RESUMO
National disease surveillance systems are essential to a healthy pig industry but can be costly and logistically complex. In 2019, Lao People's Democratic Republic (Lao PDR) piloted an abattoir disease surveillance system to assess for the presence of high impact pig diseases (HIPDs) using serological methods. The Lao Department of Livestock and Fisheries (DLF) identified Classical Swine Fever (CSF), Porcine Respiratory and Reproductive Syndrome (PRRS) and Brucella suis as HIPDs of interest for sero-surveillance purposes. Porcine serum samples (n = 597) were collected from six Lao abattoirs in March to December of 2019. Serological enzyme-linked immunosorbent assay (ELISA) methods were chosen for their high-throughput and relatively low-costs. The true seroprevalence for CSF and PRRS seropositivity were 68.7%, 95% CI (64.8-72.3) and 39.5%, 95% CI (35.7-43.5), respectively. The results demonstrated no evidence of Brucella spp. seroconversion. Lao breed pigs were less likely to be CSF seropositive (P < 0.05), whilst pigs slaughtered at <1 year of age were less likely to be PRRS seropositive (P < 0.01). The testing methods could not differentiate between seropositivity gained from vaccine or natural infection, and investigators were unable to obtain the vaccine status of the slaughtered pigs from the abattoirs. These results demonstrate that adequate sample sizes are possible from abattoir sero-surveillance and lifetime health traceability is necessary to understand HIPDs in Lao PDR.
Assuntos
Matadouros , Síndrome Respiratória e Reprodutiva Suína , Animais , Suínos , Laos/epidemiologia , Síndrome Respiratória e Reprodutiva Suína/epidemiologia , Estudos Soroepidemiológicos , Zoonoses/epidemiologiaRESUMO
A pilot animal disease surveillance program was implemented at four abattoirs in Phnom Penh, Cambodia, between October 2019 and January 2020. A total of 1141 samples were collected from 477 cattle and 664 swine. Serological testing was performed using commercial antibody ELISA kits for zoonotic and high-impact animal diseases, namely brucellosis, Q fever, classical swine fever (CSF), porcine reproductive and respiratory syndrome (PRRS) and African swine fever (ASF). Only two samples tested positive for Brucella antibodies (0.2%, 95% CI 0.4-0.6, n = 1141). The seroprevalence of Q fever was 0.8% (95% CI 0.3-2.1, n = 477) in the cattle samples, while CSF, PRRS and ASF in pigs were 55.4% (95% CI 51.6-59.2, n = 655), 81.2% (95% CI 78.1-84.0, n = 655) and 2.6% (95% CI 1.6-4.1, n = 664), respectively. All 38 doubtful and 17 positive ASF antibody ELISA samples were negative when tested by real-time PCR. Univariate analyses demonstrated that the factor significantly associated with positive results of ASF was the abattoir location (p-value = 0.002). Based on logistic regression models, significant risk factors for CSF were province of origin (p-value = 1.7 × 10-6), abattoir (p-value = 3.6 × 10-11) and PRRS positivity (p-value = 0.004), and for PRRS were province of origin (p-value = 0.0004) and CSF positivity (p-value = 0.001). In conclusion, the seroprevalences of zoonotic diseases in this study were very low. The high prevalence of CSF and PRRS antibodies were most likely the result of vaccination. All ASF seropositive pigs, including those that gave equivocal results, originated from large-scale Cambodian-based commercial farms, as well as Thailand, which raises questions about possible illegal vaccination or low-pathogenicity ASF variants. The pilot abattoir serological surveillance program described here has the potential to provide a sentinel for incursions of novel and endemic pathogens, although further work is required to demonstrate its capacity to provide information on the longitudinal disease trends.
