EUFMD- ETC 5 FMD REAL TIME TRAINING COURSE ERZURUM 03 … · FMD CLINICAL AND EPIDEMIOLOGIAL...
Transcript of EUFMD- ETC 5 FMD REAL TIME TRAINING COURSE ERZURUM 03 … · FMD CLINICAL AND EPIDEMIOLOGIAL...
EUFMD- ETC 5 FMD REAL TIME TRAINING COURSE ERZURUM 03-06 MAY 2010
FMD CLINICAL AND EPIDEMIOLOGIAL REPORT: ESENKENT 04/05/10
Introduction
Suspicion of Foot and Mouth Disease (FMD) was reported in the village of Esenkent on Monday 3rd May 2010. The official veterinarian inspected the herd, to find clinical signs suggestive of FMD. Samples at this time were taken to support the diagnosis of FMD based on the the clinical findings, and were sent to the SAP institute.
The village was visited by the ETC-5 team on Tuesday 4th May. The EUFMD-training team
was split into two groups to carry out further clinical examination, sampling, and to
undertake an epidemiological investigation.
The location
Esenkent is a small village located 20km from the Armenian border. Esenkent is located in
the Kars district of the Turkish province of Kars. The village is located 40 km away from the
capital of the province, Kars city. The human population of the village is 200. The animal
barns, which house the animals in winter, are interspersed throughout the village,
distributed between the many residential buildings in which the villagers live. There are
common grazing grounds around the village, where all animals (irrespective of owner) graze
at certain times in the year. A satellite image of the village, along with locations of the 5
barns which contained the animals examined, is shown in Fig.1.
Population at risk
Data given by the local farmers and the local official veterinarian, gave animal population
sizes in the village of 1160 cattle and 100 sheep for fattening. There are no goats and no
pigs. At this time of year, animals are all out to graze on the common pastures, with only
animals which are sick being housed in the many barns in the village.
These animals are subdivided by ownership, with 60 different farmers being present in the
village, thus the term “farm” is used to described those animals belonging to one farmer.
FMD history
The last FMD outbreak in Esenkent was reported to be in 2006. FMD is endemic in the
Anatolia region of turkey.
FMD serotype ‘O’ has been reported recently in surrounding villages. At this point we are
unable to quantify, date or pinpoint these.
Upon arrival of the local veterinarian, it was reported by the villagers that the clinical signs
which lead to the local vet being called out first occurred on the 28th April. These clinical
signs were reported to be consistent with FMD and included pyrexia, vesicular lesions and
erosions on the lips and tongue, and general lethargy. As stated, the date of notification was
3rd May.
It was reported that, on May 3rd (the day before the ETC-5 team arrived), 20 animals were
showing clinical signs consistent with FMDV infection. These were all cattle, and belonged to
5 farms.
Vaccination regime
Vaccination is compulsory in Kars, and is financed by the local administration. Cattle must be
vaccinated, with a trivalent vaccine, twice a year and sheep once a year. The first
vaccination being carried out at 2 months of age and a second booster being given 1 month
later. Vaccination must be recorded in the passport and on the Turkish database, ‘TurkVet’.
The local veterinarian alone is permitted to vaccinate the animals.
Movement of animals. Source and destination.
Movement out of the village is only allowed for vaccinated animals and they should to be
accompanied by a health certificate.
It is a common practice to buy and sell animals in the local livestock market in Kars city.
Identification and registration of animals
Tagging and registration is official and compulsory within 6 months after birth with the
application of two ear tags and the issuing of an individual passport. In small ruminants the
system is under development but in cattle this is mandatory.
Fig.1. A satellite image of Esenkent, showing the structure of the village and also the locations of the 5 Barnes visited as part of the ETC-5 visit. The entrance of the village acted as our biosecurity and disinfeciton checkpoint and is also indicated.
Epidemiological evaluation of risk factors
Herd management
During winter, cattle are housed inside the barns. Depending on the local climate and
pasture quality / growth, the animals are released from the barns after winter, to graze on
pastures. These pastures are grazed by all animals in the village, irrespective of owner
(farmer). In spring and summer, for a period of 3 to 4 months animals are moved to
common upland pastures (yayla). These are common to many villages.
