The poultry industry in Cyprus has been devastated by an outbreak of Newcastle disease, which has resulted in the loss of more than 250,000 birds so far.
The outbreak began on a broiler unit on June 11, according to a report issued by the World Organisation for Animal Health (OIE). Updates issued since that initial report show that another three units on the island have now been hit by the disease. A total of 251,000 birds have either died from the disease or been destroyed by the authorities in their response to the outbreak.
All of the affected farms are in the Lefkosia district of Cyprus.
The first farm affected was at Kokkinotrimithia, where 115, 500 birds were kept in five houses on a broiler unit. The OIE says that the signs that something was wrong included an increased mortality rate and respiratory and neurological problems amongst the birds. A total of 44, 241 birds died as a result of the disease. The rest of the flock was destroyed.
The second unit affected was just 100 metres away from the first one. The 43,500-bird broiler unit reported increased mortality, with 10,164 birds falling victim to the outbreak. Post mortem examinations said that lesions consistent with Newcastle disease were discovered on the birds. Again, the rest of the flock was slaughtered by the authorities.
On the third farm affected, 5,742 birds out of a flock of 24,000 died as a result of the disease. The rest were destroyed.
The fourth outbreak was in a 68,000-bird flock owned by the farm involved in the original outbreak. A total of 1,462 birds died from the disease. The others were slaughtered in response to the outbreak.
Giorgos Kyriakides, director of the veterinary services in Cyprus, described the situation as "very difficult” and said that the authorities were taking a series of precautionary measures to limit the spread of the virus. He said it was the first time that such an outbreak had been recorded on the island for decade.
He also suggested that the infection could have been transmitted from farms in the Turkish-occupied part of Cyprus. The island has been divided between Turkish and Greek zones since the war of 1974.
Newcastle disease is a highly contagious disease affecting both wild and domestic birds and caused by a paramyxo virus. The disease is a worldwide problem, but the last outbreak in chickens and turkeys in the United Kingdom was in 1997. It occurred here in pheasants in 2005 and in partridges in 2006.
Affected birds may show a range of signs, from mild illness to severe disease with dullness, loss of appetite, coughing, sneezing, diarrhoea and nervous signs. Hens may stop laying or their eggs may be mis-shapen. In severe outbreaks a high proportion of infected birds may die.
Newcastle disease – the forgotten pest?
With the ongoing obsession of the prophets of doom in the media about the risks to humans from the impending global pandemic of avian influenza, we could all be forgiven for forgetting about the other notifiable disease of poultry, Newcastle Disease, or Fowl Pest.
The recent announcement of an outbreak of Newcastle disease on a broiler farm in Cyprus showing as increased mortality, respiratory and nervous signs is a timely reminder of this potentially devastating disease.
Notifiable disease
Newcastle disease is a highly contagious disease of a range of bird species, caused by certain virulent (hot) strains of Newcastle disease virus, found throughout the world where domestic poultry are kept. The virus can affect chickens, turkeys, ducks, geese, pheasant, partridge, guinea fowl, ostrich and other wild and captive birds.
Due to its potential to cause high and rapidly spreading mortality in domestic poultry, virulent forms of Newcastle Disease are classified by Defra as “notifiable”. What this means in practice is that if producers, poultry keepers, or their veterinarians have suspicions that Newcastle Disease (or indeed Avian Influenza) are present on a poultry premises, these suspicions must be reported (notified) immediately to the local Animal Health Office of Defra/AHVLA.
This enables Defra officials to visit, inspect and sample suspect flocks, and where disease is suspected, put stringent controls on the premises to reduce the likelihood of further spread. If disease is subsequently confirmed disease control measures, including wider movement restrictions and destruction of infected and at risk birds can take pace to control any outbreak.
Some history
Newcastle Disease probably has its origins in the Far East, but the name originates from a very early outbreak in 1927 in Newcastle Upon Tyne, England. Since that time significant outbreaks have occurred in UK until the development and implementation of effective vaccination strategies and a stamping out policy on any identified affected premises. The last outbreak in chickens and turkeys in the UK was in 1997, and was linked to migration of wild birds driven to the UK following an exceptionally hard and cold winter in other parts of Northern Europe.
The disease
Newcastle disease can occur in a variety of forms, depending on the strain of virus involved. The clinical signs can be equally variable, ranging from very mild through to highly virulent causing 100% mortality! Clinical signs also depend on the strain involved and which organ is most severely affected, with a combination of respiratory, nervous and diarrhoea manifestations. In its most severe form it is only likely to be confused with avian influenza or some catastrophic equipment failure in controlled environment accommodation or some major toxic incident.
What might you see?
As indicated above, the signs may be variable. Clearly any exceptional or unexplained mortality should be reported to your vet immediately and the causes investigated. The clinical signs associated with Newcastle disease infection vary according to a wide range of factors which include:
• The strain of virus involved
• The species of bird affected
• The age of birds affected (young birds are very susceptible)
• Other infections present at the same time
• Environmental stresses
• Immune status (previous exposure or vaccination)
Clinical signs reported include some or all of the same signs in a single flock:
• High mortality – up to 100%!
