Co-created community contracts support biosecurity changes in a region where African swine fever is endemic - Part II: Implementation of biosecurity measures.

Smallholder subsistence pig production is common in Uganda and African swine fever (ASF) is endemic in the country, with its spread driven by human activities along the smallholder value chain. Previous research in the study area has revealed that many stakeholders are aware of how ASF is spread, its prevention and control, and have a generally positive attitude towards biosecurity. Despite this, even basic biosecurity is largely lacking. Costs, as well as a lack of adaptation to the local context, culture and traditions have been identified as factors hindering biosecurity implementation. Community engagement and local ownership of disease problems are increasingly recognised as important for improving disease prevention and control. The objective of this study was to investigate the capacity of participatory action at community level with broad inclusion of stakeholders to improve biosecurity in the smallholder pig value chain. Specific attention was paid to participants' perceptions and experiences of implementing the biosecurity measures included in their co-created community contracts. The study was conducted in Northern Uganda in villages purposively selected on the basis of previous occurrences of ASF. In each village, farmers and traders were also purposively selected. At a first meeting, basic information about ASF was shared and participants presented with a list of biosecurity measures adapted for farmers and traders respectively. Participants discussed each measure in farmer and trader subgroups, decided on the measures to implement for one year, and signed a community contract to this effect. The following year, interviews were again undertaken and implementation support given. Interview data were coded and thematically analysed. Each subgroup chose a minimum of three and a maximum of nine measures, with wide variations between villages in their selection of measures. At the follow-ups, none of the subgroups had fully implemented what had been agreed in their contract, but all had changed some of their biosecurity routines. Some frequently recommended biosecurity measures, such as not borrowing breeding boars, were not considered feasible. Relatively simple and cheap biosecurity measures were rejected for reasons of cost, highlighting the participants' general level of poverty and the relevance of poverty as a specific factor governing disease control results. The participatory methodology allowing for discussions, co-creation and the option to refuse measures seemed to facilitate the implementation of measures that had initially been thought to be controversial. The broad community approach was deemed to be positive for strengthening community identity, cooperation and implementation.

Survival of Streptococcus equi subsp. equi in Normal Saline Versus Phosphate-Buffered Saline and at Two Different Temperatures.

Streptococcus equi subsp. equi causes strangles in horses. Sampling to detect carriers is important for the control of the disease, and maximizing the sensitivity of this procedure is necessary. To provide a basis for the choice of sampling solution and transport temperature for samples, comparisons were made between the survival of Streptococcus equi subsp. equi in normal saline versus phosphate-buffered saline and at two different temperatures (cold and room temperature). At present, normal saline is used to sample the nasopharynx as well as the guttural pouches, and the sampling solution is transported without special cooling. The results revealed no significant difference in bacterial concentration levels between the two sampling solutions, but a significantly higher concentration of viable bacteria in the samples kept cold compared with room temperature. Hence, a change of sampling solution is not warranted, but maintaining the cold chain during storage and transport to the laboratory may be important for clinical samples.

Smallholders' perceptions on biosecurity and disease control in relation to African swine fever in an endemically infected area in Northern Uganda.

BACKGROUND: In Africa, intensified pig production is frequently accompanied by increased occurrence of African swine fever (ASF) outbreaks, leading to high case fatality rates and socio-economic impact for the farmers. ASF control relies on prevention of disease transmission and control of outbreaks. The aim of this study was to increase the understanding on how the knowledge of ASF epidemiology and control can be transferred into successfully implemented biosecurity interventions on farm and community level. Structured interviews with 200 randomly selected, pig-keeping households in northern Uganda were undertaken three times. Perceptions related to general biosecurity and hypothetical control interventions and attitudes towards pig farming were investigated by measuring the agreement to statements using a Likert scale. RESULTS: Respondents generally conveyed positivism towards pig farming, biosecurity, and the potential of biosecurity for preventing ASF outbreaks. These positive attitudes, as well as the will to invest in biosecurity, were reduced in households that had experienced ASF outbreaks. Among the control interventions change of boots before entering the pig stable was highly accepted and seasonal adaptation of pig rearing times accepted on medium level. Statements on preventive sales of healthy pigs in connection with outbreaks and on buying pork products from slaughter operations receiving ASF-contact pigs received low acceptance, increasing, however, for households that had experienced ASF outbreaks. Consumption of pork from ASF infected pigs was generally not accepted, medium level of agreement was expressed for statements on the zoonotic potential of ASF and for neutralizing ASF by cooking. CONCLUSIONS: To gain in-depth understanding of the complexity of people's behaviour, reasoning and decision-making processes, deeper involvement of the social sciences and a qualitative research approach might be used for further studies. Communicating information regarding the ASF not being zoonotic, and how the virus is neutralized will be important for increasing acceptance and enhancing implementation for the hypothetical control interventions preventive sales, safe slaughter, and consumption of processed and safe pork. Likewise, participatory development to adopt any control interventions to the local context on community level will be necessary for successful implementation.