Assuntos
Febre Suína Africana , Doenças dos Bovinos , Peste Suína Clássica , Síndrome Respiratória e Reprodutiva Suína , Febre Q , Doenças dos Suínos , Matadouros , Febre Suína Africana/epidemiologia , Animais , Camboja/epidemiologia , Bovinos , Doenças dos Bovinos/epidemiologia , Peste Suína Clássica/epidemiologia , Projetos Piloto , Febre Q/veterinária , Estudos Soroepidemiológicos , Suínos , Zoonoses/epidemiologiaRESUMO
Foot and Mouth Disease (FMD) is a high-impact, contagious transboundary animal disease that is endemic in Southeast Asia. Abattoir samples were routinely collected in six selected provinces between March and December 2019. A total of 1280 samples of abattoir animals were tested for FMD Non-Structural Protein (NSP) antibodies to indicate natural infections. Overall, 22.8% were seropositive for FMD NSP antibodies while seroprevalence of cattle (n = 469), buffalo (n = 214), and pigs (n = 597) were 44.6%, 35.0%, and 1.3%, respectively. The highest seroprevalence destination province was Xiengkhouang (35.3% of 272 samples), followed by Savannakhet (27.0% of 244 samples). Risk factors for evidence of natural infection identified by a multivariate logistic regression model included age groups (p-value = 0.02) and origin provinces (p-value = 2.8 × 10-5) of the animals. There were significant differences of FMD NSP seroprevalence between age groups and origin provinces of the animals. The odds ratio of a seropositive result in the less than 1 year old group was 2.5 (95% CI; 1.4, 4.4) when compared to the 3-4 years old group, while the odds ratios for animals that originated from Khammouane and Xiengkhouang provinces were 4.5 (95% CI; 1.1, 18.7) and 2.4 (95% CI; 1.4, 4.1), respectively, when compared to Champasak province. Serotype-specific antibody ELISA for 44 NSP antibody-positive samples revealed evidence of FMD serotypes O and A virus circulation in some provinces. Despite the passive abattoir survey providing useful information on FMD virus previous exposure and geographic locations of the animals, timely information on FMD virus circulation and distribution is also crucial to an effective control program. Alternative approaches to increase the cost-effectiveness of the surveillance network are also discussed.
Assuntos
Doenças dos Bovinos , Vírus da Febre Aftosa , Febre Aftosa , Doenças dos Suínos , Animais , Anticorpos Antivirais , Bovinos , Doenças dos Bovinos/epidemiologia , Surtos de Doenças , Ensaio de Imunoadsorção Enzimática/veterinária , Febre Aftosa/epidemiologia , Laos/epidemiologia , Estudos Soroepidemiológicos , Suínos , Doenças dos Suínos/epidemiologiaRESUMO
Foot and mouth disease (FMD) is a major animal health problem within Southeast Asia (SEA). Although Indonesia and more recently the Philippines have achieved freedom from FMD, the disease remains endemic on continental SEA. Control of FMD within SEA would increase access to markets in more developed economies and reduce lost productivity in smallholder and emerging commercial farmer settings. However, despite many years of vaccination by individual countries, numerous factors have prevented the successful control of FMD within the region, including unregulated 'informal' transboundary movement of livestock and their products, difficulties implementing vaccination programmes, emergence of new virus topotypes and lineages, low-level technical capacity and biosecurity at national levels, limited farmer knowledge on FMD disease recognition, failure of timely outbreak reporting and response, and limitations in national and international FMD control programmes. This paper examines the published research of FMD in the SEA region, reviewing the history, virology, epidemiology and control programmes and identifies future opportunities for FMD research aimed at the eventual eradication of FMD from the region.
