Avian flu kills more than 61 million birds, but CDC still sees only a slight threat to humans

After a summer pause, the highly pathogenic avian influenza (HPAI) epidemic in the United States resumed last month, first as a single event, then as a cluster of cases, and it is now spreading across at least 14 states.

The new outbreak cases first took the dead bird total to over 60 million, then the new spike went to over 61 million, and it continues to grow. It now includes a commercial table egg layer operation that counts its loses at 940,000 birds in Wright County, MN.  The virus last hit a commercial egg facility in Weld County, CO, on Dec. 20, 2022.

Commercial turkey operations have been prominent among the new outbreaks.

Since the summer pause, HPAI was detected in 25 commercial flocks in October and at least six more already in November. Detections were reported in 19 backyard flocks in October and four more in November.

Commercial and backyard flocks must be kept from contact with wild birds to stem the HPAI spread. State and federal officials ask that they be immediately notified whenever birds are sick or experiencing unusual deaths

The federal Centers for Disease Control and Prevention recently updated its HPAI epidemic, saying  the “viruses are currently circulating widely in wild birds and poultry in many geographic regions, relatively few human cases of A(H5N1) have been reported in recent years 

“From January 2022 through Oct. 24, 2023, seventeen sporadic human cases of A(H5N1) were reported from eight countries, including eight cases of severe disease and four deaths, two cases of mild illness, and seven asymptomatic cases.”

CDC said only one case of the A(H5N1) virus was reported in the U.S. in April 2022.

“The individual reported fatigue without other symptoms, and a low level of A(H5N1) viral RNA was detected in a single upper respiratory tract specimen, according to CDC.  “It is possible that detection of A(H5N1) viral RNA resulted from deposition of non-infectious viral material in the upper respiratory tract of the individual and did not represent true infection, similar to the environmental contamination that was attributed to the two asymptomatic cases in poultry workers reported in Spain. Transient environmental deposition may also explain the detection of A(H5N1) viral RNA in cases of A(H5N1) reported in asymptomatic poultry workers in the U.K. that were investigated as part of a surveillance study.” 

The CDC also reports that “nearly all reported cases reported since January 2022 had recent exposure to sick or dead poultry, and no cases of human-to-human HPAI A(H5N1) virus transmission were identified. Eight cases (four children four adults) had severe disease, and four died. 

“Twelve cases were associated with clade 2.3.4.4b HPAI A(H5N1) viruses, and four cases were associated with clade 2.3.2.1c HPAI A(H5N1) viruses; none of the HPAI A(H5N1) virus genetic sequences contained any known markers of reduced susceptibility to currently recommended FDA-approved influenza antiviral medications.”

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