Health officials in Vietnam have reported a severe H5N1 avian flu infection in an 8-year-old girl. The girl, who is experiencing encephalitis symptoms, appears to be the country’s first human case of bird flu in 2025.

The patient’s symptoms, which began on April 11th, included fever, headache, and vomiting. She was initially admitted to a provincial hospital. When her condition didn’t improve, she was transferred to the Children’s Hospital in Ho Chi Minh City on April 13th, where she was diagnosed as having encephalitis, according to a report by the University of Minnesota’s CIDRAP. 

The child has an underlying health condition and had surgery for a ventricular septal defect when she was only two months old.

Polymerase chain reaction tests on her respiratory samples were negative for H5 avian flu, but her cerebrospinal fluid sample was positive for the virus, with results confirmed by the Pasteur Institute in Ho Chi Minh City.

She is currently hospitalized and on a ventilator.

If the health officials had to go deep into spinal fluid to even notice the virus, is her body even capable of spreading it?

Officials claim that H5N1 infections that involve only the central nervous system are rare but have been reported before. In 2004 in Vietnam, clinicians identified H5N1 in the cerebrospinal fluid of one of two siblings who died within weeks of each other from severe neurologic symptoms. But the death occurred without respiratory symptoms, suggesting that the illness spectrum is wider than previously thought.

An epidemiologic investigation found that, before the girl had gotten sick, she had contact with a poultry flock at her grandmother’s house that had experienced mass deaths 2 weeks earlier.

Vietnam’s most recent human case of H5 bird flu was in December 2024. In this case,  an 18-year-old man from Long An province was exposed to sick poultry and died from his infection.

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