HPAI and Pediatrics: What Clinicians Need to Know
Share this article
What Pediatricians Need to Know about highly pathogenic avian influenza (HPAI) A(H5N1)
This content is jointly provided by the National Emerging Special Pathogens Training and Education Center and the Pediatric Pandemic Network (PPN).
Clinical Guidance for highly pathogenic avian influenza (HPAI) A(H5N1)
Highly pathogenic avian influenza (HPAI) can be caused by several different strain types. H5N1, the strain type recently identified in a human in Texas, was initially detected in 1996 but has primarily been found in wild birds (hence the name). Although transmission directly from birds to humans is very unusual, transmission from birds to other mammals occurs more frequently. Sporadic outbreaks in several species of mammals (both terrestrial, including commercial poultry, and marine species) have occurred and are increasing in frequency. Human transmission from animals is rare and typically occurs in adults with close occupational contact with animals. Human-to-human transmission has not been reported in the United States. Consequently, HPAI has not been reported in children in the U.S.
On March 25, 2024, an outbreak of HPAI A(H5N1) in cows was reported in multiple states. As of April 26, 2024, there are 34 herds affected in nine states (see image below). Importantly, while cows regularly contract influenza viruses, this is the first report of highly pathogenic strains in cows. There is no evidence yet of infections in beef cattle, though expanded testing of livestock has not been pursued yet.
Clinical Information:
CDC has a summary of recommendations for patients with signs/ symptoms compatible with avian influenza A infection who have had recent exposure to avian influenza virus. This includes isolating the patient, initiating empiric antivirals, notifying state and local health departments, and collecting respiratory specimens to be tested at the state health department.
Currently, there are no immediate concerns for human infections, though persons with occupational or recreational risk should take precautions. Experts anticipate an impact on agriculture. Genetic analyses are ongoing, but no new mutations that could enhance adaptability to mammalian hosts or human-to-human spread have been identified yet. The CDC has noted that this strain retains susceptibility to current antivirals, and available vaccines for H5N1 remain effective. While overall risk remains quite small, it remains worth paying attention to, as there does seem to be some significant shifting in the epidemiology.
Top 5 Facts the Pediatrician Needs to Know
- Transmission to humans remains rare, and human-to-human transmission is very uncommon.
There has been 1 human case reported in the U.S. since this outbreak. There was an additional case in 2022 in CO associated with poultry exposure. The recent case had significant exposure to dairy cattle in Texas, demonstrated mild symptoms (conjunctivitis), was treated with the antiviral Oseltamivir, and recovered well. Worldwide, since the beginning of 2024, there have also been 5 new cases of HPAI A(H5N1) infection reported in Cambodia and 1 in Vietnam, with a wide spectrum of illness and outcomes.
Those with direct contact with animals or animal feces (primarily occupational exposures) are at risk for H5N1, but there is no evidence that humans can transmit the virus to another human. The CDC continues to monitor the situation, and has found no increase in influenza.
- Milk and formula supply is safe
In late April 2024, tests of the milk supply found one in five milk samples had fragments of the H5N1 virus. However, additional testing did not find any live viable virus. The FDA also tested several samples of both infant and toddler formula and found no viral fragments in any of the testing. At this time, the U.S. Food and Drug Administration considers commercial milk and formula to be safe.
The pasteurization process should inactivate any H5N1 virus found in raw milk, and so far tests confirm this. Raw milk or milk products are not recommended, as this milk is unpasteurized and carries a heightened risk of disease.
- Testing for H5N1 requires specific subtyping typically limited to public health labs
If you have high suspicion for a patient with H5N1 with a high-risk epidemiological link, contact your local health department or public health lab to discuss availability of subtyping.
- A vaccine already exists for H5N1
There are several vaccines available for H5N1 and scientists predict that the ongoing strain would be adequately covered with the current stock. The vaccine is approved for patients six months of age and older. Since the production depends on the standard influenza vaccine infrastructure, full scale availability would take months.
- Current antivirals are likely effective against H5N1
Antivirals used for typical influenza are effective, including oseltamivir, zanamivir, baloxavir, peramivir. The majority of available medications is in the branded oseltamivir “Tamiflu.”
Sources:
- US FDA Updates on Highly Pathogenic Avian Influenza (HPAI)
- CDC H5N1 Bird Flu: Current Situation Summary
Additional Resources for Pediatricians
- H5N1 Bird Flu: Current Situation Summary (CDC) https://www.cdc.gov/bird-flu/situation-summary/index.html
- Updates on Highly Pathogenic Avian Influenza (HPAI) (USDA) https://www.fda.gov/food/alerts-advisories-safety-information/updates-highly-pathogenic-avian-influenza-hpai
- Highly Pathogenic Avian Influenza A (H5N1) Virus Infection Reported in a Person in the U.S. (CDC) https://www.cdc.gov/media/releases/2024/p0401-avian-flu.html
- Highly Pathogenic Avian Influenza A(H5N1) Virus in Animals: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations (CDC) https://www.cdc.gov/bird-flu/prevention/hpai-interim-recommendations.html
- Technical Update: Summary Analysis of Genetic Sequences of Highly Pathogenic Avian Influenza A(H5N1) Viruses in Texas (CDC) https://www.cdc.gov/ncird/whats-new/human-infection-h5n1-bird-flu.html
- Health Alert: First Case of Novel Influenza A (H5N1) in Texas, March 2024 (Texas Health & Human Services) https://www.cdc.gov/ncird/whats-new/human-infection-h5n1-bird-flu.html
- Highly Pathogenic Avian Influenza (HPAI) Detections in Livestock (USDA) https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/livestock
- CDC sequencing of H5N1 avian flu samples from patient yields new clinical clues (CIDRAP) https://www.cidrap.umn.edu/avian-influenza-bird-flu/cdc-sequencing-h5n1-avian-flu-samples-patient-yields-new-clinical-clues
- U.S. dairy farm worker infected as bird flu spreads to cows in five states (Science) https://www.science.org/content/article/us-dairy-farm-worker-infected-as-bird-flu-spreads-to-cows-in-five-states
About the Authors
Tress Goodwin, MD
Tress Goodwin is an emergency medicine physician at Children’s National Medical Center and the Pediatric Medical Director of the Region 3 Emerging Special Pathogen Treatment Center in collaboration with Medstar Washington Hospital Center. She is also a member of the Pediatric Pandemic Network focusing on Disaster Preparedness and Special Pathogens.
Clayton Mowrer, DO, MBA
Clayton Mowrer is an adult and pediatric ID physician at University of Nebraska Medical Center and Children’s Nebraska.
Doneen West, PharmD
Doneen West is a pharmacist with over 20 years of hospital experience. She currently works as a program manager for the Infectious Disease Domain of the Pediatric Pandemic Network through University of California Benioff.