Assuntos
Criação de Animais Domésticos/métodos , Pesquisa Biomédica/tendências , Controle de Doenças Transmissíveis/métodos , Controle de Doenças Transmissíveis/organização & administração , Febre Aftosa/epidemiologia , Febre Aftosa/prevenção & controle , Medicina Veterinária/tendências , Criação de Animais Domésticos/tendências , Animais , Sudeste Asiático/epidemiologia , Pesquisa Biomédica/história , Controle de Doenças Transmissíveis/história , Doenças Endêmicas , Febre Aftosa/história , História do Século XX , História do Século XXI , Medicina Veterinária/históriaRESUMO
In Cambodia, goat production and meat consumption are customary among Muslim communities. Recently, goat meat has gained popularity among Cambodians. Goat farmers use a traditional management system, including grazing, requiring minimal labour. The close proximity between humans and animals could increase the risk of zoonotic disease transmission. A serological survey was undertaken to estimate the prevalence of some priority zoonoses and high-impact animal diseases in the Cambodian goat population. A total of 540 samples were collected from goats in six provinces and analysed with commercially available enzyme-linked immunosorbent assays for Brucella species, Q fever (Coxiella burnetii), Foot and Mouth Disease virus non-structural protein (FMDV NSP) and Peste des Petits Ruminants virus (PPRV). True seroprevalences with a 95% Confidence Interval (CI), taking into account imperfect tests, risk factors and odds ratios (ORs), were calculated to better understand the disease distribution and epidemiology. Independent variables used in statistical modellings included sex, body condition score, age, vaccination history, province and commune, while dependent variables were ELISA test results. The overall true prevalence of antibodies to Brucella spp., C. burnetii, FMDV and PPRV, were 0.1% (95% CI 0.0, 1.0), 7.2% (95% CI 5.3, 9.7), 57.7% (95% CI 53.1, 62.3) and 0.0% (95% CI 0.0, 0.0), respectively. There was no identified risk factor for brucellosis and PPR. The two risk factors for C. burnetii seropositivity were sex (p-value = 0.0005) and commune (p-value <0.0001). However, only the OR of C. burnetii seropositive female goat was significant at 9.7 (95% CI 2.7, 35.5) times higher than male. The risk factors of FMD NSP seropositivity were age (p-value = 0.001) and commune (p-value <0.0001). Only the age 'more than two-year-old' group with a significant OR of 6.2 (95% CI 2.1, 18.4) using the 'up to one-year-old' group as the reference. In summary, Brucella spp. seroprevalence was low, while no evidence of PPRV antibodies was detected in the goat populations. C. burnetii seroprevalence in female goats was significantly higher than for males, and there were significant differences in C. burnetii seroprevalence between communes. The overall FMDV NSP seroprevalence was high, especially in older animals. Vaccination should be advocated to protect animals from FMDV and improve productivity. As the impacts of these zoonoses on human and animal health were still unknown, further investigation of these zoonotic diseases' epidemiology is recommended.
Assuntos
Brucella , Coxiella burnetii , Doenças das Cabras , Saúde Única , Febre Q , Doenças dos Ovinos , Animais , Humanos , Masculino , Feminino , Idoso , Pré-Escolar , Ovinos , Camboja/epidemiologia , Cabras , Estudos Soroepidemiológicos , Doenças das Cabras/epidemiologia , Zoonoses , Febre Q/epidemiologia , Ensaio de Imunoadsorção Enzimática/veterinária , Anticorpos Antivirais , Fatores de Risco , Doenças dos Ovinos/epidemiologiaRESUMO
A national animal disease surveillance network initiated by the Lao PDR government is adopted and reinforced by a joint research project between the National Animal Health Laboratory (NAHL), the Department of Livestock and Fisheries (DLF), and the Mahidol Oxford Tropical Medicine Research Unit (MORU). The network is strengthened by staff training and practical exercises and is utilised to provide zoonotic or high-impact disease information on a national scale. Between January and December 2020, large ruminant samples are collected monthly from 18 abattoirs, one in each province, by provincial and district agriculture and forestry officers. The surveillance network collected a total of 4247 serum samples (1316 buffaloes and 2931 cattle) over this period. Samples are tested for antibodies against Brucella spp., Coxiella burnetii (Q fever) and Foot-and-Mouth Disease Non-Structural Protein (FMD NSP) using commercial ELISA kits and the Rose Bengal test. Seroprevalences of Q fever and brucellosis in large ruminants are low at 1.7% (95% CI: 1.3, 2.1) and 0.7% (95% CI: 0.5, 1.0) respectively, while for FMD NSP it is 50.5% (95% CI: 49.0, 52.0). Univariate analyses show differences in seroprevalences of Q fever between destination (abattoir) province (p-value = 0.005), province of origin (p-value = 0.005), animal type (buffalo or cattle) (p-value = 0.0008), and collection month (p-value = 3.4 × 10−6). Similar to Q fever, seroprevalences of brucellosis were significantly different for destination province (p-value < 0.00001), province of origin (p-value < 0.00001), animal type (p-value = 9.9 × 10−5) and collection month (p-value < 0.00001), plus body condition score (p-value = 0.003), and age (p-value = 0.007). Additionally, risk factors of the FMD NSP dataset include the destination province (p-value < 0.00001), province of origin (p-value < 0.00001), sex (p-value = 7.97 × 10−8), age (p-value = 0.009), collection date (p-value < 0.00001), and collection month (p-value < 0.00001). Spatial analyses revealed that there is no spatial correlation of FMD NSP seropositive animals. High-risk areas for Q fever and brucellosis are identified by spatial analyses. Further investigation of the higher risk areas would provide a better epidemiological understanding of both diseases in Lao PDR. In conclusion, the abattoir serological survey provides useful information about disease exposure and potential risk factors. The network is a good base for field and laboratory staff training in practical technical skills. However, the sustainability of such a surveillance activity is relatively low without an external source of funding, given the operational costs and insufficient government budget. The cost-effectiveness of the abattoir survey could be increased by targeting hotspot areas, reducing fixed costs, and extending the focus to cover more diseases.
