Nuzzo says it’s entirely possible that the Louisiana patient’s pre-existing health conditions contributed to the severity of his illness, but he also points to the case of a teenager in Canada who was hospitalized with bird flu in November.
The 13-year-old girl was initially treated at an emergency department in British Columbia for fever and conjunctivitis in both eyes. She was discharged home without treatment and later developed cough, vomiting, and diarrhea. He ended up back in the emergency department with respiratory distress a few days later. She was admitted to the pediatric intensive care unit and suffered respiratory failure, but eventually recovered after treatment. According to a case report published in the New England Journal of Medicinethe girl had a history of mild asthma and a high body mass index. It is unknown how he contracted the virus.
“What that tells us is that we have no idea who is going to develop mild disease and who is going to develop severe disease, and that’s why we have to take these infections very seriously,” Nuzzo says. “We should not assume that all future infections will be mild.”
There is another clue that could explain the severity of the Louisiana and British Columbia cases. Virus samples from both patients showed some similarities. For one thing, they were both infected with the same subtype of H5N1 called D1.1, which is the same type of virus found in wild birds and poultry. It is different from subtype B3.13, which is dominant in dairy cows.
“Right now, the question is: Is this a more serious strain than dairy cattle?” says Benjamin Anderson, assistant professor of environmental and global health at the University of Florida. So far, scientists don’t have enough data to know for sure. A handful of poultry farm workers in Washington tested positive for the D1.1 subtype, but those individuals had mild symptoms and did not require hospitalization.
“In the case of the Louisiana infection, we know that person had comorbidities. We know that person was an older individual. These are factors that contribute to more serious outcomes when it comes to respiratory infections,” says Anderson.
In the Louisiana and British Columbia cases, there is evidence that the virus may have evolved in both patients to produce more severe illness.
TO CDC report from late December found genetic mutations in the virus taken from the Louisiana patient that may have allowed it to improve its ability to infect the upper respiratory tract of humans. The report says the changes seen were likely generated by the virus replicating throughout the patient’s illness rather than being transmitted at the time of infection, meaning the mutations were not present in the birds it was exposed to. exposed the person.
writing in the New England Journal of MedicineThe team that treated the Canadian teenager also described “worrying” mutations found in her viral samples. These changes could have allowed the virus to more easily bind to and enter human respiratory tract cells.
In the past, bird flu was rarely transmitted from person to person, but scientists are concerned about a scenario in which the virus acquires mutations that would make human transmission more likely.
For now, people who work with birds, poultry or cows, or have recreational exposure to them, are at higher risk of contracting bird flu. To prevent illness, health officials recommend avoiding direct contact with wild birds and other animals infected or suspected of being infected with the avian flu virus.