Animal Health Trust
ADDITIONAL INFORMATION FOR 2ND QUARTER 2000
Tetanus A single horse (2 year old, non-Thoroughbred, male) on a single premise was affected in May 2000 with clinical signs and was destroyed.
INTERIM REPORT DATED 17th NOVEMBER 2000
Suspected case of Japanese
A three-year old thoroughbred racehorse imported into Hong Kong from Australia on 27 March 2000 was humanely destroyed on 30 October 2000 with clinical signs of encephalitis.
The horse became mildly pyrexic on 25 October and was treated in a routine manner with antibacterial and anti-inflammatory medication. No other clinical signs were observed until 28 October when slight hyperaesthesia and inappetence were noted. The neurological signs rapidly progressed until the horse was euthanased, as he had, despite symptomatic treatment, become a severe danger to himself and personnel.
Both gross and histopathological signs of a non-suppurative meningo-encephalitis were noted.
Paired sera collected on 25 and 30 October showed a four-fold rise in Japanese encephalitis (JE) antibody from <10 to 40.
Serum, cerebrospinal fluid, brain and spinal cord samples have been/are being tested at:
Negative reports for the following diseases have so far been received:
Results are awaited for:
and will be reported when available.
All equines in Hong Kong are vaccinated annually against Japanese encephalitis virus (all racehorses continuously since 1972 and all retired racehorses and non-thoroughbreds continuously since 1993). The last equine case of JE (diagnosed on clinical signs and serology), was in a vaccinated horse in June 1981.
Currently there are 1,580 equines in Hong Kong (1,094 stabled at Sha Tin Racecourse and 486 in 9 riding schools) and none of them have shown any signs of encephalitis, either before or after this reported case.
Mosquito control programmes have been enhanced.
UNITED STATES OF AMERICA
West Nile Virus (WNV) Information is based on published reports to October 31. Twelve states in the northeast have reported the presence of the virus, Connecticut, Delaware, Maryland, Massachusetts, New Hampshire, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, Vermont, Virginia, plus Washington, D.C. The virus has been reported most frequently in dead birds and mosquitoes with 18 reported human cases, of which one was fatal and 53 equine cases, 22 of which were reported fatal. Of the human cases 13 were in New York City and 4 in New Jersey and 1 in Connecticut. The equine cases were distributed in New Jersey (25), New York (15), Connecticut (7), Delaware (3), Pennsylvania, Massachusetts and Rhode Island.
An extensive surveillance program has been undertaken in New York State which has reported 1228 positive dead birds of 56 different varieties, the majority of which were crows. In the same state evidence of infection has been found in bats (14), live birds (8), rabbits (3), squirrels (3), cats (2), raccoons (2) and a chipmunk. A positive skunk has been identified in Connecticut
The majority of positive mosquito pools have been found in and around the city of New York. Several different species were identified in 5 states including species active at dawn, dusk and during the day that feed on avian and mammals. The majority was Culex pipiens but also identified were C. restuans, C. salinarus and C. melanura; Aedes species, A. albopictus, A. japonicus, A. triseriatus, A. vexans, and A. cantator; Anopheles punctipennis and Psorophora ferox.
Whilst flocks of chickens have been used extensively as sentinels only 6 chickens, at 6 sites in New York and New Jersey, have sero-converted.
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