California health officials reported Tuesday that a child in Alameda County tested positive for H5 bird flu last week.
The source of infection is not known — although health officials are looking into possible contact with wild birds — and the child is recovering at home with mild upper respiratory symptoms.
Health officials have confirmed the “H5” part of the virus, not the “N1.” There is no human “H5” flu; it is only associated with birds.
The child was treated with antiviral medication, and the sample was sent to the U.S. Centers for Disease Control and Prevention for confirmatory testing.
The initial test showed low levels of the virus and, according to the state health agency, testing four days later showed no virus.
“The more cases we find that have no known exposure make it difficult to prevent additional” infections, said Jennifer Nuzzo, professor of epidemiology and director of the Brown University School of Public Health’s Pandemic Center. “It worries me greatly that this virus is popping up in more and more places and that we keep being surprised by infections in people whom we wouldn’t think would be at high risk of being exposed to the virus.”
A statement from the California Department of Public Health said that none of the child’s family members have the virus, although they, too, had mild respiratory symptoms. They are also being treated with antiviral medication.
The child attended a day care while displaying symptoms. People the child may have had contact with have been notified and are being offered preventative antiviral medication and testing.
“It’s natural for people to be concerned, and we want to reinforce for parents, caregivers and families that based on the information and data we have, we don’t think the child was infectious — and no human-to-human spread of bird flu has been documented in any country for more than 15 years,” said CDPH Director and State Public Health Officer Dr. Tomás Aragón.
The case comes days after the state health agency announced the discovery of six new bird flu cases, all in dairy workers. The total number of confirmed human cases in California is 27. This new case will bring it to 28, if confirmed. This is the first human case in California that is not associated with the dairy industry.
The total number of confirmed human cases in the U.S., including the Alameda County child, now stands at 54. Thirty-one are associated with dairy industry, 21 with the poultry industry, and now two with unknown sources.
In Canada, a teenager is in critical condition with the disease. The source of that child’s infection is also unknown.
Genetic sequencing of the Canadian teenager’s virus shows mutations that may make it more efficient at moving between people. The Canadian virus is also a variant of H5N1 that has been associated with migrating wild birds, not cattle.
Genetic sequencing of the California child’s virus has not been released, so it is unclear if it is of wild bird origin, or the one moving through the state’s dairy herds.
In addition, WastewaterScan — an infectious disease monitoring network led by researchers from Stanford University and Emory University, with laboratory support from Verily, Alphabet Inc.’s life sciences organization — follows 28 wastewater sites in California. All but six have shown detectable amounts of H5 in the last couple of weeks.
There are no monitoring sites in Alameda Co., but positive hits have been found in several Bay Area wastewater districts, including San Francisco, Redwood City, Sunnyvale, San Jose and Napa.
“This just makes the work of protecting people from this virus and preventing it from mutating to cause a pandemic that much harder,” said Nuzzo.