[Virus and ill person. Photo credit: Pixabay]

The Louisiana Department of Health has reported the death of the first person in the United States to suffer a severe case of H5N1 bird flu. 

After being exposed to a backyard flock of birds and wild birds, the individual, who was over 65 and apparently had underlying medical concerns, was admitted to the hospital with the flu.

According to Louisiana health officials, their investigation revealed no further human cases linked to the same strain of the virus that infected this patient.

For around 25 years, the World Health Organization (WHO) Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds has been researching the virus's family tree and this particular strain is considered to be the most dangerous strain of the virus observed to date. 

The  WHO reports over half of the approximately 900 human bird flu cases that have been documented worldwide since 2003 have resulted in death. 

Although medical experts  don't believe the virus kills half of those it infects, it would give it a 50% case fatality rate, highlighting its extreme lethality.

Mild illnesses are most likely not included in that number since severe cases are more likely to be reported than mild ones.

However, it would still be a significant infection to deal with even if the actual case fatality rate were ten times lower, at around 5%. 

For comparison, it was estimated that the ancestor strain of Covid-19 had a case fatality rate of about 2.6%.

According to researchers at the US Centers for Disease Control and Prevention (CDC), the first 46 human cases of H5N1 in the US last year were almost all mild and, with the exception of one, with nearly all infections as a result of contact with infected farm animals.

The D1.1 clade of the bird flu virus, which is prevalent in wild birds and poultry, was the strain that infected the patient from Louisiana.

Researchers remain unsure if it is linked to more serious illnesses in humans. 

A seriously ill adolescent in Canada was also infected with D1.1 and investigators have not yet determined how the 13-year-old girl was exposed. 

Fortunately,  she recovered after receiving intensive medical care. 

In late December, the CDC reported that a genetic analysis of the virus that infected the Louisiana patient revealed changes that should improve the virus's capacity to infect human upper airways and facilitate its easier transmission from one person to another.

Those identical changes did not occur in the birds the person had been exposed to, suggesting that the individual developed them after becoming infected.

While the CDC described the death as unfortunate, they emphasized that this single case does not indicate an increase in the threat level from H5N1 h.

Nonetheless, some Americans are experiencing unsettling reminders of the early days of COVID-19, when specialists in infectious diseases were discussing a new virus that was causing hospitalizations for respiratory illnesses. 

Both viruses are capable of causing respiratory issues, although they fundamentally  differ greatly from one another.

When COVID-19 first emerged in the United States in 2020, it traveled quickly from person to person, but bird flu had been around for years, primarily affecting animals. 

Moreover, scientists have a much deeper understanding of the H5N1 bird flu than they have about SARS-CoV-2, and the United States has long been bracing for the possibility of a new flu pandemic.