Investigation of Foot and Mouth Disease hotspots in northern Lao PDR

Foot and mouth disease (FMD) is an endemic transboundary disease in the Mekong region, and FMD records of reports to animal health authorities in Lao PDR between 2009 and 2011 were reviewed. FMD outbreaks occurred in 2 of 3 years in eight districts in three of the eight northern Lao PDR provinces, locations suggested as FMD ‘hotspots’. The relatively higher risk of recurrence of FMD in these districts was likely due to the presence of a dense large ruminant population, extensive animal trading including transboundary movements and ineffective animal movement controls. As an understanding of the epidemiology of FMD in these ‘hotspots’ may offer insights into improved FMD control in the region, a study of an outbreak of FMD occurring in early 2010 following failure to vaccinate was conducted in the endemic ‘hotspot’ area of Paek district in Xiengkhoung province where in early 2009, a major outbreak of FMD in the district had been prevented in two villages by vaccination. The 2010 outbreak included collection of tissue samples 1 week after the onset of FMD that confirmed infection with FMD virus serotype O (Myanmar topotype) in a population of 239 large ruminants, comprising 167 cattle and 72 buffalo. A survey by interview of 30 farmers conducted in July 2010 documented high morbidity in cattle and buffalo (>90%) and identified disease risk factors, including increased trading of animals at the end of the rice harvest, plus several failures of biosecurity. In late 2010 and early 2011, a total of 40 and 72 serum samples were collected from large ruminants prior to and post‐FMD vaccination respectively and tested by LPB‐ELISA. Antibodies were present in the pre‐vaccination samples attributable to previous exposure to FMD virus and significantly rising post‐vaccination titres indicated likely temporary protection against future FMDV infection. It was concluded that to provide sufficient control of FMD in this ‘hotspot’, regular vaccination, particularly prior to the peak risk period in December‐February, plus improved farmer knowledge of disease transmission risk and biosecurity, is required. Although low rural education standards and language barriers because of multiple ethnic groups pose a challenge for the successful delivery of extension programmes in northern Lao PDR, training to improve disease recognition and reporting plus village‐level biosecurity practices is considered important in FMD ‘hotspots’ if sustainable regional initiatives directed at FMD control are to be achieved.     

Improving Smallholder Farmer Biosecurity in the Mekong Region Through Change Management

Transboundary animal diseases including foot‐and‐mouth disease and haemorrhagic septicaemia remain a major constraint for improving smallholder large ruminant productivity in the Mekong region, producing negative impacts on rural livelihoods and compromising efforts to reduce poverty and food insecurity. The traditional husbandry practices of smallholders largely exclude preventive health measures, increasing risks of disease transmission. Although significant efforts have been made to understand the social aspects of change development in agricultural production, attention to improving the adoption of biosecurity has been limited. This study reviews smallholder biosecurity risk factors identified in the peer‐reviewed literature and from field research observations conducted in Cambodia and Laos during 2006–2013, considering these in the context of a change management perspective aimed at improving adoption of biosecurity measures. Motivation for change, resistance to change, knowledge management, cultural dimensions, systems theory and leadership are discussed. Due to geographical, physical and resource variability, the implementation of biosecurity interventions suitable for smallholders is not a ‘one size fits all’. Smallholders should be educated in biosecurity principles and empowered to make personal decisions rather than adopt prescribed pre‐defined interventions. Biosecurity interventions should be aligned with smallholder farmer motivations, preferably offering clear short‐term risk management benefits that elicit interest from smallholders. Linking biosecurity and disease control with improved livestock productivity provides opportunities for sustainable improvements in livelihoods. Participatory research and extension that improves farmer knowledge and practices offers a pathway to elicit sustainable broad‐scale social change. However, examples of successes need to be communicated both at the ‘evidence‐based level’ to influence regional policy development and at the village or commune level, with ‘champion farmers’ and ‘cross‐visits’ used to lead local change. The adoption of applied change management principles to improving regional biosecurity may assist current efforts to control and eradicate transboundary diseases in the Mekong region.     