During winter, the animals are separated spacially as they are housed inside barns. However
these barns are in close proximity to each other, and upon questioning and observation,
there do not appear to be any biosecurity measures in place.
Outside the winter months, as outlined above, all animals from the 60 different farms are all
grazed together.
In addition, it is practiced to allow sick animals to graze in the common pastures, as this is
the only source of feed that they have. As all animals in the village use common grazing
ground, this is a major risk factor for the spread of FMDV
These facts, no clear farm separations, normal lack of biosecutiry measures and intermixing
of animals, lead us to group the whole village as one epidemiological unit with respect to
FMD epidemiological investigation.
Identification and registration
In the village (and on the Erzurum livestock market (visited on 5th May), it was observed
that the majority of the cattle were correctly identified via ear tag. There were, however, a
proportion of animals that were not identified via ear tag. This makes subsequent back and
forward tracing much more difficult, as well as vaccination recording and registration of
animals on the ‘TurkVet’ database.
Animal movement
Back Tracing
Upon epidemiological questioning of the local farmers, it was discovered that one month
ago, 20 cattle were bought at the Kars livestock market and brought to the village. Further
questioning revealed that some of these animals had showed clinical signs suggestive of
FMD, but were not reported at the time. It was reported that these animals have now
recovered and were out grazing with the rest of the village animals at the time of the ETC-5
visit and therefore not available for clinical examination / sampling by the ETC-5 team.
Tracing forward
It must be highlighted that 30 animals were sold 3 weeks ago to a dealer, who had the
intention to transport the animals to Konya (1.177 Km westwards).
Nevertheless, prior to this movement the official veterinarian inspected the animals,
checking correct vaccination, absence of clinical signs and passports.
Vaccination
The official veterinarian informed the team that on 3 March, 1078 animals were vaccinated.
There is a difference between the number of animals vaccinated and the number of animals
present in the village. The reason for this, according to the official veterinarian, is that only
healthy animals are vaccinated. As well, gravid animals are not vaccinated.
After the inspection it was noted that following the check of the vaccination records of 6
animals in the database, 3 animals were recorded to be vaccinated for the last time in
Autumn 2009 and 3 have not any record of vaccination. This may be a problem of incorrect
vaccination, or of incorrect introduction of the data in the database.
Epidemiological Overview details of animals examined by ETC-5
Upon arrival at Esenkent village, most of the village animals were out at pasture. It was
explained that those which had been seen to be showing signs consistent with FMD had
been moved inside the barns in the village by the respective farmers. The animals in each
barn were thus part of a larger farm, and were all owned by a single farmer:
First set of infected animals examined (Barn 1)
Three animals were in this barn at the time of inspection. The others belonging to this
farmer were grazing outside. All of this farmer’s animals were born at the farm.
Second set of infected animals examined (Barn 2)
Two animals were in this barn at the time of inspection. This farmer owned 20 animals, 14
of which had shown clinical signs but 12 are already recovered. This farmer had bought 9
cattle from the Kars market within the last month. It was not reported that these animals
had shown signs suggestive of FMD and these animals were not available for examination.
Third set of infected animals examined (Barn 3)
About 20 young cattle were present in this barn at the time of inspection. Although all
young, the age range amongst these animals appeared large. It was suggested that these
animals were housed due to their young age. The farmer was unwilling for extensive
examination and handling of all animals in this barn, but upon observation, one cow was
seen to be showing signs suggestive of FMD and thus was permitted to be subject to
thorough examination by the ETC-5 team. lThis farmer owned 90 cttle in total, the rest
being turned out to graze on the common pasture.
Fourth set of infected animals examined (Barn 4)
Two animals were in this barn at the time of inspection. The famer who owns these animals
have not bought in animals.
The full clinical findings as a result of examination by the ETC-5 team are shown in Table.1,
and the corresponding photographs are attached in ‘Annex 1’.
Clinical Results: Esenkent 04/05/2010
Vesicular lesion location/age
Animal ID
Species/sex
DOB/ Age
Clinical signs
Rectal temp (C)
LF RF RH LH Buccal cavity
Samples taken
Photo number (Annex 1)
Comments
Elevitkormaz (Barn 1)
Cow 1 Bovine Calf Salivation 37.8 None None None None N: 2-3 days T/DP: 5 days
Epi/P/S/B
Barn 1: ‘C1 – 1’ to ‘C1 – 10’
Primary vaccination (approx 3rd March) ?
