The number of outbreaks of Porcine Epidemic Diarrhea virus (PEDv) within the swine industry in North America continues to increase, which is affecting how swine feed is distributed as the industry works to limit the spread of the disease.
PEDv is a disease caused by a member of the virus family Coronaviridae. Introduction of PEDv into a swine herd typically results in acute outbreaks of severe diarrhea, vomiting and high morbidity that often reaches 100 percent. The virus may spread via the fecal-oral route and fomites – objects capable of carrying infectious organisms.
The first U.S. cases of PEDv were confirmed in April 2013. While PEDv is not a new swine disease globally, the April 2013 occurrence represented the first time the disease was identified within the United States. PEDv is not a “listed disease” of the World Organization for Animal Health (OIE), which means that its presence does not cause marketing disruptions of U.S. pork to other countries. PEDv also is not considered a foreign animal disease by the U.S. Animal and Plant Health Inspection Service (APHIS). As such, there currently are no interstate trade restrictions within the United States pertaining to PEDv in swine. Further, PEDv is not a zoonotic disease that is transmissible to people and is not a food safety concern.
Pertaining to the outbreak, there were 265 new confirmed cases of PEDv within the United States during the week of Jan. 24. That number represents the largest number of new cases in a single week since the outbreak began in April 2013 and brings the total number of confirmed case to 2,962. The disease also is wide-spread, with 23 states reporting at least one confirmed case of the virus. In addition, outbreaks of the disease were reported in Mexico during the third-quarter of 2013, and Canada recently reported its first confirmed cases of PEDv in mid-January 2014.
Investigations of Feed, Feed Ingredients as a Potential Disease Vector
The ongoing outbreak of PEDv has affected the feed industry. Following is a timeline of information released on feed-related PEDv issues.
APHIS and FDA Investigation: APHIS, in collaboration with the U.S. Food and Drug Administration (FDA), issued the following statement on May 30, 2013 pertaining to reports the agency received that animal feed may be a possible factor in transmitting the disease:
USDA’s Animal and Plant Health Inspection Service (APHIS) is working closely with stakeholders to monitor the situation around porcine epidemic diarrhea (PED) in the United States. We received reports that animal feed may be a possible factor in transmitting this disease, so we partnered with the Food and Drug Administration (FDA) to investigate this possibility. At this time, here is what we know – we tested samples of feed and feed ingredients associated with one case of PED at the National Veterinary Services Laboratories (NVSL), with no positive results for PED antigen by polymerase chain reaction (PCR). However, our investigation with FDA is ongoing. We are also collaborating closely with American Association of Swine Veterinarians (AASV), National Pork Board (NPB) and the National Pork Producers Council (NPPC) on a broad epidemiological investigation to help identify any risk factors in the transmission of this disease.
Neither APHIS nor FDA have issued subsequent statements related to the potential of feed being a vector for PEDv.
Testing Feed for PEDv: The University of Minnesota Veterinary Diagnostic Laboratory reported in June 2013 that: 1) there currently are neither official nor validated methods for testing the virus status of a feed sample; and 2) historically, feed samples testing positive for infectious virus have rarely been documented. Polymerase chain reaction (PCR) assays of feed and feed ingredients do not distinguish between live and inactive virus.
AASV Epidemiologic Survey: AASV collaborated with NPB, NPPC, and the U.S. Department of Agriculture’s Center for Epidemiology and Animal Health to conduct an epidemiologic survey to identify risk factors potentially associated with the introduction of the PEDv into the U.S. swine herd. As an outcome, AASV released a statement in August 2013 concerning preliminary findings of the survey, which included the following:
Over 100 variables were assessed during the survey. Of these, only seven were considered significantly likely to have some association with the introduction of PEDv into the herds involved in the survey. These seven risk factors were associated with the process of feeding the animals. The questions were broad in scope and did not implicate any specific finished feed, feed ingredient, feed manufacturer or ingredient supplier.
The results of this initial survey should not be over-interpreted. The sample size was small, with many common on-farm practices and potential biases.
To date, all feed and ingredient samples tested for PEDv have tested negative. There is no diagnostic indication that feed was in any way related to the introduction of PEDv into the U.S. swine herd. The feed industry has been, and continues to be, fully cooperative with all efforts to identify any possible sources of viral introduction. We want to stress that we do not have any evidence that any feed ingredient, finished feed or feed manufacturer was associated with the introduction of PEDv.