Water quality modelling: microbial risks associated with manure on pasture and arable land.

While agricultural activities, such as the application of manure on arable land and animal grazing on pastures, provide economic and environmental benefits, they may also pose microbial risks to water sources. The aim of this paper was to study the microbial fate and transport in an agricultural catchment and recipient water source through further development of the hydrological model HYPE. Hydrological modelling was combined with hydrodynamic modelling to simulate the fate and transport of Salmonella spp., verotoxin-producing Escherichia coli O157:H7 (VTEC) and Cryptosporidium parvum in an agricultural catchment of a drinking water source, Lake Vombsjön, in Sweden. This approach was useful to study the influence of different processes on the pathogen fate and transport, and to interpret the relative changes in the simulated concentrations. Sensitivity analysis indicated that the largest uncertainties in the model were associated with the estimation of pathogen loads, parameterisation of the pathogen processes, and simulation of partitioning between surface runoff and infiltration. The proposed modelling approach is valuable for assessing the relative effect of different risk-reducing interventions.

Patterns of between-farm contacts via professionals in Sweden.

BACKGROUND: Infectious diseases of livestock have negative consequences for animal production as well as animal health and welfare and can be transmitted between farms via direct (live animal movements) as well as indirect (via physical vectors such as, people, transport vehicles and fomites) contacts. The objective of the study was to examine the travel patterns of professionals visiting Swedish farms (veterinarians, milk tanker drivers, artificial inseminators, maintenance technicians and livestock hauliers). This was done by obtaining records of the farms visited by a sample of professionals in the above categories in one week in January, one week in April, one week in July and one week in October in the Swedish counties Västerbotten, Södermanland, Västergötland and Skåne. RESULTS: There were twelve participating organisations, and data was provided for one to three individuals/vehicles/veterinary practices per professional category and per geographic region (except for dairy service technicians and livestock hauliers who did not provide data from all regions). There was a trend towards larger areas covered and smaller number of farms visited per week in the north, but exceptions occurred and there were regional variations. Generally, the greatest areas were travelled by milk tankers and livestock hauliers, and the profession travelling over the smallest areas tended to be the veterinarians. Milk tankers visited most farms per week, one milk tanker could visit between 23 and 90 farms per week and travel over areas between 717 km² and 23,512 km² per week. CONCLUSIONS: Valuable insight into the travel patterns of Swedish professionals has emerged although the implications of the study largely concern highly infectious diseases. Movement of live animals pose the greatest risk for the spread of infectious animal diseases; however indirect contacts are important for many diseases. The results of this study indicate that in Sweden a highly contagious disease might spread over a large area in the time span of one incubation period, which ought to be kept in mind in case of an outbreak and in outbreak investigations. The difficulties in contacting some professionals visiting farms could be a problem in an outbreak situation.

A survey of visitors on Swedish livestock farms with reference to the spread of animal diseases.

