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.     

Improvement in Smallholder Farmer Knowledge of Cattle Production,Health and Biosecurity in Southern Cambodia between 2008 and 2010

Farmer knowledge surveys were conducted in 2008 and 2010 in Cambodia to evaluate the impact of a research project studying interventions that can improve cattle production and health, including biosecurity and practices relating to risks of transmission of transboundary diseases. The project hypothesis is that by increasing the value of smallholder‐owned large ruminants through nutritional interventions and improved marketing, knowledge‐based interventions including risk management for infectious diseases such as foot‐and‐mouth disease (FMD) can be implemented into a more sustainable pathway for rural development. Between 2008 and 2010, significant improvements in farmer knowledge and attitudes were recorded in three villages in three provinces of southern Cambodia. This was achieved through participatory ‘applied field research’, ‘on the job’ training plus ‘formal’ training programmes. No cases of FMD were recorded during the study period in the ‘high‐intervention’ (HI) villages despite the common occurrence of the disease in a nearby ‘low‐intervention’ and many other villages in the three provinces. Whilst it is likely that protection of these villages from FMD infection was from increasing the herd immunity by vaccination, it could also have been partly because of a decrease in risk behaviours by farmers as a result of their increasing knowledge of biosecurity. The research indicates that smallholder farmers are motivated by nutritional interventions that improve the value of their cattle ‘bank’ and offer better marketing opportunities. This provides a more receptive environment for introduction of disease risk management for infectious and other production limiting diseases, best implemented for smallholder farmers in Cambodia by intensive training programmes. In lieu of a widespread public awareness programme to deliver mass education of smallholder farmers in disease prevention and biosecurity, livestock development projects in South‐East Asia should be encouraged to include training in disease risk management as an important intervention if the current momentum for trade in large ruminant livestock and large ruminant meat is to continue to progress and contribute to addressing global food security concerns.     

Assessment of Farmer Knowledge of Large Ruminant Health and Production in Developing Village‐Level Biosecurity in Northern Lao PDR

The purpose of this study was to determine baseline knowledge and identify knowledge gaps of farmers on biosecurity, risk of transmission of transboundary diseases and large ruminant health and production in three provinces of northern Laos, Hua Phan (HP), Luang Prabang (LPB) and Xieng Khoung (XK). The survey was conducted in six villages that are project sites for an Australian Centre for International Agricultural Research (ACIAR) project, with two villages located in each of the three provinces. A census survey was conducted by interview with all 238 farmers participating in the ACIAR project, using a structured questionnaire. The interviews were conducted in Lao language and took 1–2 h per farmer. The answers were recorded in Lao and the survey data were translated into English and transcribed into Microsoft Excel, and a linear mixed model in the Genstat statistical analysis package was used to compare quantitative traits between the target provinces. The results showed that the prediction mean of farmer knowledge scores on parasitic disorders, infectious disease, reproduction and nutrition management were significantly different between the target provinces. The prediction mean of farmer knowledge scores on infectious disease questions ranged between 5.11 in HP to 8.54 in XK of 24 marks (P < 0.001). The prediction mean of total knowledge scores was 13.48 in LPB and 19.29 in XK of 42 marks (P < 0.001). The results indicate both the need for and scope required to attain improvements in farmer knowledge of large ruminant health and production. It was concluded that a participatory research and extension programme to address village‐level biosecurity and reduce disease risks, plus enhance large ruminant production capabilities of smallholder producers, is a valid and potentially important strategy to address transboundary disease risk and rural poverty in northern Laos.     

Cost Implications of African Swine Fever in Smallholder Farrow‐to‐Finish Units: Economic Benefits of Disease Prevention Through Biosecurity

African swine fever remains the greatest limitation to the development of the pig industry in Africa, and parts of Asia and Europe. It is especially important in West and Central African countries where the disease has become endemic. Biosecurity is the implementation of a set of measures that reduce the risk of infection through segregation, cleaning and disinfection. Using a 122‐sow piggery unit, a financial model and costing were used to estimate the economic benefits of effective biosecurity against African swine fever. The outcomes suggest that pig production is a profitable venture that can generate a profit of approximately US$109 637.40 per annum and that an outbreak of African swine fever (ASF) has the potential to cause losses of up to US$910 836.70 in a single year. The implementation of biosecurity and its effective monitoring can prevent losses owing to ASF and is calculated to give a benefit‐cost ratio of 29. A full implementation of biosecurity will result in a 9.70% reduction in total annual profit, but is justified in view of the substantial costs incurred in the event of an ASF outbreak. Biosecurity implementation is robust and capable of withstanding changes in input costs including moderate feed price increases, higher management costs and marginal reductions in total outputs. It is concluded that biosecurity is a key to successful pig production in an endemic situation.     

