Ειδικές Δράσεις /Special Actions

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HELLENIC REPUBLIC
MINISTRY OF AGRICULTURE
D.G. OF VETERINARY SERVICES
ANIMAL HEALTH DIRECTORATE
DEPT. OF INFECTIOUS DISEASES,
EPIDEMIOLOGY & DOCUMENTATION

Address : 2 Acharnon Str.
101 76 Athens, Greece
Telephone : 0030-1-88 35 420 / 88 36 420
Fax : 0030-1-82 52 614 / 82 29 188
E-mail : vetserv@ath.forthnet.gr
Web Site : httm://www.minagric.gr/greek/2.3.1.html

The Prefecture of Arta lies in mid-western Greece, on the Ionian Sea, and 70% of its territory is covered by mountains, in some cases inaccessible (see attached Map).

The indigenous livestock population is small comprising of (census of 2000) :

• 353 herds with 2.046 bovines
• 1.271 flocks with 160.509 sheep
• 700 flocks with 36.160 goats
• 611 mixed flocks (sheep + goats) with 60.480 animals

The mountains of Arta can sustain large numbers animals (bovines,sheep and goats) and during summer are an often destination of animals originating in other areas and following a long established and seasonal transhumance pattern.

During the 1999 epizootic, clinical and serological surveillance had failed to identify any evidence of disease in Arta.

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(*) Prepared for and presented at the Standing Veterinary Committee on 07 - 08 November 2000

Initial suspicion was raised in late September on the basis of clinical signs in sheep involving nasal discharge, lesions on the lips and muzzle, fever and, occasionally, slight and transitory lameness.Mild facial edema but tongue swelling was observed.

The morbidity rate in affected flocks was very low (5%) and the mortality rate was, and remains, nil. A provisional diagnosis of orf was made locally and treatment was advised. Invariably animals responded well to treatment and appeared to recover fully.

The mild disease, however, persisted and even spread locally and, in early October, blood samples, both from affected flocks and from flocks contiguous to them, were submitted for serological and virological tests for BT.

Results were issued on 18^th October and are summarized in Table 1 below.

Table 1 : Laboratory results for BT in Arta, Greece

• Footnotes to Table 1 :

(1) = Flocks with clinically affected sheep in the index case(s)
(2) = Targeted serology in clinically affected sheep for diagnostic purposes.
(3) = Flocks contiguous to index case(s).
(4) = Random sampling for epidemiological purposes.Some animals displayed non-
specific clinical symptoms which, in the light of serology results, are probably
due to orf.

On 27^th October the single field isolate of BTV was definitively typed as sero-type 4.

Assessment of clinical evolution of BT in Arta is obscured by a concurrent and heavy
infection by orf.

The clinical manifestation of BT, in conjunction with laboratory findings for BT and orf,
is presented in Table 2.

Table 2 : Clinical picture of BT in Arta

• Comments on Table 2 :

a) Reported BT outbreaks are true outbreaks only on the basis of serological
findings.This approach, however, presents legal and practical problems relating
to the definition of an "outbreak".
b) Even positive serology results are subject to valuation and interpretation in the
light of further laboratory tests and epidemiological inquiries before they are
taken to mean active outbreaks.
c) Figures in brackets give the numbers of clinically sick animals perceived by the
local veterinary service. This assessment, however, is highly subjective and
probably inaccurate considering the results of serology for orf.

On the basis of available information, the BTV most likely originated in Magnesia and spread to Arta some time in early June probably due to illegal movement of beef cattle following the seasonal transhumance pattern.
It is reminded that the Pref.of Magnesia had been affected in 1999 by BTV and the
sero-type involved was also 4.

Also, is has been retrospectively established that cattle were indeed moved from Magnesia to Arta and their detailed tracing is currently in progress. Specifically, the epidemiological investigation is addressing such issues as their exact place of origin, time and circumstances of their movement and their current serological profile for BT.

According to the predominant working hypothesis, spreading of BTV to Arta can be explained by the following scenario :

As has been observed in the past,once the virus was introduced into naïve susceptible animals the disease progressed in waves,the first one being geographically limited and
affecting very small numbers of animals so as to elude detection.

Therefore,what was seen in early October must have been the second wave of disease which was due to secondary spreading inside Arta after the local vectors became infected.

Judging by the clinical and serological profile of affected and contiguous flocks, the following qualified assumptions can be made :

a) In most, if not all, cases of affected flocks there was an overlapping infection by orf which probably accounts for the severe clinical symptoms observed.
b) Morbidity in affected flocks was approx.5% and mortality was nil.
c) The mild clinical symptoms attributed to BT infection are explained by the type of virus involved (in 1999, type 4 was much less virulent than 9).

With the notable exception of the index case(s), secondary spreading of BT appears to be geographically limited and involving small numbers of animals in affected flocks. In addition, sero-prevalence in contiguous flocks is quite low.

This is probably due to absence or small populations of efficient vectors (C.imicola) at local level.

With a view to determine the spreading of infection the following actions are currently organized :

a) Random serological screening of susceptible animals in different regions of Arta in order to delineate the spread of infection.
b) Placement of light traps for vector identification and monitoring.
c) Placement of sentinel bovines and serological surveillance for BT virus circulation.

By Ministerial Decision No.393263 / 18.10.00, the Prefecture of Arta was subjected to restrictive measures and surveillance procedures specified in Annex I to Commission Decision 2000/350/EC.

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