Outbreak and management of Marek's disease in 16 weeks old pullets in Nigeria: a case report

Abstract

Marek's disease (MD) remains a major concern to chicken farmers, especially because of its adverse effect on birds' growth, livability, and egg production. Veterinarians often consider the prognosis poor, especially when tumors are seen in organs like the liver, spleen, and lungs. This is a report of an outbreak of acute MD in commercial chickens. In the present study, carcasses of 16 weeks old Isa brown pullets were presented at the Veterinary Teaching Hospital, the University of Jos for investigation. They had been vaccinated at the hatchery against Marek's disease at day old. The disease was diagnosed as Marek's disease based on mortality pattern, necropsy findings, histological observations, and polymerase chain reaction analysis. Secondary bacterial infection was caused by Staphylococcus aureus, susceptible to gentamicin. The affected flock was revaccinated using Izovac® HVT Marek's vaccine. As a follow-up, a gentamicin-doxycycline-based oral preparation: Doxygen®, was administered for five consecutive days at 100g/200 litres of drinking water. A significant reduction in mortality was observed within two weeks of the commencement of treatment. Owing to the slow spreading/killing nature of Marek's disease (unlike Gumboro disease), its early detection and management via revaccination and treating secondary bacterial infection can significantly reduce losses.