Cow 2 Bovine Calf None 39.4 None None None None T: 10 days DP:7 days
P/S/B Barn 1: ‘C2-1’ to ‘C2-4’
Primary vaccination (approx 3rd March) ?
6443 Bovine Calf None 38.5 None None None None None P/S/B None Primary vaccination only (approx 3rd March) ?
Kadir Demirkaya (Barn 2)
TR 36153 9070
Bovine Female
27/06/09
Recumbent 39.8 None Pain ID, secondary infection
CB secondary infection. Surface skin temp. increased
None DP: 14 days T: 14 days
S Barn 2: ‘9070-1’ to ‘9070-9’
Vacc . 15/10/09. Also vaccinated approx 3rd March ?
TR 36168 6176
Bovine Female
21/07/09
None 39.4 None None None None DP: 14 days S/P Barn 2: ‘6176-1 to ‘6176-2’
Primary vaccination (approx 3rd March) ?
Vesicular lesion location/age
Animal ID
Species/sex
DOB/ Age
Clinical signs
Rectal temp
LF
RF RH LH Buccal cavity
Samples taken
Photo number (Annex 1)
Comments
Kazim Agdaf (Barn 3)
Cow 3 Bovine 4 months
Lame LF ID: 2-3 days
Non
e
None None None Epi/B/S/ Saliva
Barn 3: ‘C3-1’ to ‘C3-4’
Primary vaccination (approx 3rd March) ?
Atakan Demirkaya (Barn 4)
TR 36139 3931
Bovine Female
25/06/ 08
None None Non
e
None None DP: 10 days Tongue tip: 10 days
None (risk of abortion)
Barn 4: ‘3931-1’ to ‘3931-3’
Vacc. 01/11/09. Also vacc. approx 3rd March ? Heavily in calf
TR 36139 5224
Bovine Adult steer
02/05/ 08
None None Non
e
None Caudal CB separation
DP: 7-10 days Tongue:
S/Saliva Barn 4: ‘5224-1’ to ‘5224-2’
Primary vaccination (approx 3rd March) ? Late castrated.
Atalay Kuru (Barn 5)
TR 36148 8813
Bovine Female
12/12/ 08
Salivation/Lame
Medial claw CB under
As LF
Secondary bacterial infection coronary
Secondary bacterial infection coronary
DP: 6 days T: 10 days
Epi/S Barn 5: ‘8813-1’ to ‘8813-3’
Nasal lesion. Primary vaccination (approx. 3rd
-mined
band and separation heel bulb
band and separation heel bulb
March) ?
TR 36140 5058
Bovine Female
21/07/ 08
None None Non
e
Dorsal ID space: 1 day
None DP: 5 days T: 2-3 days
Epi/S/ Saliva/P
None Vacc. 20/04/09. Primary vaccination only .
Key:
Lesions: CB: Coronary band T: Tongue Samples: Epi: Epithelium P: Probang
ID: Interdigital space B: Blood
DP: dental pad S: Serum
Please see ‘Annex 1' for photographs of clinical findings
Table 2. A table showing the test results for samples collected from each animal examined in Table 1.
