An Article by, Kathryn Reynolds

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Marek’s disease (MD) is one of the most persistent and economically significant viral threats to poultry worldwide. Caused by *Gallid herpesvirus 2*, an alpha-herpesvirus, Marek’s continues to evolve despite decades of widespread vaccination. As a result, both commercial farms and small-scale keepers face ongoing challenges.

 

Figure 1. Classical paralysis posture in Marek’s disease.

Types of Marek’s Disease

1.  Classical / Neurolymphomatosis

The most recognized form of MD, involving T-cell infiltration and tumor formation in peripheral nerves. Birds display unilateral or bilateral paralysis, wing droop, and wasting.

2.  Acute Visceral Marek’s

A rapidly progressing form in which T-cell lymphomas develop in internal organs, including the liver, spleen, heart, and kidneys. Birds may die suddenly without showing paralysis.

3. Cutaneous Marek’s

Causes raised lesions in feather follicles. Although less common, it indicates systemic viral burden.

 

Figure 2. Ocular symptoms, leg paralysis, and crop issues associated with MD.

The Complex Challenge of Vaccination

Marek’s vaccination—using HVT, SB-1, or Rispens strains—remains the primary method of reducing tumor formation and mortality. However, these vaccines are non-sterilizing, meaning they do not prevent infection or viral shedding. As a result: Vaccinated birds may still become infected. They can shed virulent MDV into the environment. They may become lifelong carriers. This phenomenon is known as the “leaky vaccine effect,” which allows highly virulent MDV strains to circulate while suppressing symptoms in vaccinated hosts.

 

Figure 3. Marek’s paralysis and ocular changes.

Breed Susceptibility

Some breeds demonstrate significantly higher susceptibility to Marek’s disease. These include: Silkies Polish Mediterranean-type breeds such as Leghorns Show/ornamental lines under genetic bottleneck Certain high-production hybrids More resistant birds often come from lines that experienced natural selection pressures or selective breeding for MD resistance.

 

Figure 4. Classic wing and leg paralysis presentation.

Traditional Chinese Herbal Strategies

Several studies and Chinese veterinary patents describe herbal blends for viral support in poultry. These herbs appear repeatedly across research: Honeysuckle (Jin Yin Hua) – antiviral, heat-clearing Forsythia (Lian Qiao) – antioxidant, antiviral Astragalus (Huang Qi) – powerful immune tonic Andrographis (Chuan Xin Lian) – antimicrobial and antiviral Codonopsis (Dang Shen) – supports stamina and immunity Bupleurum (Chai Hu) – immune regulation and liver support Alisma (Ze Xie) – regulates fluid metabolism Licorice (Gan Cao) – harmonizing, anti-inflammatory

 

Figure 5. Symptom overview useful for flock monitoring.

Feed-Based Herbal Dosage Guide

Using TCM Granules or Tea Pills

• Preventive support: 0.1–0.2 g per kg feed

• Outbreak support: 0.4–0.6 g per kg feed for 5–7 days

Using Herbal Decoction (“Teapot Method”)

Simmer 50–100 g of mixed herbs in 2 L water for 30–40 minutes.

• Preventive: 200–300 mL per kg feed

• Outbreak support: 400–500 mL per kg feed

 

Figure 6. Severe visceral lymphomas characteristic of acute MD.

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References

1. Sun Y. Screening compounds of Chinese medicinal herbs anti-Marek’s disease virus.

2. CN102716282A. Traditional Chinese medicine granule for Marek’s disease.

3. Reviews on Astragalus polysaccharides in poultry immune modulation.

4. Studies on Forsythia, Andrographis, and Bupleurum in viral response.

5. Documentation on leaky vaccine dynamics in MDV evolution.