Marek's Disease. Questions, Questions, Questions...HELP!

[casportpony]

farm-gal91, if you took any pictures that you feel like sharing, I know that Dr Shivaprasad, the avian pathologist that I work with would probably like to see them. If you decide to send some to him, make sure you resize them. http://faculty.vetmed.ucdavis.edu/faculty/hlshivaprasad/

 

[farm-gal91]

Ok will do. I'm still debating on weather to or not. Breaks my heart I had to cut her open and see this. Not to even mention her disposal.

 

[farm-gal91]

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So saddening and heartbreaking that they were happy healthy chickens (bottom photo)then were sick (top photo)

 

[casportpony]

I know the feeling... Wish I could say something to make you feel better.

 

[cowcreekgeek]

I am very well aware that there are certain types of Marek's. i said ONLY my seabright hens because they are the ONLY clinically ill birds. No one knows for sure every other chicken of mine had Marek's. Four board certified veterinarians, one veterinarian specializing in Avians, and I all talked about Marek's today. I was informed that all birds will not probably carry the disease, and at their age, they are almost completely safe also, the birds being vaccinated helped. I have found there is a lot of misleading information on the web but this information from this forum seems to be true. I have learned a lot about Marek's disease today from work and I'm grateful I get to work in such a place where I can ask my boss "what's wrong with my bird?" The necropsy was very helpful to. I deal with many nasty tumors on a day in day out basis on animals at work, but let me tell ya, these were something else.

Havin' access to constant/qualified advice is one heck of a benefit ~'-)

But, in regard to the potential for being carriers, despite having no clinical signs of infection? From the very report you posted: "The virus is shed in feather dandruff and can remain viable for years in the environment under optimal conditions. Apparently healthy birds may carry and shed the virus," which gives good cause for concern, most esp. when adequate consideration is given to both points.

My own flocks are not innoculated, which is a decision I sorta regret, as one of our flocks when I was a child were culled as the result of infection ... but, I've played the scenarios out in my head; if what happened to you, happens to me? I'll almost certainly continue, and will add additional birds w/o innoculation, accepting the losses as they come, as this creates flocks of birds resistant to this viciously hateful virus. I think ... I hope )-;~

 

[cowcreekgeek]

Ok will do. I'm still debating on weather to or not. Breaks my heart I had to cut her open and see this. Not to even mention her disposal.

[/URL]

So saddening and heartbreaking that they were happy healthy chickens (bottom photo)then were sick (top photo)

Sorry for your losses, and respect all you had to work through ... so much more difficult, when they're so much more personal. The hopes that they can provide useful informations for others brings the hopes their loss can serve to improve the chances for others -- if you wish to have a way to share the images in full and original resolution, or wish to have them edited to any very specific requirements, contact me via pm ... I'd be glad to help.

 

[farm-gal91]

Havin' access to constant/qualified advice is one heck of a benefit ~'-)

But, in regard to the potential for being carriers, despite having no clinical signs of infection? From the very report you posted: "The virus is shed in feather dandruff and can remain viable for years in the environment under optimal conditions. Apparently healthy birds may carry and shed the virus," which gives good cause for concern, most esp. when adequate consideration is given to both points.

My own flocks are not innoculated, which is a decision I sorta regret, as one of our flocks when I was a child were culled as the result of infection ... but, I've played the scenarios out in my head; if what happened to you, happens to me? I'll almost certainly continue, and will add additional birds w/o innoculation, accepting the losses as they come, as this creates flocks of birds resistant to this viciously hateful virus. I think ... I hope )-;~

I do understand that, but there are some factors that have to be considered;
1) these birds (healthy) have been vaccinated
2) they also are away from them and are much older mature hens

So that is why I and this vet who wrote the article both use the word "may" so much. There is such a big "if" in any disease once all factors are taken into consideration.

In regards to the photos, thank you for your concerns and willing to help. As soon as I get over some of this I may send them in over.

 

[farm-gal91]

One other I found from a board certified. This one is bland. Looking into better ones
Marek's Disease

Mareks disease is one of the most common problems we see in a flock of small birds. It causes great distress as it is often seen in pullets between 12 and 20 weeks of age and it will be fatal. The control of the disease is difficult and you need to have a good understanding of the basic principles in order to reduce the chance of your birds becoming infected.
Cause
Mareks is caused by a Herpes virus which can survive for long periods of time in the environment. It is thought that in feather dust it can survive on a farm for at least 12 months and it is this problem which leads to it being so common.

The virus infects the young bird as early as 1 day old and initially circulates in the blood stream causing no clear symptoms. Within 7 days, the virus will have infected the white blood cells and initially causes the death of the B Lymphocytes. These white blood cells are the type that produce antibodies and are essential for a fully working immune system.
Antibodies are proteins that are specific for individual pathogens such as bacteria and viruses. The antibody attaches to the pathogen and it is this attachment which stimulates other immune cells in the body to recognise the pathogen as foreign material and to start a complicated process of destroying and removing it from the body. So, if the B Lymphocytes are destroyed by the Mareks virus you will have a bird that, as long as it survives, will have a compromised immune system. This will make the chicken more susceptible to other diseases such as Respiratory disease and Coccidiosis.

