The poultry sector in Sudan serves as a critical pillar of food security and rural livelihoods. However, the industry is constantly threatened by infectious pathogens, chief among which is Newcastle Disease (ND). Caused by virulent strains of avian paramyxovirus serotype 1, ND remains a major limiting factor for both commercial investments and smallholder backyard systems in the country. This article provides a comprehensive overview of the poultry industry in Sudan, the historical timeline of ND, the molecular epidemiology of circulating genotypes, and current vaccination and control strategies.

1. The Poultry Industry in Sudan

Poultry Population and Sectors

Sudan’s poultry industry is split into two primary production systems:

• The Traditional/Backyard Sector: This system makes up the vast majority of poultry assets, consisting of approximately 30 million birds out of an estimated total chicken population of 45.3 million. It is dominated by indigenous “Baladi” breeds (such as the Large Baladi, Bare-neck, and Betwil) reared under scavenging, low-input conditions.
• The Commercial Sector: Prior to recent geopolitical disruptions, the commercial sector was expanding rapidly around urban centers, particularly Khartoum State, using intensive and semi-intensive systems with high-performing hybrid broiler and layer strains.

Current Situation Note: The conflict in Sudan has severely damaged commercial poultry infrastructure, feed mills, and supply chains in major urban areas. Consequently, the resilient, low-input traditional backyard sector has temporarily reclaimed its status as the primary source of local poultry meat and eggs for millions of citizens.

Consumption Patterns

• Poultry Meat Consumption: Nationally, per capita consumption of poultry meat has historically been low (averaging 1.0 to 2.0 kg per capita/year), though comprehensive national strategies targeted increases up to 5.5 kg. In metropolitan areas like Khartoum, poultry plays a more regular role in diets, with families consuming an average of 5.3 whole chickens per month (averaging 0.22 kg per capita serving size per meal).
• Egg Consumption: Traditional Baladi hens produce roughly 40 to 80 eggs per hen per year under scavenging conditions. Egg consumption is highly localized, serving as a critical, highly accessible protein source for rural children and vulnerable households.

2. Newcastle Disease: A Brief Overview and First Detection

Disease Etiology and Pathogenesis

Newcastle Disease is caused by Avian Orthoavulavirus 1 (AOAV-1), historically classified as Avian Paramyxovirus 1 (APMV-1). It is a negative-sense, single-stranded RNA virus belonging to the family Paramyxoviridae. The virus is categorized into three pathotypes depending on virulence in chickens:

1. Lentogenic: Low virulence, causing subclinical or mild respiratory infections (often used as live vaccine platforms).
2. Mesogenic: Moderate virulence, presenting with respiratory and nervous signs.
3. Velogenic: High virulence, causing rapid, systemic, and fatal disease. Velogenic strains are further divided into viscerotropic (causing severe intestinal hemorrhages) and neurotropic (causing neurological damage, tremors, and torticollis).

First Detection in Sudan

The formal history of ND in Sudan began in 1951, when the virus was first officially reported in poultry flocks in Khartoum. Since this initial detection, the disease has become highly endemic across all states, causing massive recurring mortalities. In the commercial sector, historical outbreaks have caused devastating losses—averaging up to 70% mortality in chicks, 98% in growers, and 62% in adult layers—highlighting its catastrophic economic impact.

3. Most Prevalent Genotypes and Recent Outbreaks

The molecular epidemiology of NDV in Sudan has evolved significantly over the decades. Phylogenetic analysis of the fusion (F) protein gene has revealed a diverse co-circulation of different genotypes:

Key Circulating Genotypes

• Genotype II (Class II): Includes low-virulence lentogenic strains (such as Dongola 88/1), which are frequently isolated from apparently healthy chickens, reflecting the persistence of vaccine-like strains in the environment.
• Genotype VI: Specifically subgenotype VIb (e.g., TY-1/90 and DIK-90), which represents pigeon paramyxovirus type 1 (PPMV-1). This subgenotype is regularly identified in wild and domestic pigeons in Sudan, occasionally spilling over into chicken flocks.
• Genotype V (Subgenotype 5d): For a long period, genotype 5d was the primary driver of major outbreaks in Sudan. Comprehensive phylogenetic analysis of isolates collected during the devastating outbreaks of 2003–2006 proved that genotype 5d (originating from East Asia/Middle East) was highly prevalent, characterized by the virulent F0 cleavage site motif 112-RRQKRF-117.
• Genotype VII (Subgenotype VII.1.1): In recent years, sub-genotype VII.1.1 (previously designated as VIId or VII.1) has emerged as the dominant and most destructive velogenic strain circulating across East Africa, including Sudan, Ethiopia, and Eritrea. Genotype VII.1.1 is highly velogenic, causing severe lymphoid depletion, hemorrhagic lesions, and near-100% mortality. Alarmingly, genotype VII strains have been frequently isolated from fully vaccinated flocks, signaling a high level of viral shedding and potential antigenic divergence from classic vaccine strains.

Recent Outbreak Context

While systematic surveillance has been severely crippled by the ongoing national crisis, field reports and regional epidemiological tracking indicate that velogenic Genotype VII.1.1 remains highly active. The combination of collapsed veterinary infrastructure, lack of quarantine controls, and erratic vaccine supplies has fueled localized outbreaks in both backyard and remaining commercial flocks.

4. Control, Recommendations, and Vaccination

Controlling ND in Sudan requires a dual approach tailored to the unique challenges of the traditional backyard sector and modern commercial farms.

Vaccination Strategies

The core defense against ND is a robust vaccination regime:

• Conventional Live Vaccines: Strains such as LaSota and HB1 (Genotype II) are widely used for mass priming. However, because LaSota is highly sensitive to heat, its utility in Sudan’s hot climate is restricted to areas with functional cold chains.
• Thermostable Vaccines (I-2 Strain): To protect the village backyard sector, Sudan’s Central Veterinary Research Laboratory (CVRL) has championed the production and distribution of the thermostable ND I-2 vaccine. This vaccine remains active at high ambient temperatures (up to 56°C for 30 minutes) and can be easily administered via eye drops, drinking water, or mixed with local grains, making it the gold standard for rural poultry defense.
• Inactivated and Genotype-Matched Vaccines: In intensive setups, priming with a live vaccine is followed by an injection of an inactivated oil-emulsion vaccine. To combat the dominant Genotype VII.1.1, incorporating genotype-matched (Genotype VII) inactivated vaccines is highly recommended. Studies show that while classic Genotype II vaccines protect against mortality, genotype-matched vaccines are far superior at reducing viral shedding and maintaining egg production during field challenges.

Strategic Recommendations

1. Strengthen the Rural Cold Chain Bypass: Expand the local production and training of farmers on the thermostable I-2 vaccine to safeguard village flocks, which currently represent a vital food security net.
2. Adopt Genotype VII-Matched Regimens: Commercial operations must upgrade their biosecurity and shift toward vaccines containing Genotype VII antigens to suppress the active transmission and shedding of velogenic VII.1.1 field strains.
3. Enhance Community-Based Surveillance: Establish localized, community-led veterinary reporting networks to detect outbreaks early, allowing for rapid ring vaccination even in volatile regions.
4. Rebuild Diagnostic Capabilities: Re-equip regional veterinary laboratories with PCR and sequencing tools to continuously monitor genetic drift and detect the introduction of new genotypes.

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