A meta-analysis for prevalence of infectious laryngotracheitis in chickens in mainland China in 1981-2022.

BACKGROUND: Infectious laryngotracheitis (ILT) is a highly infectious upper respiratory tract disease of chickens caused by infectious laryngotracheitis virus or Gallid herpesvirus 1 (GaHV-1). ILT is an important respiratory disease of chickens and annually causes significant economic losses in the chicken industry. Although numerous relevant studies have been published, the overall prevalence of ILT infection among chicken in mainland China is still unknown, and associated risk factors need to be evaluated to establish preventive measures.

RESULTS: The present study reviewed the literature on the prevalence of ILT in chickens in China as of December 20, 2022, retrieved from six databases-CNKI, Wanfang, VIP, PubMed, Web of Science, and ScienceDirect-were used to retrieve relevant studies published between January 1, 1981 and December 20, 2022. The literature quality of studies was assessed, and 20 studies with a total of 108,587 samples were included in the meta-analysis. Results of the meta-analysis showed that the overall prevalence of ILT was 10% (95% confidence interval: 8 -12%) through the random-effects model, which showed high heterogeneity, I2  = 99.4%. Further subgroup analyses showed that the prevalence of ILT decreased over time; furthermore, the prevalence in Northwest China was slightly lower than that in North China and South China, and the prevalence estimated using the diagnostic technique AGP was higher than that reported using other diagnostic techniques.

CONCLUSIONS: ILT is prevalent to some extent in mainland China. Given that the ILT attenuated live vaccine has a certain level of virulence and the prevalence differences between regions, we recommend controlling breeding density, improving immunization programs and continuously monitoring viruses and to prevent ILT prevailing in mainland China.