I do hope this blog will be useful, sometimes entertaining, and interesting to you. It will tend to involve my favorite things: chickens, dogs, horses, country living, wildlife, and H and H Feed. I encourage you to email me pics and a blurb about your favorite pet and how they are doing on H and H Feed so I can share here.
In the meantime I wanted to share this excellent article at Mareks Disease which affects MANY chickens and is valuable to know about for all backyard and commercial chickens owners.
MAREKS DISEASE By: Peter J. Brown, First State Veterinary Supply, Inc.
Actually they are one in the same. Range Paralysis is an older term that was used before it was understood exactly what caused this disease. Birds that were ranged on open range and became lame were said to have Range Paralysis. Today the modern term for this disease is Mareks Disease. Mareks,was first described in 1907 by Dr. Marek who was a Hungarian researcher. Thus the name Mareks disease.
So, just what is Mareks Disease ? It is a highly contagious Avian Herpes Virus that is highly Cell Associated. This means that the Virus must be inside a Cell of the bird in order to spread. Mareks Disease must be differentiated between Avian Leukosis Complex,which is made up of three separate diseases. Those Diseases are, Mareks Disease,Lymphoid Leukosis and Reticuloendotheliosis Virus. The last two diseases are caused by Retroviruses and Reticuloendotheliosis Virus is rare in Poultry. What Mareks Disease really boils down to is Chicken Cancer. It is a virus that causes skin lesions as well as lesions of the Visceral ( gut ) organs. It is a Tumor forming Virus.
How does Mareks Disease spread ? The mechanism by which Mareks Disease spreads from bird to bird is quite complicated. So,I will tell you that it spreads through the infected birds feather follicles and is in the dander that comes from the birds feathers. The spread to other tissues in the birds body can only take place through the blood stream. The virus must infect white blood cells and travel about inside them in order to infect other tissues. The Mareks Disease virus is related to the Epstein-Barr virus that causes Hodgkins disease in humans. However the Mareks Disease virus poses no threat as it is incapable of growing in mammalian cells.
So what organs are affected by the Mareks Virus ? Generally the virus will attack the nervous system as well as other body organs such as the eye. You may see a crippling of the birds or a discoloration of the iris in the eye. The virulence ( strength ) of the particular virus affecting your birds will usually determine the severity of the disease. The discoloration in the iris of the eye has led to the term Gray Eye. You may only see a reddening of the tissue around the feather follicle,this tissue may be raised around the base of the feather shaft and is generally called skin Leukosis but it is actually caused by Mareks Disease. The spread of the virus to the periphial nerves usually results in the enlargement of the nerves which will eventually lead to paralysis of the affected limb or organ. The spread of the virus to the birds eye may result in blindness as well as depigmentation of the iris of the eye.
Can older birds be vaccinated for Mareks Disease ? The answer to this question is ,yes. The age of the bird really does not matter as long as the bird has not been exposed to the Mareks Virus prior to vaccination. If a bird that has not been vaccinated for Mareks Disease comes down with the obvious symptoms of Mareks it may be of value to vaccinate anyway. There is some research to show that some birds may recover after vaccination. This would possibly work on birds whether or not they were vaccinated before. Some research has suggested that re-vaccination 4 to 6 weeks after the initial vaccination was of value in preventing new cases of Mareks disease in high risk areas. It is important to keep in mind that birds that have been infected are shedding this virus at a very heavy rate from their follicles and it would be of value to keep feathers about your coop cleaned up. Regular spraying with oxine will go a long way in keeping this disease as well as other diseases under control. Concerning the use of bleach as a disinfectant: go ahead and use it if you so desire but be aware that to my knowledge there are no studies to show the effectiveness of bleach against any disease organism. Oxine has reams of test data against a wide range of Pathogens and is designed to be used specifically for disinfection purposes. Consider this: during the anthrax scare of a few years ago, The Hart Senate Office Building in Washington,D.C. was heavily contaminated with Anthrax. The disinfectant of choice (although it was used in its Gaseous Form) was Oxine. I don’t recall them using bleach as an alternative. Remember that you get what you pay for . My Dad once told me that if you want good clean quality Oats that they come at a price,and that if you want the Oats after they come through the horse they come a bit cheaper. Nuf said.
