Swine Enteric Coronavirus: Worldwide Threat to Global Pig Sector?15 January 2015
As winter returns to the northern hemisphere, so too does the threat of Swine Enteric Coronavirus Diseases (SECD). What is the current status of the disease around the world and have control measures been effective?
Since its appearance in the United States in April 2013, the Porcine Epidemic Diarrhoea virus (PEDV) has spread within the swine industry, causing much distress to affected farmers and disruption to the pork supply. In early 2014, an additional related virus, Porcine Delta Coronavirus (PDCoV), appeared in this country.
Infections with these novel Swine Enteric Coronavirus Diseases (SECD) can cause significant morbidity and mortality, particularly in young piglets. It has been estimated that more than eight million pigs have died.
Progress on PED in the United States
In response to the significant impacts of these SECD on the US pork industry, USDA issued a Federal Order in June 2014.
The two basic requirements of the Federal Order are that:
- Producers, veterinarians, and diagnostic laboratories must report all cases of novel SECD to USDA or State animal health officials and
- Pig herds or premises that are confirmed to be affected with these viruses must work with a veterinarian – either their herd veterinarian, or USDA or State animal health officials – to develop and implement a reasonable herd/premises management plan to address the detected virus and prevent its spread.
The aim of the Order, along with other measures, is to allow the USDA and the states to collaborate with herd veterinarians and producers to manage the diseases in a manner that supports business continuity for commercial pork producers and maintains a plentiful supply of pork.
In a report in December 2014 on the progress since the Federal Order was introduced, USDA says it is now receiving more accurate and timely information about SECD-affected herds and their locations. This is allowing animal health officials to understand better how the disease spreads and what measures are most effective in containing it.
Prior to the Federal Order, information on these diseases was basic and limited, according to the USDA, which made it difficult to monitor the spread or conduct disease investigations.
So among the main advantages USDA gives for the Federal Order is that the number of tests submitted with a premises identification number has increased from 20 per cent to more than 75 per cent. This allows more accurate monitoring of current disease incidence and spread. The proportion is likely to rise further as the USDA has not been reimbursing the cost of SECD samples submitted unless a Premises Identification Number is included on the submission form since mid-December 2014.
USDA says the Federal Order has also allowed the two conditional licenses for vaccines to be granted, which provide producers with additional options to help protect their herds.
The Order has also improved the ability of the USDA to detect new viruses and changes to existing viruses through viral genetic sequencing, it says.
Finally, receiving information quickly and electronically through an improved information technology network with the laboratories allows for federal and state health officials to understand better the spread of a foreign animal disease outbreak in nearly real time.
As a result, USDA epidemiologists are studying a number of potential routes SECD may have entered the country. A report is due on their findings in the next few months.
This work comes at a cost, of course. In June 2014, more than $26.2 million in funds was committed to the cost of diagnostic testing, biosecurity and herd plans for producers and veterinarians, measures that will continue as long as funding remains.
The USDA’s Animal and Plant Health Inspection Service (APHIS) publishes weekly updates on the numbers of US pig farms testing positive for PEDV and PDCoV.
As expected with viral diseases, the numbers fell during the summer of 2014.
Moving into the colder weather of winter, there are signs of an increase in the number of virus-positive findings, attributed to truck washes being less effective in cold weather.
During the summer months, there were between 50 and 70 new PEDV-positive results per week and this has increased to more than 100 since November. This is still below the 300-plus figure at the height of the previous winter, however.
In November 2014, Hawaii reported its first PEDV-positive findings, bringing the total number of states affected to 33.
For PDCoV, 17 states have reported virus-positive findings since testing began but the rate of new cases is slower than PEDV, currently running at between 10 and 20 per week. PDCoV also causes lower mortality than PEDV.
Dual infections with both PEDV and PDCoV simultaneously are also being monitored in the US.
PED in Other Countries
Thought to have originated in China, the PEDV has not been confined to the United States.
As it is not a notifiable disease, there is no requirement for countries to report PED outbreaks to international agencies such as the World Organisation for Animal Health (OIE) and national animal health agencies vary widely in their monitoring and reporting of the situation.
Canada has also reported losses, mostly in Ontario, since January 2014. There too, cases tailed off as temperatures rose during the summer but seem to be picking up again. Four confirmed PEDV-positive farms were reported in the province in December 2014, bringing the total to 69.
Last year, PED was reported in Mexico - where losses in production hit the country’s pork market – in Colombia and in December 2014, Peru was hit by its first outbreak.
In Asia, outbreaks continue to be confirmed in different regions in Japan.
The highly virulent Asian-American PEDV has been reported recently for the first time in Europe. So far, the first outbreak in Ukraine has not spread to any European Union countries. A low-pathogenic PEDV, however, has been detected in Germany, the Netherlands and France, and some cases are suspected in Spain.