First US Bird Flu Death Reported In Louisiana After Severe Case Of H5N1

A Louisiana resident has died after being hospitalized with bird flu, the state's health department announced Monday, marking the first U.S. death from the H5N1 virus.

"The patient was over the age of 65 and was reported to have underlying medical conditions," Louisiana's health department said in a statement, saying that health officials still judge the public health risk from the virus as low for the general public. 

The patient tested positive and developed severe illness after being exposed to wild birds and a personal backyard poultry flock that was infected with the virus, according to the health department. No other people were found to have been sickened by the virus in Louisiana. 

"CDC has carefully studied the available information about the person who died in Louisiana and continues to assess that the risk to the general public remains low. Most importantly, no person-to-person transmission spread has been identified," the Centers for Disease Control and Prevention said in a statement Monday.

H5N1 has been linked to at least seven other deaths from other countries in recent years. Since 2003, the World Health Organization has counted more than 400 deaths from the virus.

One other U.S. hospital patient tested positive for the virus last year in Missouri, though officials said that the person had not been admitted because of the virus. Instead, the patient was in the hospital being treated for other preexisting medical conditions.

The Louisiana patient was sickened by the D1.1 strain of the bird flu virus, genetic sequencing by the CDC determined last month. 

The patient's virus did have some rare and potentially worrying mutations, the sequencing revealed. Those genetic changes to the virus likely arose later during the person's infection, the CDC's investigation concluded and were not found in the animals that likely infected them.

"Although concerning, and a reminder that A(H5N1) viruses can develop changes during the clinical course of a human infection, these changes would be more concerning if found in animal hosts or in early stages of infection," the CDC said. 

The D1.1 strain is the same as the virus behind a severe illness of a 13-year-old girl who was hospitalized late last year in Canada. 

Health authorities in the Canadian province of British Columbia said last year that they had been unable to identify the source of the infection, but did find that the virus sequence closely matched wild birds that were flying through the province in October.

This D1.1 strain of H5N1 bird flu is different from the B3.13 genotype which has been fueling this past year's unprecedented outbreak on dairy farms across the U.S. 

Including the Louisiana case, the CDC tallies 66 reported human cases in the U.S. since last year from any of the H5 strains of bird flu. 

How is bird flu spread?

Most of the human cases have been in workers who got sick with the B3.13 strain after working with infected cattle. None of those human cases have been hospitalized or have died from the virus.

The CDC has said there remains "no evidence of sustained human-to-human" spread of H5N1. There are some past outbreaks overseas where the agency says "limited" H5N1 transmission is suspected to have occurred within small clusters of people.

Wild birds or poultry have now tested positive for at least one of the H5N1 strains in every state. In November, Hawaii became the 50th state to report detecting an infected bird. Hundreds of cattle herds across at least 16 states have also tested positive for H5N1.

"While the current public health risk for the general public remains low, people who work with birds, poultry, or cows, or have recreational exposure to them, are at higher risk. The best way to protect yourself and your family from H5N1 is to avoid sources of exposure," Louisiana's health department said.

What are the symptoms of bird flu?

Bird flu has led to a wide variety of symptoms during recent outbreaks, including common flu symptoms like cough and vomiting. Many have also had conjunctivitis or pink eye as their only symptom, which experts suspect is from contaminated milk from cows infected by bird flu being splashed onto workers.

Most of the U.S. cases have seen their symptoms resolve a median of four days after first getting sick. The majority were also treated with the antiviral oseltamivir, also known by the brand name Tamiflu, which may have helped to speed their recovery.

The hospitalized child in Canada initially had conjunctivitis and fever before later developing cough, vomiting, and diarrhea. She was later intubated after respiratory failure.