BACKGROUND: In addition to livestock movements, other between-farm contacts such as visitors may contribute to the spread of contagious animal diseases. Knowledge about such contacts is essential for contingency planning. Preventive measures, risk-based surveillance and contact tracing may be facilitated if the frequency and type of between-farm contacts can be assessed for different types of farms. The aim of this study was to investigate the frequency and types of visitors on farms with cloven-hoofed animals in Sweden and to analyse whether there were differences in the number of visitors attributable to region, season, and type of herd. Data were collected from Swedish farmers through contact-logs covering two-week periods during four different seasons. RESULTS: In total, 482 (32%) farmers filled in the contact log for at least one period and the data represent 18,416 days. The average number of professional and non-professional visitors per day was 0.3 and 0.8, respectively. Whereas the number of professional visitors seemed to increase with increasing herd size, this relation was not seen for non-professional visits. The mean numbers of visitors per day were highest in the summer and in the farm category 'small mixed farm'. Reports of the visitors' degree of contact with the animals showed that veterinarians, AI-technicians, animal transporters and neighbours were often in direct contact with the animals or entered the stables and 8.8% of the repairmen were also in direct contact with animals, which was unexpected. In a multivariable analysis, species, herd size and season were significantly associated with the number of professional visitors as well as the number of visitors in direct contact with the animals. CONCLUSION: In conclusion there was a large variation between farms in the number and type of contacts. The number of visitors that may be more likely to spread diseases between farms was associated with animal species and herd size.

Influence on disease spread dynamics of herd characteristics in a structured livestock industry.

Studies of between-herd contacts may provide important insight to disease transmission dynamics. By comparing the result from models with different levels of detail in the description of animal movement, we studied how factors influence the final epidemic size as well as the dynamic behaviour of an outbreak. We investigated the effect of contact heterogeneity of pig herds in Sweden due to herd size, between-herd distance and production type. Our comparative study suggests that the production-type structure is the most influential factor. Hence, our results imply that production type is the most important factor to obtain valid data for and include when modelling and analysing this system. The study also revealed that all included factors reduce the final epidemic size and also have yet more diverse effects on initial rate of disease spread. This implies that a large set of factors ought to be included to assess relevant predictions when modelling disease spread between herds. Furthermore, our results show that a more detailed model changes predictions regarding the variability in the outbreak dynamics and conclude that this is an important factor to consider in risk assessment.

Geographical distribution of salmonella infected pig, cattle and sheep herds in Sweden 1993-2010.

BACKGROUND: The Swedish salmonella control programme covers the entire production chain, from feed to food. All salmonella serotypes are notifiable. On average, less than 20 cases of salmonella in food-producing animals are reported every year. In some situations, the cases would be expected to cluster geographically. The aim of this study was to illustrate the geographic distribution of the salmonella cases detected in pigs, cattle and sheep. METHODS: Data on all herds with pigs, cattle and sheep found to be infected with salmonella during the time period from 1993 to 2010 were obtained from the Swedish Board of Agriculture. Using the ArcGIS software, various maps were produced of infected herds, stratified on animal species as well as salmonella serotype. Based on ocular inspection of all maps, some were collapsed and some used separately. Data were also examined for temporal trends. RESULTS: No geographical clustering was observed for ovine or porcine cases. Cattle herds infected with Salmonella Dublin were mainly located in the southeast region and cattle herds infected with Salmonella Typhimurium in the most southern part of the country. Some seasonal variation was seen in cattle, but available data was not sufficient for further analyses. CONCLUSIONS: Analyses of data on salmonella infected herds revealed some spatial and temporal patterns for salmonella in cattle. However, despite using 18 years' of data, the number of infected herds was too low for any useful statistical analyses.

Network analysis of cattle and pig movements in Sweden: measures relevant for disease control and risk based surveillance.

Registration of cattle and pig movements is mandatory in Sweden and all registered movements between farms in the years 2006-2008 were investigated using network analysis. The networks were analysed as monthly and yearly networks, separately per species and with the two species together. Measures that have been previously discussed in relation to outbreaks and disease control were calculated; moreover a measure of the ingoing infection chain was constructed. The ingoing infection chain captures ingoing contacts through other holdings, taking the temporal aspect and sequence of the movements into account. The distribution of the contacts among the holdings was skewed. Many farms had few or no contacts, while others had many, a pattern which has also been described from other countries. The cattle network and the combined network showed a recurring seasonal pattern, while this was not seen in the pig network. The in-degree was not equivalent to the ingoing infection chain; there were holdings with limited direct contacts, but a large number of indirect contacts. The ingoing infection chain could be a useful measure when setting up strategies for disease control and for risk based surveillance as it identifies holdings with many contacts through live animal movements and thus at potentially higher risk for introduction of contagious diseases.

