Biosecurity – PRRSControl

Is there any possibility of incursion and spreading of PRRSV through pork brought in by farmworkers?

Andrea Ladinig — Mon, 21 Mar 2022 09:37:14 +0000

Is there any possibility of incursion and spreading of PRRSV through pork? Should farmworkers avoid touching or bringing pork to the farm for PRRS prevention? The risk of spreading PRRSV through pork cannot be 100% excluded; however, the likelihood is very low. First, a comparatively high amount of virus would be needed to infect a pig with PRRSV through the oral route (1 x 105.3 TCID50) compared to parenteral exposure (≤20 particles can result in infection). Also, the probability of acute infection with high amounts of replicating virus being present is rather low in slaughter age pigs compared to younger piglets. Nevertheless, some pigs might bring PRRSV to the slaughterhouses. Target cells for PRRSV replication are cells of the monocytic lineage, mainly fully differentiated macrophages, while muscle cells are not susceptible to the virus. Therefore, resident virus that might be present in pork mainly results from residual infected blood not from infected myocytes. Therefore, rather low levels of virus can be expected in pork. The probability of survival of the virus will highly depend on pH value (while the virus is stable at pH 6.5 – 7.5, it will rapidly loose infectivity outside this range) and temperature (PRRSV […]

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How to clean and disinfect the material before introducing it into a farm?

Enric Marco — Tue, 08 Mar 2022 09:00:13 +0000

Repair and maintenance workers can unintentionally bring PRRS virus onto farms. How can we prevent this when some of their equipment is hard to wash and disinfect? Farm maintenance is one of the ways a new PRRS virus strain can be introduced on a farm. Obviously, without maintenance there would not be this specific risk, but everyone knows that farms need maintenance. After reviewing some outbreaks due to this reason, we realized that the key is the proper management of the tools used. Very often maintenance teams working in farms are specialized in this type of facilities, and therefore they are moving between farms often, sometimes even in a matter of minutes or hours. PRRS virus is not very resistant in the environment, but it is resistant enough to infect a farm if the infected material is introduced and there is direct contact with pigs. The material to be used can be disinfected in the disinfection and drying room (D&D room). A specific room should be used as a D&D room for fomites. All incoming supplies should be placed in this room, disinfected on all sides, and allowed the minimum 2 hour contact time prior to entry. This […]

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Cleaning and disinfection during PRRSv eradication

Enric Marco — Tue, 13 Apr 2021 06:27:23 +0000

What steps should be taken to wash and disinfect a farm in order to control PRRS virus during depopulation process? The cleaning and disinfection process required to eliminate PRRS virus from a farm is no different than the cleaning and disinfection process that is routinely performed in any facility. In fact, finishing barns that are positive for the disease during one batch are often negative the next if the pigs introduced are also negative. However, in the case of a depopulation, and given the importance of the process, it is important to ensure good cleaning and disinfection, which will not only eliminate the PRRS virus but also other potential pathogens present on the farm. Among the steps to follow would be: Proper washing and disinfection should also include water lines and tanks. Finally, we cannot forget to replace (or clean and disinfect) any equipment present on the farm such as: brushes, shovels, boards for moving pigs, boots, etc. The washed and disinfected equipment, as well as the facilities, must be dried for 15 days before being used again. If you want to know more about how cleaning and disinfection could affect PRRS virus, please visit the chapter “Physical […]

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In a PRRS stable farm, we’d like to invest to improve PRRS biosecurity. Which part is most valuable to improve first?

Enric Marco — Tue, 19 Jan 2021 08:43:53 +0000

I always think than one of the weakest areas when considering biosecurity are loading bays. If we think in sow farms, weaners or finishers as well as culled sows must be move out routinely, but also in many farms, replacements have to be moved in. “The biggest the farm is, the more transfer of animals are necessary weekly and the higher the biosecurity risk is” When it comes to biosecurity in sow farms, should be always 2 loading bays if replacements are needed: 1. One for clean animals (replacements) 2. Another for animals moved to market or other locations Keys for a secure loading bay, by Enric Marco A good loading bay should: Clearly define what’s the farm limit; it means up to what point a lorry driver can step on. Avoid the possibility of external person to go into the clean area as well as the opposite. Avoid also liquids and animals to go backwards. And last but not least, a good loading bay should be cleaned and disinfected after being used, every time, which means the construction material has to allow so. A good loading bay should allow lo load animals in a dirty truck (as […]

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How should the quarantine, acclimation, and monitoring of replacement gilts be carried out on PRRS-positive farms?

Enric Marco — Tue, 28 Jul 2020 12:53:26 +0000

Length of the quarantine: When we want to introduce negative replacements to a PRRS positive farm, the quarantine, or acclimation rather, must be long. “Long” meaning a period of not less than 2 months, because during this period our intention is to infect the new arrivals, giving them time to recover from the infection and lose their status as virus shedders before introducing them into the farm and starting to work with them. PRRS status of the gilts when entering the breeding herd: The aim is for the gilts to be introduced to acquire immunity to PRRS, and therefore become ELISA positive, but without shedding the virus; that is, they become PCR negative. How to perform the acclimatization? There are many techniques to achieve this status, although some work better than others, especially when it comes to the risk of producing disease. 1. Virus exposure with shedding animals: The most common method is to put the gilts in contact with animals on the farm that we know are shedding the virus. This contact should last about 15 days and should allow direct contact between the shedders and the gilts. 2. Live virus inoculation: Another more effective, but more […]

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Can using the same needle to vaccinate multiple sows be a cause of transmission of PRRS virus or other swine infectious diseases? How often would you recommend changing the needle?