Avian Influenza H5N1 Surveillance and its Dynamics in Poultry in Live Bird Markets,Egypt

H5N1, a highly pathogenic avian influenza (H5N1 HPAI), is an endemic disease that is significant for public health in Egypt. Live bird markets (LBMs) are widespread in Egypt and play an important role in HPAI disease dynamics. The aim of the study was to evaluate the H5N1 HPAI prevalence in representative LBMs from 2009 to 2014, assess the effects of other variables and evaluate past outbreaks and human cases. It was found that ducks and geese are high‐risk species and that the prevalence of H5N1 HPAI was higher immediately after the political crises of 2011. The end of a calendar year (June to December) was a high‐risk period for positive samples, and the risk in urban LBMs was twice the risk in rural LBMs. Winter and political unrest was associated with higher H5N1 HPAI prevalence. Both human and poultry populations will continue to rise in Egypt, so continued poultry outbreaks are likely to be linked to more human cases. LBMs will continue to play a role in the dynamics of poultry disease in Egypt, and there is a need to reorganize markets in terms of biosecurity and traceability. It may also be beneficial to reduce inter‐governorate inter‐regional movements associated with poultry trade through promotion of regional trade or in the alternative provide sanitary features along the poultry market chain to reduce the speed of H5N1 HPAI infections. Policy formulation, design and enforcement must be pro‐poor, and consideration of the sociocultural and economic realities in Egypt is important. The LBMs provide ideal platforms to carry out sound surveillance plans and mitigate zoonotic risks of H5N1 HPAI to humans.     

Risk Factors for Highly Pathogenic Avian Influenza in Commercial Layer Chicken Farms in Bangladesh During 2011

A case–control study conducted during 2011 involved 90 randomly selected commercial layer farms infected with highly pathogenic avian influenza type A subtype H5N1 (HPAI) and 175 control farms randomly selected from within 5 km of infected farms. A questionnaire was designed to obtain information about potential risk factors for contracting HPAI and was administered to farm owners or managers. Logistic regression analyses were conducted to identify significant risk factors. A total of 20 of 43 risk factors for contracting HPAI were identified after univariable logistic regression analysis. A multivariable logistic regression model was derived by forward stepwise selection. Both unmatched and matched analyses were performed. The key risk factors identified were numbers of staff, frequency of veterinary visits, presence of village chickens roaming on the farm and staff trading birds. Aggregating these findings with those from other studies resulted in a list of 16 key risk factors identified in Bangladesh. Most of these related to biosecurity. It is considered feasible for Bangladesh to achieve a very low incidence of HPAI. Using the cumulative list of risk factors to enhance biosecurity pertaining to commercial farms would facilitate this objective.     

Limiting the Impacts of Foot and Mouth Disease in Large Ruminants in Northern Lao People’s Democratic Republic by Vaccination: A Case Study

Foot and mouth disease (FMD) is the most important global transboundary livestock disease and is endemic in Lao People’s Democratic Republic (Lao PDR) with outbreaks occurring regularly. Lao PDR shares borders with five countries and as a major thoroughfare for transboundary livestock movement, is vulnerable to the social and economic impacts of FMD. The FMD outbreak occurred in January 2009 in the Pek District, located in the north‐eastern Lao PDR province of Xieng Khuang and involved all 111 villages in that district. In March 2009, we conducted a case study on the impacts of FMD in four villages in Pek District. In two villages cattle and buffalo were vaccinated for FMD recently and prior to the outbreak as part of an ongoing research project. In one of these villages, all cattle and buffalo were vaccinated and just over half the large ruminant population was vaccinated in the other village. The other two villages involved in the case study were located nearby but not part of the ongoing research project and no animals had been vaccinated. Data were collected from the four villages by interviewing the village animal health worker in each village using a standard questionnaire. Morbidity rates for the fully vaccinated village were 1% and 7.9% for the partially vaccinated village and were much lower compared with the two adjacent, unvaccinated villages where morbidity rates were 61% and 74.3% respectively. Estimates of the financial losses incurred were USD 1.7–1.9 per cow or buffalo for the fully vaccinated village, USD 6.9–8.1 for the partly vaccinated village and 52.4–70.8 USD in the unvaccinated villages, providing evidence that a large opportunity cost is incurred by failing to vaccinate in areas where the risk of FMD incursions is high.     