Direct and indirect transmission of four Salmonella enterica serotypes in pigs.

BACKGROUND: Feed-borne spread of Salmonella spp. to pigs has been documented several times in recent years in Sweden. Experiences from the field suggest that feed-associated serotypes might be less transmittable and subsequently easier to eradicate from pig herds than other serotypes more commonly associated to pigs. Four Salmonella serotypes were selected for experimental studies in pigs in order to study transmissibility and compare possible differences between feed-associated (S Cubana and S Yoruba) and pig-associated serotypes (S Derby and S Typhimurium). METHODS: Direct contact transmission was studied in four groups of pigs formed by six 10-week-old salmonella negative pigs commingled with two fatteners excreting one of the four salmonella serotypes. Indirect transmission was studied by putting six 10-week-old salmonella negative pigs in each of four salmonella contaminated rooms. Each room had previously housed a group of pigs, excreting one of the four selected serotypes.All pigs were monitored for two weeks with respect to the faecal excretion of salmonella and the presence of serum antibodies. At the end of the trial, eight samples from inner tissues and organs were collected from each pig at necropsy. RESULTS: In the four direct transmission groups, one pig shed Salmonella (Cubana) at one occasion. At necropsy, S Typhimurium was isolated from one pig.In the indirect transmission groups, two pigs in the Yoruba room and one pig in each of the other rooms were excreting detectable levels of Salmonella once during the study period of two weeks. At necropsy, S Derby was isolated from one of six pigs in the Derby room and S Typhimurium was isolated from four of the six pigs in the Typhimurium room.No significant serological response could be detected in any of the 48 pigs. CONCLUSIONS: These results show that all four selected serotypes were able to be transmitted in at least one of these field-like trials, but the transmission rate was low in all groups and no obvious differences between feed-associated and pig-associated serotypes in the transmission to naïve pigs and their subsequent faecal shedding were revealed. However, the post mortem results indicated a higher detection of S Typhimurium in the ileocecal lymph nodes of pigs introduced into a contaminated environment in comparison with the other three serotypes.

Anthrax outbreak in a Swedish beef cattle herd--1st case in 27 years: Case report.

After 27 years with no detected cases, an outbreak of anthrax occurred in a beef cattle herd in the south of Sweden. The outbreak was unusual as it occurred in winter, in animals not exposed to meat-and-bone meal, in a non-endemic country. The affected herd consisted of 90 animals, including calves and young stock. The animals were kept in a barn on deep straw bedding and fed only roughage. Seven animals died during 10 days, with no typical previous clinical signs except fever. The carcasses were reportedly normal in appearance, particularly as regards rigor mortis, bleeding and coagulation of the blood. Subsequently, three more animals died and anthrax was suspected at necropsy and confirmed by culture and PCR on blood samples. The isolated strain was susceptible to tetracycline, ciprofloxacin and ampicillin. Subtyping by MLVA showed the strain to cluster with isolates in the A lineage of Bacillus anthracis. Environmental samples from the holding were all negative except for two soil samples taken from a spot where infected carcasses had been kept until they were picked up for transport. The most likely source of the infection was concluded to be contaminated roughage, although this could not be substantiated by laboratory analysis. The suspected feed was mixed with soil and dust and originated from fields where flooding occurred the previous year, followed by a dry summer with a very low water level in the river allowing for the harvesting on soil usually not exposed. In the early 1900s, animal carcasses are said to have been dumped in this river during anthrax outbreaks and it is most likely that some anthrax spores could remain in the area. The case indicates that untypical cases in non-endemic areas may be missed to a larger extent than previously thought. Field tests allowing a preliminary risk assessment of animal carcasses would be helpful for increased sensitivity of detection and prevention of further exposure to the causative agent.

