Vet World   Vol.14   November-2021  Article-24

Occurrence of Marek's disease in vaccinated Algerian broiler breeder flocks: A histopathological survey

Background and Aim: Marek's disease (MD) is a lymphoproliferative disease that occurs in chickens. In the absence of control measures, MD causes devastating losses to commercial poultry flocks. Vaccination has enabled dramatic success in the prevention and control of MD. However, the MD vaccination program has failed frequently, and occasional clinical outbreaks have been reported in the vaccinated flocks as well. The present study aimed to describe the clinical and histopathological characteristics of the field cases of MD in broiler breeder flocks.

Materials and Methods: A survey on the update of MD occurrence in Algerian broiler breeder flocks was conducted from June 2020 to September 2020. Ten vaccinated broiler breeder flocks located in Central Algeria and having progressive tumors in different visceral organs were evaluated for MD virus infection by conducting a histopathological examination of the birds.

Results: The age of the birds affected with MD ranged from 13 to 22 weeks. The mortality rate varied sensitively from 4% to 10%. The clinical symptoms reported in the affected flocks included locomotor, nervous, digestive, and respiratory symptoms. Necropsy of the dead or euthanized birds revealed visceral lymphomatosis in several organs and macroscopic changes in the peripheral nerves (including loss of longitudinal striation, color change [grayish], and volume increase). The histopathological findings included the infiltration and proliferation of lymphocytes and blast cells (lymphoblasts) in various organs of the birds, which are the typical characteristics of MD and, therefore, confirmed the field infection of MD in these birds.

Conclusion: The present study provided evidence for the high prevalence of MD in the broiler breeder flocks vaccinated with a bivalent vaccine (turkey herpesvirus+Rispens) at the hatchery. The findings of the present study may indicate highlevel failure of vaccination in these birds. Keywords: Algeria, broiler breeder flocks, histopathological findings, Marek's disease, Tumors.

Keywords: Algeria, broiler breeder flocks, histopathological findings, Marek's disease, Tumors.

How to cite this article: Lounas A, Besbaci M, Akkou M, Tali O (2021) Occurrence of Marek's disease in vaccinated Algerian broiler breeder flocks: A histopathological survey, Veterinary World, 14(11): 3021-3027.

Received: 19-08-2021  Accepted: 27-10-2021     Published online: 28-11-2021

Corresponding author: Lounas Abdelaziz   E-mail: azizovet@yahoo.fr

DOI: 10.14202/vetworld.2021.3021-3027

Copyright: Lounas, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.