The Socioeconomic Impacts of Clinically Diagnosed Haemorrhagic Septicaemia on Smallholder Large Ruminant Farmers in Cambodia

Haemorrhagic septicaemia (HS) is an acute fatal infectious disease of mainly cattle and buffalo and outbreaks occur commonly in Cambodia. Disease outbreak reports were examined to select five villages from three provinces for a retrospective investigation of HS epidemiology and socioeconomic impact on smallholders, with an aim of identifying potential benefits from improving disease prevention through biosecurity and vaccination. The Village Animal Health Worker (VAHW) or Chief in each village and 66 affected smallholders were surveyed. At the village level, 24% of all households were affected with an estimated mean village herd morbidity of 10.1% and mortality of 28.8%. Affected farmers reported HS disease morbidity and mortality at 42.7% and 63.6% respectively. Buffalo had a higher morbidity (OR = 2.3; P = 0.003) and mortality (OR = 6.9; P < 0.001) compared with cattle, and unvaccinated large ruminants a higher morbidity (OR = 2.9; P = 0.001). The financial impact varied depending on whether the animal survived, provision of treatment, draught replacement and lost secondary income. The mean cost per affected household was USD 952.50 based on ownership of five large ruminants. The impact per affected animal was USD 375.00, reducing the pre‐disease value by 66.1%. A partial budget revealed an overwhelming incentive for farmers to practice biannual vaccination, with a net benefit of USD 951.58 per household based on an annual disease incidence rate of 1. Sensitivity analysis showed that a net benefit of USD 32.42 remained based on an outbreak every 20 years. This study indicates HS can cause a catastrophic financial shock to smallholders and remains a critical constraint to improving large ruminant productivity and profitability. Addressing HS disease control requires a focus on improving smallholder farmer knowledge of biosecurity and vaccination and should be priority to stakeholders interested in addressing regional food insecurity and poverty reduction.     

Risk for Highly Pathogenic Avian Influenza H5N1 Virus Infection in Chickens in Small‐Scale Commercial Farms,in a High‐Risk Area,Bangladesh, 2008

Small‐scale commercial chicken farms (FAO‐defined system 3) with poor biosecurity predominate in developing countries including Bangladesh. By enroling fifteen highly pathogenic avian influenza (HPAI) cases occurring in such farms – (February – April 2008) and 45 control farms (March–May 2008) with similar set up, we conducted a case–control study to evaluate the risk factors associated with HPAI H5N1 virus infections in chickens reared in small‐scale commercial farms in a spatially high‐risk area in Bangladesh. Data collected by a questionnaire from the selected farms were analysed by univariable analysis and multivariable conditional logistic regression. The risk factors independently associated were ‘dead crow seen at or near farm’ [odds ratio (OR) 47.4, 95% confidence interval (CI) 4.7–480.3, P = 0.001], ‘exchanging eggtrays with market vendors’ (OR 20.4, 95% CI 1.9–225.5, P = 0.014) and ‘mortality seen in backyard chicken reared nearby’ (OR 19.4, 95% CI 2.8–131.9, P = 0.002). These observations suggest that improved biosecurity might reduce the occurrence of HPAI outbreaks in small‐scale commercial farms in Bangladesh.     