Demonstrating freedom from Mycobacterium bovis infection in Swedish farmed deer using non-survey data sources.

Sweden has been considered free from bovine tuberculosis (BTB) since 1958. In 1987 an infected consignment of farmed deer was imported to Sweden and in 1991 the first infected deer was identified. Despite a thorough trace back investigation, all deer originating from the infected consignment could not be traced. Therefore a national control programme for BTB in farmed deer was implemented. At present the control programme is in its final stage and all deer holdings that have not obtained BTB-free status are put under restrictions. This study aimed to determine the probability that the Swedish farmed deer population is free from BTB using methods that allow analysis of non-structured data, i.e. results from meat inspection, necropsies and tuberculin testing. Surveillance data from 1994 to October 2006 from farmed deer affiliated to the voluntary control programme were analysed using the model described in Martin et al. (2007a). The model was adjusted to allow the within-herd design prevalence to be defined as one infected deer per herd and the between-herd design prevalence to be defined as one infected deer herd in the country. Depending on the chosen within-herd design prevalence: 1, 2, 3 or 4 infected deer per herd or 5% infected deer per herd, the probability of freedom from BTB infection in the Swedish farmed deer population varied between 87% and 97%. Based on the obtained results, it can be concluded, with high confidence, that the Swedish farmed deer population is free from M. bovis.

Spatial and temporal investigations of reported movements, births and deaths of cattle and pigs in Sweden.

BACKGROUND: Livestock movements can affect the spread and control of contagious diseases and new data recording systems enable analysis of these movements. The results can be used for contingency planning, modelling of disease spread and design of disease control programs. METHODS: Data on the Swedish cattle and pig populations during the period July 2005 until June 2006 were obtained from databases held by the Swedish Board of Agriculture. Movements of cattle and pigs were investigated from geographical and temporal perspectives, births and deaths of cattle were investigated from a temporal perspective and the geographical distribution of holdings was also investigated. RESULTS: Most movements of cattle and pigs were to holdings within 100 km, but movements up to 1200 km occurred. Consequently, the majority of movements occurred within the same county or to adjacent counties. Approximately 54% of the cattle holdings and 45% of the pig holdings did not purchase any live animals. Seasonal variations in births and deaths of cattle were identified, with peaks in spring. Cattle movements peaked in spring and autumn. The maximum number of holdings within a 3 km radius of one holding was 45 for cattle and 23 for pigs, with large variations among counties. Missing data and reporting bias (digit preference) were detected in the data. CONCLUSION: The databases are valuable tools in contact tracing. However since movements can be reported up to a week after the event and some data are missing they cannot replace other methods in the acute phase of an outbreak. We identified long distance transports of cattle and pigs, and these findings support an implementation of a total standstill in the country in the case of an outbreak of foot-and-mouth disease. The databases contain valuable information and improvements in data quality would make them even more useful.

Probability of freedom from disease after the first detection and eradication of PRRS in Sweden: scenario-tree modelling of the surveillance system.

In July 2007, PRRS was detected for the first time in Sweden. A total of eight positive herds were identified and various measures were taken to eradicate the disease, including restrictions and slaughter of infected herds. Subsequently, both active and passive surveillance activities were undertaken. This study describes stochastic scenario-tree modelling of all the various surveillance system components, to estimate the current probability that Sweden is free from PRRS. The model includes all actions taken after the first positive herd was detected. The surveillance system components included in the model were as follows: investigations undertaken in association with the outbreak, a serological study based on samples collected at slaughter, samples collected in the national PRRS surveillance programme and passive clinical surveillance. The probability of freedom was estimated in time steps of 1 month, from July to December 2007. After each time step, the calculated posterior probability of freedom from the previous month, combined with the probability of introduction, was used as a prior probability for the next month. The result from the model showed a 99.8% probability that Sweden was free from PRRS at the end of December 2007. The estimated total sensitivity of the surveillance system varied between 81.2% and 94.3% and was highest during the first months after the outbreak. For sensitivity analysis purposes, the model was also applied using higher risks of introduction. However, this did not make considerable difference to the final estimates.