CDC confirms first serious human case of bird flu in US: NPR

This color electron microscope image released by the National Institute of Allergy and Infectious Diseases in March shows avian influenza A H5N1 virus particles (in yellow). The CDC says the first serious case of bird flu detected in a human during the current US outbreak.

AP/The National Institute for Allergy and Infectious Diseases

hide caption

change caption

AP/The National Institute for Allergy and Infectious Diseases

Federal health officials are treating the first serious case of bird flu detected in a human during the U.S. outbreak.

Louisiana health officials initially reported the infection last weekthat says one person was hospitalized after being exposed to sick and dead birds in backyard flocks.

On Wednesday, the Centers for Disease Control and Prevention shared their findings indicating that the H5N1 virus responsible for the disease belongs to a genetic lineage that circulates in wild birds and poultry — different from what spreads in dairy cattle and drives the majority of infections in agricultural workers.

In the US is more than 60 people have been infected so far, although some studies suggests the official tally may be an undercount.

The diseases associated with dairy cattle have largely led to mild diseases in humans.

The version of the virus in the Louisiana case is the so-called “D1.1 genotype.” It has previously appeared in poultry workers in Washington State, who developed mild symptoms after testing positive in October. Recently, however, a teenager in British Columbia was hospitalized after contracting this D1.1 strain of the virus.

Canadian health officials were unable to determine how this person was infected.

The case in southwest Louisiana was discovered during routine influenza surveillance and was eventually sent to the CDC for confirmation. There is no indication that the person is spreading bird flu to others, and the case does not change the CDC’s assessment that the risk to the public remains low.

Still, the hospitalization is a reminder that bird flu has a well-established history of causing serious illness and death over the past 20 years in other countries, Dr. Demetre Daskalakis of the CDC told reporters Wednesday during a press conference.

Daskalakis said his agency is doing additional sequencing to look for any worrisome changes in the virus that could signal it is evolving to better infect humans or cause more serious disease.

Researchers were concerned that the British Columbia case showed certain mutations that could spell trouble, although more research was needed to understand the exact implications.

Daskalakis referred reporters to Louisiana officials investigating the case for further details on how the person caught the virus and their symptoms.

As with the Louisiana infection, most cases have been linked to some form of exposure to sick animals. Dairy cattle have large amounts of the virus in their milk, and it is suspected of causing infections in farm workers. Those who work with infected poultry can also catch the virus.

However, several cases have emerged in the United States that cannot be traced back to infected livestock, including in California and Missouri.

“Infections without a clear source of exposure do occur, neither these cases nor the cases with known animals or animal products have resulted in human-to-human transmission,” Daskalakis said.