Overview
On August 22, 2024, the Missouri Department of Health and Social Services (DHSS), and the U.S. Centers for Disease Control and Prevention (CDC), reported the first human case of avian influenza A (H5), pending identification of the subtype (H5Nx) in the state. This case represents the fifteenth human case of avian influenza in the United States since 2022.
Avian Influenza A (H5Nx) Updates - Missouri
- According to the available report, the patient is an adult with unspecified underlying health conditions who was admitted to a local hospital in Missouri on August 22, 2024. The patient was confirmed to have influenza A virus through the ongoing influenza screening program.
- Reports did not disclose respiratory symptoms or the reason for hospitalization, nor were details provided about the influenza screening. After additional testing at the Missouri Public Health Laboratory, the influenza was determined to be of avian origin (H5Nx), and this was later confirmed by the U.S. Centers for Disease Control and Prevention (CDC).
Additional details about the case:
- There was no history of exposure to infected animals, and the source of exposure to the virus remains unknown (i.e., no details about exposure to contaminated environments or sick people have been determined).
- The patient has recovered and been released from the hospital.
- There have been no additional cases reported among close contacts or in dairy cattle herds in Missouri.
Additional information:
- Avian influenza A(H5) virus is typically associated with wild birds and poultry, although recent cases have involved cattle in other states.
- There have been no reported cases of H5 in cattle in Missouri, but H5N1 cases have been confirmed in commercial poultry and wild birds. The last animal disposal event was in February 2024.
- This is the first human case in Missouri, bringing the national total to 15 human cases of H5N1 since 2022.
- Thanks to ongoing surveillance and testing programs by state health authorities, the case was identified, and no sustained human-to-human transmission has been observed following epidemiological investigations.
- The Department of Health and Social Services (DHSS) has assured the public that the risk of transmission is low, and no additional human cases have been reported in the area.
Level of Concern:
- The level of concern is low at the local, regional, and global levels, with slightly elevated concern among individuals exposed to animals or bird-contaminated environments due to their occupations, although this case is not associated with direct animal exposure.
Factors Considered:
- The case was identified early due to effective surveillance systems, underscoring the importance of continued screening for potential transmission.
- Genetic surveillance and influenza testing remain critical to understanding the potential source of infection (e.g., avian, environmental, or accidental transmission).
- Some missing information is still necessary to better understand the public health implications and accurately reassess the risks to the population, including potential source of exposure, clinical symptoms, screening and treatment of contacts
References:
- CDC.
- World Health Organization.