APHIS Disease Pathway Assessment: APHIS conducted a meeting on Dec. 11-12, 2013, with other regulatory agencies and industry groups to gain information as part of a project to assess disease pathways. The purpose of the project was to conduct an entry assessment as the first step toward determining whether significant gaps exist in import regulations that may result in infections of U.S. domestic swine with exotic viral pathogens of swine. Participating in the meeting were representatives from the NGFA, American Feed Industry Association (AFIA), FDA, Customs and Border Protection, NPB and AASV.
Representatives from NGFA, AFIA and FDA during the meeting provided information about regulatory requirements associated with feed ingredients, and industry practices pertaining to sourcing and using such products. APHIS is using this and other information to make a likelihood estimation concerning the potential of feed being a pathway for introduction into the United States of exotic viral pathogens of swine. APHIS has made an initial draft of the entry pathways assessment available to the meeting’s participants for review and comment. It is anticipated that APHIS will issue a final report by the end of March.
Statement by National Renderers Association: In response to concerns that rendered products and blood products used in animal feed may be a potential factor in transmitting the disease, the National Renderers Association on Feb. 11 issued a statement that provides scientific information pertaining to the safety of such products.
Canadian Food Inspection Agency Investigation: The Canadian Food Inspection Agency (CFIA) on Feb. 18 issued a statement related to its PEDv investigation, which included the following information.
Testing [by CFIA] has determined that PED virus was present in samples of US-origin plasma obtained [by a Canadian feed manufacturer]. This plasma was used as an ingredient in feed pellets produced by the company. Testing with a swine bioassay has determined that the plasma ingredient contains PED virus capable of causing disease in pigs.
Further testing will be done to assess if the feed pellets are capable of causing disease in piglets, and results are expected within days. Testing will continue to confirm a direct link between the feed and the spread of the disease, as the virus is only confirmed in a single ingredient at this time.
Testing with a swine bioassay involves feeding pigs with the ingredient and/or feed in question and monitoring the animals for the disease. Within the United States, APHIS’s National Veterinary Services Laboratories (NVSL) in Ames, Iowa is the only laboratory capable of performing bioassay testing for official purposes.
Biosecurity during Feed Delivery
The use of prudent biosecurity practices during feed delivery assists in limiting the spread of infectious diseases among livestock, including PEDv. Following are sample feed delivery biosecurity practices based upon recommendations made by the NPB that feed manufacturers may wish to consider when delivering feed to swine producers.
Delivery Equipment: The cleanliness of feed delivery equipment plays an important role in preventing the spread of disease. Trucks and trailers used for feed delivery should be thoroughly cleaned, washed, disinfected and dried. To appropriately clean delivery equipment:
- Scrape/remove dirt and/or debris that may be present on the equipment prior to washing.
- Soak the equipment with soap and/or degreaser.
- Pressure wash the equipment with hot water.
- Disinfect the vehicle with an appropriate disinfectant, following all label directions. The effectiveness of disinfectants is reduced when applied to a surface that is not clean.
- Cleaning and disinfecting also is to occur within the interior of the truck cab.
- Other equipment associated with delivery of feed – e.g., brooms, shovels, etc. – are to be cleaned and disinfected.
- All delivery equipment is to be thoroughly dried prior to being placed back in service.
Delivery Driver Practices
- Drivers are to wear clean clothes and footwear.
- Drivers are to put on clean, disposable boots in the truck before exiting the cab at the delivery site.
- Drivers are to put on clean, disposable coveralls immediately after exiting the truck cab.
- Drivers are to stay as close to the delivery truck as possible to minimize the areas accessed.
- Drivers are to only access areas of the delivery site for which they are authorized. This likely means not entering the barn office or other facilities. Feed invoices and tags also should be left in a designated area, such as mailboxes attached to the bin leg or outside of the office.
- For bulk feed deliveries, if possible, drivers should communicate with the farm staff and ask them to open and close the bin lids.
- For sack feed deliveries, drivers are to only unload products within designated areas.
- After unloading of feed is complete, drivers are to remove coveralls and disposable boots when climbing back into the truck. These items are to be disposed of in a separate garbage bag or container.
- Drivers are to apply hand sanitizer to maintain a clean cab before touching surfaces after re-entering the truck.
Visit NPB’s website to access specific transportation and delivery practices recommended by the NPB to assist in preventing the transmission of infectious diseases.
The NGFA will provide additional information pertaining to PEDv and feed-related issues as it becomes available. Members with questions about PEDv may contact NGFA Vice President of Feed Services David Fairfield by phone at (712) 243-4035 or by email at firstname.lastname@example.org.