Lars Erik Larsen — Mon, 17 Feb 2020 16:00:46 +0000

The iatrogenic transmission by contaminated needles can indeed be a source of PRRS virus and other diseases transmission – this has been proved in several controlled experimental studies. In the field, it is difficult to estimate how often this happens because there are several other potential routes of transmission. A review from Spain from 2016 (Pileri and Mateu Vet Res, 2016) provided a very illustrative calculation of how little blood volume is needed to transmit the PRRS virus. Here is a slightly revised quote from the paper: “In the peak of the viraemia, infected animals have a viral load of at least 103 to 104 TCID50/mL. Assuming a minimum infectious dose (MID) of 101-102 TCID50 for the percutaneous route, blood volumes of 1–10 µL could be sufficient to produce transmission”. The tip of the needle may easily be contaminated with 1–10 µL blood/exudate from the last pig injected. Changing needles frequently is important for many other reasons, but in relation to PRRS virus the needle must be changed at least between pens to avoid the needle becoming a vector and contributing to transmission within the herd. You can ask your own question! Visit Pig333.com and submit your question […]

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Can a PRRSv positive boar that has been vaccinated be used for artificial insemination?

Enric Mateu — Tue, 09 Jul 2019 08:22:25 +0000

To answer this question, the first thing to be considered, it´s that it is not possible to differentiate, by a serum antibody test, an animal infected with PRRSv from a vaccinated one. Secondly, the pathogenesis of infection should be considered. Pathogenesis of PRRSv infection in boars An infected boar usually develops viremia (the presence of virus in blood) that normally lasts for a week or two. During this viremia period, the semen also contains the PRRS virus. From the second week, the shedding of the virus in semen can last several weeks. However, at this stage the presence of the virus in semen is intermittent, so an animal can be negative by PCR in semen one day but be positive at a later date. In addition, if a boar is vaccinated, the vaccine virus can also be shed in semen and reach females without immunity. Finally, it must be considered that a vaccinated animal could eventually become infected, although the probability is much lower than it would be if it had not been vaccinated. As a summary, PRRSv positive animals should not be used on a PRRS-free farm, even if they were vaccinated. If you want to learn […]

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“Together Against PRRS”: Results of the systematic monitoring program and its impact on the control of PRRS

HIPRA Swine Unit — Wed, 20 Mar 2019 12:17:06 +0000

In previous posts we talked about “Together Against PRRS”, a global integrated program developed by HIPRA for the control of PRRSv. In this entry we’ll focus on the results of the systematic monitoring program and its impact on the control of PRRS on pig farms within a Spanish large production group. A total of 40 Spanish breeding herds enrolled in the program. All of them were classified following the Holtkamp classification system (Holtkamp et al., 2011) following the same diagnostic monitoring protocol: monthly individual blood sampling of 30 due-to-wean piglets. Samples were pooled and tested for PRRSv RNA by RT-PCR. As we explained in the previous post, some PCR-positive result samples were also sequenced with the objective of describing the PRRSv genetic diversity among the study herds. What was the trend in terms of PRRSv status? 13 samplings per farm were performed during the one-year monitoring period on the 35 PRRSv positive farms included in the study. Farm classification trends according to PRRS status (PUS: PRRS positive unstable; PSS: PRRS positive stable) are shown in Figure 1. As shown in the figure above, the percentage of PSS farms increased from the beginning of the study until […]

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“Together Against PRRS”, a systematic monitoring program for PRRS on swine farms

HIPRA Swine Unit — Tue, 19 Feb 2019 00:01:34 +0000

Introducing “Together Against PRRS”: HIPRA’s new program for the control of PRRS which includes systematic monitoring, biosecurity evaluation, vaccination plan design and productive and economic impact evaluation. Porcine Reproductive and Respiratory Syndrome (PRRS) is still the disease with the greatest economic impact on swine production worldwide, causing significant productive and economic losses on pig farms due to reproductive failure in breeding females and respiratory distress in pigs of different ages (Rossow KD, 1994). Owing to the fact that it is a disease with important aspects still to be clarified, the success of disease control depends on a combination of different strategies. The role of monitoring in the global strategy against PRRS Biosecurity, management or vaccination are three of these strategies, but in this post we are going to focus in monitoring, which allows us to use the most common diagnostic techniques for PRRS so that we can be informed of the status of the animals at all times, know at what age they are infected and how the virus is transmitted within the farm. For this reason, epidemiological knowledge not only at farm but also at regional level is key for the control strategy for this […]

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What are the most effective ways to prevent PRRSV infection?

Enric Marco — Wed, 03 Oct 2018 09:01:41 +0000

Preventing a farm to be infected by PRRS virus is not so difficult as long as the farm has a reasonable location, and obviously it is necessary some basic biosecurity measures: Complete fence, visitor control (clothes and shoes changing should be compulsory) and if there is entrance of animals they should come from a negative source. But from my point of view, there are two areas which should be well controlled to prevent the disease to come into the herd: 1. Control the maintenance people People who work on other farms often tend to go from one to the other with the same tools and sometimes with same clothes and shoes. The best solution is to have own people and equipment if the farm is big enough. If not, service personnel should follow same rules as other visitors and tools should be disinfected before entering the farm. 2. Transport of pigs A farm can not exist without a truck to transport pigs. Trucks and trailer should be always considered dirty (as they are very difficult to clean). They should be considered dirty even if we know they are well cleaned. The most risky transport is the one taking […]

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