Assessment of Biosecurity Measures Against Highly Pathogenic Avian Influenza Risks in Small‐Scale Commercial Farms and Free‐Range Poultry Flocks in the Northcentral Nigeria

There is considerable global concern over the emergence of highly pathogenic avian influenza (HPAI) that has affected domestic poultry flocks in Nigeria and other parts of the world. There have been little investigations on the proposition that free‐range flocks are potentially at higher risk of HPAI than confined small‐scale commercial enterprises. The objective is to analyse the biosecurity measures instituted in the small‐scale commercial poultry farms and established free‐range bird flocks owned by households in the rural areas and qualitatively assess the risk status at the two levels of poultry management systems in northcentral Nigeria. We used data collected through questionnaire administration to farms and flock owners and subjected them to a traffic light system model to test for relative risks of HPAI infection based on the biosecurity measures put in place at the farm and flock levels. The results indicate that free‐range flocks are at lower risk compared to small‐scale commercial operations. These findings are plausible as birds from free‐range flocks have more opportunities to contact wild bird reservoirs of low‐pathogenic avian influenza (LPAI) strains than small‐scale commercial poultry, thus providing them with constant challenge and maintenance of flock immunity. The development of efficient and effective biosecurity measures against poultry diseases on small‐scale commercial farms requires adequate placement of barriers to provide segregation, cleaning and disinfection, while concerted community–led sanitary measures are required for free‐range poultry flocks in the developing topical and subtropical economies.     

Emergence of an exotic strain of serotype O foot‐and‐mouth disease virus O/ME‐SA/Ind‐2001d in South‐East Asia in 2015

The O/Middle East‐South Asia (ME ‐SA )/Ind‐2001 lineage of foot‐and‐mouth disease virus (FMDV ) is endemic in the Indian subcontinent and has been reported in the Middle East and North Africa, but it had not been detected in South‐East Asia (SEA ) before 2015. This study reports the recent incursions of this viral lineage into SEA , which caused outbreaks in Vientiane Capital of Lao People's Democratic Republic (PDR ) in April 2015, in Dak Nong, Dak Lak and Ninh Thuan Provinces of Vietnam from May to October 2015, and in Rakhine State of Myanmar in October 2015. Disease investigations were conducted during the outbreaks and followed up after laboratory results confirmed the involvement of FMDV O/ME ‐SA /Ind‐2001 sublineage d (O/ME‐SA/Ind‐2001d). Affected host species included cattle, buffalo and pig, and all the outbreaks resolved within 2 months. Animals with clinical signs were separated, and affected premises were disinfected. However, strict movement restrictions were not enforced, and emergency vaccinations were only implemented in Vientiane Capital of Lao PDR and Dak Nong and Ninh Thuan Provinces of Vietnam. Clinical samples were collected from each outbreak and examined by nucleotide sequencing of the FMDV viral protein 1 coding region. Sequence analysis revealed that the O/ME ‐SA /Ind‐2001d isolates from Lao PDR and Vietnam were closely related to each other and similar to viruses previously circulating in India in 2013. Viruses collected from Myanmar were divergent from viruses of the same sublineage recovered from Lao PDR and Vietnam but were closely related to viruses present in Bangladesh in 2015. These findings imply that at least two independent introductions of O/ME ‐SA /Ind‐2001d into SEA have occurred. Our study highlights the transboundary nature of foot‐and‐mouth disease (FMD ) and reinforces the importance of improved FMD surveillance and promotion of safer cross‐border trade in SEA to control the risk of introduction and spread of exotic FMDV strains.     

