On April 13, she was brought to Children's Hospital 1 in HCM City with symptoms of drowsiness, confusion, and mild neck stiffness. She was initially diagnosed with suspected encephalitis.

Doctors took her cerebrospinal fluid and respiratory samples and sent them to the Hospital for Tropical Diseases and the Pasteur Institute in Ho Chi Minh City for testing. The cerebrospinal fluid results tested positive for influenza A/H5N1, while the respiratory samples were negative.

The Pasteur Institute in HCMC has quickly informed the Ministry of Health's Department of Preventive Medicine of the case.

The patient is staying at the Infectious Diseases ICU of Children's Hospital 1 for treatment under ventilator support. She is struggling with a fever of 38.5°C, but her vital signs remain stable.

The girl was exposed to a group of chickens that had died en masse at her grandmother's home two weeks ago. She also has a history of congenital heart disease and underwent surgery at Children's Hospital 1 at just two months old.

The H5N1 avian influenza virus mostly impacts poultry and waterfowl, with human infections occurring through close contact with infected birds. Infected individuals can see severe pneumonia with a fatality rate of over 50 percent.

H5N1 has not shown the ability to transmit from human to human.

According to infectious disease experts, the girl's case is rare, as the H5N1 avian influenza virus damaged the central nervous system without affecting the respiratory system.