diff --git a/ers/filecsv.go b/ers/filecsv.go
index 4098e6273..6b7fcf986 100644
--- a/ers/filecsv.go
+++ b/ers/filecsv.go
@@ -97,6 +97,11 @@ func (rdr *CSVFileER) Serve() (err error) {
 	case time.Duration(0): // 0 disables the automatic read, maybe done per API
 		return
 	case time.Duration(-1):
+
+		// Ensure that files already existing in the source path are processed
+		// before the reader starts listening for filesystem change events.
+		processReaderDir(rdr.sourceDir, utils.CSVSuffix, rdr.processFile)
+
 		return utils.WatchDir(rdr.sourceDir, rdr.processFile,
 			utils.ERs, rdr.rdrExit)
 	default:
diff --git a/ers/filefwv.go b/ers/filefwv.go
index 27cb2a281..c58e1ddcd 100644
--- a/ers/filefwv.go
+++ b/ers/filefwv.go
@@ -106,6 +106,11 @@ func (rdr *FWVFileER) Serve() (err error) {
 	case time.Duration(0): // 0 disables the automatic read, maybe done per API
 		return
 	case time.Duration(-1):
+
+		// Ensure that files already existing in the source path are processed
+		// before the reader starts listening for filesystem change events.
+		processReaderDir(rdr.sourceDir, utils.FWVSuffix, rdr.processFile)
+
 		return utils.WatchDir(rdr.sourceDir, rdr.processFile,
 			utils.ERs, rdr.rdrExit)
 	default:
diff --git a/ers/filejson.go b/ers/filejson.go
index d81bbf548..fed968c88 100644
--- a/ers/filejson.go
+++ b/ers/filejson.go
@@ -100,6 +100,11 @@ func (rdr *JSONFileER) Serve() (err error) {
 	case time.Duration(0): // 0 disables the automatic read, maybe done per API
 		return
 	case time.Duration(-1):
+
+		// Ensure that files already existing in the source path are processed
+		// before the reader starts listening for filesystem change events.
+		processReaderDir(rdr.sourceDir, utils.JSNSuffix, rdr.processFile)
+
 		return utils.WatchDir(rdr.sourceDir, rdr.processFile,
 			utils.ERs, rdr.rdrExit)
 	default:
diff --git a/ers/filexml.go b/ers/filexml.go
index 9c7514a52..df3e4ea97 100644
--- a/ers/filexml.go
+++ b/ers/filexml.go
@@ -82,6 +82,11 @@ func (rdr *XMLFileER) Serve() (err error) {
 	case time.Duration(0): // 0 disables the automatic read, maybe done per API
 		return
 	case time.Duration(-1):
+
+		// Ensure that files already existing in the source path are processed
+		// before the reader starts listening for filesystem change events.
+		processReaderDir(rdr.sourceDir, utils.XMLSuffix, rdr.processFile)
+
 		return utils.WatchDir(rdr.sourceDir, rdr.processFile,
 			utils.ERs, rdr.rdrExit)
 	default: