Occurrence of infectious laringotracheitis on farms in Vojvodina

Abstract

For over 10 years infectious laringotracheitis has occurred rarely in Vojvodina. In such situations morbidity was 40% and mortality was 16%. Drop in egg production was over 30% and after 4 weeks egg production returned to normal. After the disappearance of clinical symptoms and after 30 days of quarantine and disinfection of eggs with formaldehyde and 5% hydrogen peroxide there was no appearance of the disease in hatched chickens. Clinical observation and pathohistology results are valuable proof for diagnosis of ILT. Diagnosis of ILT should be confirmed by virus isolation or applying serological tests such as ELISA on sera from diseased chickens

Diagnosis of Infectious Laryngotracheitis Outbreaks on Layer Hen and Broiler Breeder Farms in Vojvodina, Serbia

“…In the broiler breeder flock, the decrease in egg laying was 2.7%, but in this flock, the mortality rate was also lower (0.8%), as well as the duration of the disease. According to the results from a study previously published of Orlić et al (2003), the percentage of mortality in infected breeder flocks was 16%, while the decrease in egg-laying capacity was 30% [ 15 ], which was a higher percentage compared to the data obtained in our study. We assumed that such a small percentage of egg laying, low mortality and shorter duration of symptoms on Farm VI were the result of vaccination that prevented the spread of field virus in the flock from infected to healthy individuals and prevented replication of field virus in the trachea.…”

“…It is present in regions with developed poultry farming, and it most commonly appears on industrial farms and also in poultry raised in extensive conditions [ 4 , 17 ]. The last time this disease was recorded on the territory of the Republic of Serbia was almost two decades ago when Orlić and associates (2003) recorded it in three broiler breeder flocks [ 15 ]. In April 2020, the ILT infection appeared on the laying hen farm, and after that, it spread to four more laying hen farms and one farm of broiler breeders.…”

“…In our study, the increase in mortality was accompanied by a decrease in egg laying; it fell by 2.7–42.0%, depending on the age of the flock and the condition. Most authors describe the clinical picture with respiratory symptoms, high morbidity and variable mortality, with a significant decrease in egg laying [ 8 , 15 , 24 ]. In our research, the egg-laying capacity of flocks fell by 15% at the beginning of the production period, while egg laying fell by 42% in the middle of the production cycle.…”

“…In the territory of Serbia, the last reported case of ILT was almost two decades ago on the farms of broiler breeder flocks [ 15 ]. There is no data on the appearance of the ILT virus before this period.…”