Comparison of Web‐Based Biosecurity Intelligence Systems: BioCaster,EpiSPIDER and HealthMap

Three web‐based biosecurity intelligence systems – BioCaster, EpiSPIDER and HealthMap – are compared with respect to their ability to gather and analyse information relevant to public health. Reports from each system for the period 2–30 August 2010 were studied. The systems were compared to the volume of information that they acquired, their overlaps in this information, their timeliness, their sources, their focus on different languages and their focus on different geographical regions. Main results were as follows: EpiSPIDER obtains the most information and does so mainly through Twitter; no significant difference in systems’ timeliness was found; there is a relatively small overlap between the systems (10–20%); the systems have significant differences in their ability to acquire information relevant to different countries, which may be due to the sources they use and the languages they focus on.     

Assessment of Farm‐Level Biosecurity Measures after an Outbreak of Avian Influenza in the United Kingdom

During Avian Influenza outbreaks in England, the ‘AI Order’ states that a poultry keeper may be required to keep domestic birds separate from wild birds. This study aimed to assess a) how effectively this was done and b) the negative impact this had for bird owners and animal welfare during the November 2007 Highly Pathogenic Avian Influenza (HPAI) outbreak in Suffolk, UK. A voluntary questionnaire was posted to holdings (n = 296) that were within 10 km of an infected premises; these holdings were required to separate domestic and wild birds where possible. Holdings were identified during outbreak investigations conducted by the authorities. Holdings of all sizes were included. A sample of holdings received a follow‐up visit or telephone call to validate the questionnaire (n = 29). From the 38% of eligible holdings that responded, 13% (95% CI 7–22%) left their birds outdoors throughout the outbreak. If game birds were excluded, 9% (CI 4–17%) of holdings did not house their birds. Major cost and welfare problems were rare; however, there were exceptions. Enforced housing was often relaxed before a minor welfare problem deteriorated. Contact between wild and domestic birds was greatly reduced during the outbreak, resulting in a reduced probability of HPAI transmission via wild birds for most, but not all, holdings.     

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.     

Spatio‐Temporal Dynamics of African Swine Fever Outbreaks in Nigeria, 2002–2007

African swine fever (ASF) was first introduced into Nigeria through Lagos state in 1997. The disease rapidly spread to Ogun state in 1998 and extended to the Niger Delta (Delta, Rivers and Akwa Ibom states) in the same year. In 1998, Kaduna, Plateau and Benue states all north of the country experienced ASF for the first time. Poor farm biosecurity, bad abattoir practices and extensive/free range pig farming systems led to extensive spread of the diseases to about 16 Nigerian states excluding the far northwest and north east. A total of 1036 field samples collected over a 6‐year period covering 19 Nigerian states were analysed during the period under review; 805 samples were PCR positive and 231 negative. Positive samples were detected in all three surveillance phases and from all agroecological zones across the country. For the first time since its incursion, ASF was identified in some states; Bauchi, Adamawa Taraba and Gombe with chances of control very slim and further spread of the virus northward envisaged. Outbreaks of the disease are now a perennial problem with an increasing disease burden in areas where high numbers of pigs are produced in the country. The National Veterinary Research Institute (NVRI), Vom, since 2002 investigated ASF based on tissue submissions and reports made by individuals, private & commercial farms and agricultural bodies. We present an analysis of geographical and temporal distribution of ASF in the country from 2002 to 2007 and a review of historic outbreaks since the first incursion. Risk factors and prospects for control are discussed.     

