Did your first chicken die at 7 days of age? If so, that is REALLY REALLY young to die from Marek's. Now on the other end of the scale, I lost my first one at 7 months, the next at 10, and the last at 11 months. So, the 5 month cut off is not necessarily the case.
According to this article by Peter Brown you won't see paralysis until around 5 weeks. I just don't see how they could get infected and die in 7 days. This article also talks about vaccinating older birds.
http://www.firststatevetsupply.com/poultry-health/mareks-disease.html
"Approximately five weeks after infection takes place the Mareks Virus has sufficiently infiltrated vital organs and nerves that paralysis soon occurs."
I have a great vet, and when she saw my chicken she thought Marek's, and she was right. But she will also tell you that she doesn't really know much about it. I am not saying that your state vet is wrong or not familar with Marek's but I certainly wouldn't take what he said as gospel. There are many things that change when it comes to disease and not everyone stays on top of it all, they can't. Too many different kinds of animals.
I wouldn't cull until the bird is suffering IMO.
AlsoFYI, I have a hen with the eye form of Marek's and she has not layed in about 6 weeks. I noticed the eye about the same time. I am not saying that it is the Marek's that stopped her, but she was a 5 day a week girl before that. She is only about 1 year old and no sign of molt. No reasons that she should not be laying, but she isn't. But I agree that you can't just say Marek's = no eggs. It would depend on what organ it affects.
Good luck with your birds. I hope it isn't Marek's.
According to this article by Peter Brown you won't see paralysis until around 5 weeks. I just don't see how they could get infected and die in 7 days. This article also talks about vaccinating older birds.
http://www.firststatevetsupply.com/poultry-health/mareks-disease.html
"Approximately five weeks after infection takes place the Mareks Virus has sufficiently infiltrated vital organs and nerves that paralysis soon occurs."
I have a great vet, and when she saw my chicken she thought Marek's, and she was right. But she will also tell you that she doesn't really know much about it. I am not saying that your state vet is wrong or not familar with Marek's but I certainly wouldn't take what he said as gospel. There are many things that change when it comes to disease and not everyone stays on top of it all, they can't. Too many different kinds of animals.
I wouldn't cull until the bird is suffering IMO.
AlsoFYI, I have a hen with the eye form of Marek's and she has not layed in about 6 weeks. I noticed the eye about the same time. I am not saying that it is the Marek's that stopped her, but she was a 5 day a week girl before that. She is only about 1 year old and no sign of molt. No reasons that she should not be laying, but she isn't. But I agree that you can't just say Marek's = no eggs. It would depend on what organ it affects.
Good luck with your birds. I hope it isn't Marek's.