Newcastle Disease (NDV) current situation in Iraq

Newcastle disease (ND) continues to be one of the most prevalent viral threats to Iraq’s poultry sector, resulting in continuous financial losses and rendering efforts to ensure food security more challenging. The virus’s endemic status is maintained by a variety of complex environmental and epidemiological factors.

1. Poultry Industry in Iraq

The Iraqi poultry sector is a vital component of the national agricultural economy, With Average Consumption of 13.3 kg of poultry meat per capita and approximately 175 eggs per year. The demand for poultry meat in the nation has increased by an average of 7.6% per year over the last four years.

2. Newcastle Disease Virus (NDV) Brief

In 1968, the Newcastle Disease Virus (NDV) was discovered and isolated for the first time in Iraq. Newcastle disease is caused by the Newcastle disease virus (NDV), a highly contagious member of the family Paramyxoviridae.

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).

• 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

Iraq’s NDV epidemiology is characterized by a high level of genetic variation. Recent molecular surveillance suggests a shift toward more virulent strains, despite the historical prevalence of classic genotypes (such Genotype II).

• Genotype VII Dominance: Sub-genotype VII has been mostly associated with recent outbreaks (2023–2024) in governorates like as Basrah, Babil, Wasit, Kirkuk, and Baghdad.

• Genetic Features: The F-protein cleavage site motif 112RRQKRF117, which is characteristic of velogenic (particularly virulent) strains, is present in isolates from these recent outbreaks. High phylogenetic closeness (97.95%–98.01%) between these Iraqi viruses and isolates from Iran and Afghanistan suggests regional cross-border viral transmission.
• Vaccine Mismatch: Traditional vaccine strains such as LaSota (Genotype II) differ genetically from the field isolates. The main cause of “vaccination failure,” in which vaccinated flocks continue to exhibit clinical disease, is this antigenic drift.

4. Control, Recommendations, and Vaccination

In order to control ND in Iraq, integrated disease management must replace single-strain vaccination.

• Maternal Antibody Monitoring: To identify the best opportunity for primary vaccination, routine serological screening (such as ELISA or HI tests) is crucial because high levels of maternally derived antibodies (MDA) in day-old chicks can neutralize live vaccines.
• Heterologous Vaccination: In contrast to conventional LaSota-based vaccines, experts advise using inactivated vaccines made with genotype-matched antigens to provide more cross-protection due to the frequency of Genotype VII.
• Enhanced Biosecurity: To separate commercial flocks from wild bird reservoirs, stringent “all-in/all-out” production methods, movement controls, and efficient disinfection procedures are implemented.
• Integrated Monitoring: Veterinary labs should regularly perform molecular surveillance (RT-PCR and sequencing) to monitor circulating genotypes and modify vaccine choices as necessary. • Stress Control: Using climate-controlled housing and dietary supplements (vitamins C, E, and electrolytes) to strengthen innate immunological resistance in the face of ambient heat stress.