Bred to Perfection Ep4 – Virulent Newcastle Disease (NDV)

Once again, the Newcastle Disease virus (NDV) is hitting Southern California hard and threaten other states as well. I felt compelled to enlighten you on the facts about this highly contagious disease, and what to do about it.

In this article, we will discuss past outbreaks, the severity of this disease, all the signs, transmission and bio-security measures that should be taken. And much, much more!

THE HISTORY

This is not a new disease; in fact, the first reported case was in 1927 by Doyle of Newcastle-upon-Tyne, Surrey, England. He named it after the town it was discovered in, so that the disease would not become confused with any other disease during that time, as this disease had many symptoms similar to other infectious diseases.

However, evidence of this virus had already existed in Java, Indonesia in 1926   as well as, Central Europe and other lands, but under different names and were thought to be other diseases during this time period.

The first recorded panzootics (outbreak of an infectious disease, of an animal, that spreads across a large region) by D.J. Alexander, Poultry Dept. of Veterinary Laboratory in Surrey, England, stated that three more panzootics of NDV had occurred since the first recorded detection. The first arising in Southeast Asia between 1926 and 1927, moving slowly through Asia to Europe, taking over 30 years to spread worldwide.

The second panzootics is suggested to have begun in the Middle East in the late 1960’s, more rapidly, reaching most countries by 1973. This occurrence was due to the poultry industry going through many advance changes since the 1920’s with major commercial poultry businesses arising and considerable import and export poultry internationally being traded.

After this serious worldwide spread of the NDV, the development of vaccines and poultry protections followed. Restrictions on imports and exports of birds began to take place.

However, in 1971, NDV hit Southern California hard, infecting 1,341 flocks of the commercial poultry industry, resulting in 12 million birds destroyed and costing tax payers 56 million dollars. This outbreak increased the price of poultry and poultry products, and severely disrupted many commercial producers.

The third recorded panzootics occurred with racing pigeons, which were mistakenly forgotten, and were not added to the strict international trade transportation restrictions. Doves and pigeons kept for racing, shows, and food consumption in European countries, represented several million birds.

This outbreak occurred in the Middle East in the late 1970’s and by 1981 had reached Europe before spreading throughout the rest of the world. NDV was contracted during pigeon racing events, pigeon and dove shows and international trade, rapidly spreading to 24 countries in all.

Furthermore, NDV spread, this time, by contaminated chicken feed, which had become infected by pigeon feces carrying the Newcastle Disease virus. Great Britain took a large hit with 20 outbreaks of the Newcastle Disease virus in 1984.

In 1940, reported by Dr. J.R. Beach, stated that California was hit with the deadly Newcastle’s Disease virus. It was first misdiagnosed and was thought to be a few different kinds of illness among chickens and not NDV. The “chicken-flu” and “nine-day pneumonia” was thought to be the cause of this epidemic.

Two to ten-week-old chicks contracted a disease not previously observed. This particular disease began in the respiratory system, and within a few days had moved into the nervous system.  Dr. J.R. Beach reported that, due to the rapid spread of this illness among flocks, the death rate, as well as, respiratory and nervous systems being afflicted, concluded that this had to be NDV and not a respiratory-nervous disorder, as previously assumed.

By 1945, reports stated that avian pneumoencephalitis (Newcastle’s Disease) had become the most dreaded disease of chickens in India. Furthermore, reports from other countries, such as, the Dutch East Indies, parts of the Orient, some South Pacific islands, Australia, Palestine, the Kenya colony, Italy, Germany, the French Equatorial and South Africa were among those reporting the respiratory and nervous system ailments with a high death rate and rapid spread of the infection among the flocks.

In 2002-2003, the NDV outbreak took place in Southern California starting with a backyard poultry enthusiast, then spread to commercial poultry operations in California, backyard poultry in Arizona, Nevada, and Texas.

The Governor of California declared a State of Emergency, the USDA declared an Extraordinary Emergency, local emergencies were declared in San Diego, Riverside, Los Angeles, and San Bernardino counties. The USDA and California Dept. of Food and Ag. formed the “CDFA” task force.

