Detection of Laryngotracheitis Virus in Poultry Flocks with Respiratory Disorders in Slovenia

Abstract

Infectious laryngotracheitis (ILT) is an acute, highly contagious infectious disease of the upper respiratory tract in chickens and other poultry species that causes significant economic losses in countries worldwide. Between 2017 and 2019, seven outbreaks of mild to severe respiratory disorders with high suspicion of ILT occurred in commercial and backyard poultry flocks in Slovenia. In all submissions, infection with ILT virus (ILTV) was confirmed by PCR, which is the first report of ILT in Slovenia. Circulating ILT strains were characterized by the sequence and phylogenetic analysis of two fragments of the ICP4 gene. Four strains—three detected in non-vaccinated flocks and one in a flock vaccinated against ILT—were identical or very similar to the chicken embryo–origin live virus vaccines, and the other three were closely related to Russian, Chinese, Australian, and American field strains and to tissue culture origin vaccine strains. As in other diseases, coinfections with other respiratory pathogens in confirmed ILT cases may cause a more severe condition and prolong the course of the disease. In our study, coinfections with Mycoplasma synoviae (7/7 tested flocks), infectious bronchitis virus (5/5 tested flocks), Mycoplasma gallisepticum (4/7 tested flocks), Ornithobacterium rhinotracheale (3/4 tested flocks), and avian pox virus (1/2 tested flocks) were confirmed, indicating the importance of these pathogens in the occurrence of ILT infections.

Questionnaire study suggests grave consequences of infectious laryngotracheitis, infectious coryza and mycoplasmosis in small chicken flocks

“…1 ) suggest that these infections are geographically widespread in Sweden. Several earlier studies from other countries suggest that respiratory infections are common in SCF both in Europe [ 2 , 23 ] and North America [ 3 , 4 , 12 ]. In Finland, a neighbouring country to Sweden, 12% of 51 backyard chicken flocks were seropositive for ILTV [ 24 ].…”

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

“…ILT is a contagious disease of poultry and is spread all over the world. 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 ].…”

“…The diseased flocks were not vaccinated against ILT. In the countries of our region, outbreaks of this disease have been reported in two flocks of commercial layers in North Macedonia [ 18 ], in commercial and backyard poultry flocks in Slovenia [ 17 ] and in an organic broiler farm and surrounding flocks in Greece [ 19 ].…”

“…The clinical picture of the disease in many cases does not include the acute signs (nasal discharge, lacrimation, moist rales, expectoration of blood, etc. ), which may be a feature of a virus of low pathogenicity [ 17 ] or reflect immunity stimulation by vaccination. In our case, the disease was first noticed in the last third of the building, in the last cages.…”

“…Our results showed that the highest mortality (31.5%) was in the flock that was the oldest and had coinfection with A. paragallinarum , while the highest decrease in egg laying (42.0%) and decrease in feed consumption (40.0%) were in the flocks that did not have coinfection with A. paragallinarum ( Table 1 ). Coinfections can cause increased mortality, as shown by the results of Tamilmaran et al (2020) [ 23 ] and Zorman Rojs et al (2021) [ 17 ].…”