Biosecurity and Circulation of Influenza A (H5N1) Virus in Live‐Bird Markets in Bangladesh, 2012

Bangladesh has been considered as one of the five countries endemic with highly pathogenic avian influenza A subtype H5N1 (HPAI H5N1). Live‐bird markets (LBMs) in south Asian countries are believed to play important roles in the transmission of HPAI H5N1 and others due to its central location as a hub of the poultry trading. Food and Agriculture Organization (FAO) of the United Nations has been promoting improved biosecurity in LBMs in Bangladesh. In 2012, by enrolling 32 large LBMs: 10 with FAO interventions and 22 without assistance, we assessed the virus circulation in the selected LBMs by applying standard procedures to investigate market floors, poultry stall floors, poultry‐holding cases and slaughter areas and the overall biosecurity using a questionnaire‐based survey. Relative risk (RR) was examined to compare the prevalence of HPAI H5N1 in the intervened and non‐intervened LBMs. The measures practised in significantly more of the FAO‐intervened LBMs included keeping of slaughter remnants in a closed container; decontamination of poultry vehicles at market place; prevention of crows’ access to LBM, market/floor cleaning by market committee; wet cleaning; disinfection of floor/poultry stall after cleaning; and good supply of clean water at market (P < 0.05). Conversely, disposal of slaughter remnants elsewhere at market and dry cleaning were in operation in more of the FAO non‐intervened LBMs (P < 0.05). The RR for HPAI H5N1 in the intervened and non‐intervened LBMs was 1.1 (95% confidence interval 0.44–2.76), suggesting that the proportion positive of the virus in the two kinds of LBM did not vary significantly (P = 0.413). These observations suggest that the viruses are still maintained at the level of production in farms and circulating in LBMs in Bangladesh regardless of interventions, albeit at lower levels than in other endemic countries.     

Transplacental Infection and Apparently Immunotolerance Induced by a Wild‐type Bluetongue Virus Serotype 8 Natural Infection

Until recently, bluetongue (BT) virus (BTV) serotypes reportedly causing transplacental infections were all ascribed to the use of modified live virus strains. During the 2007 BT epidemic in Belgium, a significant increase in the incidence of abortions was reported. A study including 1348 foetuses, newborns and young animals with or without suspicion of BTV infection, was conducted to investigate the occurrence of natural transplacental infection caused by wild‐type BTV‐8 and to check the immunocompetence of newborns. BTV RNA was present in 41% and 18.5% of aborted foetuses from dams with or without suspected BTV involvement during pregnancy, respectively. The results of dam/calf pairs sampled before colustrum uptake provide evidence of almost 10% transplacental BTV infection in newborns. Apparently immunotolerant calves were found at a level of 2.4%. The current study concludes that the combined serological and real‐time PCR (RT‐qPCR) result of pregnant dams gives no indication of the infection status of the offspring except in the case of a double negative result. In a group of 109 calves with clinical suspicion of BT, born during the vector‐free period, 11% were found to be RT‐qPCR positive. The true prevalence was estimated to be 2.3%, indicating the extent of transplacental infection in a group of 733 calves of one to 4 months of age without BT suspicion. Moreover, virus isolation was successful for two newborn calves, emphasizing the need for restricting trade to BT‐free regions of pregnant dams possibly infected during gestation, even if they are BTV RT‐qPCR negative.     

The Pathogenesis of Foot‐and‐Mouth Disease II: Viral Pathways in Swine,Small Ruminants,and Wildlife; Myotropism,Chronic Syndromes,and Molecular Virus–Host Interactions

Investigation into the pathogenesis of foot‐and‐mouth disease (FMD) has focused on the study of the disease in cattle with less emphasis on pigs, small ruminants and wildlife. ‘Atypical’ FMD‐associated syndromes such as myocarditis, reproductive losses and chronic heat intolerance have also received little attention. Yet, all of these manifestations of FMD are reflections of distinct pathogenesis events. For example, naturally occurring porcinophilic strains and unique virus–host combinations that result in high‐mortality outbreaks surely have their basis in molecular‐, cellular‐ and tissue‐level interactions between host and virus (i.e. pathogenesis). The goal of this review is to emphasize how the less commonly studied FMD syndromes and host species contribute to the overall understanding of pathogenesis and how extensive in vitro studies have contributed to our understanding of disease processes in live animals.     

