CDC urges faster testing as bird flu affects more people, animals
The Centers for Disease Control and Prevention issued an advisory Thursday urging health care workers treating patients hospitalized with the flu to perform an additional test for bird flu within 24 hours of admission.
The advisory reflects increasing concern about the widening outbreak of H5N1 avian influenza that is sickening more people and animals in the United States and Canada. Earlier this month, a Louisiana man became the first person in the United States to die of bird flu. A severe infection nearly killed a Canadian girl who was hospitalized for two months. More domestic cats are getting infected after exposure to raw milk or raw pet food, authorities said.
Any hospitalized patients, especially those in intensive care units, with suspected seasonal influenza or bird flu should also be started on the antiviral treatment Tamiflu as soon as possible without waiting for results of influenza testing, the advisory said.
Nirav Shah, the CDC’s principal deputy director, said the recommendation for accelerated testing for hospitalized patients is being prompted by cases in which patients were confirmed with bird flu late, including after being discharged.
“So having seen that now … a couple of times, that was really the motivation for changing” the testing pace, Shah said.
Delays in confirming a case of bird flu can affect the public health investigation, treatment for potential household contacts and infection control for hospital staff.
“The more time that passes, the more (a patient’s) memories fade,” Shah said.
Patients who are not tested promptly can struggle to remember where they may have been exposed seven to 10 days before becoming sick, or whom else they may have exposed. Also, knowing whether a patient has garden-variety flu or bird flu is essential for hospital staff so that they can wear the appropriate personal protective gear and assign patients to hospital rooms designed to prevent disease spread, he said.
The CDC continues to say the risk from bird flu remains low for most people. With seasonal flu cases high across the nation, nearly all patients hospitalized with influenza probably have the standard variety – not bird flu.
But the risk of bird flu is higher for farm workers exposed to sick animals or their by-products, and for backyard bird flock owners, animal care workers, veterinarians and staff at public health departments, the CDC said in an updated risk assessment Wednesday.
The CDC is monitoring developments closely because the United States is in the middle of flu season. With more patients flooding hospitals seeking care for seasonal flu, testing for avian influenza could slow down, and that could delay public health measures needed to prevent disease spread.
Most hospitals do not have the capacity to test for bird flu and typically send batches of specimens to public health labs “every few days or so,” Shah said. In some cases, by the time test results come back, the patients may already be discharged and their household contacts may no longer be candidates for effective antiviral treatment, he said.
The CDC is recommending that such testing be done on an accelerated basis. About 100,000 people have been hospitalized for flu this season, and another 100,000 are likely to need hospital care by the end of the flu season, CDC data show. About 15% of hospitalized flu patients might need ICU admission.
The new recommendation is not designed to increase the volume of tests being conducted but is instead aimed at accelerating them, Shah said.
Bird flu is caused by a type of influenza A virus, a category that includes seasonal flu viruses that routinely circulate among people. Most influenza tests at urgent care clinics, doctors’ offices and hospitals can confirm an influenza A virus infection and determine whether that infection is from seasonal flu. But those tests cannot detect bird flu.
Testing for H5N1 avian influenza requires a second test that most hospitals and health-care facilities do not have. Hospital staff and clinicians should send specimens to one of about 100 public health labs in the United States that can perform bird flu tests, the CDC said.
Most of the 67 people who have been sickened in the ongoing outbreak are dairy or poultry workers, and all of those workers recovered. The Louisiana man whose death was reported Jan. 6 had contact with sick and dead birds in backyard flocks on his property. Authorities in British Columbia, where the 13-year-old girl was hospitalized in early November, do not know how she was infected.
On Wednesday, the CDC confirmed a bird flu infection in a child whose illness – symptoms included fever and conjunctivitis – was flagged by San Francisco health authorities last week. In a statement, the San Francisco health department said the child was not hospitalized and has recovered.
The child was initially tested for the coronavirus, respiratory syncytial virus (RSV) and flu. After testing positive for influenza A, follow-up testing revealed bird flu. The child’s household contacts had no symptoms and tested negative for the virus, Shah said. Officials are investigating how the child was exposed to the virus.
Public health experts have also raised concerns about the increasing number of cats sickened by bird flu from eating raw pet food or raw milk. The Los Angeles County Department of Public Health has reported multiple confirmed cases of bird flu in domestic cats that drank raw milk meant for human consumption or ate commercially available raw pet food. Some of the cats, including ones that were indoor-only pets, died.
How bird flu spreads
Bird flu can spread from sick cows, birds or other infected animals to people when:
- Splashing raw milk from an infected cow in eyes, nose or mouth.
- Touching eyes, nose or mouth with unwashed hands.
- Touching raw milk, cow or bird feces, or other contaminated items or surfaces.
- Handling sick or dead animals infected with the virus.
- Drinking raw milk.