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Biosecurity and disease preparedness
Mitigating between-farm disease transmission through vehicle rerouting and enhanced cleaning and disinfection protocols. G. Machado, North Carolina State University
The movement of vehicles between farms is one of the main routes of indirect transmission of numerous infectious agents. Truck cleaning, washing, and disinfection systems leave us with doubts as to their effectiveness, especially in trucks that are used for the return trip. Knowing the sanitary status of the origin/destination farms is critical to establishing the most appropriate routes, loading procedures, work done by the transporter in contact with the animals, and travel times. The management and travel plan of both loads by health pyramids and optimizing return trips between farms from higher to lower health status allow us to optimize times and reduce the risk of transmission.
Researching the way out of barriers for disease control. M. Schwartz, University of Minnesota and Schwartz Farms
The Swine Disease Eradication Center at the University of Minnesota was founded in 2001 to study the mechanisms of spread and control of the most prevalent diseases in our changing world (PRRSV, Mycoplasma hyopneumonia, Influenza, Streptococcus suis, Glaesserella parasuis, TGE, Hemorrhagic dysentery, PED).
At the most basic level, the design of effective strategies for the control and/or elimination of PRRSV relies on an accurate and comprehensive understanding of virus transmission. In areas where the livestock industry is dense, both in terms of the number of animals per area and the total number per site, the mechanism of spread must be considered in multiple possible pathways.
In 1820, during the influenza epidemic in Europe, research centers were already asking the same questions. They give the example of the black swan book by Nassim Nicholas (2008) on whether or not there is evidence of a PRRSV problem. Research on the control pathway of different barriers to the spread of the virus focuses on its transmission routes, requiring collaboration at all stages of the chain, asking the right questions, and finding the right answers to continue to work effectively.
Mortality disposal practices during Foreign Animal Disease (FAD) outbreaks: A snapshot from the poultry industry. R. Marusak, University of Minnesota
Between 2014 and 2025 there have been two influenza virus outbreaks in poultry farming in the USA: 2014-15 H5N2/H5N8 (211) and 2022-24 - H5N1 (714). In both cases, there were nervous symptoms with high mortality. The former did not involve wild birds and the latter did. They were able to limit horizontal transmission in the second case due to rapid detection by rapid diagnosis and depopulation of infected animals (24-36 hours versus 5-7 days in the first outbreak). They allowed the movement of animals out of high-risk areas using the established Safety Guide, which includes biosecurity basics to mitigate spread, using real-time pre- and post-movement testing methodologies, employing isolation periods, and prohibiting risky practices before and after movements (major risks are vehicles, non-essential person visits, carcass disposal, and animal movements). The risk of spreading the disease is considered safe inside the farm and high risk outside, not allowing any movement of live animals, and using exclusively dedicated trucks and traceability of vehicles and drivers. Of the carcass disposal practices, the lowest risk is incineration, followed by moderate risk for composting, and moderate-high risk for carcass collection. A typical layer farm has 100-200,000 birds with an average weekly mortality of 0.1-0.2% from 0-19 weeks and 0.05-0.15% from 19-100 weeks. Chickens have an average weekly mortality of 0.85%, which is very dependent on the type of litter. They normally practice external incineration and in some cases previously freezing before the movement of carcasses. For turkeys, on-farm incineration and on-farm composting are the most commonly used (1 gram of tissue could contain 104 infective doses of the virus). In 2017, the North American Renderers Association established an emergency plan. Carcass treatment is critical and plays a key role in transmission, followed by establishing waterfowl monitoring and control areas.
From farm to safety: Dead animal disposal practices and PRRSV risk. I Paploski, University of Minnesota
The amount of PRRS virus in carcasses is very high, so the risk of contagion from the movement of carcasses is significant. At the University of Minnesota, they are studying the presence of virus particles in the environment associated with mortality. They take 10 samples from 200 farms taking into account the type of dead animal, their handling patterns for removal, contact with other animals and people, cleaning systems/disinfections performed, the times of day when they take place, and the procedures within the farm for both biosecurity and euthanasia.
They consider it important to strictly clean and disinfect the areas where the dead animals are located and the corridors/paths they are moved through during their removal. They also require having specific areas for the location of the dead animals in each production area, and a monthly washing and disinfection program should be established for these areas.