Perspectives on Australian Animal Health Aid Projects in South‐East Asia

Future food security poses many challenges and with increasing prosperity and demand for meat, the emerging but largely unregulated trade in livestock and their products from developing countries in South‐East Asia and particularly the Mekong region, pose enormous risks of transboundary disease epidemics. However this is a challenge that should be met as substantial improvements in large ruminant production through appropriate knowledge‐based interventions can potentially move the largely rural smallholder populations of Lao PDR and Cambodia from subsistence to a productivity focus, offering a new pathway for poverty alleviation. Large development projects have been implemented in the Mekong region to facilitate this process and research is needed to define problems, identify and test solutions, and then suggest the most appropriate delivery mechanisms for promulgating the interventions that are most sustainable. Animal health aid projects are needed to improve livestock productivity, minimize risk to trade and human health and enhance the capacities of countries where there are significant gaps in the provision of veterinary services. Improving large ruminant production, particularly through forages technology and infectious disease risk management including village‐level biosecurity, provides a potential driver of foot and mouth disease (FMD) control and eventual eradication in the region. A perspective on issues involved in Australian aid projects addressing regional animal health research and development and a checklist of strategies to consider when designing and managing such projects is provided.     

Factors influencing chicken farmers' decisions to implement prevention and control measures to reduce avian influenza virus spread under endemic conditions

The ongoing circulation of Highly Pathogenic Avian Influenza (HPAI) H5N1 poses a threat to both poultry and public health. Adapting the constructs of the Health Belief Model (HBM) framework, we investigated perceptions of backyard, commercial broiler and layer chicken farmers to implement HPAI prevention and control measures in Bangladesh. Two cross‐sectional studies were conducted in 2016 and 2017 on 144 backyard, 106 broiler and 113 layer chicken farms. Using Structural Equation Modelling, we modelled the direct and indirect effects on farmers' perceptions on taking HPAI prevention and control actions. Our results indicate that farmers of different chicken production systems have different decision‐making processes. While perceived barriers to the implementation of prevention and control measures (e.g. wearing protective equipment when handling chickens) prevented both broiler and backyard farmers to adopt interventions, perceived benefits of measures (e.g. maintaining high biosecurity will reduce the risk of birds becoming sick) strongly influenced commercial farmers' decisions, but not backyard farmers' decisions. Information provided on HPAI through media, meetings or via information campaigns played an important role in farmers' decision‐making in all production systems. Outcomes of this research can be used to tailor advice on HPAI control and prevention to different poultry farming groups by accounting for specific factors influencing their decision‐making, instead of using one‐size‐fit‐all communication approach.     

Assessing Potential Risks of Influenza A Virus Transmission at the Pig–Human Interface in Thai Small Pig Farms Using a Questionnaire Survey

Influenza A viruses pose a major public health threat worldwide, especially due to the potential for inter‐species transmission. Farmers could be among the first people to be infected with a novel reassortant virus in a pig herd and may serve as a source of the virus for their communities. In this study, the pig production systems of smallholders in rural Thailand were examined to qualitatively evaluate the potential risks that may contribute to the spread of influenza A viruses. The investigation was based on questionnaire interviews regarding pig farmers' practices and trading activities. We found that extensive pig–human contacts, commingling of pigs and chickens and suboptimal biosecurity practices adopted by farmers and traders may constitute substantial risks for inter‐species influenza virus transmission, thereby posing a threat to pig populations and human public health. The regular practices of using manure as field fertilizer, hiring boars from outside and trading activities could contribute to the potential spread of influenza viruses in the local community. To mitigate the potential risks of influenza A virus transmission and spread in the local community, it is recommended that appropriate public health strategies and disease prevention policies for farmers and traders should be developed including improving biosecurity, encouraging separation of animals raised on farms and minimizing the exposure between pigs and humans. Furthermore, surveillance systems for pig diseases should be targeted around the festival months, and on‐farm identification of pigs should be promoted.     

