Nuzzo says it’s very possible that the Louisiana patient’s pre-existing health conditions contributed to the severity of their illness, but also points to the case of a teenager in Canada who was hospitalized with bird flu in November. had entered
A 13-year-old girl was initially seen in an emergency department in British Columbia for fever and conjunctivitis in both eyes. He was discharged home without treatment and later developed cough, vomiting and diarrhea. She wound up back in the emergency department a few days later in respiratory distress. She was admitted to the pediatric intensive care unit and developed 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 caught the virus.
“What this tells us is that we have no idea who is going to develop mild disease and who is going to develop severe disease, and because of that 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 may explain the severity of the Louisiana and British Columbia cases. Virus samples from both patients showed some similarities. For one, both were infected with the same subtype of H5N1 called D1.1, which is the same type of virus found in wild birds and poultry. This is different from the B3.13 subtype, which is predominant in dairy cows.
“At this point, the question is, is this a more serious stress than the dairy cattle stress?” says Benjamin Anderson, assistant professor of environment 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 have 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 immunity. We know that the person was an elderly person. These are factors that already 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 can evolve to cause more severe disease in both patients.
A CDC report from late December A virus taken from a Louisiana patient has been found to have a genetic mutation that allowed it to increase its ability to infect the upper respiratory tract of humans. The report states that the changes observed were likely produced by replication of the virus during the patient’s illness rather than being transmitted at the time of infection, meaning the mutations were not present in the birds that had been exposed.
writing in New England Journal of MedicineThe team caring for the Canadian teenager also described “alarming” mutations found in his viral samples. These changes allowed the virus to more easily bind to and enter cells in the human respiratory tract.
In the past, bird flu has rarely been transmitted from person to person, but scientists are concerned about a scenario where the virus would acquire mutations that would increase the likelihood of human transmission.
Currently, people who work with, or entertain with birds, chickens, or cows are at a higher risk of contracting bird flu. To prevent illness, health officials recommend avoiding direct contact with wild birds and other animals that are infected or suspected of being infected with the bird flu virus.