We must standardize the time of day when the carcasses are taken out of the rooms and avoid keeping them inside, in the corridors, or close to other animals since they are a significant source of transmission (fluids), which is significant in carcass storage facilities.
In their research, the positivity of carcass fluid samples shows a clear presence of PRRSV and PEDV in animals from farms that are positive for these viruses, which means a high risk of contagion and persistence of infectious agents on farms and their transmission to other production centers. Thus, the flow of movement of dead animals and the vehicles and people transporting them is critical.
Alternatives to rendering for nursery/grow-finish mortality management: A cost and feasibility analysis. M. Schleper, Christensen Farms
Sustainable practices are needed in our society, so it is essential to manage mortality, minimize it as a principle, use safe practices, ensure employee satisfaction, minimize risk through biosecurity, and perform the most effective early diagnosis and treatment.
For lower risk tolerance, destroying pathogens, improving work efficiency, and optimizing carcass handling procedures are critical. There are numerous options for handling carcasses: incineration, composting, and storage in containers, with variations in terms of required working times, technical implications, and flexibility, depending on the number of animals processed.
In terms of biosecurity risks, carcass storage in stalls is high, while for incineration and composting it is medium-low.
Regarding pathogen destruction, incineration destroys the pathogen while composting depends on how the process is handled. With storage, the agent remains.
Incineration and composting pose a medium to high risk at the environmental level.
In terms of costs, the lowest is storage (minimum capital and operating cost), followed by composting (variable capital and operating cost), with incineration being the highest. The operating and capital costs in the medium to long term should be considered, evaluating the mortality rates to understand the needs of the systems.
Biosecurity is the best method to reduce the number of carcasses to be handled by any of the systems, in addition to the fact that the lower the mortality, the lower the risk of dissemination.
Detangling the causality web: Late nursery phase PRRS virus introductions. B. Leuwerke, Swine Vet Center
Monitoring weaned piglets week by week is important to know if they are positive or negative for PRRSV. This helps prevent the movement of positive piglets or detecting the virus after they've been moved to protect the finishing phases and safeguard future breeding sow production units.
To investigate how the virus has been introduced on the farm, we sometimes have limited information on the virus situation in the production area and the biosecurity practices applied. Clearly, transport is a risk, but it is not the only risk. Within the production pyramids, the management of transport trucks is essential, considering the sanitary status of each farm/production phase. We know a lot about biosecurity measures, but we know we make many mistakes in the procedures, both in some processes and in their daily application. The work on environmental contamination is being intensified to more precisely understand the transmission of the virus between batches and sites. It is necessary to intensify health downtime programs, supervise them, and implement technologies that allow us to evaluate the environmental contamination/facilities in real time on the farm.
Ro virus transmission between farms is 2.48 to 1.14. Genetic sequencing is as important as its interpretation, both at the time of the clinical presentation and over time. We must try to know if the batch has been contaminated or if the virus has been recently introduced, reviewing biosecurity measures, and analyzing the time from introduction to detection to determine the area of dissemination.
Life at the bottom of the biosecurity pyramid: The economics of market haul sanitation. E. Magalhaes, Iowa State University
From January 2002 to August 2024 the margin per pig has varied from +90 to -60 $, with farm sanitation being one of the critical factors in companies' financial results, logically linked to the market price. The cost of biosecurity measures in transport involving the washing/disinfection of trucks is usually around $1/pig (the cost of washing a truck is $125-175). In cases of chronic epidemic diarrhea, they estimate the cost per pig to be $3 (WL Hollis) or $4.4 (E. Spronk). The average washing time per truck is 35 minutes with highly variable water consumption.
Environmental sampling at PRRS outbreak sites: Detection frequency and semi-quantification. C. Corzo, University of Minnesota
PRRS virus continues to be a major problem on susceptible farms and so does seasonality (fall and winter). New variants are spreading rapidly both regionally and between different states. Some questions arise: Are we unaware of a transmission pathway? How long is the virus viable? Are we correctly assessing the percentage of positive/negative samples and the Ct value? Can we detect RNA on surfaces such as fans, the floors outside the room entrances, and other areas (jars, farm equipment)? The question is whether we can detect viable infective virus. Preliminary studies have detected it, but in low quantities, finding Ct ranges of 23.5-35.8, so the concentration of viral RNA in the sample may be significant.
