Newcastle Disease Virus (NDV) Current Situation in Syria

1. Poultry Industry in Syria

Syria’s poultry sector has long served as an important agricultural resource, acting as the main source of low-cost animal protein. However, the industry has overcome significant operational obstacles to undertake a significant phase of transition and restoration.

• Production Dynamics and Population: Syria’s poultry sector produced more than 300,000 tons of white meat and about 5 billion table eggs a year before regional instability. Across roughly 12,000 to 13,000 operational farms, production stabilized at 172,000 tons. Syria implemented a strict prohibition on frozen poultry imports in August 2025 in order to protect domestic farmers from foreign fluctuations in prices and promote local growth. This led to a large reinvestment in broiler flock repopulation.

• Per Capita Consumption: Consumption trends show how the economy is recovering. Poultry meat consumption is currently estimated at approximately 6.8 to 8.5 kg per capita annually, while egg consumption revolves around 85 to 90 eggs per capita per year. As local supply distribution networks solidify, these figures are increasing.

• Sector Challenges: Syrian producers deal with very unstable working conditions, such as high prices for imported feed ingredients (soy and corn), ongoing fuel shortages for winter environmental heating, and limited access to regional veterinary extension services.

2. Newcastle Disease Virus (NDV) Brief

In 1952, Newcastle Disease was first officially reported and recognized in Syria ,Newcastle disease Virus (NDV remains one of the most destructive viral pathogens affecting the poultry industry globally.

The three main pathotypes of Newcastle Disease Virus (NDV) strains in birds are lentogenic (low virulence, mild/no symptoms), mesogenic (moderate virulence), and velogenic (very pathogenic, causing severe respiratory/nervous manifestations and significant mortality).

• Etiology: The disease is caused by virulent strains of Avian Orthoavulavirus 1, family Paramyxoviridae (formerly known as Avian Paramyxovirus 1 or APMV-1). It is an enveloped, single-stranded, negative-sense RNA virus.
• Transmission: The virus spreads via inhalation or ingestion of contaminated secretions. Migratory birds act to introduce new strains into local poultry populations.
• Clinical Signs: Infected birds shows severe respiratory distress, greenish diarrhea, and neurological signs, as torticollis and leg paralysis.
• Pathology: Postmortem examinations typically shows proventricular, cecal tonsils, and intestinal lymphoid patches hemorrhages, in addition to catarrhal tracheitis

The amino acid motif at the viral Fusion (F) protein’s cleavage site is the main factor that determines NDV pathogenicity.

3. Most Prevalent Genotypes and Recent Outbreaks

Genotype VII dominates the epidemiological landscape of Syria. This virulent lineage is still extremely endemic throughout Middle Eastern poultry hubs, gradually displacing older lineages (including Genotype II and historical regional strains).

The field environment in Syria is characterized by persistent viral pressure, with outbreaks frequently occurring in important production zones in Damascus, Hama, Homs, and Aleppo.

Severe, high-mortality episodes in commercial broiler flocks that have received comprehensive routine immunization campaigns have been a persistent problem in recent field outbreaks.

Affected flocks show dramatic surges in mortality, greenish watery diarrhea, facial edema, and rapid, acute onset of severe respiratory distress.

Free-range operations and a sizable backyard poultry industry exacerbate the epidemiologic cycle. These flocks serve as permanent reservoirs that continuously release the virus back into commercial corridors because they frequently maintain minimal biosecurity buffers and mingle with migratory or wild birds along local water basins.

4. Control, Recommendations, and Vaccination

In order to achieve strong control over Genotype VII NDV in Syria, a highly coordinated, structurally solid health protocol must replace Basic control procedures.

Standard live lentogenic vaccinations (LaSota, Clone 30) given by drinking water or coarse spray, along with traditional inactivated oil-emulsion vaccines, have always been a major part of Syrian commercial farms. Vaccine failures, however, continue to be a significant field problem. This is primarily caused by antigenic mismatch: traditional vaccinations are developed using Genotype II strains, which are phylogenetically distinct from the field strains of Genotype VII that are currently in circulation.. Although Genotype II live vaccinations offer adequate cross-protection to prevent complete flock collapse, they are unable to stop virus replication, which allows birds to develop into subclinical shedders.

• Switch to Genotype-Matched vaccinations: High humoral antibody levels are ensured by using inactivated oil-emulsion vaccinations that correspond to the circulating Genotype VII strain.
  • Structural Climate Control & Biosecurity: It is essential to maintain steady ventilation without causing thermal stress due to Syria’s extreme seasonal temperature changes (cold winters needing extensive coal/fuel heating). To prevent feed contamination by wild pigeons and sparrows, which serve as extremely efficient mechanical vectors, houses must be properly bird-proofed.• Optimizing Stocking and Hygiene: By keeping densities below 10 birds per square meter, overcrowding is reduced, which lowers ambient ammonia levels and protects the integrity of the tracheal cilia, the flock’s principal physical defense against respiratory diseases.

• Strengthening Diagnostics: Increasing the number of localized diagnostic networks with fast real-time RT-PCR and F-gene sequencing capabilities makes it possible to quickly distinguish between velogenic field challenges and benign lentogenic vaccination strains, allowing for quick, focused reactions.