**3. On farm investigation**

#### **3.1. Regulation associated to investigation**

In the Republic of Korea, in case of FMD outbreak, control measures are implemented based on the investigation of outbreak epidemiology. Both investigation and control measures were stipulated by the Act on the Prevention of Contagious Animal Diseases, the FMD Control Guidelines, and the standard operation procedure for FMD. These regulations include notification of suspected cases, movement control, stamping‐out, disinfection, regular and emergency vaccination, import quarantine, disposal, compensation, and penalties [8, 9].

#### **3.2. Principle of investigation**

A smart investigation on the epidemiology of outbreak is crucial in order to implement control measures in case of confirming FMD. In case of FMD outbreak, the veterinary epidemiology division of the Animal and Plant Quarantine Agency (QIA) took overall responsibility for the epidemiological investigation throughout Korea. Field investigation and contact tracing were performed for each outbreak farm and putative dangerous contacts. All movements in‐and‐ out associated with animals, people, vehicles, and materials were investigated for each farm for at least 21‐day period (14 days in case of vaccination) immediately before the outbreak date. Then, the forward‐and‐backward tracings, which list up all the places visited before and after being at the outbreak farm, were performed for each visitor, resident, and worker related to the farm [10].

#### **3.3. Example of field investigation in Korea**

A template to guide epidemiological investigation on the outbreak site is is prepared. The investigation process includes three steps: confirming infection, estimating date of first infection and determining mode of introduction. Below is example of investigation on FMD outbreak in Korea.

#### *3.3.1. Confirming infection*

maternal antibodies because they were born before the beginning of vaccination, and pigs at 3–4 weeks before delivery. And deer and goats were also added to the vaccine object. Since September 2011, it was mandatory for all cloven‐hoofed animals to be implemented with trivalent (O, A, Asia 1) vaccination by 6‐month interval. Before nationwide vaccination, all animals in the outbreak farm were stamped out. However, after 27 January 2011, when the nationwide vaccination was successfully completed, only animals showing symptoms or a

8 Epidemiology of Communicable and Non-Communicable Diseases - Attributes of Lifestyle and Nature on Humankind

On 23 July 2014, the suspected animals were reported from 1 pig farm with 1,500 animals in Euseong, Gyeongsangbuk‐do. The presence of FMD virus was confirmed in the next morning. Clinical signs appeared in unvaccinated animals in that farm. Subsequently, FMD was

After 4 months, on 3 December 2014, a veterinarian of a farm with 15,884 animals in Jincheon, Chungcheongbuk‐do, observed vesicles and ataxia in 30 pigs and reported the same to the county office. FMD was confirmed on the next day. During the next 147 days, until 28 April

In the Republic of Korea, in case of FMD outbreak, control measures are implemented based on the investigation of outbreak epidemiology. Both investigation and control measures were stipulated by the Act on the Prevention of Contagious Animal Diseases, the FMD Control Guidelines, and the standard operation procedure for FMD. These regulations include notification of suspected cases, movement control, stamping‐out, disinfection, regular and emergency vaccination, import quarantine, disposal, compensation, and penalties [8, 9].

A smart investigation on the epidemiology of outbreak is crucial in order to implement control measures in case of confirming FMD. In case of FMD outbreak, the veterinary epidemiology division of the Animal and Plant Quarantine Agency (QIA) took overall responsibility for the epidemiological investigation throughout Korea. Field investigation and contact tracing were performed for each outbreak farm and putative dangerous contacts. All movements in‐and‐ out associated with animals, people, vehicles, and materials were investigated for each farm for at least 21‐day period (14 days in case of vaccination) immediately before the outbreak date. Then, the forward‐and‐backward tracings, which list up all the places visited before and after

positive reaction were stamped out [8].

**2.6. Epidemic in July to August 2014**

**3. On farm investigation**

**3.2. Principle of investigation**

**3.1. Regulation associated to investigation**

diagnosed in two more farms by 6 August 2014 [9].

2015, 180 pig farms and 5 cattle farms were confirmed with FMD [9].

**2.7. Epidemic in December 2014 to April 2015**

FMD suspected animals were reported from a pig farm with 1,552 pigs in two houses located adjacent to buildings of pork‐processing plant, on 2 June 2002. FMD outbreak in this farm was confirmed on 3 June, based on serological and virological tests.

#### *3.3.2. Estimating date of first infection*

In the late evening of 1 June, one of the farm workers notified "something abnormal on the hooves of the growing pigs to the owner. O the next morning, upon reporting of the owner, staffs of QIA (it was named National Veterinary Research and Quarantine Service, NVRQS, at that time) visited the site and observed intact vesicles (nasal plane, oral cavity, and coronary band), ruptured vesicles (coronary band), lameness, anorexia, and fever on nine animals examined in detail. Based on the number of animals with clinical signs and the age of the oldest lesion, the first clinical sign was estimated to have been developed since 7 days. Considering the incubation time of 4 days (a range of 2–14 days), FMD virus infection in this herd was the most likely to start on on 22 May (12 May at the earliest to 24 May at the latest)s.

#### *3.3.3. Determining mode of introduction*

Through field investigation and tracing, a total of 229 farms had contacts with this out‐ break farm during 21‐day period before the notification, either via people or vehicles vis‐ ited to this farm or via slaughterhouse to which pigs were sent from this farm. No pigs had been introduced onto this farm. Preemptive slaughter was undertaken on three farms having epidemiological associations: One farm had dangerous contact such as sharing a common pig‐transport truck, and the other two were located within 3‐km distance from the outbreak farm.

A direct link was identified between this farm, reported on 2 June and the index farm, reported on 2 May. There was a person (man) worked at the neighboring pork‐processing plant on a part‐time basis, which was operated by the same owner with the outbreak farm. He has also participated in the culling operations on the index farm during three consecutive days from 3 May. He drove his car to the local animal health service then transported to the slaughter site, in wearing a T‐shirt, a pair of blue jeans, and a pair of boots. At the slaughter site, disposable work‐suit and boot covers were provided. After completing the operation, he cleaned himself at a public bath together with other work‐

ers. Then, he put new underwear and shirts provided by the local government. But, he put again the same trouser that he wore in working because he had no spare one. While he took a bath, his jean was wrapped in a vinyl bag after being sprayed disinfectant. He returned back home by his own car in which no disinfection measures were implemented. He worked at the port‐processing plant for three or four occasions, starting on 8 May. FMD virus was probably transmitted by this person considering that the index farm, on which 330 (4.0%) of 8,302 pigs showed clinical signs or died at the time of culling, was heavily contaminated at the time of culling. FMD virus must survive in environment such as interior of his car, and transmitted to the pork‐processing plant and adjacent pig hous‐ es during 17 days of interval between the completion of culling (5 May) and the most like‐ ly date of first infection (22 April) [10].
