The strategy for Gumboro disease control: Experience from the field
Gumboro disease, or Infectious Bursal Disease (IBD), remains one of the most significant immunosuppressive challenges in poultry production worldwide. Despite decades of control efforts, the emergence of new strains and subclinical infections continues to impact flock health and performance.
The first step for a veterinarian is to establish a correct diagnosis, particularly of Gumboro disease. Broiler chickens can undergo early viral attacks (such as CAV, reovirus, adenovirus, Marek’s disease) especially before 3 weeks of age and have a significant impact on the chickens’ immunisation abilities, their performance, and their overall health.
Gumboro disease is still present in its classic form: mortality of 2-30% with hemorrhage or edematous lesions of the Bursa of Fabricius after 25 days of age. However, since 2020, early forms have become increasingly frequent with (non-specific) manifestations from 7 days of age affecting the quality and consistency of faces (picture 1).
At the necropsy, few or no macroscopic observations of the bursa are seen, but in more than 80% of cases, hypertrophy of the thymic lobes with congestion and petechiae is observed (picture 2 and 3).
In the immunohistochemical analysis of the Bursa of Fabricius (and other primary immune organs) reveals significant colonisation of tissues by the Gumboro disease virus (picture 4). Moreover, the chicken or future breeder hen may excrete IBDv over a long period if the vaccination programme is not properly adapted.
The research on different variants of IBDv highlights the extensive colonisation of primary immune organs (spleen, thymus, bursa of Fabricius) and secondary ones (Harder’s gland, BALT, cecal tonsils, GALT), leading to broad and lasting immunosuppression.
IBDv primarily targets immature B-cells in the bursa of Fabricius, leading to immunosuppression and increased susceptibility to secondary infections. The severity of the disease depends on factors such as:
- Age and maternal antibody (MDA) levels
- Strain pathogenicity, ranging from mild to very virulent IBDv
- Bird type and management conditions
Recent trends show a shift from classical very virulent IBDv infections to subclinical forms caused by variants and reassorted strains. These infections often go unnoticed but significantly reduce performance indicators like growth rate, feed conversion ratio (FCR), and vaccine efficacy.
Control strategy
The primary goal is early and uniform protection of the bursa to prevent immunosuppression. Key pillars include:
Biosecurity and management- Effective cleaning and disinfection
- Adequate downtime between flocks
- Passive immunity
- High and uniform MDA levels through breeder vaccination
- Active immunity
- Use of advanced vaccines to ensure early onset of immunity and complete flock coverage
Nextmune: A new generation solution
- Earlier onset of immunity
- Faster flock coverage
- Superior protection against very virulent IBDv and variants IBDv
- Improved technical performance and economic benefits
Field evidence: Displacing variants and improving KPIs
Field trials in Brazil, Peru, and Indonesia demonstrated better FCR and body weight, lower mortality, and increased profitability (up to €165 with better, consistent and the earliest control of IBD and the safety of W2512 strain).
Indonesia
In a large broiler integration producing 800,000 birds/cycle the monitoring by duplex PCR (20 bursas per cycle per multiple houses) revealed that field strain displacement takes time, typically 1-5 cycles, but Nextmune accelerates this process compared to other vaccination programmes, leading to recovery of normal performance.
Figure 1 – 100 individual bursa samples per cycle in farm 800,000 broilers per cycle.
Conclusion: In large farm with high Gumboro pressure, Nextmune can displace the field strain in few cycles.
Peru
In a reused litter production in Peru, with high IBDv pressure, 2 vaccination programmes were compared on the variants IBDv along 3 cycles. These are the results of the variant IBDv positivity across cycles:
- Nextmune: 81.8% → 41.7% → 20.8%
- rHVT-IBD: 100% → 87.5% → 75%
Figure 2 – Variant IBDv positivity per cycle by Nextmune vs rHVT IBD vaccines
Interpretation: The immune complex vaccine reduces variant pressure ~4× faster over three cycles, critical for breaking the shedding‑reinfection spiral.
Brazil
In a reused litter production in Brazil, with variant IBDv pressure, 2 vaccination programmes were compared on the variants IBDv along the cycles. The field necropsy showed bursas with gross lesions under rHVT-IBD vaccination programme, indicating ongoing IBDv infection.
On the Nextmune programme, the bursas were uniform and the flocks performed better FCR (1.623 vs 1.652) and higher profit was achieved (+€24.88 per 1,000 birds), with macroscopic bursa aspect as expected.
Take-home messages
- Gumboro disease has evolved: less mortality, more immunosuppression, and earlier contamination.
- Blocking the bursa and stopping virus shedding as early as possible is critical.
- Nextmune offers the best balance of efficiency, safety, and consistency, ensuring optimal flock health and performance.
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