Indicators and risk factors of infectious laryngotracheitis in layer hen flocks in Algeria.

BACKGROUND AND AIM: Since 2017, there have been epidemics with respiratory disorders in the laying hen farms in Algeria, as signs and lesions, respiratory difficulties, and hemorrhagic tracheitis, which closely like laryngotracheitis. This study aimed to analyze the epidemiological, serological, and clinical indicators, as well as the risk factors, of infectious laryngotracheitis (ILT) in layer hen flocks in Algeria. MATERIALS AND METHODS: A total of 1728 layer hens were sampled randomly from 48 poultry houses. Blood samples were collected from each hen at the wing vein area, and an indirect enzyme-linked immunosorbent assay was done using an IDvet® kit. RESULTS: The flocks showed 56.25% seroprevalence. Clinical signs and gross lesions of ILT suspect cases included respiratory signs characterized by hemorrhagic tracheitis and sinusitis; conjunctivitis; egg drop; and a low mortality rate varying from 5% to 20%. Statistical analyses showed the effect of risk factors on the seropositivity for ILT in 48 layer flocks. When the vaccination was not applied, flocks were significantly more seropositive by 54% (odds ratio OR=1.54, p=0.01) compared to vaccinated flocks. Furthermore, flocks with poor hygiene were more seropositive by 68% (OR=1.68, p=0.002) compared to those with good hygiene. Finally, flocks with decreased egg production between 10% and 30% were significantly more seropositive by 42% (OR=1.42, p=0.04) than those with egg production >30%. CONCLUSION: The serological survey revealed anti-ILT virus antibodies, signifying the circulation of this virus in layer hen farms in Algeria. Correct vaccination protocol, strict biosecurity measures, rapid diagnosis, and detection of latent carriers are necessary to control and eradicate the disease from layer farms.

Serological, clinical, and risk factors of the Newcastle disease on broilers flocks in Algeria.

AIM: The work aimed at studying the serological and clinical factors, as well as the risk factors of the Newcastle disease (ND) on broilers herds in Algeria. MATERIALS AND METHODS: A sample of 1248 birds was randomly selected from 52 broiler flocks. We took blood samples from each bird at the level of the wing vein area where an indirect enzyme-linked immunosorbent assay technique was carried out through the use of an IDvet kit. RESULTS: The flocks showed 82.69% of seroprevalence. Clinically speaking, the most common symptoms were sneezing, rale, greenish diarrhea, torticollis, and motor discords. Most commonly observed postmortem lesions were the proventriculitis, tracheitis, and enteritis. Especially, the caeca are hemorrhagic. The scores show the effect of risk factors. There was a significant effect on the mortality, the hygiene and vaccination groups on antibody titers in time 2. The antibody titers were elevated in the herd that recorded a high mortality (more than 10%) compared with those which recorded a low mortality (<10%) (p=0.002). Therefore, the antibody titers were elevated in herds with bad hygiene, compared with the ones with good hygiene (p=0.04). At last, when broiler chicken were not boosted by ND vaccine, flocks appeared to be more seropositive (p=0.02). CONCLUSION: The serological survey conducted in this study provided an important scope for ND as a dominant viral disease in broilers. Many factors are responsible for the onset of these diseases; correct biosecurity measures are needed to reduce the impact of this pathology in poultry farms.