for purpose in passive surveillance. However, weaknesses were discovered for some matrices when it comes to the early phase of infection or recovery. The antigen LFD showed variable results with best performance in the clinical phase. The antibody LFD was quite comparable with ELISA systems. Concluding, alternative approaches are feasible but have to be embedded in control strategies selecting test methods and sample materials following a “fit-for-purpose” approach.

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Role of African swine fever virus (ASFV) proteins EP153R and EP402R in reducing viral persistence and virulence from attenuated BeninΔDP148R

10.1101/2021.04.16.439957 ◽

2021 ◽

Author(s):

Vlad Petrovan ◽

Anusyah Rathakrishnan ◽

Muneeb Islam ◽

Lynnette Goatley ◽

Katy Moffat ◽

...

Keyword(s):

Virus Replication ◽

Vaccine Development ◽

African Swine Fever Virus ◽

Clinical Signs ◽

African Swine Fever ◽

Viral Persistence ◽

Fever Virus ◽

Post Immunization

The limited knowledge on the role of many of the approximately 170 proteins encoded by African swine fever virus restricts progress towards vaccine development. In this study we investigated the effect of deleting combinations of different genes from a previously attenuated virus, BeninΔDP148R on: virus replication in macrophages, virus persistence and clinical signs post immunization, and induction of protection against challenge. Deletion of either EP402R or EP153R genes individually or in combination from BeninΔDP148R did not reduce virus replication in vitro. However, deletion of EP402R dramatically reduced viral persistence in vivo, whilst maintaining high levels of protection against challenge. The additional deletion of EP153R (BeninΔDP148RΔEP153RΔEP402R) further attenuated the virus and no viremia or clinical signs were observed post immunization. This was associated with decreased protection and detection of moderate levels of challenge virus in blood. Interestingly, the deletion of EP153R alone from BeninΔDP148R did not result in further virus attenuation and a slight increase in virus genome copies in blood was observed at different times post immunization when compared with BeninΔDP148R. These results show that EP402R and EP153R have a synergistic role in promoting viremia, however EP153R alone does not seem to have a major impact on virus levels in blood.

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Estimation of the transmission dynamics of African swine fever virus within a swine house

Epidemiology and Infection ◽

10.1017/s0950268817001613 ◽

2017 ◽

Vol 145 (13) ◽

pp. 2787-2796 ◽

Cited By ~ 3

Author(s):

J. P. NIELSEN ◽

T. S. LARSEN ◽

T. HALASA ◽

L. E. CHRISTIANSEN

Keyword(s):

African Swine Fever Virus ◽

African Swine Fever ◽

Simulation Models ◽

Fever Virus ◽

Economic Consequences ◽

Estimation Of Parameters ◽

Swine Industry ◽

Transmission Parameters ◽

The Individual ◽

The Impact

SUMMARYThe spread of African swine fever virus (ASFV) threatens to reach further parts of Europe. In countries with a large swine production, an outbreak of ASF may result in devastating economic consequences for the swine industry. Simulation models can assist decision makers setting up contingency plans. This creates a need for estimation of parameters. This study presents a new analysis of a previously published study. A full likelihood framework is presented including the impact of model assumptions on the estimated transmission parameters. As animals were only tested every other day, an interpretation was introduced to cover the weighted infectiousness on unobserved days for the individual animals (WIU). Based on our model and the set of assumptions, the within- and between-pen transmission parameters were estimated to βw = 1·05 (95% CI 0·62–1·72), βb = 0·46 (95% CI 0·17–1·00), respectively, and the WIU = 1·00 (95% CI 0–1). Furthermore, we simulated the spread of ASFV within a pig house using a modified SEIR-model to establish the time from infection of one animal until ASFV is detected in the herd. Based on a chosen detection limit of 2·55% equivalent to 10 dead pigs out of 360, the disease would be detected 13–19 days after introduction.

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