A Refined Guinea Pig Model of Foot‐and‐Mouth Disease Virus Infection for Assessing the Efficacy of Antiviral Compounds

An antiviral containment strategy for foot‐and‐mouth disease (FMD) outbreaks could support or replace current contingency plans in case of an outbreak in Europe and could spare many healthy animals from being pre‐emptively culled. Recently, substantial progress has been made towards the development of small molecule drugs that inhibit FMD virus (FMDV) replication in vitro. For the initial in vivo evaluation of antiviral lead molecules, a refined FMDV‐infection model in guinea pigs (GP) is herewith described. This GP model was validated by demonstrating the antiviral effect of T‐1105 (an influenza virus inhibitor with reported activity against FMDV). Sixteen animals were orally administered with T‐1105 twice daily (400 mg/kg/day) for five consecutive days and inoculated intraplantarly with 100 GPID₅₀ of the GP‐adapted FMDV strain O₁ Manisa 1 h after the first administration. The efficacy of T‐1105 was compared with that of prophylactic vaccination with a highly potent double‐oil emulsion‐inactivated O₁ Manisa vaccine. Ten animals received a single, full (2 ml) cattle vaccine dose and were inoculated 3 weeks later. Fourteen T‐1105‐treated and all vaccinated GP were completely protected from generalization of vesicular lesions. At 2 dpi, viral RNA was detected in serum of 9/16 T‐1105‐treated and of 6/10 vaccinated animals. At 4 dpi, viral RNA was detected in serum, organs and oral swabs of half of the T‐1105‐treated animals and only in the serum of 1/10 of the vaccinated animals. Mean viral RNA levels in serum and organs of T‐1105‐treated and vaccinated animals were reduced compared to untreated controls (P < 0.01). T‐1105 conferred a substantial clinical and virological protection against infection with O₁ Manisa, similar to the protection afforded by vaccination. These results validate the suitability of the enhanced GP model for the purpose of initial evaluation of inhibitors of FMDV replication and illustrate the potential of selective inhibitors of viral replication to control FMD outbreaks.     

Detection of BPV‐1 and ‐2 and Quantification of BPV‐1 by Real‐Time PCR in Cutaneous Warts in Cattle and Buffaloes

Bovine cutaneous warts (CWs) were investigated in Northern India. Of 49 cases, 44 were recorded in cattle and 5 in buffaloes. These animals had mild to moderate grade infections. Grossly, cases of CWs appeared to be of exophytic type, however, different types of growth patterns were observed. A total of 26 biopsies (cattle 21 and buffaloes 5) from CWs‐affected animals studied histopathologically were diagnosed as exophytic and cauliflower‐like fibropapilloma 13, exophytic and dome‐shaped fibropapilloma 5, occult and/or fibroblastic type papilloma 3, cauliflower‐like papilloma 3, endophytic fibropapilloma 1 and fibroma 1. On PCR analysis, 11 CWs and 2 normal skin samples showed BPV‐1, ‐2 mixed infections. A rapid, sensitive and reliable real‐time SYBR Green PCR test to detect BPV‐1, BPV‐2 and to quantify BPV‐1 was developed. Results of amplification and dissociation plot of real‐time PCR revealed that six samples were BPV‐1 positive, eight were BPV‐2 positive and six were positive for both BPV‐1 and ‐2. CWs samples from different dairy farms testing positive for BPV‐1 by PCR assay were also positive using Quantitative real‐time SYBR Green PCR assay. For the first time, mixed infection of BPV‐1 and ‐2 was detected in India and BPV‐1 load was quantified by real‐time SYBR Green PCR assay.     

Clinical Pattern Characterization of Cattle Naturally Infected by BTV‐8

Forty‐one cattle from seven Belgian farms and two French farms confirmed as infected with bluetongue virus serotype 8 (BTV‐8) were monitored from the onset of clinical signs to describe the disease pattern and estimate the duration of blood RT‐qPCR and competitiveELISA positivity under field conditions. On each visit, blood samples were taken, and a standardized clinical form was filled in for each animal. A clinical score was calculated for every week until the end of clinical signs. A classification and regression tree (CART) analysis was conducted to determine the most important clinical signs every week for the first 7weeks. The highest scores were recorded within 2 weeks of clinical onset. The first recorded clinical signs were quite obviously visible (lethargy, conjunctivitis, lesions of nasal mucosa, nasal discharge). Skin lesions, a drop in milk production and weight loss appeared later in the course of the disease. A biphasic pattern regarding nasal lesions was noticed: the first peak concerned mainly congestive and ulcerative lesions, whereas the second peak mainly concerned crusty lesions. The median time estimated by survival analysis to obtain negative RT‐qPCR results from the onset of clinical signs was 195 days (range 166–213 days) in the 23 cattle included in the analysis. Serological results remained strongly positive until the end of the study. These results should ensure more accurate detection of an emerging infectious disease and are of prime importance in improving the modelling of BTV‐8 persistence in Europe.