Case study of human infection of Avian Influenza H10N3 that occurred in China in March 2024

Influenza News: In March 2024, a new case of human infection with avian influenza H10N3 was reported in Kunming, Yunnan Province, China. This marked the first known human case of H10N3 infection since the global COVID-19 pandemic ended. This Influenza News report explores the key findings from this case and the clinical, epidemiological, and laboratory analyses that followed. The study aims to enhance our understanding of the source of infection, risk factors, and the measures needed to prevent and control H10N3 virus infection.


Case study of human infection of Avian Influenza H10N3 that occurred in
China in March 2024

Researchers from the Kunming Center for Disease Control and Prevention (CDC) and various collaborating institutions investigated this case, shedding light on the virus's behavior and transmission risks.
 
The Case Presentation
The patient, a 51-year-old man from Kunming, had a complex medical history, including a previous COVID-19 infection and a 30-year smoking habit. He worked in livestock breeding, primarily raising poultry such as chickens, ducks, and peacocks. On February 28, 2024, the man developed symptoms of fever and chills, which progressed to severe pneumonia and respiratory failure over the following days.
 
His medical history revealed a significant exposure to sick and dead poultry, particularly in the days leading up to his illness. Despite multiple visits to healthcare facilities, his condition worsened, and he was eventually diagnosed with severe pneumonia, influenza, and respiratory failure on March 6, 2024. The man was hospitalized and placed on mechanical ventilation due to his deteriorating respiratory function.
 
Laboratory Findings
Laboratory tests confirmed the presence of the H10N3 virus in samples taken from the patient’s respiratory tract. The gene sequencing results showed a high similarity to a strain responsible for a previous H10N3 case in China in 2022. Environmental samples collected from the patient’s farm also revealed the presence of avian influenza sub-types H9 and H5 in peacock feces and waterfowl specimens. However, no direct evidence of H10N3 was found in these environmental samples.
 
The patient’s infection was ultimately controlled after more than a month of intensive treatment. He was discharged from the hospital on April 17, 2024, but required ongoing home oxygen therapy and regular follow-up care.
 
Epidemiological Investigation
The epidemiological investigation focused on tracing the source of the infection. The man’s farm was located in an area with mixed captive and free-range farming, and he had been in close contact with sick poultry. Despite his long history of handling livestock, he had not used any personal protective equipment (PPE) while working. His exposure to dead poultry and contaminated environments likely contributed to his infection.
 
None of the man’s six close contacts, including family members and farm workers, developed symptoms or tested positive for the virus. This indicates that the H10N3 virus had not yet acquired the ability to spread between humans.
 
Key Findings from the Case Study
The study highlighted several important points:

-Virus Characteristics: The H10N3 virus in this case showed a high degree of genetic similarity to the strain responsible for the second global case of H10N3 infection in 2022. Genetic sequencing revealed mutations in the virus that are adaptive to mammals, though no evidence suggested that the virus had acquired the ability for sustained human-to-human transmission.
 
-Symptoms and Diagnosis: Human infection with H10N3 initially presents symptoms similar to common respiratory infections, such as fever, cough, and shortness of breath. These similarities can result in delayed diagnosis and treatment. In this case, the man’s condition worsened over several days before a diagnosis was confirmed.
 
-Environmental Factors: The man’s farm was identified as a high-risk environment due to its poor hygiene conditions and the co-existence of humans and animals. The proximity of the farm to other wildlife habitats, such as the nearby Baisha River Reservoir, increased the risk of cross-infection between different species of poultry and wild birds.
 
-Potential for Future Cases: While the study concluded that the H10N3 virus is unlikely to spread widely among humans, it emphasized the importance of ongoing surveillance. The possibility of additional human cases cannot be ruled out, particularly in regions where humans and poultry interact closely.
 
Recommendations for Prevention and Control
The study made several recommendations to reduce the risk of human infection with avian influenza:
 
-Enhanced Surveillance: Increased monitoring of avian influenza sub-types, including H10N3, is essential in high-risk areas. Health officials should focus on detecting cases of pneumonia of unknown origin, particularly in individuals who have been in contact with poultry.
 
-Public Health Measures: The report emphasized the need for public health campaigns to educate farmers and others who work with poultry on the importance of using PPE when handling sick animals. Additionally, government agencies should enforce stricter regulations on livestock farming to minimize the risk of disease transmission.
 
-Healthcare Worker Training: Medical professionals should be trained to recognize the early signs of avian influenza and conduct thorough epidemiological assessments when diagnosing patients with respiratory symptoms. This includes considering a patient’s history of exposure to animals or poultry.
 
Study Limitations
One limitation of the study was the lack of environmental samples testing positive for the H10N3 virus, despite the presence of avian influenza sub-types H5 and H9 in the area. This could indicate that the virus may not have spread widely in the environment, or it could be due to the limited number of samples tested. More research is needed to fully understand the transmission dynamics of the H10N3 virus in poultry and wild birds.
 
Conclusion
This case report highlights the importance of continued vigilance in monitoring avian influenza sub-types, particularly in regions with high levels of human-animal interaction. Although the H10N3 virus has not yet acquired the ability for sustained human-to-human transmission, the potential for future cases remains.
 
Enhanced surveillance, stricter farming regulations, and public health education are crucial in preventing the spread of this virus.
 
The study findings were published in the peer-reviewed journal: BMC Infectious Diseases.
https://link.springer.com/article/10.1186/s12879-024-09830-y
 
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