The H5N1 bird flu virus has been detected in a man who claims not to have been in contact with animals. To find the origin of the contamination, experts are wondering whether he may have been infected by another person.
A Missouri resident has contracted H5N1 bird flu, the ministry said. Missouri Department of Health and Senior Services (DDHSS)on September 6th. Well, this is the 15th human case reported in 2024 in the United States, its situation is intriguing experts. This is the first infection not linked to an activity in the agricultural sector, where the disease normally occurs. The possibility that the H5N1 virus was transmitted from one individual to another is widely considered, but this would be an extremely rare case.
What exactly do we know today about this patient, who has been closely examined since these suspicions? The infected man went to the hospital on August 22 with symptoms such as nausea, chest pain and diarrhea. After tests, it turned out that he was carrying the H5N1 bird flu virus. In the following days, the Missouri Centers for Disease Control and Prevention (CDC) announced that two other people who had been in contact with the patient had similar symptoms, but the virus was not detected in them. The first person, who lived in the same home as the hospitalized patient, was not tested, and the second person, a member of the medical team in charge of the patient, was tested without any trace of the virus being detected.
A new risk of pandemic?
In France, bird flu is mainly known because of the H1N1 virus and the 2009 pandemic that affected the agricultural world. While bird flu is still present periodically today, the fear is about other viruses. In the United States, H5N1, a different virus, has been very present since last spring and affects both birds and cattle and, through contamination, humans. Mexico, for its part, is facing the H5N2 virus, last June. WHO reported the first fatal case of human infection with the virus, but a link between the disease and the cause of death has been ruled out.
Like all zoonoses, H5N1 is transmitted by contact with an infected animal. Infected people most often work in the agricultural sector, where they are in direct contact with animals, but with the discovery of very high quantities of virus in the milk of sick cows, the forms of transmission have evolved. From now on, a farmer can be infected by the virus if he receives splashes of milk during his work. For the population the risk is more moderate since in the United States the sale of unpasteurized milk is very regulated. For almost a century, unpasteurized cheeses have been banned on American territory unless they have been matured for at least 60 days and 90% of the milk sold is pasteurized.
Transmission between individuals possible
What makes the Missouri patient’s case so unique is that he testified that he had no exposure to known sources of bird flu transmission. In fact, Missouri is not among the 14 states that have been declared hotbeds of the virus. In the Midwestern state, H5N1 has only been found in poultry farms. And in the past, wild birds have been reported to carry bird flu.
The supposed absence of contact with an infected animal worries the American health authorities in charge of infectious diseases. It is not uncommon for cases of human infection to fail to be traced by scientists, but the question of transmission from one individual to another arises.
If the virus is confirmed to be transmissible to humans, H5N1 could cause a new pandemic, although for the moment the risk of such a phenomenon remains unlikely, especially since the virus is not transmitted by air. The more current risk is that the CDH have missed many cases because in the United States