Trade restrictions were strongly enforced, which meant absolutely no birds were to be sold or moved off your property during this outbreak. This movement lasted 11 months and 3.16 million birds were depopulated. This included both commercial and backyard flocks.

In 2006 to 2009, Iran, South Africa, Israel, China, Vietnam, Columbia, Romania, South Korea, Kuwait and Sweden became infected, ending in 56 countries reporting outbreaks, therefore, on average per year from 2006 to 2009, the poultry NDV reports only took 2^ndto rabies reports.

This is how fast and how easily this disease had spread. This outbreak costed 161 million dollars.

Definition of the Newcastle Disease 

Now that I have spent a little time informing you of the Newcastle Disease Virus timeline, let’s break down and go into what this disease is all about.

Virulent Newcastle’s Disease, formerly known as “Exotic Newcastle’s Disease” is the most severe of the many strains of NDV, and is a highly contagious viral disease. It is 4^thin line to the most problematic disease of poultry behind the highly pathogenic Avian Influenza, Avian Infectious Bronchitis, and the Low Pathogenic Influenza. Out of all the animals lost through destruction, disease or slaughter, NDV ranks 8^thout of 71 diseases evaluated. The absolute most toxic strain is the Viscerotropic Velogenci Newcastle Disease (VVND), also known as “Exotic Newcastle Disease.

The incubation period is only 2 to 15 days but may take up to 21 days to show signs of the disease. However, some may not show any signs but suddenly drop dead. Death usually takes place within 72 hours with up to 100% mortality rate.

This disease affects the respiratory, nervous, and digestive systems. Signs of this infection can show in one, two or all three of these systems, one after the other or simultaneously. Easily transmittable, and having a good survival rate off the host, the Newcastle Disease Virus thrives and does best in cooler climates. It’s only natural predator is the sun. The ultra-violet rays from the sun will kill it instantly.  A strong disinfectant will do the job, as well.

Transmission of Newcastle Disease Virus

Transmission of the Newcastle Disease Virus is accomplished in many ways. The passing of the egg through the ovum during laying may become infected because of porous texture of the shell. Also, the virus can live in a soiled nest box in which the eggs are laid from a diseased hen and contraction may be accomplished there.

The flock can become infected by:

• Tainted water exposed to the virus from an infected chicken as this virus can live in the water.
• Cracked egg shell of infected chicks can infect other chicks in the clutch that were not infected during incubation.
• Infected birds shed this virus, infecting their bedding, roost, water, and feed via respiratory secretions from the nares, mouth, and eyes.
• Feces and body fluids can discharge thousands of microorganisms to be spread, not only by the flock, but by you, as well. Via our shoes and clothing, we track the virus all around our house and car. We carry it with us where ever we go.

Remember, this virus is only killed by ultra-violet rays or a strong disinfectant, such as bleach; therefore, we must be diligent in the biosecurity of our yards.

Special note: even though you keep a closed yard, you can still contract this virus. For example, when you go to your local feed store to buy feed or have it delivered to your house, you may assume that you are safe, because no one has been on your yard and you have not visited any other yards that have chickens. But, how can you be sure that every person that has walked through that feed store has disinfected their shoes before walking into that store? The delivery driver goes to many houses along his delivery route per day. Has his shoes been properly disinfected each time, after making each delivery? Probably not!

What parts of the body are affected?

The Newcastle Disease Virus attacks three main systems of its host, the respiratory, nervous, and digestive system. Your flock may only show signs from one of the systems or simultaneously show signs from all three systems.

• In the respiratory systems, the symptoms will be gasping for air, coughing and nasal discharge.
• In the nervous system, the symptoms will be uncoordinated walk and movements, such as, stumbling, lack of proper balance, abnormal head and neck position, such as, head tilt or wry neck in appearance or unilateral or bilateral partial or complete paralysis of the legs and wings.
• The digestive system may show signs of diarrhea with hemorrhage (blood in the stool) which is a classic sign of VVND (Virulent Newcastle Disease).