• Respiratory signs – gasping, coughing, sneezing etc
• Nervous signs – tremors, twisted necks, paralysis, leg weakness
• Digestive signs – diarrhoea (classically reported a green or yellow but this is not definitive)
• Reproductive signs – sudden egg drop, soft shells or other quality issues
How is the disease spread?
This is the same as for many infectious diseases of poultry, but the most important are:
• Direct contact with diseased birds that are shedding the virus
• Contaminated faeces or respiratory droplets
• Vehicles, people, clothing or equipment contaminated with the virus
The virus can survive for several weeks in the environment, but most virus is excreted when a flock is clinically affected. The virus is very contagious within a flock with morbidity and mortality being almost immediate in very susceptible flocks. On the other hand, some ducks, seabirds and other wild birds can carry large amounts of the virus without any clinical signs and hence can be very significant in the introduction of virus into a country or geographical area during seasonal migrations. They are an especial danger when winters are very hard, birds migrating further than their usual routes and looking for food sources, potentially close to domestic poultry flocks, especially those on range or near stretches of open water.
How do we control this disease?
Due to the capacity of the virus to spread and cause very high mortality and economic loss, most countries have a national Government control strategy. This can be a stamping out policy, as UK has for avian influenza, or can depend on a combination of good biosecurity measures, import controls and widespread vaccination. In UK, after a number of significant outbreaks the Government strategy, supported by the industry, for the last 25 years or so has depended on an approach of vigilance, import controls and a voluntary vaccination policy. This has served UK well, enabling trade with EU and Third Countries without compromising national poultry health, with only isolated outbreaks affecting game birds or small unvaccinated groups since.
Vaccination strategy
The vaccination of domestic poultry is on a purely voluntary basis, although is strongly advised, especially for breeding and laying stock. In the layer sector in both layer breeders and commercial laying flocks the approach adopted tends to be a robust combination of live priming with inactivated vaccines at point of lay. The aim is protect young stock and layers through the laying period.
What do I do if I suspect Newcastle Disease in my flock?
As with any health issues your first stop should be your veterinary surgeon. In the case of virulent Newcastle Disease in fully susceptible flocks then often the only disease that it needs to be differentiated from is avian influenza. However, as in UK we have vaccinated flocks it is possible for disease to be much less obvious. Due to the “herd immunity” we have through our vaccination policy the likelihood of primary disease in domestic poultry in UK is extremely unlikely, but we should remain vigilant, especially in meat flocks where vaccination may not be routinely practiced.
What happens if suspicions are reported?
If your veterinary surgeon is suspicious of Newcastle Disease in a flock they will, as with avian influenza, report these suspicions immediately to Defra/AHVLA. This should trigger an immediate visit from AHVLA staff. If they are suspicious of notifiable disease they will take samples and put immediate restrictions on the flock (no movement of birds or eggs on or off site). If disease is not confirmed then these restrictions will be lifted. If disease is confirmed then further movement restrictions in the area will be introduced (usually a 3 Km Protection Zone and a 10 Km Surveillance Zone). This is to enable AHVLA to identify and isolate any other infected premises, establish the source and begin the stamping out of any infected premises. During such investigations, if wild bird introduction is suspected then a much wider Restricted Zone may be introduced requiring ALL poultry in that area to be housed. This would apply to all free range flocks in the announced control area, and could affect a large number of flocks.
Contingency planning
All poultry keepers are expected to establish a Contingency plan for their premises in relation to natural emergencies or disease outbreaks. Whereas the controls for Newcastle Disease (and avian influenza) imposed for a specific infected premises are broadly directed by AHVLA staff, if you just happen to be in the wrong place, in the wrong time (e.g. your flock is included in one of the zones or stock are required to be housed) then you have to be prepared to be able to cope with this.
For individual flock farmers the most important things to think about in peacetime are the following:
• Always maintaining high standards of biosecurity on your farm
• Strictly control visitor movements on and off your premises
• Avoid sharing equipment with other premises
• Do not allow your birds to have direct contact with wild birds by avoiding feeding outside or feed spillages at delivery
• Promptly report any suspicions of disease to your veterinarian
• Think about how your flock would cope with a sudden housing order preventing access to range area
• Think about how you might get feed to your birds if there are restrictions in a given area
• Think about how you might store eggs on farm if there are restrictions in your area
So do I need to worry?
The short answer is no! Common things are common and we have a well vaccinated national flock, generally good levels of farm biosecurity and tight import controls. So the risk is very low. However, another strapline is that we should “expect the unexpected”, and in that case it is advisable to have a contingency plan or at least give some thought as to how you might cope on your farm if there were restrictions in your area. In this regard Government has established a national control strategy for notifiable diseases and it is worth a read when you have a quiet moment as it lays out all the measures that might be introduced during a disease outbreak. This strategy can be found using the following link:
