Nearly a year passed since the first case of porcine epidemic diarrhea (PED) in seven years was reported in Japan. The outbreak spread to 38 prefectures, with more than 1.2 million pigs falling victim. The disease killed roughly 370,000 of them, mainly piglets. It posed a serious threat to the hog farmers’ business, bringing renewed attention to the importance of biosecurity.
Following the outbreak of PED reported in Okinawa Prefecture on Oct. 1, 2013, the disease spread throughout the nation, especially in the southern Kyushu region. Although it seemed to be nearly under control this summer, another case was reported in the Kanto region in September. The risk of the disease has not disappeared completely. Another concern lies in the shipments of pigs in the coming months. The number of butchered pigs is estimated to mark a 6.1 percent year-on-year drop in October and decline 5.3 percent from the same period last year in November and December, according to the Ministry of Agriculture, Forestry and Fisheries. Farmers will be hit hard, with their incomes likely to be largely reduced or stopped. If the domestic pork production becomes sluggish, it could be replaced by imports.
Why did the disease spread nationwide? Maybe people have been off their guard because it was the first case in seven years and was reported in the island prefecture of Okinawa.
Under the Act on Domestic Animal Infectious Diseases Control, epidemics are classified into notifiable diseases and those designated by law. PED is classified as a notifiable infectious disease which, unlike diseases designated by law, does not require farmers to take disease control or prevention measures under administrative guidance. Such classification might have made farmers less alarmed, but disease control and prevention measures are required also for notifiable diseases. People need to be more aware of biosecurity procedures.
Another reason for the spread of the disease is the difficulty of detecting PED infections. Infected piglets face a high risk of death, but adult pigs, even if they are infected, recover quickly or may not show any symptoms.
Concerns remain regarding immunization to prevent infection. It took time for vaccines to be distributed to farms, due to inventory shortages and slow production. There were also cases of buying up vaccines or misusing them, such as vaccinating infected piglets despite the fact that vaccines are effective only when pregnant sows are inoculated.
Experts also point out the disease was spread by vehicles that go in and out of hog farms. It is necessary to ask for cooperation of vehicle operators which visit a number of farms, such as those delivering feed, and make them be aware of disease control measures. It is possible to reduce infection risks by taking such measures as disinfecting vehicles, drivers’ shoe soles and car mats at farm entrances, prohibiting drivers from getting off the vehicles when they are inside the farms and asking them to visit infected farms last when making deliveries.
It is difficult to investigate on how the virus entered the country in the first place, but various factors for the spread of the disease have been revealed. Farmers also must have become aware by now of why the disease occurred and spread. It is important to share the lessons drawn from this experience and convey correct information to farmers, regional communities and the overall pork industry, so that appropriate measures will be taken to prevent future outbreaks of PED and other animal diseases.
PED virus becomes active when the weather gets cooler. There is a possibility of viruses still remaining in farms where the infection occurred. Farmers must tighten their guard against the disease and review their prevention measures such as vaccination and disinfection.
(Sept. 24, 2014)