Serotype Antigen elisa results carried out on Epi
Animal ID Oldest lesion age
LFD Antigen ELISA O
Antigen ELISA A
Antigen ELISA Asia 1
NSP Multiplex PCR Probang
Multiplex PCR Saliva
Ecevitakormaz (Barn 1)
Cow 1 5 Pos 0.21 Neg 0.072 Neg 0.076 85/86Pos Positive - Type O N/A
Cow 2 10 N/A N/A N/A N/A 91/92 Pos Negative N/A
6443 No Lesion N/A N/A N/A N/A
64/61 Pos Negative N/A
Kadir Demirkaya (Barn 2)
TR 36 153 9070 14 N/A N/A N/A N/A 88/88 Pos N/A N/A
TR 36 168 6176 14 N/A N/A N/A N/A 86/85 Pos Negative N/A
Kazim Agadf (Barn 3)
Cow 3 3 Pos 0.134 Neg 0.076 Neg 0.056 92/92 Pos N/A Negative
Takan Demirkaya (Barn 4)
TR 36 139 3931 10 N/A N/A N/A N/A N/A N/A N/A
TR 36 139 5224 10 N/A N/A N/A N/A 91/89 Pos N/A Negative
Atalay Kuru (Barn 5)
TR 36 148 8813 10 Pos REPEAT + VI REPEAT + VI REPEAT + VI 90/91 Pos N/A Negatie
TR 36 140 5058 5 Pos > 3.00 Neg Neg 48/46 Neg Positive - Type O Weak Positive
0.1 OD value threshold for Antigen Elisa N/A indicates samples not taken
Fig.2. Esenkent predicted timeline of disease
The timeline shows the approximate dates of infection, and tracks the probable course of infection through the barns. It can be seen that from
the oldest lesion dates, that infection appears to have entered the village initially into Barn 2, then spread to Barns 1, 4, 5 (at approximately
the same time) and finally to Barn 3. This only represents our investigated barns as we do not have ınformation for the whole vıllage.
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Most likely incubation period
Incubation period
Pre-lesion virus shedding period
Clinical lesions
Sampling and testing for the presence of / exposure to FMDV
Samples taken depended on availability of sample and whether we were permitted to take
samples by the farmer.
Epithelium – Where loose epithelium was available, this was removed with forceps and
placed into virus buffer which was pH adjusted and was part of the LFD collection kit.
Blood – Blood collected into plain tubes was taken from the majority of animals.
Probang – Probang sampling was restricted to cattle where this was permitted by the
farmer, and also where clinical lesions were seen to be older.
Testing of samples
LFD and Antigen Elisa testing on the epithelium collected. This tested the presence of
viral capsid antigen in the sample (LFD and antigen elisa), and also serotyped these
viral antigens. The serotypes tested for were O,A, Asia-1.
NSP testing of serum collected. This tested for the presence of antibodies to viral
non-structural proteins (NSP) in the sample. Detection of these suggests viral
replication had occurred in this animal.
Multiplex PCR on Saliva and probing samples. This tested for the pesence of viral
RNA in the sample, and also indicated the serotype of the virus from which this RNA
derived from. The serotypes tested for were O,A, and Asia-1.
Cardiac Troponin T (cTnT) on serum samples. This tested for the presence of
circulating cTnT, which would indicate he presence of myocardial damage in the
animal. This was part of a pilot study.
Results of diagnostic tests
All results obtained are summarised in Table 2. Red indicates a positive result for the
corresponding test. Orange indicates an inconclusive result and will undergo further testing
at the SAP institute.
Discussion of diagnostic testing results:
Barn 1:
There were 3 animals on this barn. Two had clinical signs and one did not. They were all NSP
(non-structural protein antibody) positive. The cow with the freshest lesions had a sample of
epithelium taken, which was positive for LFD and for antigen elisa, Type O being the
suggested serotype from this test. Probangs were taken from all 3 animals, with only one,
the one with the freshest lesions, being PCR positive, again typed as serotype O from
multiplexing. The fact that all 3 cows were NSP positive suggests that all had significant virus
replication at least 4-8 days previously, if not longer (NSP correlation with onset of clinical
signs, personal observations, IAH Pirbright). The animal with no history of FMDV infection
(6443) may have been NSP positive for 2 reasons: One is that the test may have given a false
positive, however more likely is that this animal had been subclinically infected, without
showing clinical signs. This scenario is even more likely given the fact that this animal has
been vaccinated: subclinical infection of animals may occur in the face of vaccination against
FMDV.
Barn 2:
The two cattle infected here showed 14 day old lesions. No epithelium was available for
examination, and the probang collected from one of these animals was negative via PCR.
Serum samples were both positive for NSP. These results are expected form animals with 14
day old lesions, which have had time to mount an immune response to the NSP of the virus.
Viral clearance appears to have occurred in the pharynx of these animals.