Biosecurity compliance: A guide for non-levitating farm staff. L. Dufresne, Demeter Veterinary Services
Since 1970, the Danish model has divided the workers' farm entrance into clean and dirty areas. Some theoretically clean zones are not so clean in practice (farm shoes, shower areas, dining area, disinfectant mats, hand washing).
Another critical point is the carcass containers and the interaction of the farm tractor with the collection truck. We must consider the one way flow of trucks arriving and leaving the farm and that the transporters are not necessarily experts in biosecurity protocols. We must have simple action plans to apply and understand what is non-negotiable.
Things are not always as they seem: A roadmap to evaluate potential virus transmission and mitigation in feed. J. Shurson, University of Minnesota
We live with the uncertainty of the numerous risks of virus transmission by different routes. We know the minimum infective dose of certain viruses, inoculated in feed or by direct oral inoculation, to cause a sanitary problem. The probability of infection at different infective doses can vary according to numerous factors.
We need to see the general framework of the problem: whether a raw material is contaminated, whether the pathogen survives (and for how long) in different temperature, humidity, processing, or storage conditions, analyze a significant number of samples, and determine the most sensitive and specific techniques.
It is important to question our own answers. An example is the minimum infective dose of ASF virus in finished feed (104) or the presence of virus in liquid porcine plasma at doses of 104.3 or 105.1 for 14 days that do not result in infections. The inactivation kinetics of viruses over time is a critical point in determining their infective capacity. Some of the most studied raw materials in the U.S. have been soybean meal and dried plasma protein. In 2022, the FDA developed guidance for the feed industry outlining points of uncertainty and control for contaminants including bacteria, parasites, and viruses, providing probabilistic estimates of the moderate to negligible range of transmission of certain swine viruses from feed to animals consuming the feed. The guide is based on risk quantification work based on models of the presence of certain viruses in certain raw materials. Some studies show that applying good management practices reduces the risk of contamination with four risk factors (proximity between farms, animal movements between farms, animal transport, and vehicle movements between production units) in 94% of PRRS and PED outbreaks.
Prevention is the key and additive treatments provide partial inactivation, with decontamination being difficult in practice. Extending storage time, together with high-temperature treatment of raw materials/feedstuffs can impair the bioactivity of vitamins, reduce the digestibility of amino acids, and facilitate fat oxidation while allowing the growth of bacteria and fungi.
Infectivity of PRRS virus in feed: With and without mitigants. M. Hood, Reicks Veterinary Research and Consulting
The dissemination of PRRS virus through feed shows mixed results in some cases and controversial results in others (Scott Dee, Blomme - KSU). The minimum infective dose is not specified. The dissemination of PED, ASF, and delta coronavirus in feed is fairly well known. A Ct of 16-19 is equivalent to a dose of 104 infective dose 50 in the case of PRRSV in their study, where they found no clinical signs in pigs that ate feed contaminated with that amount of virus. They question whether the movement of feed from the mill to the truck to the hopper together with climatic conditions may influence the degree of virus infectivity.
Virus
PRRSV-2 genetic variant classification: What is it and why we need it? K. VanderWaal, University of Minnesota and Paul Yeske, Swine Vet Center
PRRS virus dynamics have not stopped changing since 1990, creating numerous problems for the American industry, with more than 73,000 strains sequenced in the USA. Each strain passes the baton to the next to continue causing problems. PRRSV-2 is classified according to the genetic distance between some strains and the preceding ones. They are also classified according to the RFLP type into 1-7-4, 1-8-4, and 1-3-2. Phylogenetic classification is based on ORF-5 ancestral families.
Their work aims to establish a classification system for genetic variants in the USA that can be expanded with new genetic diversity. Identification focuses on the reproducibility of numerous analyses with different data and robustness during prospective implementation testing, adding data every three months over seven years. Lines and sublines consist of many small groups in terms of variants. Sequences of the same variant have an average genetic distance of 2.5% and can be up to 5%. They use a specific nomenclature to identify variants (number letter. number) https://stemma.shinyapps.io/PRRSLoom-variants/ and assess whether each variant is increasing or decreasing, being motivated to discriminate between vaccine and wild strains, discriminate between previous and new strains on the same farm (43% of farms have changes in their RFLP), detect the introduction of new strains into a farm or production system, trace the spread of a strain between farms, and introduce possible new sources of infection.