At about the same time of the initial infection and when the B cells are destroyed, the viruis will also infect the T cells. This type of cell is involved in controlling the bird’s response to infection and in a way moderates the effects on the immune system. It is also involved in the control of viral infections. The T cell is not killed by the Mareks virus, but is modified in a way which will eventually kill the bird. The infected T cells stay dormant and when the bird is around 10 weeks post infection, start to multiply. These cells then form tumours in various organs including liver, kidney and spleen. The bird slowly loses weight but outwardly appears normal, until at some stage it will become incapacitated and is normally presented to the vet as a sudden problem, which obviously is not the case.

Another more classic form of the disease is the infection of the cells making up the nerve sheath which is similar to the outside coating of an electrical wire. These cells multiply due to infection from the virus and lose their efficacy, resulting innerve failure and paralysis in the bird. This is commonly the sciatic nerve supplying the legs and leads to a bird with a classic one legged paralysis.
Feather follicles, another cell type, in the skin can also become infected. This will cause small tumours in the feather follicles and is a major problem when meat birds become infected. Unfortunately this feather follicle infection leads to the virus being present in feather dust which infects more birds.

Mareks virus has been with us for a very long time and continues to evolve, meaning it is now becoming more resistant to the effects of various vaccines and, due to this evolution, more virulent. It is now common to see older infected birds which have been vaccinated previously; also the classic paralysed bird is a lot less common. At Chicken Vet, we frequently see thin, weak, young adult birds with severe weight loss; it can be very traumatic for the owner to be told that their new pet chicken is already dying and has an extremely poor prognosis.
Treatment and Diagnosis
If a bird has Mareks there is no treatment and infected birds will eventually die. Try not to buy chickens from unknown sources, and if possible buy vaccinated birds. However, very stressed chicks subjected to a high field challenge can still get Mareks disease. Use recommended disinfectants such as Interkokask and follow strict biosecurity rules to try and prevent spread of the disease.
use footdips on your site with Interkokask or Rhodasept.
vehicles and equipment can always be a cause to spreading disease, disinfect regularly.
chickens can only be diagnosed through post mortem and samples sent off for histopathological examination.

 

[farm-gal91]

Glad they are looking further into it. Such a widespread disease. It's almost like parvovirus.



Marek's disease virus: from miasma to model.
Osterrieder N, Kamil JP, Schumacher D, Tischer BK, Trapp S.
Source
Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA. [email protected]
Abstract
Marek's disease virus (MDV) is an oncogenic herpesvirus that causes various clinical syndromes in its natural host, the chicken. MDV has long been of interest as a model organism, particularly with respect to the pathogenesis and immune control of virus-induced lymphoma in an easily accessible small-animal system. Recent advances in MDV genetics and the determination of the chicken genome sequence, aided by functional genomics, have begun to dramatically increase our understanding not only of lytic MDV replication, but also of the factors and mechanisms leading to latency and tumour formation. This new information is helping to elucidate cellular signalling pathways that have undergone convergent evolution and are perturbed by different viruses, and emphasizes the value of MDV as a comparative biomedical model. Furthermore, the door is now open for rational and efficient engineering of new vaccines against one of the most important and widespread infectious diseases in chickens.

 

[farm-gal91]

Makes you think. This is interesting about the vaccine. I'm sorry, I'm a nerd haha I love to research things. This subject of Marek's just might be my next term paper in animal health class next year (veterinary studies).


Expert Rev Vaccines. 2005 Feb;4(1):77-88.
Use of Marek's disease vaccines: could they be driving the virus to increasing virulence?
Davison F, Nair V.
Source
Head and Avian Immunology Group, Institute for Animal Health, Compton, Newbury, Berkshire, RG20 7NN, UK. [email protected]
Abstract
Marek's disease (MD) is an economically important neoplastic disease of poultry. MD almost devastated the poultry industry in the 1960s but the disease was brought under control after Marek's disease herpesvirus (MDV) was identified and vaccines were developed. This is the first effective use of an antiviral vaccination to prevent a naturally occurring cancer in any species. MDV infection has many effects. Initially causing a cytolytic infection in B-lymphocytes, MDV infects activated T-lymphocytes where it becomes latent. In susceptible chicken genotypes MDV transforms CD4+ lymphocytes, causing visceral lymphomas and/or neural lesions and paralysis. Fully productive infection and shedding of infectious virus only occurs in the feather-follicle epithelium. Vaccination of newly-hatched chicks with live vaccines has been widely used to successfully control MD since the early 1970s. However, vaccinated chickens still become infected and shed MDV. Vaccine breaks have occurred with regularity and there is evidence that the use of MD vaccines could be driving MDV to greater virulence. MD continues to be a threat and a number of strategies have been adopted such as the use of more potent vaccines and vaccination of the embryonic stage to provide earlier protection. Recombinant MD vaccines are useful vectors and are being exploited to carry both viral and host genes to enhance protective immune responses. The future aim must be to develop a sustainable vaccine strategy that does not drive MDV to increased virulence.
PMID: 15757475 [PubMed - indexed for MEDLINE]
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