Late last week, health officials with the Centers for Disease Control and Prevention (CDC) and the Missouri Department of Health and Senior Services (DHSS) announced the first human H5 avian flu case in a patient with no known connection to infected animals.
The alarming development hints at possible human transmission or from an unknown source, as health officials await further tests to determine the neuraminidase—the "N" of H5N1 and other flu strains—and clues from attempts to sequence the virus.
In a September 6 statement, the CDC said it has confirmed a finding from Missouri that surfaced during routine surveillance. Shortly before, the DHSS said the sample that tested positive for H5 at the state lab was from a patient who was hospitalized on August 22. The patient is an adult with underlying conditions who has since recovered.
First US case without occupational exposure
The case is the fourteenth human H5 case of the year and the first in a patient who didn't have known occupational exposure to sick animals.
Missouri hasn't reported any cattle outbreaks. According to University of Missouri Extension, the state is the nation's 26th-largest milk producer, with dairy production concentrated in the southwest and south central parts of the state. Missouri has reported sporadic avian flu outbreaks in poultry, but not since February. The virus has also been found several times in wild birds in the state, but none of the latest notifications had recent sample collection dates.
The CDC said its surveillance hasn’t found any unusual sign of flu activity in the United States, including in Missouri.
Health officials are eager to see if sequencing sheds light on whether the virus is linked to the B3.13 genotype circulating in cows, if there are links to other human cases, or if there are ties to other animals, which could include birds or even cats, mice, or other wildlife.
Experts are also looking at the possibility of exposure to raw milk. Raw milk sales are legal in Missouri, but only directly from farms to consumers.
The CDC said the main priority is to see if any ongoing transmission is occurring, but for now, the risk to the public remains low. "Findings from the ongoing investigation will inform whether guidance changes are needed," it said.
H5N1 strikes cows in another Michigan county
In other avian flu developments, the Michigan Department of Agriculture and Rural Development (MDARD) today announced an H5N1 outbreak at a dairy farm in Shiawassee County, which is about 35 miles northwest of Lansing.
The outbreak brings Michigan's total to 29 affected dairy herds in 12 counties. In a statement, MDARD said the samples, which were positive at the Michigan State University Veterinary Diagnostic Laboratory, will be sent to the US Department of Agriculture (USDA) National Veterinary Services Laboratory for confirmation testing.
The USDA has confirmed 197 outbreaks in 14 states.