The question is which classified variants may or may not tell us something. The unclassified strains provide information on virulence and the clinical picture since the apparent virulence can be influenced by coinfections or external factors. They don't give us information on cross-immunity but do serve to compare information between research centers and laboratories which allows us to continue to better understand the virus dynamics. The new nomenclature system provides us with greater reliability and expandability in the fight against PRRSV.
They have created a committee within the AASV to know the status of PRRS virus in swine companies. The increase in outbreaks occurs in the fall and winter months, year after year in wean-to-finish units. There are a few more specific strains detected in the U.S. that vary by region and production stage. The mortality rate in finishing pigs on negative farms is 3.2% vs. 6% on positive farms. Farm closure and depopulation systems do not work in all cases, and disease resurgences are frequent in both sows and piglets/finishers.
Updates on the economic impact of PRRSV to U.S. pork producers. H. Osemeke, Iowa State University
Two previous NPB studies in 2005 and 2013 estimated the economic losses from PRRS in the USA, so we need to update them based on the factors that affect the annual cost in each country, focusing on the distribution of the problem on the farm, the impact on productivity, the price of the animals, production costs, and the current pig inventory in the country.
The AASV classification of sow farms is based on five categories: negative, stable positive, unstable positive in the last 16 weeks, with clinical presentation in the last 16 weeks on a positive farm, and with clinical presentation in the last 16 weeks on a negative farm. In finishing barns, the classification according to the status of piglets at weaning is divided into positive and negative (stable at slaughter, which can be positive or negative previously during finishing).
They analyze numerous production parameters by taking data from 12 companies and 297 farms, with a total of 1.1 million sows, using a mixed model while randomly assigning effects by farm and season. The number of piglets born per litter ranges from 14 to 11 in the gradient from negative to positive. Pre-weaning mortality ranges from 15% to 35% and the number of litters per sow per year from 2.4 to 2. Sow mortality ranges from 12% to 18%.
Analyzing the impact in finishing barns, they take a sample of >20 million pigs from 9 companies. Mortality ranges between 7% and 12.2% on average and the conversion rate is between 2.4 and 2.45. The economic impact in 2020 is estimated at $1.2 billion versus $664 million in 2010, having adjusted for inflation (change in prices and costs) and farm size in the USA, which is a daily cost of $3.3 million and an impact per sow of $49, $124, $207, and $408 depending on the initial farm classification. In 2020, 380 million were from losses in breeding sows and 820 million in finishing pigs, while in 2010 it was split almost 50/50.
Some papers presented, including a Spanish one referring to the Rosalia strain, reflect mortalities in weaned piglets of up to 50%.
PRRS in the U.S. industry: Why do we continue to battle with this well known virus? S. Dee, Pipestone Research; L. Dufresne, Demeter Veterinary Services y P. Yeske, Swine Vet Center
They evidence the importance of biosecurity (Next Generation Biosecurity) by controlling direct routes, mechanical routes, aerosols, and feed to reduce the economic impact of the PRRS virus. In a high-density area, with 76 farms and 384,000 sows, there is little difference between 2021 and 2024. In these three years, the risk of incidence has been reduced by 8% on all the company's farms, with no difference in the proportion of positive farms per year and associating infections with the degree of biosecurity, in addition to reducing the incidence of other pathologies such as Mycoplasma hyopneumoniae, PED, and influenza. The impact on productivity has been to wean 190,115 more piglets per year on farms that have completed the new biosecurity program. The new paradigm is to prevent reinfections.
In recent years we have increased our diagnostic capacity, virus elimination strategies, and biosecurity guidelines. The problem lies in the current production model in the USA (multi-state systems), plus the fact that we focus on biosecurity and not biocontainment. Moving infected animals between farms and regions is a serious problem. The high pig density affects biosecurity and thus the control of virus spread both within and between farms.
Porcine astrovirus 4 as a cause of tracheitis and bronchitis in young pigs. M. Rahe, North Carolina State University
Astroviruses are single-stranded RNA viruses associated with gastrointestinal neurological disorders in numerous animal species, including humans. Porcine Astrovirus 4 (PoAstV4) was initially associated with respiratory disorders causing lesions such as tracheitis and bronchitis, but it has not been possible to reproduce the disease experimentally.
They performed nasal and intratracheal infections, detecting a peak of infection by PCR in nasal swabs at 6 days after infection and seroconversion to IgG at 14 days. They found epitheliotropic lesions with mononuclear infiltration in the lamina propria of the nasal turbinates, trachea, and bronchi.
