Infectious bursal disease (also known as Gumboro disease) is a highly contagious viral disease caused by a small, hardy Avibirnavirus belonging to the family Birnaviridae which causes significant economic losses due to mortality, reduced performance and immuno-supression that lead to increased susceptibility to other diseases. The virus is resistant to a wide range of temperatures and pH, although can be removed by most disinfectants. It is rapidly spread by direct contact between birds and can survi-ve for extended periods of time on inanimate objects, contaminated feed, etc. Currently, the disease has a worldwide prevalence and therefore it is not completely controlled. It is essential to know its main features to minimize the great economic impact which repre-sents for poultry farming. Thus, as veterinary surgeons have to face with this condition in their daily work, this hand-book performs a thorough review where the authors, highly qualified and experienced in dealing with this disease, supply visual resources (images, tables, flowcharts, etc.) accompanied by short pieces of text to describe the topic in an understandable and simple way. Therefore, the information included in this handbook helps the veterinarians to get an overview of the topic so as to tackle it successfully day after day.

Authors:

Emmanuel Baraza Sasita

BSc, MSc, PhD (currently involved).

Bachelor of Science in Biomedical Laboratory Technology and MSc in Molecular Biology and Biotechnology both from the Faculty of Veterinary Medicine of Makerere University. Currently, he is pursuing his PhD in virology. He has done recently a publication related to the prevalence of infectious bursal disease in local chickens around Kampala (Uganda). Besides, he works as academic writer, editor and reviewer. He works for academiaresearch based in USA as well as all writers based in UK. He reviews manuscripts with Microbiology Research International (www.netjournals.org). Currently, he is working in a project about contagious caprine pleuropneumonia at International Livestock Research Institute.

William Olaho-Mukani

BVM, MSc, PhD.

EAC Regional Veterinary Governance Project Coordinator for the African Union. Member of the Editorial Board of the African Journal of Animal and Biomedical Sciences, Journal of Camel Practice and Research, the Bulletin of Animal Health and Production.

Sabenzia Nabalayo Wekesa

BVM, MSc, PhD.

Researcher and Senior Assistant Director of Veterinary Services (SADVS) in the ministry of Agriculture in Kenya, based at the National Foot and Mouth Disease (FMD) laboratory, Embakasi (Nairobi).

Romona Ndanyi

BVM, MSc.

Researcher at the Kabete Veterinary Research Laboratories, Kangemi (Nairobi).

Messo Watson

BVM, MSc.

Working in a fully integrated poultry company in East and Central Africa.

Table of contents:

1. Aetiology

Overview

IBD virus (IBDV)

Classification

Viral protein structure and function

IBDV particle

Genome

Gene expression

Replication

2. Importance

History

Current status in the world

Economic significance

Poultry production and its contributions

Effects on poultry

Impact on food security

How IBDV causes disease and death

3. Epidemiology

Distribution and persistence

Geographical distribution

Serological survey

IBD status

New epidemiological situation

Morbidity and mortality

Characteristics in the environment

4. Pathology

Type of birds at risk

Transmission

Incubation period

Pathogenesis

Potential risk of spread through trade

5. Clinical signs

Factors influencing disease severity

Clinical signs associated with acute disease

Classical form

Immunosuppressive form

Acute form

What next after subclinical infection

Relationship between clinical signs and diagnosis

6. Diagnosis and treatment

Clinical and differential diagnosis

Histological diagnosis

Post-mortem examination

Serological diagnosis

Molecular identification and characterization

Sampling

7. Prevention and control

Disinfection

Vaccination

Vaccination programmes

Routes of vaccine administration

Categories of IBD vaccines

Advices for vaccinating chickens

8. Actions to take

Measures taken to reduce morbidity and

mortality during an outbreak

Recommended actions after an outbreak

9. References