RESUMO
Although animal health surveillance programmes are useful for gaining information to help improve global health and food security, these programmes can be challenging to establish in developing economies with a low-resource base. This study focused on establishing a national surveillance system initiated by the Lao PDR government using a passive surveillance system of abattoir samples as a pilot model, and to gain information on contagious zoonoses, particularly Q fever and brucellosis, in the large ruminant population. A total of 683 cattle and buffalo samples were collected from six selected provinces of Lao PDR between March-December 2019. Out of 271 samples tested, six samples (2.2%, 95% confidence interval (CI) of 1.0, 4.8) were positive in the Q fever antibody ELISA test. Only one sample (out of 683; 0.2%, 95% CI 0.0, 0.8) tested positive to the Brucella antibody ELISA test. Seroprevalence of these important zoonoses in Lao PDR were relatively low in cattle and buffaloes; however, extensive animal movement within the country was identified which could increase risks of spreading transboundary diseases. The study highlights the importance of ongoing animal health surveillance and the need to find cost-effective approaches for its long-term sustainability.
RESUMO
African Swine Fever (ASF) is a transboundary animal disease of pigs and wild suids that appeared in Lao People's Democratic Republic (Lao PDR) in mid-2019, having spread across China and Vietnam in the months prior. Despite the scale of the Asian ASF pandemic and the availability of pen-side rapid diagnostic tests (RDT) on the market, few locally produced and easily available ASF RDTs have been evaluated for diagnostic accuracy. In this study, an ASF antigen detection RDT from Shenzhen Lvshiyuan Biotechnology Co. Ltd was evaluated using clinical field samples submitted to the National Animal Health Laboratory (NAHL) from ASF suspect cases between June and December 2019 in Lao PDR. Positive (nâ¯=â¯57) and negative (nâ¯=â¯50) samples of whole blood, serum and haemolysed serum were assessed by RDT and PCR, with the latter used as the gold standard reference comparator. Overall the RDT had a diagnostic sensitivity (DSe) of 65 %, 95 % CI [51-77] and diagnostic specificity (DSp) of 76 %, 95 % CI [62-87]. The RDT demonstrated improved performance on samples with lower PCR cycle threshold (ct) values with each additional cycle reducing the odds of the RDT returning a positive by 17 % relative to the previous cycle, 95 % CI [8 %-28 %] (Pâ¯<â¯0.01). While this test shows promise for field application, complete validation of diagnostic accuracy requires a larger sample size.
Assuntos
Febre Suína Africana , Febre Suína Africana/diagnóstico , Animais , Testes Diagnósticos de Rotina , Testes Imunológicos , Laos , Reação em Cadeia da Polimerase , SuínosRESUMO
Foot-and-mouth disease (FMD) causes sporadic disease outbreaks in the Lao People's Democratic Republic (Lao PDR) and appears to be endemic within a livestock population largely susceptible to infection. As Lao PDR is a major thoroughfare for transboundary animal movement, regular FMD outbreaks occur causing economic hardship for farmers and their families. The dominant serotype causing outbreaks between 1998 and 2006 was type O. Using phylogenetic analysis, type O isolated viruses were divided into two topotypes: South East Asia (SEA) and the Middle East-South Asia (ME-SA). Type A virus was reported only in 2003 and 2006 and type Asia 1 only in 1996 and 1998.