Identification of Potential Risk Factors Associated with Highly Pathogenic Avian Influenza Subtype H5N1 Outbreak Occurrence in Lagos and Kano States,Nigeria, During the 2006–2007 Epidemics

Highly pathogenic avian influenza HPAI H5N1 was first reported in Africa in 2006, in Nigeria. The country experienced severe outbreaks in 2006 and 2007, strongly affecting the poultry population. Current knowledge on potential risk factors for HPAI H5N1 occurrence in poultry farms in Nigeria is limited. Therefore, we conducted a case–control study to identify potential farm‐level risk factors for HPAI H5N1 occurrence in two areas of the country that were affected by the disease in 2006 and 2007, namely the States of Lagos and Kano. A case–control study was conducted at the farm level. A convenience sample of 110 farms was surveyed. Data on farm characteristics, farm management and trade practices were collected. Logistic regression was used to identify factors associated with farms that confirmed positive for HPAI. Having a neighbouring poultry farm was identified as a potential risk factor for disease occurrence [OR, 5.23; 95% CI, (0.88–30.97); P‐value = 0.048]. Farm staff washing their hands before handling birds was a protective factor [OR, 0.14; 95% CI, (0.05–0.37); P‐value <0.001], as well as not allowing traders to enter the farm [OR, 0.23; 95% CI, (0.08–0.70); P‐value = 0.008]. Our study highlighted the importance of trade and proximity between poultry farms in the epidemiology of HPAI H5N1 and the role of biosecurity in disease prevention in Kano and Lagos States. Despite the limitations owing to the sampling strategy, these results are consistent with other risk factor studies previously conducted on HPAI H5N1 in both Africa and other regions, suggesting similar risk factor patterns for HPAI H5N1 virus spread and substantiating current knowledge regarding the epidemiology of the disease. Finally, this study generated information from areas where data are difficult to obtain.     

Highly pathogenic avian influenza subtype H5Nx clade 2.3.4.4 outbreaks in Dutch poultry farms, 2014–2018: Clinical signs and mortality

In recent years, different subtypes of highly pathogenic avian influenza (HPAI) viruses caused outbreaks in several poultry types worldwide. Early detection of HPAI virus infection is crucial to reduce virus spread. Previously, the use of a mortality ratio threshold to expedite notification of suspicion in layer farms was proposed. The purpose of this study was to describe the clinical signs reported in the early stages of HPAI H5N8 and H5N6 outbreaks on chicken and Pekin duck farms between 2014 and 2018 in the Netherlands and compare them with the onset of an increased mortality ratio (MR). Data on daily mortality and clinical signs from nine egg‐producing chicken farms and seven Pekin duck farms infected with HPAI H5N8 (2014 and 2016) and H5N6 (2017–2018) in the Netherlands were analysed. In 12 out of 15 outbreaks for which a MR was available, MR increase preceded or coincided with the first observation of clinical signs by the farmer. In one chicken and two Pekin duck outbreaks, clinical signs were observed prior to MR increase. On all farms, veterinarians observed clinical signs of general disease. Nervous or locomotor signs were reported in all Pekin duck outbreaks, but only in two chicken outbreaks. Other clinical signs were observed less frequently in both chickens and Pekin ducks. Compared to veterinarians, farmers observed and reported clinical signs, especially respiratory and gastrointestinal signs, less frequently. This case series suggests that a MR with a set threshold could be an objective parameter to detect HPAI infection on chicken and Pekin duck farms at an early stage. Observation of clinical signs may provide additional indication for farmers and veterinarians for notifying a clinical suspicion of HPAI infection. Further assessment and validation of a MR threshold in Pekin ducks are important as it could serve as an important tool in HPAI surveillance programs.     

Highly Pathogenic Avian Influenza H5N8 Clade 2.3.4.4 Virus: Equivocal Pathogenicity and Implications for Surveillance Following Natural Infection in Breeder Ducks in the United Kingdom

