The US Centers for Disease Control and Prevention (CDC) said Thursday that it has not yet identified a “clear source” of infection for a Missouri patient who tested positive for the avian influenza virus despite having no known contact with poultry or dairy cows.
CDC (Centers for Disease Control and Prevention) The incident was revealed last FridayThe patient was admitted to hospital on August 22 and has since recovered, it said.
Since March, 13 poultry and dairy workers have been reported infected with avian influenza while the H5N1 virus has spread rapidly among cows on 200 dairy farms in 14 states. According to the CDC:.
Officials believe the patient was hospitalized not because of the infection, but because of an underlying condition the patient had, though they declined to say what that was because it would disclose personal health information.
The patients, whose symptoms included chest pain, nausea, vomiting, diarrhea and weakness, were not initially linked to influenza, Dr. Nirav Shah, principal deputy director of the CDC, said in a conference call Thursday, though they were later tested for influenza. The patients, whose illnesses were not severe and did not require intensive care, were treated with antiviral drugs.
Missouri health officials are still investigating the incident. Although the patient reportedly had no contact with animals, public health officials are now conducting more detailed interviews, including asking about any wild birds or animals seen around the patient’s home and the use of bird feeders. They are also asking about the types and sources of meat and dairy products the patient has consumed, as well as raw milk.
Shah said none of the patient’s close contacts have shown signs or symptoms of infection and there is no evidence of person-to-person transmission of the virus. So far, officials have not identified any new cases, and there are no signs of rising flu infection rates in the patient’s area.
“The investigation is not over yet,” Shah said. “The usual 10-day period for infection has passed, and every day that passes makes it less likely that this is happening deep down.”
But on Friday, the C.D.C. Flu Weekly Report Quietly Released on FluView A close contact of the Missouri patient developed symptoms around the same time but was not tested for influenza.
“One close contact of the patient also developed symptoms around the same time but was not tested and has since recovered,” officials wrote.
It was unclear why close contacts were not mentioned during Thursday’s briefing. The CDC did not immediately respond to a request for comment.
Authorities insist the risk to the general population remains low.
“We continually assess the risk with every case and every change, and we continue to see the risk as low,” Dr. Demetre Daskalakis, director of the CDC’s National Center for Immunization and Respiratory Diseases, said on a conference call.
Shah said the case may be a “one-off,” meaning the infection may not have spread beyond the patient.
“That’s what happens with new strains of influenza,” he said, adding that there have been several cases of swine flu so far this year that have not spread beyond a single infected person.
Missouri health officials said last week that there have been no reported cases of avian flu in dairy cows. A few cases have been reported in commercial poultry farms, household chickens and wild birds. No additional human cases have been confirmed.
Officials are also investigating whether the H5N1 virus has changed in a way that might suggest it could spread from person to person, but so far none have been found.
Shah noted that the infection was discovered thanks to Missouri’s flu surveillance program.
