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Summary of Equine Influenza outbreak in JRA facilities

Re: Equine Influenza outbreak in JRA facilities
(Interim Report)

Preface:
This document contains information on the Equine Influenza outbreak in Japan but limited to those in the JRA facilities. It is intended to provide up to date information on the development and measures taken by JRA since the initial EI case was found on 15 August. Epidemiological research is still ongoing and technical information and analysis will be made available to the International Movement of Horses Committee at later date. Please also note that this document does not contain information about outbreak outside of JRA facilities such as breeding farms and NAR tracks.

Overview:
On 15th August at the Miho Training Center (TC) located in Ibaraki Prefecture, Japan, a nasal swab sample taken from a febrile Thoroughbred race horse reacted positively to the influenza detection kit, (Fuji-revio, Japan). The nasal sample was sent to the Epizootic Research Center, Equine Research Institute, JRA and subjected to an RT-PCR test to detect HA gene of equine influenza 2 virus (H3N8).

Movement ban was immediately ordered for horses and people at JRA racecourses and training centers where thoroughbred and pleasure horses are present.

On 16th and 17th of August, JRA conducted equine influenza examination to the 967 horses out of 4,235 horses stabled at various JRA facilities which presented 19.4% positive.

On Saturday, 18th and Sunday 19th of August, total of six race meetings scheduled at Sapporo, Niigata and Kokura Racecourses were cancelled. Number of febrile horse became maximum on Saturday, 18th August with 38 horses testing positive on the single day however the situation started to settle down soon after with limited number of new positive cases found each day. (See appendix 1)

On 20th and 21st of August, JRA conducted equine influenza examination to the 2,012 out of 4,235 horses (47.5%) stabled at various JRA facilities which presented 9.0% positive which showed substantial decrease from the same equine influenza examination conducted on the 16th and 17th of August.

On 25th of August, JRA race meeting was resumed under following epizootic conditions.
1) Horses' movement limited between JRA facilities only.
2) Accept entries from the horses tested negative to the equine influenza simplified test by the influenza detection kit (the simplified test).
3) All entries must be retested after accepting entries with the simplified test and any horse found positive is excluded from the field.
4) Clinical inspections to all horses (by official vets) carried out on the race day (of the horse).

On 4th of September, the ban on the movement of horses between JRA and non-JRA facilities was partially lifted sighting that the situation begin to come under control with no clinically positive case reported since 27th August. The removal of this ban comes into effect at the Miho and Ritto Training Centers only and is limited to about 50 horses per day. Other strict requirements established by JRA must also be fulfilled. The basic outline of the requirements is as follows:

1) Horses departing JRA facilities must be stabled at a designated quarantine space in the facility for seven days prior to departure and must be free from any equine influenza symptoms during that time.
2) Horses departing JRA facilities must show a negative result to the simplified test on both the first day and the last day of the confinement.
3) Horses departing JRA facilities must have a valid health handbook recording every treatment.
4) The health information on the horse must be reported to the receiving farm and the relevant local authorities.
5) The receiving farms are asked to place the horse coming from the JRA facility in isolation for seven to ten days and to conduct the necessary precautionary test for equine influenza.
6) Horses coming into JRA facilities must go into isolation upon entry and have their temperatures taken twice during the isolation period and gain clinical approval from the veterinarian.
7) Horses coming into JRA facilities must test negative for equine influenza.
8) Horses coming into JRA facilities are recommended to receive a booster vaccination for equine influenza at least two weeks prior to entry into JRA facilities. Horses arriving without booster vaccination will be vaccinated during the isolation period.
9) Horses coming into JRA facilities must fulfill the current equine influenza vaccination protocol established by JRA.

Since the initial occurrence to today, total of 8,351 clinical and epizootic tests were conducted at JRA facilities and 603 cases were found positive to equine influenza. In detail, 413 positive cases were found from 7,745 epizootic test (5.3%) and 194 positive cases were found from 606 clinical cases (32.0%) on the febrile horses (above 38.5?).

JRA's equine influenza (EI) vaccination program:
Horses must fulfill following vaccination program in order to enter into JRA. This program has been in place soon after equine influenza outbreak which forced JRA to cancel races at eastern Japan region for about two month in 1972.

For horses born in Japan after 2003;
1) Horses must be vaccinated twice in interval between two weeks and two month as yearlings and must receive an initial booster vaccination in the same year.
2) Horses must receive booster vaccination every six months thereafter.

For horses born outside of Japan after 2003;
1) Horses must be vaccinated twice in interval between two weeks and two months as soon as possible upon arrival into Japan. Furthermore, horses must receive an initial booster vaccination between four weeks to seven months.
2) Horses must receive booster vaccination every six months thereafter.

Every horse registered with JRA are mandated to follow EI vaccination program. JRA subsidizes 50% of cost associated with the vaccination program. All race horses have been vaccinated twice a year (most recently in May, 2007).

Isolation measure:
In general, any horses with febrile symptom are put into isolation. Where separate stable facility is not available for isolation, febrile horses must be separated as much as possible from non-symptomatic horses in the same stable.

Sterilization measures:
1) Premises
• Sterilization is to be conducted on routine basis.
• Stables and stalls- Spray with centuple diluted cationic soap.
• Tracks, walk path and other premises- Spray with di-centuple diluted cationic soap.
2) Horse floats
• Horse floats must be sterilized at each entry and exit to JRA facilities. Horse floats are sterilized with spray or disinfection mat and area around the tires must be thoroughly sterilized.
• Horse cabin and tires must be thoroughly sterilized each use upon carrying horses.
3) People
• People coming into the JRA facilities must sterilize the footwear at each entry and exit. Furthermore, people must wash their hands before contacting horses.
• People coming into the JRA facilities must refrain from coming into contact with race horses outside of JRA facilities.
• In case people come into contact with horses outside of the JRA facilities, they must change their cloth before contacting horses in the JRA facilities.
4) Used bedding, manure and fodder
• Processed at JRA's refuse compost.

Results of EI epidemiological test conducted at JRA facilities:
Date Number of tests
(A) Positive cases
(B) Percentage of positives
(B/A)
16-17 August 967 188 19.4%
20-21August 2,012 181 9.0%
23-August 1,321(*) 41 3.1%
30-August 1,245(*) 1 0.1%
6-September 1,069(*) 1 0.1%
13-September 1,131(*) 1 0.1%
(*) – Test conducted on all entries.

Causal agent:
Virus isolates from affected horses were identified as equine 2 influenza virus (H3N8) Florida sub-lineage by sequence analyses of HA1 and NA genes.

- Japan Racing Association


 

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