Since early 2014, several outbreaks involving novel reassortant highly pathogenic avian influenza (HPAI) A(H5N8) viruses have been detected in poultry and wild bird species in Asia, Europe and North America. These viruses have been detected in apparently healthy and dead wild migratory birds, as well as in domestic chickens, turkeys, geese and ducks. In this study, we describe the pathology of an outbreak of H5N8 HPAIV in breeder ducks in the UK. A holding with approximately 6000 breeder ducks, aged approximately 60 weeks, showed a gradual reduction in egg production and increased mortality over a 7‐day period. Post‐mortem examination revealed frequent fibrinous peritonitis, with severely haemorrhagic ovarian follicles and occasional splenic and pancreatic necrosis and high incidence of mycotic granulomas in the air sacs and lung. Low‐to‐moderate levels of HPAI H5N8 virus were detected mainly in respiratory and digestive tract, with minor involvement of other organs. Although histopathological examination confirmed the gross pathology findings, intralesional viral antigen detection by immunohistochemistry was not observed. Immunolabelled cells were rarely only present in inflamed air sacs and serosa, usually superficial to granulomatous inflammation. Abundant bacterial microcolonies were observed in haemorrhagic ovaries and oviduct. The limited viral tissue distribution and presence of inter‐current fungal and bacterial infections suggest a minor role for HPAIV H5N8 in clinical disease in layer ducks.     

Determinants of biosecurity practices in French duck farms after a H5N8 Highly Pathogenic Avian Influenza epidemic: The effect of farmer knowledge,attitudes and personality traits

Biosecurity is crucial for infectious disease prevention, more importantly in the absence of vaccination. The need for improving the implementation of biosecurity practices was highlighted in French duck farms following the 2016–2017 H5N8 Highly Pathogenic Avian Influenza (HPAI) epidemic. Farmers have multiple reasons for not implementing biosecurity practices: external (time, money) and internal (socio‐psychological). The purpose of this study was to determine how sets of socio‐psychological factors (i.e. knowledge on biosecurity and avian influenza transmission, attitudes, personality traits, social background) affect the adoption of on‐farm biosecurity practices. Biosecurity practices and socio‐psychological determinants were assessed during 127 duck farm visits, in South West France, using both questionnaires and on‐farm observations. Factorial analysis of mixed data (FAMD) and hierarchical clustering analysis (HCA) identified three groups of farmers with different socio‐psychological profiles: the first group was characterized by minimal knowledge, negative attitudes towards biosecurity, little social pressure and a low level of conscientiousness. The second group was characterized by more extensive experience in poultry production, higher stress and social pressure. The third group was characterized by less experience in poultry production, better knowledge and positive attitudes towards biosecurity, increased self‐confidence and orientation towards action. The first group had a significantly lower adoption of biosecurity measures than the two other groups. A better understanding of the factors involved in farmers' decision‐making could improve the efficiency of interventions aiming at improving and maintaining the level of on‐farm biosecurity in the duck industry.     

Surveillance and investigative diagnosis of a poultry flock in Great Britain co‐infected with an influenza A virus and an avirulent avian avulavirus type 1

A detailed veterinary and laboratory investigation revealed an unusual case of concurrent avian avulavirus type 1 (AAvV‐1, formerly called avian paramyxovirus type 1) and low pathogenicity avian influenza (LPAI) virus infections of chickens during March 2010 in a mixed poultry and livestock farm in Great Britain. Respiratory signs and daily mortality of 5–6 birds in a broiler flock 8‐weeks of age prompted submission of two carcasses to an Animal and Plant Health Agency (APHA) regional laboratory. Infectious bronchitis virus infection was suspected initially and virus isolation in SPF embryonated fowls’ eggs was attempted at APHA‐Weybridge. Avirulent AAvV‐1 was detected in the first sampling. Both in vitro nucleotide sequencing of the fusion gene and in vivo pathotyping by intracerebral pathogenicity index revealed an avirulent AAvV‐1 not definitively ascribed to licensed vaccine. Upon initial detection of the AAvV‐1 virus, statutory restrictions were placed on the farm, an official veterinary visit was performed and further samples were submitted to APHA‐Weybridge for official statutory disease investigation. An H2N3 LPAI virus was subsequently isolated from tissue samples and swabs submitted from the follow‐up statutory investigation. The subtype was confirmed by haemagglutination inhibition test (HAIT) and neuraminidase inhibition (NI) tests on egg‐amplified virus. As neither virus was notifiable according to the internationally recognized EU and OIE standards, and/or definitions of disease, statutory farm restrictions were lifted. Veterinary investigations identified the broiler flock to be free‐range, next to a river and duck pen, reinforcing the suspicion of wild bird origin for both viruses which may have been co‐circulating in ducks. It could not, however, be established as to whether there were separate introductions of the two viruses or whether there had been a single co‐introduction of the viruses. The described case highlights the value of integrated surveillance and laboratory approaches, including veterinary field investigations, international standards and definitions of notifiable avian disease, validated RRT‐PCR assays, and virus isolation in achieving rapid and accurate diagnostic results.     