Influenza: H5N! outbreaks in dairy cattle. S. Daniels, Circle H Headquarters, LLC
As a multispecies clinical veterinarian, he expected a new infectious disease in cattle. In his area affected by the influenza virus, he only produces calves. In their bovine-focused lab they test milk microbiology, milk nutritional components, milk quality (added water, SCC, SPC, and certifications), ELISA for BVD, Johne's disease, and pregnancy, PCR for BVD and mastitis pathogens, NIR for feed and forages, and ISO for 17025 accreditation. The production system commonly involves inter-state movements.
At the beginning of March, some of his clients reported mysterious clinical signs in dairy cows with reduced rumination, activity, and milk production, affecting more cows in mid-lactation and older cows, with constipation and diarrhea. On March 12 there was an alert in the ISU VDL and on March 15 the H5N1 virus was diagnosed on a chicken farm in Moore County, Texas with an increase in mortality and it affected cats. On the same date, March 15, the first group meeting of the American Association of Bovine Practitioners (AABP) was held. On March 17, he sent samples from a client's four affected cows, and on March 18, the nasal swabs were PCR-negative for influenza. On March 20, 20 samples were sent to the Iowa State University laboratory with positive results for milk. The USDA confirmed H5N1 on a cow farm in Texas, on April 29 in Maryland, on April 2 in Ohio with subclade 2.3.4.4b, on April 9 in North Carolina, and on April 25 in Colorado. As of April 29, federal orders to test dairy cows prior to movement between states for influenza testing went into effect, with the effect of less testing.
Recently in Colorado, they have reported that clinical signs resolve in 2-3 weeks demonstrating how many farms stop milk excretion within six weeks. Massachusetts has recently tested all farms in the state and all were negative. Fortunately, they have the technology to identify/diagnose the problem. The cattle industry is much less integrated than the swine industry. The impact on production has been one-tenth that of swine PED. Pasteurization of milk is effective for food safety, and biosecurity measures are strictly implemented. Bovine veterinarians focused on early diagnosis at the farm level, limiting its spread.
Highly pathogenic avian influenza A virus research insights and applications in swine. B. Arruda, United States Department of Agriculture (Sponsored by the National Pork Board)
For the influenza virus to adapt to other species it needs to overcome some genetic barriers, some of which are not well defined. Highly pathogenic influenza strains have been panzootic since 2021, infecting mammals. In wild birds, more than 10,000 virus strains are identified and very few adapted. In cattle, four cases have been reported, and in humans more, with one in question with two adapted strains.
The mammary glands in cows appear to be the factor where most viruses are found. Among the different avian strains, they find variations in infectivity, transmission capacity, diagnostic tissues, recombination, and virulence.
In wild boar, out of 4,120 sera, only 3% were positive for influenza and <0.5% for H5N1. In the future, it is necessary to identify additional strains, additional study models (sow model or pig to ferret transmission study), the impact of the virus on immunity, the evaluation of new vaccines, and to develop or optimize assays and types of samples for greater sensitivity and specificity in the detection of highly pathogenic influenza virus in pigs (serology, oral fluids). The risk of H5N1 incursion in swine is low.
Helping farms eliminate flu by understanding the serological immune response. S. Storms, University of Illinois
The main strains of the virus in swine in the USA are H1N1, H3N2, and H1N2, not yet identifying H5N1, being endemic in many farms. Acute infections last 5-7 days, with acute inflammation and progressive reaction in lung tissue. In natural exposure to high virulence strains by aerosols, the tropism is centered in the lower respiratory tract and if there are no previous antibodies, the severity is high. In infections by high virulence strains, the upper respiratory tract is affected and if antibodies are present, the clinical manifestations are scarce.
Vaccination is aimed at adaptive immunity. Killed vaccines typically have good humoral immunity (antibody response) and poor T and B cell-mediated response. These vaccines need 2-3 doses to have measurable serum antibody titers which are reached at two weeks. Vaccination limits the severity of the disease and sterilizing immunity is not possible. The virus causes inflammation in the nasal cavity, larynx, trachea, and bronchi. Vaccination of dams produces antibodies with a half-life of 12 days. There may be interference with maternal antibodies as they are transferred via colostrum and milk. In 2021 in the USA, 51.4% of farms vaccinated dams and 21.6% vaccinated piglets according to the USDA. Maternal antibody production under experimental conditions when vaccinated at 6 and 2 weeks before farrowing results in protective titers in piglets (40) for 8 weeks. If sows are not vaccinated, nor do they have vaccinal antibodies, we can vaccinate piglets at different times by finding serum antibody levels after the second vaccination. Thus, in the presence of maternal antibodies, we should delay the vaccination of piglets.