Assuntos
Doenças dos Bovinos/virologia , Vírus da Febre Aftosa/genética , Febre Aftosa/epidemiologia , Epidemiologia Molecular , Doenças dos Suínos/virologia , Animais , Sudeste Asiático/epidemiologia , Proteínas do Capsídeo/genética , Bovinos , Doenças dos Bovinos/epidemiologia , Febre Aftosa/virologia , Filogenia , Suínos , Doenças dos Suínos/epidemiologiaRESUMO
Classical swine fever (CSF) is a highly contagious and severe viral disease of swine resulting in substantial production losses in different farming systems in many regions of the world. The accurate and rapid detection of CSF outbreaks is reliant on sensitive and specific laboratory testing and is a key component of disease control. Specific detection of CSF virus can be achieved by virus isolation in tissue culture, antigen capture or the detection of viral RNA using molecular techniques. In order to reduce the time taken to achieve a diagnostic result and simplify testing methods, an antigen capture ELISA using immunomagnetic beads (IMB) as the solid phase was developed and compared to a microplate-based antigen capture (AC)-ELISA. The IMB-ELISA has up to 64-fold greater analytical sensitivity than the AC-ELISA and initial estimates of diagnostic sensitivity and specificity are 100%. The IMB-ELISA has a highly robust, rapid and stable test format and is simpler to perform than the AC-ELISA. The IMB-ELISA has the added advantage that a result can be sensitively and specifically determined by eye, lending it to the possibility of adaptation to a near-to-field test with minimal equipment or expertise needed.
Assuntos
Antígenos Virais/análise , Vírus da Febre Suína Clássica/imunologia , Separação Imunomagnética/veterinária , Doenças dos Suínos/diagnóstico , Doenças dos Suínos/virologia , Animais , Ensaio de Imunoadsorção Enzimática/veterinária , Separação Imunomagnética/métodos , Suínos , Doenças dos Suínos/imunologiaRESUMO
The E2 genes of 21 classical swine fever viruses (CSFV) were genetically characterized and compared with reference CSF viruses. The viruses originated from CSF outbreaks that occurred in the Lao People's Democratic Republic (Lao PDR) during 1997 though to 1999. All viruses characterized belonged to genogroup 2 and were members of subgroups 2.1 and 2.2. Results demonstrated a geographic delineation between subgroups 2.1 that was only found in the North-Central region, and subgroup 2.2 that was mostly found in the South-Central regions of Lao PDR. Although it was not possible to determine the origin of these viruses, it is probable that they may have been introduced to Lao PDR following cross-border trade. Alternatively, they have evolved independently of other viruses in the region.
Assuntos
Vírus da Febre Suína Clássica/classificação , Peste Suína Clássica/virologia , Proteínas do Envelope Viral/genética , Animais , Peste Suína Clássica/epidemiologia , Peste Suína Clássica/genética , Vírus da Febre Suína Clássica/genética , Vírus da Febre Suína Clássica/isolamento & purificação , Laos , Epidemiologia Molecular , Filogenia , SuínosRESUMO
The 5' non-coding region (5'-NCR) of 27 classical swine fever virus (CSFV) isolates from Lao People's Democratic Republic (Lao PDR) during 1997 and 1999 were amplified by RT-PCR. A 150-bp region of the 5'-NCR amplicons was analysed and compared with reference CSFV of European and Asian origin and a phylogenetic dendrogram constructed. Following analysis, all viruses were determined to belong to genogroup 2. Viruses from Lao PDR grouped on a geographical basis with the majority of northern/central isolates falling into subgroup 2.1 and southern/central isolates falling into subgroup 2.2. These results concur with previous studies of CSF viruses from Lao PDR, although this study recognized the first occurrence of subgroup 2.1 in southern Lao PDR.