On‐farm Study of Human Contact Networks to Document Potential Pathways for Avian Influenza Transmission between Commercial Poultry Farms in Ontario,Canada

Human movements associated with poultry farming create contact networks that might facilitate transmission of avian influenza (AI) between farms during outbreaks. In Canada, no information is available about how these networks connect poultry farms. The purpose of this study was to document human contacts between commercial poultry farms in Ontario, Canada, to learn how AI might be transmitted during outbreaks. We used face‐to‐face interviews with people entering the farm biosecurity perimeter on four layer, one turkey and three broiler breeder poultry farms in Ontario to collect information on between‐farm contacts and biosecurity practices. Over a four‐day study period on each farm, a median of 10.5 people entered the farm biosecurity perimeter (range 2–31). Ninety‐six per cent (111/118) of people consented to be interviewed. Of these, fifty‐three per cent (59/111) had contact with one or more (median 2, degree range 1–14) other poultry farms within 72 h. A median of 25 (range 7–65) human contacts linked study farms to other poultry farms. The mean distance of between‐farm contacts was 53 km. Eighty‐six per cent of people who answered the biosecurity questions (94/109) reported using one or more biosecurity practices. However, on 7/8 farms, at least one person reported that they did not use any biosecurity practices. Fifty per cent of social visitors used biosecurity, whereas 96% of all other people used biosecurity. Ninety‐two per cent of people that entered the poultry barns (46/50) used one or more biosecurity practices, whereas 81% of people (48/59) that did not enter the poultry barns used one or more biosecurity practices. Because our study documented farm visitors who did not use any biosecurity practices and moved between commercial poultry farms, we suggest that rapid trace‐out of human movements is as important as containment zoning to limiting disease spread during an outbreak of highly pathogenic AI in Ontario.     

Spatio‐temporal distribution of outbreaks of highly pathogenic avian influenza virus subtype H5N1 in Vietnam, 2015– 2018

Despite strong commitments of the central and provincial veterinary authorities in Vietnam to control highly pathogenic avian influenza H5N1 (HPAI‐H5N1) in poultry and to diminish the risk of human infection, outbreaks continue to occur in poultry. This study describes the spatio‐temporal distribution of HPAI‐H5N1 outbreaks in Vietnam for the period December 2014–April 2018 using the space‐time K‐function and the space‐time scan statistic. The space‐time K‐function analyses showed statistically significant spatio‐temporal clustering of HPAI‐H5N1 outbreaks in poultry during the study period of up to 50 days and 60 kilometres. The space‐time scan statistic test identified three statistically significant space‐time clusters of HPAI‐H5N1 in the south of the country where the incidence of HPAI‐H5N1 outbreaks was greater than that expected if outbreaks were randomly distributed in space and time. The analyses indicated shortfalls in the effectiveness of control measures used to control HPAI‐H5N1 throughout the study period. Development of a better understanding of the relative impact of HPAI‐H5N1 control measures (depopulation of infected flocks, vaccination, movement restrictions) on space‐time interaction would allow animal health authorities to focus their efforts on control measures shown to have the greatest relative effect.