Incubation period and survival of the virus off the host

The incubation period of the Newcastle Disease is between 2 to 6 days, but may take as long as 15 to 21 days to show signs of the infection. In severe cases, the entire flock can be dead within 72 hours from Newcastle Disease without showing a single sign of the virus or at the first signs of the virus.

The survival rate outside the host is fairly robust for this virus. It does well in cooler conditions, living off the host for several weeks. When it is protected by associated organic material, such as, bedding litter, carcasses, water, eggs and feathers, it will thrive until it meets its next victim only to be killed by the sun’s rays and a strong disinfectant.

Who is at risk?

Unfortunately, for chicken owners, the chicken is the most vulnerable with the Turkey taking a close second. Ducks and Geese can carry the virus without ever showing any signs of the disease and is less lethal to them. Parrots, pigeons, quail, wild cormorants and wild birds are also at risk of contracting this disease.

Diagnoses of the Newcastle Disease Virus

This disease cannot be confirmed (diagnosed) on clinical signs or post mortem lesions alone. One of these 3 events must be confirmed via special labs results.

• The identification and pathotyping of the virus
• Demonstration of the viral genetic material within the lesions
• Significant rise in antibody titre between an acute and convalescent sera coinciding with the disease

What about humans? Do we need to worry about this disease?

Yes, humans can contract this virus, however, no worries. At most, this virus will cause conjunctivitis and/or a low-grade fever. There is no contraction from eating eggs or meat from an infected bird (Newcastle’s Diseased) but if you vaccinate, you must wait several days before slaughtering this bird before it is safe to eat. I will provide more detail in the vaccination section of this article. Usually, the people that will contract this virus are those that work in the labs where this virus is being investigated or research or the poultry crews that come in contact with many diseased flocks.

Clinical sign list

Here are the clinical signs of the Newcastle Disease Virus:

• Head tremors
• Head tilt
• Twisted neck
• Incoordination convulsions
• Circling muscle spasms
• Head shaking unilateral or bilateral
• Partial or complete leg and wing paralysis
• Diarrhea possibly with blood dropping
• Respiratory distress
• Hoarseness
• Gasping for air
• Reduced appetite
• Lethargy
• Fluffed up feathers
• Reduced egg production
• Falling of perch
• Abnormal egg

Vaccinations

Vitamin A or Vitamin rich foods have been known to delay clinical signs of the Newcastle Disease, however, do not be fooled into thinking that as long as you keep Vitamin A as part of your feeding regiment, you will be protected from this disease. Vitamin A helps to reduce the mortality rate by 36% in some studies with less impact of the virus on the body but will not fully protect your flock from exposure.

Inactive vaccines became commercially available in the United States in 1945. However, this form of vaccination was not commonly used among the poultry industry, back then, because of the high cost of the vaccine.

Live vaccines were licensed in 1948. Two NDV strains of low virulence, B1 and LaSoto, were developed. A live NVD given in ovo at 18 or 19 days of embryonation became available and was used just before the hatching eggs were moved into the hatching trays. This NDV antigen to the respiratory and gastrointestinal tracts allowed the newly hatched chicks to develop an early immune response.

However, this practice caused a decrease in hatchability rate and hatched weak chicks, in some cases.

Problematic issues with the Newcastle Disease vaccines

There are many issues with the Newcastle Disease vaccinations that may help in making the decision on whether or not to go the route of vaccinating your flock. Here is a list of vaccination challenges:

