Welcome, Guest
Username: Password: Remember me

TOPIC: mareks disease

mareks disease 28 Aug 2012 13:41 #11

  • pearl
  • pearl's Avatar
  • OFFLINE
  • Posts: 1359
mereks in a carrier bird,can be brought out by stress,ie movement of growers,an birds coming into lay.
The administrator has disabled public write access.

mareks disease 28 Aug 2012 13:53 #12

  • marco
  • marco's Avatar
  • OFFLINE
  • Posts: 135
Thats an interesting point egghead but if " the virus needs to gain entry to the body in the first few days of life " as ive read ,how can 2 month old growers pick it up from my carriers?
The administrator has disabled public write access.

mareks disease 28 Aug 2012 13:56 #13

  • marco
  • marco's Avatar
  • OFFLINE
  • Posts: 135
sorry pearl missed yours
The administrator has disabled public write access.

mareks disease 28 Aug 2012 14:16 #14

hi marco
im sorry but i dont know were you read that the virus need to gain entry to the bird in the first few days of life this is not right ,if is was right you need only quarantine them for the first few days of there life and they wont get the virus after that , a bird can get markes at any age,, i have to wonder what do breed meen when they say that they quarantine as markes is air born and a bird 30milds away can get the virus
The administrator has disabled public write access.

mareks disease 28 Aug 2012 15:38 #15

marco wrote:
Thats an interesting point egghead but if " the virus needs to gain entry to the body in the first few days of life " as ive read ,how can 2 month old growers pick it up from my carriers?

Is there any chance Marco that the confusion is coming from what you read and it actually meant that "Vaccination must take place in the first few days of life to prevent the bird contracting the full blown virus,and even with vaccinated birds they will be shedders in the future" just a thought as to where the confusion might have come from as has been said the most vulnerable are growers up to about six months but older birds can come down with it too.
The administrator has disabled public write access.

mareks disease 28 Aug 2012 20:07 #16

thats right pearl markes can be brought on by stress.. but if his birds were carriers the first birds to go down with mareks would be the new birds as his own birds would carriers but not showing the disease thay may be immun to mareks and the new ones were not
im only saying it is possible
Last Edit: 28 Aug 2012 20:09 by egghead. Reason: to add
The administrator has disabled public write access.

mareks disease 28 Aug 2012 20:16 #17

you may like to read this
The Condition

Marek’s disease is caused by a herpes virus and is one of the most widespread diseases afflicting chickens. The disease was first recognised by the Hungarian veterinarian Jozsef Marek in 1907 (Sluis, 1997), and was at one time the most common cause of losses in the poultry industry. It is now largely controlled by the use of vaccines.

Over the last ten years, the UK Veterinary Investigation Centres have diagnosed around 60 cases of Marek’s disease each year. Although there are no recent published data on incidence in the UK, losses from Marek’s disease in broilers in the UK are thought to be very low. It has been estimated that national mortality rates in layer flocks in 1977 were approximately 1.23% (Bennett et al, 1999).

Since the virus is not transmitted through the egg, chicks are born free of the disease. The infectious virus matures in the epithelium of feather follicles and infects other birds by inhalation of infected dust or dander.

Most flocks are infected, although clinical disease is not always seen (Biggs, 1997). It is a highly contagious disease that may survive for months or years in litter and poultry dust. Infection occurs through the respiratory tract and infected birds can remain carriers long after infection. Incubation periods range from 3 weeks to months. Chicks become infected at an early age, whilst the disease normally manifests itself at 8-24 weeks, although it may be observed, in some cases, much earlier or later.

There are three serotypes of the virus. Serotype 1 and 2 are found in chickens, while serotype 3 is related to herpesvirus in turkeys (HVT). Strains of serotype 1 can be divided into mildly virulent, virulent and very virulent. There is little information on the relative frequency of the serotypes, but mixed infections of serotype 1 and 2 are found in the same flock.

There are several forms of the disease. In the acute form the disease occurs rapidly and can result in high mortality rates. In a more classical latent form, Marek’s disease results in more persistent but much lower mortality rates. In the acute form, death frequently occurs within seven days and is often only preceded by a short period of depression. This acute or productive-restrictive infection occurs in lymphocytes, normally of B-cell origin, and results in antigen production leading to cell death. The classical form can lead to progressive paralysis of wings and legs, and in some cases respiratory signs may develop. In the classical form, the latent infection of T-cells is responsible for the long term carrier status of recovered birds. In some cases, latently infected lymphocytes undergo neoplastic development, and may develop into characteristic lymphoid neoplasms.

Classical Marek’s disease is characterised by enlargement of peripheral nerves up to three times the normal size. The most commonly affected nerves are the brachial and sciatic plexi, coeliac plexus, abdominal vagus and the intercostal. Nerve lesions are also found, and occasionally lymphomas (tumours). The acute form of the disease demonstrates lymphoma and enlargement of the liver, lungs, heart, gonads and kidney.

As the virus is widespread in poultry flocks, diagnosis of the disease cannot be made by detection using serological or virological tests. Marek’s disease is diagnosed by clinical signs and by the presence of gross and microscopic lesions. The presence of the virus, without clinical signs, can be demonstrated by isolation of the virus or by agar gel precipitation of the viral antigen in feather tips or serum antibody.

Marek’s condition can be confused with lymphoid leukosis. The two diseases are differentiated by the age at which birds are affected, the presence and focus of lesions, the presence and absence of paralysis and the category of neoplastic lymphoid cell affected

Recently, very virulent strains (vvMDV) (Witter, 1997; Venugopal, 1996) have emerged, which can induce a high incidence not only of lesions in the central nervous system, but also of visceral and nerve lesions in Marek's disease-resistant chickens (Cho et al, 1998). The impacts of more virulent strains are demonstrated and discussed by Hafez (1997).

The disease is immunosuppressive, and the degree of suppression is linked to the virulence of the virus strain (Calnek et al, 1998).

The most important route of infection is considered to be the airborne spread via the respiratory system. The darkling beetle (Alphitobius diaperinus) can carry the virus for several weeks, although this is not
The administrator has disabled public write access.

mareks disease 29 Aug 2012 00:44 #18

  • marco
  • marco's Avatar
  • OFFLINE
  • Posts: 135
Hi all The quote i used earlier comes from an article by Bob Cross entitled healthy hens in the P . P. book called " Avoiding the Vet " . he also says that "susceptibility decreases rapidly with age " and " where the disease is a problome " chicks can be reared on a clean site for 4 weeks beforeplacing them where the disease is known to prevail" This is the reason for my confusion
The administrator has disabled public write access.

mareks disease 29 Aug 2012 01:39 #19

i bit more to read
Control of the disease is most effective through vaccination or the isolation of growing birds from sources of infection or the use of resistant breeds. The disease is not vertically transmitted and therefore all chicks hatched are virus free. Since the disease is highly infectious and the virus is present in most flocks, good management is required to delay infection and suppress the risk of serious disease. This should involve isolation of young chicks from older birds for the first 2-3 months. An all-in all-out housing policy, coupled with disinfection, is also recommended. Insects may act as virus reservoirs, and therefore creating conditions with low insect populations is desirable.
The administrator has disabled public write access.

mareks disease 29 Aug 2012 11:31 #20

Building up a resistant flock i think is the best way to go as Vaccinations are beyond nearly all small breeders and it,s mainly only the big commercial hatcheries that practice it.
Fayoumi,s as far as i know are the only(or one of the only) breeds that are totally resistant to it,has anyone else heard of any others ?
The administrator has disabled public write access.