My thought would be Marek's too. The timing is actually part of it as Marek's outbreaks are often triggered by stress and the onset of laying is a stressful time for pullets as their hormones surge and they are confused about what is happening.
One of the many symptoms of Marek's is that it suppresses the immune system and that means that birds are vulnerable to things that they would normally have resistance to like coccidiosis. The watery poop and lethargy may have been symptoms of that (not all coccidia cause bloody poop) so whilst the vaccine may have protected her from the fatal tumours, a secondary infection like coccidiosis may have killed her.
I understand your anxiety as regards this as I have had Marek's in my flock for 3 years now and all I can say is that whilst each death is heart breaking, overall things are not as bad as a lot of what you read, and after the initial outbreak things do settle down quite a bit. That is not to say that this will be your sole Marek's victim but as the seasons pass the surviving chickens seem to develop a level of resistance. That said I have no direct experience with vaccinated birds but there are two main schools of thought on managing your flock once you have it..... one is that you are best to only bring in vaccinated chicks to replace losses and practice strict biosecurity for the first few weeks and the other that you breed within the flock from the survivors and keep them unvaccinated. I'm in the latter camp and out of 56 chicks hatched last year only 3 showed symptoms of Marek's, the two pullets died and the cockerel (typical!) made a miraculous recovery.
There is research to suggest that the vaccine may in fact be leading to more virulent strains of Marek's mutating because the virus does not usually kill the host, but that could also be said of my birds that survive outbreaks of it and I am seeing things improve over time rather than deteriorate. Each season I have less problems with it.
I hope that helps you feel a little less pessimistic about your situation. I was pretty horrified when I realised that my flock had this disease and everything I read was really doom and gloom, but on the whole things have not been anywhere near as bad as I was led to believe. Yes I am always on the look out for a bird showing symptoms..... I noticed one of my favourites has a problem with her eyes this morning not quite opening properly..... not a classic Marek's issue but it is always at the back of my mind that it may be related.... but I don't panic anymore. I will deal with the problem as it presents itself and I now have the knowledge to give the best supportive care I can and I know the point at which there is no hope and I need to end it for them. I have had quite a few that have made truly remarkable recoveries, so as long as they are eating there is hope.
Best wishes
Barbara
One of the many symptoms of Marek's is that it suppresses the immune system and that means that birds are vulnerable to things that they would normally have resistance to like coccidiosis. The watery poop and lethargy may have been symptoms of that (not all coccidia cause bloody poop) so whilst the vaccine may have protected her from the fatal tumours, a secondary infection like coccidiosis may have killed her.
I understand your anxiety as regards this as I have had Marek's in my flock for 3 years now and all I can say is that whilst each death is heart breaking, overall things are not as bad as a lot of what you read, and after the initial outbreak things do settle down quite a bit. That is not to say that this will be your sole Marek's victim but as the seasons pass the surviving chickens seem to develop a level of resistance. That said I have no direct experience with vaccinated birds but there are two main schools of thought on managing your flock once you have it..... one is that you are best to only bring in vaccinated chicks to replace losses and practice strict biosecurity for the first few weeks and the other that you breed within the flock from the survivors and keep them unvaccinated. I'm in the latter camp and out of 56 chicks hatched last year only 3 showed symptoms of Marek's, the two pullets died and the cockerel (typical!) made a miraculous recovery.
There is research to suggest that the vaccine may in fact be leading to more virulent strains of Marek's mutating because the virus does not usually kill the host, but that could also be said of my birds that survive outbreaks of it and I am seeing things improve over time rather than deteriorate. Each season I have less problems with it.
I hope that helps you feel a little less pessimistic about your situation. I was pretty horrified when I realised that my flock had this disease and everything I read was really doom and gloom, but on the whole things have not been anywhere near as bad as I was led to believe. Yes I am always on the look out for a bird showing symptoms..... I noticed one of my favourites has a problem with her eyes this morning not quite opening properly..... not a classic Marek's issue but it is always at the back of my mind that it may be related.... but I don't panic anymore. I will deal with the problem as it presents itself and I now have the knowledge to give the best supportive care I can and I know the point at which there is no hope and I need to end it for them. I have had quite a few that have made truly remarkable recoveries, so as long as they are eating there is hope.
Best wishes
Barbara
