Epidemiology of porcine epidemic diarrhea virus among Chinese pig populations: A meta-analysis

Porcine epidemic diarrhea results from infection with porcine epidemic diarrhea virus (PEDV). It is an acute and highly contagious enteric disease in swine characterized by watery diarrhea and vomiting. Here, we performed a systematic review and meta-analysis in order to assess the prevalence of PEDV infection in pig populations from mainland China. We conducted a literature search on the prevalence of PEDV infection in pigs between Jan 1, 1988 and Aug 20, 2018 in English and Chinese databases, including PubMed, Google scholar, Cochrane library, Clinical Trials, VIP, CNKI and WanFang database. Selections were made based on the title and the abstract of paper, and duplicated literature was excluded along with other host studies, and data incomplete literature according to the exclusion criteria we formulated. Finally, we extracted the number of swine with PEDV infection from the obtained studies and provided information that permitted us to estimate the prevalence of PEDV infection in pigs in mainland China. A total of 45 studies (including data from 15,990 pigs) met our evaluation criteria. In China, the overall estimated prevalence of PEDV infection in pigs was 44% (7113/15,990), while the estimated prevalence of PEDV infection in pigs from northern China was 37% (793/2136), lower than those in other regions of China. The prevalence of PEDV infection was associated with sampling season, category of pigs and clinical signs (diarrhea) in pigs. However, the prevalence of PEDV among pigs in China was not significantly associated with the effect of detected target genes, nor was it associated with date of study publication. Our findings suggest that PEDV infection is common among pigs in China. It is therefore necessary to carry out further research and monitor the prevalence of PEDV infection. Furthermore, powerful and effective regulatory measures should be taken in order to prevent the transmission and spread of PEDV among pig populations.