Disentangling the role of wild birds in avian metapneumovirus (aMPV) epidemiology: A systematic review and meta-analysis

Abstract

Given the avian metapneumovirus (aMPV) disease burden in poultry worldwide and the evidence of a possible role played by wild birds in the virus epidemiology, the present study summarizes aMPV serological and molecular data on free-ranging avifauna available in the literature by conducting a systematic review and meta-analysis. A computerized literature research was performed on PubMed, Scopus, CAB Direct and Web of Science to identify relevant publications across the period 1990-2021, along with the screening of reference lists. A random-effect model was applied to calculate pooled prevalence estimates with 95% confidence intervals. The inconsistency index statistic (I² ) was applied to assess between-study heterogeneity. Subgroup analyses for molecular studies only were performed according to geographical area of samplings, taxonomic order, genus and migration patterns of the birds surveyed. A total of 11 publications on molecular surveys and 6 on serological ones were retained for analysis. The pooled molecular prevalence was 6% (95% CI: 1-13%) and a high between-study heterogeneity was detected (I² = 96%, p < .01). Moderator analyses showed statistically significant differences according to geographical area studied, taxonomic order and genus. Concerning serological prevalence, a pooled estimate of 14% (95% CI: 1-39%), along with a high between-study heterogeneity, was obtained (I² = 98%, p < .01). Moderator analysis was not performed due to the scarcity of eligible serological studies included. Overall, molecular and serological evidence suggests that some wild bird taxa could play a role in aMPV epidemiology. Particularly, wild ducks, geese, gulls and pheasants, according to scientific contributions hereby considered, proved to be susceptible to aMPV, and due to host ecology, may act as a viral carrier or reservoir. Further surveys of wild birds are encouraged for a better comprehension of the poultry/wild bird interface in aMPV epidemiology and for better characterizing the virus host breadth.

Keywords: avian metapneumovirus; meta-analysis; seroprevalence; systematic review; viroprevalence; wild birds.

FIGURE 1

Flow diagram of the selection process of molecular studies on aMPV in free‐living wild birds, identified via databases and reference list reading

FIGURE 2

Word cloud showing the sample size of wild bird species molecularly tested for aMPV. Data are ordered from low to high, with light colours and a smaller font size for lower number of studies on a species, darker colour and bigger font size for higher number of studies

FIGURE 3

Flow diagram of the selection process of serological studies on aMPV in free‐living wild birds, identified via databases and reference list reading

FIGURE 4

Word cloud showing the sample size of wild bird species serologically tested for aMPV. Data are ordered from low to high, with light colours and a smaller font size for lower number of studies on a species, darker colour and bigger font size for higher number of studies

FIGURE 5

Forest plot of the random‐effects meta‐analysis of aMPV molecular prevalence. I ² (inverse variance index), τ² = the between‐study variance, χ² and p value of the Cochran's Q test for heterogeneity

FIGURE 6

Forest plot of the random‐effects meta‐analysis of aMPV serological prevalence. I ² (inverse variance index), τ² = the between‐study variance, χ² and p value of the Cochran's Q test for heterogeneity