In cases of problem farms where we vaccinate the sows and not the piglets, we may find that the piglets are infected starting from the 5th week of life. Depending on the percentage of piglets that excrete the virus at weaning, reinfections will be earlier or later. If we have few maternal antibodies and low virus excretion, vaccination of the piglets will protect them. In the case of vaccinating all positive dams: 10% of the piglets will excrete the virus in lactation, 97% will excrete it at weaning, and only 8% will have protective antibodies at weaning.
When is the right time to vaccinate sows? It will depend on the farm, how much antibody is passed to the piglets, the precise time to vaccinate piglets, and how many piglets have seroconversion to be protected (>90%). The ELISA technique is not specific.
Bacteria
Field evaluation of an autogenous vaccine against Mycoplasma hyosynoviae. H. Schwecke, University of Minnesota
Mycoplasma hyosynoviae is a commensal bacterium that can cause locomotor problems in finishing pigs. We have limited measures, both for prevention and control; there are no commercial vaccines so far, and autogenous vaccines are used to alleviate the problem. They conducted a trial on a farm of 9,000 sows with a history of lameness in finishing pigs due to this bacterium, vaccinating sows intramuscularly at 5 and 3 weeks before farrowing, versus another unvaccinated group, resulting in some 12,377 pigs that arrived at the slaughterhouse from the vaccinated dams. They found no significant differences in the performance parameters of pigs from vaccinated dams (average daily gain in piglets and finishing, as well as final weight) and they observed a lower incidence of pigs with lameness in the group of vaccinated dams.
Impact of Mycoplasma hyopneumoniae elimination on the reproductive performance and retention of sows. L. Britton, North Carolina State University
Mycoplasma hyopneumonia (MHP) is the causative agent of enzootic pneumonia, causing slowed growth and poorer feed efficiency, but the impact on sows is not fully defined. They conducted a study on 64 sow farms comparing their results according to whether they are MHP negative, stable positive, or unstable positive. The farrowing rate and adjusted farrowing rate was between 1.3% and 0.7% higher in the high health status farms versus MHP, with these farms having fewer non-productive days (58.6 vs. 70).
Similarly, the total number of piglets born, born alive, and weaned was better by 0.7, 0.6, and 0.4 piglets per litter, with productivity of 24.44 vs. 23.14 piglets weaned per sow per year. As for replacement sows, the difference in those reaching their third parity between being MHP negative or positive was 65.4% vs. 48.3%, producing 1.3 to 1.4 more piglets born alive and total born per litter on farms with low prevalence of MHP vs. high prevalence.
Salmonella in fresh pork and regulatory update. A. Asmus, Hormel Foods and University of Minnesota
Raw meat products are a source of salmonellosis in the United States. While regulatory measures and efforts in the poultry industry have reduced the prevalence in fresh chicken meat, it has not been sufficiently reduced in humans. Thus, the public health agency has set a target of 11.5 cases per 100,000 people by 2030, a 25% reduction from 2023.
Two new specific directives have been implemented: the first on adulterated breaded ready-to-eat chicken products and the second to detect 10 cfu/g of Salmonella in various ground chicken products. While fresh chicken is associated with the highest estimate of Salmonella outbreaks, fresh pork is next as a supplier of high-value protein. Using PCR they analyzed the presence of salmonella in two pork product manufacturing lines for six weeks, both in the meat and the environment. They found a high correlation between the genotypes of both lines found in both meat and the environment, with the daily prevalence being affected by variations in manufacturing processes.
In a study conducted in Spain, it was shown that vaccination against ileitis in piglets at three weeks reduces the excretion of salmonellae. In the same study, the prevalence of Lawsonia intracellularis on farms is high (73%), although the prevalence in piglets (3-80%) is very variable between farms. Other studies demonstrate the efficacy of ileitis vaccines on productive parameters (average daily gain) and reduction of therapeutic costs. The presence of maternal antibodies should be considered when defining the age at which to vaccinate to avoid interferences.
Antonio Palomo Yagüe
