A randomized controlled trial across five Iraqi provinces has shown that a polyphenol-rich plant herbal extract (PHE) cut mortality in very virulent infectious bursal disease virus (vvIBDV)-challenged broilers from 36.7% to 3.3% when given as a combination regimen, with viral loads falling by up to 69.6%.

What did the trial actually test?

Researchers enrolled 150 Ross 308 broiler chickens (mean age 4.2 ± 0.9 weeks; 52% male, 48% female) between August 2025 and January 2026. The flock came from Baghdad (30%), Basrah (20%), Erbil (18.7%) and other production regions. Investigators randomized the birds into five groups of 30: a positive control (vvIBDV-infected, untreated), three vvIBDV-infected groups receiving 20, 40, or 60 mg/kg PHE, and a combination therapy group. A sixth group of 30 uninfected, untreated birds served as the negative control. All birds carried documented absence of IBDV, avian influenza, and Newcastle disease virus at enrollment.

Lead author Sarah Abdul-Hussein Hassan and colleagues monitored viral load, bursal index, cytokine profile, antibody titer, clinical signs, and mortality over 21 days post-challenge.

How much did the extract reduce viral load?

The 60 mg/kg dose lowered viral load by 3.82 ± 0.51 log units (53.2%) versus infected controls. The combination group performed better, dropping viral load 2.48 ± 0.42 log units (69.6%) relative to the positive control. Both comparisons reached p < 0.001. The effect followed a clear dose-dependent pattern across the 20, 40, and 60 mg/kg arms.

What happened to the bursa?

Bursal index — a marker of bursal tissue integrity — rose to 1.25 ± 0.18 in the combination group, compared with 0.42 ± 0.08 in the positive control (p < 0.001). That nearly three-fold improvement addresses the central lesion of IBDV: acute lymphocyte destruction in the bursa of Fabricius that leaves 3- to 6-week-old broilers immunosuppressed and vulnerable to secondary infections and vaccine failure.

Did the extract shift the immune response?

PHE treatment modulated the cytokine cascade. Interleukin-1β and IL-6 levels fell, while IL-10 and IFN-γ rose. The authors interpreted this pattern as a rebalancing of pro- and anti-inflammatory signaling rather than blunt immunosuppression. Mortality data followed the same trend: 36.7% in the infected, untreated birds versus 3.3% in the combination therapy arm (p < 0.001).

Why does this matter for Iraqi producers?

Available vaccines do not always confer enough protection against very virulent strains circulating in the Middle East. Hassan and co-authors, writing in the discussion, framed the combination regimen as a candidate adjunct rather than a vaccine replacement. The work positions phytochemicals alongside phytogenic products already under evaluation for avian coronavirus tolerance and other viral challenges.

What changes at the farm level?

For a flock experiencing an IBDV outbreak in the 3- to 6-week susceptibility window, the data suggest a phytogenic intervention could:

• Cut case mortality by roughly 90% versus untreated controls
• Preserve bursal mass, the organ responsible for B-cell maturation
• Lower circulating virus enough to reduce environmental contamination

The authors stressed that the Iraqi field design — distributed across multiple provinces — strengthens external validity for regional production systems but does not substitute for larger scale validation.

What's next?

The team called for additional studies to confirm efficacy under commercial conditions and to define dose, duration, and any interaction with live vaccines. Combination therapy's outperformance of the 60 mg/kg single dose suggests multi-component phytochemical blends may be worth pursuing as part of integrated IBDV control programs in Iraq and comparable production systems.