Questions and Answers
What is the primary mode of transmission of vND among animals?
Direct contact with feces, respiratory secretions, and indirect contact through contaminated feed, water, equipment, and human clothing.
Why is it challenging to assess the true geographical distribution of vND?
Vaccine use makes it difficult to assess the true geographical distribution of vND.
What is the significance of morbidly and mortality rates in understanding vND epidemiology?
Morbidity rates can be up to 100%, and mortality rates can be as high as 90%, varying greatly depending on factors such as virulence, avian species, environmental conditions, and vaccination history.
What is the role of migratory birds and feral pigeons in vND transmission?
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Why is it essential to avoid contact with avian species for individuals at high risk of vND transmission?
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What is the significance of the incubation period in vND epidemiology?
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What is the role of contaminated or incompletely inactivated vaccines in vND transmission?
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Why is biosecurity crucial for preventing vND transmission?
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What is the significance of vaccination programs in controlling vND outbreaks?
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What is the characteristic of vND that makes it a significant human health concern?
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Study Notes
Postmortem Lesions
- Acute focal lymphoid necrosis in the duodenum and hemorrhage in the small intestine
- Focal ulceration and hemorrhage in the small intestine
- Haemorrhagic lesions along the entire length of the intestine
- Ulcers with fibrin accumulation in the mucosa of the cloaca
- Enlarged spleen with numerous white lesions
- Odema and hemorrhages in the mucosa of Fabricius
- Severe acute hemorrhages and congestion in the ovarian follicles
Differential Diagnosis
- Highly pathogenic avian influenza
- Mycoplasmosis
- Infectious bronchitis
- Fowl cholera
- Laryngotracheitis
- Coryza
- Fowl pox (diphtheritic form)
Clinical Diagnosis
- Sudden decrease in egg production
- High morbidity and mortality
- Characteristic signs and gross lesions
Laboratory Diagnosis
- Virus isolation
- RT-PCR
- Serology
- Samples should only be sent under secure conditions and to authorized laboratories
Diagnostic Samples
- Tracheal swabs
- Cloacal swabs
- Faecal swabs
- Serum
Pathogenesis
- The virus replicates in the mucosa of the upper respiratory and intestinal tracts
- Virus spreads via blood to spleen and bone marrow causing infection of other organs
Clinical Signs
- Drop in egg production
- Numerous deaths within 24 to 48 hours
- Deaths continue for 7 to 10 days
- Surviving birds may have neurological or reproductive damage
- Edema of head, especially around eyes
- Greenish, dark watery diarrhea
- Respiratory and neurological signs
- Twisting and circling of head and neck (Torticollis)
- Square appearance of the head due to bilateral facial edema
Postmortem Lesions
- Edema of head, neck, and face
- Edema, hemorrhage, necrosis or ulceration of lymphoid tissue
- Hemorrhagic lesions in tracheal mucosa, proventriculus, and intestinal mucosa
- Subconjunctival hemorrhages with external lesions
- Odema and hemorrhages in the conjunctiva and infraorbital sinus
- Congestion and hemorrhages in the pharynx and proximal trachea
- Inflammation with pinpoint hemorrhagic lesions in the proventriculus mucosa
- Necrosis of lymphoid tissue at the caecal lymph node
- Extensive hemorrhages and ulcers of caecal tonsils mucosa
Epidemiology
- Endemic in Asia, the Middle East, Africa, Central and South America
- Vaccine use makes assessment of true geographical distribution difficult
- International monitoring by FAO and OIE
- Enzootic: Endemic in animals
- Zoonotic: a disease that normally exists in animals but can infect humans
Morbidity/Mortality
- Morbidity: up to 100%
- Mortality: 90%
- Varies greatly depending on virulence and strain, avian species and susceptibility of host, environmental conditions, and vaccination history
Transmission
- Direct contact with feces, respiratory secretions
- Indirect contact through feed, water, equipment, and human clothing
- Contaminated or incompletely inactivated vaccines
- Survives for long periods in the environment
- Incubation period: 2 to 15 days, average of 5 to 6 days
- Migratory birds, feral pigeons, and contaminated poultry feed
Human Transmission
- Mild conjunctivitis through virus shed in ocular secretions
- Lab workers and vaccination crews most at risk
- No cases from handling or consuming poultry products
- No human-to-human spread
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Description
This quiz covers various postmortem lesions found in the intestine, spleen, and other organs, including haemorrhages, ulcers, and congestion.
