Two new cases of bird flu confirmed in California

The first two human cases were H5N1 bird flu in California CDC testing of samples submitted by the state on Thursday confirmed the infection, and a California-led investigation is underway.

At the same time, tests for antibodies are conducted to confirm infection among contacts of infected people. An unusual incident in Missouri It will begin soon, with results expected in mid-to-late October. At a press conference Friday morning, CDC officials explained why the investigation into this incident is taking so long.

First human infection found in California

California reported its first H5N1 outbreak in dairy cows in August. The two confirmed cases in the state on Thursday bring the total number of cases nationwide this year to 16, CDC Principal Deputy Director Nirav Shah, MD, JD, said in a call with reporters on Friday. said.

Demetre Daskalakis, MD, MPH, director of the CDC's National Center for Immunization and Respiratory Diseases, who was also on the call, said six of the 16 cases (including two newly reported cases in California) are linked to the outbreak. He explained. in dairy cows. Nine incidents are related to: Colorado's “Poultry Population Reduction Activities” It was reported in July. The cause of the Missouri incident is unknown.

Shah said the California patients were farm workers at two separate dairy farms where avian influenza was already known to be occurring among cattle.

The cases were discovered through “active symptom monitoring,” a strategy the state of California and local county health departments continue to use to target exposed workers in outbreak locations. he added.

The two people with confirmed H5N1 infections experienced mild symptoms, including conjunctivitis. Neither reported any respiratory problems and neither was hospitalized. Shah said one person said he thought he had a fever.

“Both have been tested, are receiving antiviral treatment and are recovering,” he added.

Meanwhile, a public health investigation is ongoing. The CDC will work with California public health officials to investigate the two confirmed cases and monitor other possible infections. Shah said the household's contacts (other dairy workers) have been contacted by public health authorities or will be contacted for follow-up.

“There is no known epidemiological link between these two cases, and therefore, based on what we currently know, these cases are separate instances of virus spread from animals to humans.” Mr Shah said.

He said the discovery of these two cases was “not unexpected” and stressed that the CDC's risk assessment to the general public “remains low.”

Two weeks ago, there were 16 positive herds in California. There are now 56 people, he said. “The more herds that test positive, the more workers will become infected. And the more workers who become infected, the more likely it will be transmitted to humans,” he said.

Missouri mystery case

Meanwhile, investigators continue to investigate another human case confirmed in Missouri on September 6, but with no known exposure to infected animals or animal products.

The public health response included “intensive interviews” of the patients and their family contacts, as well as infection control investigations at the hospitals where the patients were admitted. Although the interviews did not identify any known sources of exposure to the H5N1 virus, the discovery of family contacts who became ill with symptoms similar to those of the identified cases and who experienced symptoms at the same time suggests that “person-to-person transmission'' is possible. “This suggests common exposure rather than infection,” Daskalakis said.

Missouri public health officials also Retrospective investigation at the hospitalidentified 112 healthcare workers who had contact with the patient.

Six out of 112 healthcare workers reported respiratory symptoms. One person underwent a PCR test for influenza, but the result was negative. The remaining five people have recovered, but have not undergone PCR tests.

The state of Missouri obtained blood samples from each of these individuals for antibody testing by the CDC and determined that “their symptoms are unlikely to be related to H5 infection resulting from patient interaction.” Daskalakis said.

Antibody tests for H5 are not commercially available. The CDC has been developing a specific antibody test for the Missouri virus for three weeks, which is one reason why serological testing is taking more time, Daskalakis said.

The process is expected to be completed by Monday, at which point serological testing of the samples will begin.

Daskalakis said final serological test results are expected by mid-to-late October. “CDC is moving at a highly accelerated pace, conducting rigorous science to ensure the validity of these results,” he said.

The CDC is also revising its H5 protocol to address evidence of “cross-reactivity” between seasonal H1 antibodies and the H5N1 virus, which will ensure test accuracy and avoid false-positive results. He said this is another step to be taken.