I thought it would be of value to walk you through the Mareks Disease infection from start to finish from the birds perspective. This way you might get a better understanding of just what is going on during an active outbreak of the disease. Infection usually takes place as the birds inhale the Mareks Virus and it sets up shop in the respiratory system. Witnin five days the Mareks Virus will invade White blood Cells in the Respiratory System and be carried to the Spleen,Bursa and the Thymus. The Virus likes to grow in White Blood Cells and starts growing in B-cells and starts to infect and kill off B-cells in the Spleen,Bursa and the Thymus. The Mareks virus is now killing so many B-cells that the Immune System begins to react to the Virus Infection. Many T-cells are generated by the Immune response. These activated T-cells can be susceptible to a latent infection by the Mareks Virus. These infected T-cells may eventually become active Mareks Disease Tumor Cells. The Immune System mounts a measurable Antibody response but a temporary Immune Suppression also occurs as well. Keep in mind that all of this is taking place in a very short period of time. Usually within one weeks time. The Virus now spreads throughout the blood stream through the infected White Blood Cells. The Mareks Virus will spread to various other organs at this time as well as the feather follicle epithelial ( surface ) cells where the Virus will divide and form cell free extremely infectious Virus Particles. The birds then shed the Virus from their bodies in the form of dander. This dander is highly infective and when susceptible birds breathe in the Virus particles contained in the dander,infection will take place as earlier described. Within two weeks post infection a permanent Immune Suppression takes place that affects both the B-cells and the T-cells. Approximately five weeks after infection takes place the Mareks Virus has sufficiently infiltrated vital organs and nerves that paralysis soon occurs. Birds may become listless and show a paralysis of one wing or drag a leg behind them. Some birds may only show a weakness of the legs or both wings. Starting at about six weeks post infection birds will start to form Tumors due to the infected T-cells starting to multiply and are now transformed into Cancer Cells. They are also responsible for Atherosclerosis or Hardening of the Arteries. Tumors may affect any of the organs of the body and the degree of Tumor formation will depend upon the Virulence (strength) of the infecting Virus.
Vaccinating for Mareks with the Mareks vaccine : Vaccination should take place as close to one day of age if at all possible,but may be done at any age as earlier discussed. Mareks vaccine is unique in that it does not stop a bird from becoming infected with the virus,but it stops the formation of the Tumors that are caused by the Mareks virus. Birds that are newly vaccinated should not be exposed to adult birds for at least fourteen days to allow the vaccine to take hold. The vaccine comes as a two part vaccine. One bottle contains a small freeze dried wafer which is the actual vaccine. This is a Live Virus vaccine and can not be saved once it is mixed. Once mixed the life of the vaccine is approximately two to two and one half hours. The second part of the vaccine is a bottle of diluent which is 200 cc/ml of extender. It is not just water but a broth so to speak of special growth media for the Vaccine Virus to survive on during mixing and vaccination. I would suggest to you that you split the vaccine into four equal parts so that you may get four uses out of one bottle of vaccine. Cut the small vaccine wafer into quarters as best as you can.Use care not to contaminate the Mareks Diluent. Never actually open the bottle but use a clean needle and work through the rubber stopper and draw what you need from that. Always check the Diluent bottle for contamination before using: cloudiness or something growing in the bottle. If the Diluent is contaminated or you are unsure discard the bottle and get a fresh bottle of Diluent before proceeding. Take the large Diluent bottle and transfer 50 cc/ml into a clean baby food jar or similar glass bottle. This bottle must be glass. Now take the 1/4 vaccine wafer and mix with the 50 cc/ml of Diluent in the baby food jar and you are ready to vaccinate. Remember to immediately put the remaining Diluent and the small bottle of Vaccine back in the refrigerator. You are now ready to administer the Vaccine. The dose is .2 cc 2/10 cc under the skin of the neck of each bird.Remember to keep track of time so that you don’t use Vaccine that is to old. Putting the mixed vaccine bottle in an ice bath will have some value in preserving the life of the mixed vaccine.
MIXED VACCINE CAN NOT BE SAVED UNDER ANY CIRCUMSTANCES EVEN IF YOU FREEZE IT.
If you have any question about this article or any other health issue, please feel free to contact Peter Brown at 1-800-950-8387. This thread and its contents are the property of Peter Brown and firststatevetsupply.com. Please do not link to this article from another site without posting full credits to both firststatevetsupply.com and the Author, Peter Brown.