Barn 3:
Cow 3
The animal examined in this barn had lesions aged at 3 days old. The epithelium sampled
was positive for viral antigen on the antigen ELISA, and suggested to be type O. Saliva
sample from this animal was negative on PCR. Interestingly, this animal was strongly
positive for NSP. Assuming the lesions ageing is correct, 3 days post-lesion onset is very fast
to develop a strong NSP response. This discrepancy may be due to the lesion age actually
being longer, in the range of 5 days +, or that this animal received a very large infectious
dose of virus, thus developing NSP antibodies much faster than normal.
Barn 4:
One of the animals in this barn could not be sampled due to it being pregnant. Both animals
examined had lesions of around 10 days of age. Serum from the one animals sampled was
NSP positive, with saliva sample being negative via PCR. These results are consistent with an
animal which has cleared virus infection and produced and thus produced an NSP response.
Barn 5:
Both animals examined in this barn were positive via LFD assay applied to collected
epithelium. Epithelium from the younger lesions (cow 5058) was positive via antigen ELISA,
which indicated Type O infection, whilst antigen ELISA result from the other cow (8813) was
inconclusive. The younger lesion (1 day) epithelium gave a much stronger response than
the older 10 day old lesion.
The serum from the 10 day old lesion cow (8813) was NSP positive, however that from cow
5058 (1 and 5 day old lesions) was negative. The high amount of antigen combined with the
relative young age of the lesion in cow 5058 suggests that the NSP negative result of the
serum is most likely due to the immune response not having enough time to mount a
response to the NS Proteins of the virus.
Discussion of Esenkent disease and vaccinal status
Information collected at the time of the visit from the farmers and from the local vet.
suggested that a vaccine was administered to all the animals in Esenkent on (approximately)
3rd March 2010. It was stated that no secondary/booster vaccination was given due to the
farmers’ perception of adverse reactions (milk drop).
From the ‘Turkvet’ database, it was noted that vaccine had been administered in October
2009/November 2009/April 2010 to three animals (see table), with no further vaccinations
recorded. However, the database has not been updated in some cases since the sale of the
animals; hence vaccination dates may be unrecorded. Reliable vaccination data is therefore
not available.
There has evidently been a failure of vaccination protocol in Esenkent. There has been
sporadic administration and recording, and the datasheet instructions have not been
followed (unwillingness to give a second booster for example). A solid immune response to
FMDV may not, therefore, have been illicited. The generally mild nature of clinical signs
noted in these animals may, however, be due to some degree of partial immunity.
A second possible cause of failure of protection in Esenkent is a lack of antigenic matching
for this serotype/sub-serotype. The vaccine administered was a trivalent killed vaccine (for
Serotypes O, A and Asia 1). The virus serotype was identified as Type-O via antigen ELISA
and PCR and thus most likely should be covered by administration of the trivalent vaccine.
There may be a possibility, however, that antigenic drift/mutation may reduce vaccine
matching to the outbreak strain, resulting in a degree of clinical disease (although this is less
likely than if the virus had been typed as serotype A). To investigate this data, generation of
R values by VNT, and ideally vaccine challenge experiments would need to be carried out.
However, the most recent evaluation of the current Type O FMDV virus circulating in the
area showed an r value of greater than 0.3 by VNT, which indicates sufficient vaccine strain
homology.
Ranking of risk factors for spreading of the disease
According to the result of the epidemiological investigation the major risk is the livestock
markets. This opinion is fully shared by the farmers.
Proper vaccination of cattle reduces the chance of infection, and if infection does occur,
clinical signs are normally not present, with a much reduced shedding and transmission rate
of disease to other animals. As vaccination protocol does not appear to be adhered to, this
is a major risk factor, making clinical infection and thus significant viral shedding and
transmission much more likely.
Once the disease is introduced in a farm, the herd management system, such as the practise
of common grazing, lack of inter farm biosecurity, provides a fast route of spread for the
virus to all animals in the village.
The surrounding villages may be involved in both the source and spread of infection via
direct or indirect contact (common grazing), or windborne infection. The involvement is
difficult to quantify in this case.
Important factors for stopping the spread of the disease
Improved vaccination administration, with rigorous and complete coverage of animals, with
an aim of eliciting a strong protective immunity in all animals.
Movement control should be reinforced, particularly ensuring that animals are moved
following veterinary examination and accompanied with the correct documentation.
Improve biosecurity and quarantine at both farm and village level.