Hi
Sadly it does look like Marek's. It is interesting that she has an eye closing as this can be one of the more subtle symptoms.
Nothing new since a few months ago when we brought some new girls in- and I can’t confirm if any/all of them had the vaccination, either- they’ve come from various places over the years!
This puts your flock at high risk of getting infected with Marek's even if you perform strict quarantine for a few weeks. Bringing in anything other than day old chicks from a hatchery or hatching eggs yourself, increases the risks, especially if they are from various sources. The incubation period is at least 3 weeks, so it may have been the new girls that brought it in most recently or your current sick girl could have come to you infected and it has just been dormant until now.
The virus is spread via dander dust which is inhaled into the respiratory system to infect other birds. It then goes through an apparently dormant phase (at least from external observation) and will remain so for at least 3 weeks but it can be significantly longer like months or perhaps even years until an outbreak is triggered. This is often stress related and what stresses one bird may not stress another. Common triggers are integration of youngsters into an adult flock, too many adolescent cockerels in the flock running amok, surge of hormones at point of lay, change of hormones during moult etc but can be as individual as a minor challenge for position in the pecking order. Like people, stress is perceived differently by individuals.
It is surprising how quickly onset occurs, often overnight they go from perfectly normal to hobbling. I've had a few that within a space of a week, went from being perfectly fine to hobbling, to floundering on their side unable to get up, in classic Marek's splits posture, to up and limping to then running around like there had never been anything amiss. They are of course prone to future attack which might happen in a matter of weeks or even longer than a year, but during that time you just cannot tell that there is anything wrong with them. Others take weeks or even months of supportive care but can make considerable improvement and some deteriorate and either die or are euthanized once they lose interest in food.
They are actively shedding the virus whilst they are symptomatic but I take the view that my flock have already been exposed, so I keep them in contact with the flock as much as possible. Separating them stresses or depresses them and then they get worse or give up fighting it.
It is a very odd disease as no two birds respond the same and some recover from an episode without any treatment, so people who claim that their bird responded to St John's Wort or various other remedies may have found that their bird recovered regardless of the remedy administered and I am sceptical of such claims. I've tried some of these suggested treatments and in the end the most important thing is to keep the bird as happy as you can. If you make their food unpalatable with supplements or additives or force feed them medication, it is counter productive. I now give them a good poultry vitamin supplement to support their immune system which they find palatable, put them out in a large cage on grass in the sunshine whenever possible within sight of the flock and give them extra nutritious treats to keep their interest in food. Encouraging the flock to forage around them by scattering a bit of scratch helps to stimulate them to eat and fermented feed or probiotics help to support the digestive system.
There are however people who cull to prevent further shedding of the virus and I think that may be a very valid practice. I just cannot personally bring myself to euthanize a bird that is bright eyed and keen to eat and wants to live unless I know there is no hope and my experience indicates that some do recover and have a very good quality of life in between outbreaks. That said I have one of the milder strains of the disease and everyone has to make their own decisions based on their own situation and goals.
I still broody rear chicks within my flock.... I currently have a broody who had a Marek's episode 6 months ago about to hatch eggs this coming weekend. 1 (or 2 if I am unlucky) may get the disease and die, 1 or 2 may get it and survive and if my previous experience continues, most will not get it but of course, at least half will be cockerels that will be culled anyway, so they may never get the chance to show symptoms.
I hope your girl is a survivor, but entirely understand if you do not want to take the risk and decide to cull her. Good luck whichever way it goes and if you have any questions about it or need some support, please feel free to ask.
Best wishes
Barbara
PS. If she doesn't make it, it can be beneficial to have a necropsy done to give you a confirmed cause of death.... Marek's is an extremely common and widespread disease, so it is the likely diagnosis for your girl but it is possible that she has something else. State Ag Dept diagnostic labs will perform this service and it is usually significantly cheaper contacting them direct rather than submitting a bird through a vet or getting a vet who may have little knowledge of poultry to perform it themselves. Most have websites which list services and charges.