• Can cause a decrease in the hatchability rate among the vaccinated embryos
• Weak chicks from vaccination in the embryo
• Does not provide a lifelong immunity and additional vaccinations would be necessary in layers and breeders
• Vaccinations are not yet perfected
• Been in use since 1950 and used vaccine strains are 3 to 7 decades old
• Old strains are genetically distant from the current circulating virulent Newcastle Disease Viral strain
• The high genetic distance between the outdated vaccine and the contemporary NDV strains prevent effective reduction of shedding of the virulent virus from vaccinated birds
• Vaccinations may cause clinical respiratory disease
• Drop in egg production for a short time but will eventually come back to normal
• Difficulties with administration techniques in larger commercial settings
• Uneven vaccine application when vaccinating mass quantities of flocks
• Difficulties with administration techniques in free-ranged flocks
• Improper and incomplete immunization resulting in death and disease of the flock after infection appears
• Decrease efficiency due to existence of antibodies in birds which can neutralize the vaccine, reducing the effectiveness of potency
• Difficulties in maintaining the right temperature to preserve the thermos-labile antigen in the vaccine, however, in recent years a newly development of thermostable vaccines now can be transported safely to reach small rural villages
• Vaccine can deteriorate after storage of one to two hours in a room temperature setting
• If stored in the direct sunlight or allowed to reach 37degress Celsius for more than a few hours, deterioration sets in or can become non-effective
• Must wait 21 days before vaccinated birds are slaughtered
• The entire contents of the vial must be used once it has been opened
• Must vaccinate all susceptible birds on the premises at the same time
• Burn the vaccine container and all its unused contents after use
• Avoid carrying the vaccine particles on your shoes, clothing, etc. into unvaccinated flock area for 10 to 14 days after vaccination

Biosecurity

The absolute best method for protecting your flock from the deadly Virulent Newcastle’s Disease is having a good biosecurity plan in place and never detour from the strict rules applied.

• Restrict access to your flock area at all times. It takes just one soiled shoe tainted with the virus to infect your flock.
• Clean and disinfect any and all equipment that will come in contact with your flock and never borrow or buy used equipment from anybody or anywhere, not even your friendly neighbor whose chickens look perfectly healthy to you.
• Avoid visiting other farms that house poultry and while in an outbreak situation area, never go to a poultry show or any fairs where a poultry show was or is about to take place. This situation is a breeding ground for the Newcastle’s Disease virus, laying in wait for its next host.
• Buy your seed stock from reputable dealers that have certification of birds being legally imported into the United States, maintain a strict biosecurity system on their yard and known for their good farm management and breeding techniques.
• Maintain all sales and shipments receipts of any birds received and upon arrival of your newly purchased flock.
• Isolate them for 30 days away from your flock for verification of being healthy birds. If they don’t come down within those 30 days with an illness, it’s a safe bet that they are healthy and will not infect your birds with disease.
• Keep younger birds in separate areas from your mature birds, as your mature birds may have a built-up immunity to some aliments that the younger birds may not be able to tolerate. Also, make sure to feed and care for the youngest birds first, and the oldest birds last.
• Disinfect you clothing and shoes regularly, especially after visiting the feed and pet stores.
• Wash your hands often while visiting another farm, disinfect your shoes upon returning home and change your clothes.
• Report all sick birds to the USDA @ 1-866-536-7593.

6 Basic Steps to Biosecurity

1. Keep your distance by isolating birds from visitors and other birds
2. Keep it clean, such as, shoes, tools, and poultry equipment which will prevent germs from spreading
3. Don’t haul disease home by keeping your vehicle tires disinfected
4. No buying used cages or borrowing cages from another farm or neighbor
5. Know the warning signs of infectious bird diseases by watching for early signs to prevent the spread of disease
6. Report any unusual signs of disease or/and all unexpected deaths

State and Federal laws on the Newcastle Disease

It is your duty, as a poultry owner, to report any and all suspected cases of the Newcastle’s Disease infection to the CDFA, if in California, or the USDA. Infected birds must be isolated and, above all, not removed from your property.

Field Contacts in the California region

CDFA Modesto District

209-491-9350

CDFA Ontario District

909-947-4462

CDFA Redding District

530-225-2140

CDFA District

559-685-3500

Currently, in the San Bernardino County, an outbreak is occurring of the most dangerous strain of NDV. This Virulent Newcastle Disease is very serious and should not be taken lightly. Please adopt a strict Biosecurity plan for the safety of your flock and pray this outbreak remains confined to a small area and not spread nationwide.

Good luck to all!

Nancy