The use of the timeline in a FMD outbreak investigation

hello my name is maria de la puente and i work 
for the european commission for the control of   food and month disease in this presentation i'm 
going to introduce you to the use of the timeline   in an fmd outbreak investigation in summary this 
is what we are going to see we will remember how   we age fm deletions we will see how to construct 
a timeline and a little example on how to use it so why we age fm deletions the first thing 
is that we do it to take the relevant samples   that will allow us to confirm or rule out fmd 
so for example if you look at this picture   think about how old this lesion is 
and therefore which kind of sample   would you take from this animal i'll let you 
think about it okay so if you look at here   we could say that these lesions are one day 
old and therefore here what we would do is to   take a sample of vesicular fluid or 
epithelium to try to isolate the virus so now try again with this other picture so 
look at it estimate the age of the lesion   and then think about which would be 
the sample of election in this case okay give you the answer so now this lesion would 
be 10 days or older which means that the virus   infected the animal much longer ago than in the 
previous case and therefore we could expect to   find antibodies in this case we would probably 
take a blood sample to do a serological test the second reason why we age deletions in 
the case during an outbreak investigation   is to be able to build a timeline that help us to 
trace back and forth the most relevant contacts   and this is what we are going to see now 
how to build this timeline and how to use it so first of all to build a timeline we 
need an excel sheet that has these rows and   as you can see that i put in the following names 
that will make more sense in the following slides   calendar discount day zero visions 
infection window and excretion window so the first step now that we have 
this um timeline or this sheet   is to put the date when we go to the 
farm to do the outbreak investigation   so here you can see in the 
example it's the 1st of december so once we have it we can add the rest of the 
days in the row calendar so after and before then we need to identify when the 
first lesion appeared in the farm   and to do this we need to be able to age 
lesions so we need to find the oldest solution   in the farm and in this example imagine 
that this lesion was four days old   so in the line editions we are going to color 
the following days so if it is four days old   on the first of december when we went to the farm 
then we count three two one and we color here then we are going to add the day zero date zero 
will be will represent the prodromal period   which will be in the case of fmd one day which 
is the period like um before the lesions appear   when the animal will show like in a specific 
symptoms like inappropriate so we color it here   the zero and then we add the zero and the rest 
of the count minus one minus two minus three etc and now we are going to define 
the infection window and to do this   we consider the incubation period 
a of a fmd and the equation   period is the period that goes from the infection 
of the animal until the clinical signs appear   and in cattle it is 2 to 14 days so we are 
going to color it here you see minus 2 2 to -14 but the most likely incubation period is shorter 
is from 2 to 6 days so in this case we are going   to color it a bit darker because it was this 
will represent the most likely incubation   period and we will use this to define which 
is the most likely infection window also   so now that we have the infection window we 
are going to define the extraction window   so um in an animal the this will happen two 
days before the onset of the clinical signs um   and in milk we could find a virus up to 
four days before the onset of the disease   in this example we are going to think that 
we are a like working with a young male   so we will forget about those four and 
we will color from minus two onwards and again we will have a most likely 
expression window that will go from day 0   to day 3 and we put it in a darker color and basically that's it we have for 
timeline so now we need to use it um   i'm putting here one example on how to use 
the timeline in this case we are going to   define a which would be the most likely source of 
introduction of fmd in the farm so i'm giving you   here three examples for you to think which 
one do you think is the most likely source   the first example is two cows that were bought 
on the 29th of november then we have the farmer   who visited his cousins farm on the 23rd of 
november and finally some hay that was brought   to the farm on the 11th of november so i'll let 
you think a bit about it before giving the answer so take your time to look at the timeline 
and place those three events in the timeline so let's see the solution okay i'm 
sure you got it right the farmer   who visited his cousin on the 23rd of november 
is the most likely source of infection and this   is because if you place the three events in 
the timeline you can see that the two cows   were brought into the farm much later and 
like it doesn't fall in the incubation   a period in the infection window the farmer 
visited his cousin's farm in the most likely   infection period while the hay was brought to 
the farm too early in our timeline so that's it   i hope you found it useful and now it's a bit 
clearer how to construct a timeline thank you you

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