Officials in Alameda County on Tuesday identified a child with bird flu who had no known exposure to the state’s growing number of infected dairy and poultry farms.
But close family members of the child, who had mild respiratory symptoms and is recovering at home, were not infected, testing showed. That news eases worry among state health experts that the virus, H5N1, could gain the ability to spread more efficiently among people.
“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 California Department of Public Health Director and State Public Health Officer Dr. Tomás Aragón.
Public health experts are investigating whether the child was exposed to wild birds, which carry the virus.
The child attended daycare with mild symptoms before the test was reported as a possible bird flu infection. Out of an abundance of caution, other individuals who had contact with the child are being notified and offered preventive treatment and testing.
Officials did not disclose the location, age or gender of the child.
The positive test showed a low-level detection of the virus, indicating the person was not likely infectious to others, according to CDPH. Repeat bird flu testing four days later was negative. Samples have been sent to the Centers for Disease Control and Prevention for confirmation.
Additional testing found that the child was also positive for other respiratory viruses that could have caused their cold and flu symptoms.
Genetic analysis of the virus will reveal the source of the infection, wrote John Korslund, a retired U.S. Department of Agriculture veterinarian epidemiologist who studies livestock diseases. If it is a genotype known as “B3.13,” that would link it to the dairy and poultry outbreaks currently ravaging the state, he said. If it belongs to the “D1.2” genetic lineage, that would lend credence to a wild bird source of infection.
Korslund also cautioned against assuming that there was no human-to-human spread.
“This child was in a daycare situation and may not have been the index case,” he wrote. “The stakes are too high to not follow up.”
Symptoms of bird flu can include fever, cough, sore throat, muscle aches, headache, shortness of breath and conjunctivitis or “pink eye,” say health experts. Symptoms usually appear within two to eight days. An antiviral drug, like Tamiflu, can help if taken within two days of the first symptoms.
The seasonal flu vaccine does not protect against bird flu. But the federal government is developing vaccines against the virus, in case it is needed.
Until now, California’s 26 confirmed human cases of bird flu were all in adult farm workers who were exposed to infected dairy cows. To date, all have reported mild symptoms, primarily conjunctivitis — and none have been hospitalized.
The leap in the number of infected dairy herds — jumping from 10 to 335 of California’s 1,000 herds since October — is troubling to the state’s vibrant dairy industry, a major part of the state’s agricultural industry and the nation’s top milk producer.
The climbing case count also worries epidemiologists and health experts. Prolonged outbreaks can increase the chances of the virus mutating and spreading.
One change in the virus’s genetic code enabled it to jump from birds to cows — and further changes could ease its entry to people, raising the prospect of a human outbreak. The flu pandemic of 1918, which killed more than 50 million people and sickened 500 million others worldwide, was caused by a virus that began with infected birds.
Some public health experts are urging federal officials to provide “point of care” testing of dairy cattle. Currently, every case must be confirmed at the National Veterinary Services Laboratories in Ames, Iowa, requiring physical shipment and resulting testing and announcement delays.
A recent case in a previously healthy British Columbia teenager is garnering substantial attention. That’s because the teen is very ill, hospitalized in critical condition. And the source of the teen’s infection has not been determined.
Moreover, the genetic sequence of the virus that infected the teenager in British Columbia had undergone mutational changes that would make it easier for it to infect other people, scientists told STAT. It is likely, they said, that the mutations developed during the course of his or her infection.
If you suspect you have bird flu and are sick in California, you should immediately isolate yourself from othersand contact your local public health department to arrange testing and treatment, according to CDPH. If you suspect bird flu in your livestock, call 1-866-922-2473.
