A study on incidence of Marek's disease (visceral- nerves and integument) in broiler flocks of Tehran province.
2006
Habl Ol- Varid, Mohammad Hassan | Gholami, Mohammad Reza | Marandi, Vasfi | Momayyez, Reza | Boka`i, Sa`id | A`rabestani, Hossein | Taleb Lu, Fatemeh
Marek's disease (MD) is a common lymphoproliferative disease of chickens, usually characterized by mononuclear cellular infiltration in peripheral nerves, and various other organs and tissues including iris and skin. The disease is caused by a herpes virus and is transmissible. Prior to use of vaccines, MD constituted a serious economic threat to the poultry industry causing up to 60% mortality in layer flocks and 10% condemnation in broiler flocks. MD has been a common, important problem for poultry industry in our country, Iran. The objective of present study was to determine the incidence of MD (visceral – nerves and skin forms) in broiler's flocks of some selected regions in Tehran province (Savojbolagh- Karaj- Shahriar and Varomin). This was implemented by 35 times visiting of some poultry slaughter houses, in Tehran province, and sampling of different tissues of slaughtered chickens (from 80 broiler's flocks that reared in Tehran province). Tissue samples were processed to prepare histological slides. Based on gross and microscopic examinations, the incidence of MD in mentioned regions of Tehran province revealed that 24 out of 80 flocks (30%) have been infected to different forms of the disease. This data indicated that MD has a relatively high occurrence in broiler's flocks of the four regions in Tehran province. Varamin and Karj with 66.7% and 16.2% were the highest and lowest infected regions in Tehran province, respectively. The rate of incidence of cutaneous, visceral and mixed cutaneous and skin forms in these regions (four regions) was determined as 16.2%, 3.8% and 10%, respectively. Thus, based on these resultsthe cutaneous form of MD is the commonest form of the disease in the four regions of Tehran province. No cases of nerve and ocular forms were seen in this study.
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