A third man infected with the H5N1 virus in the United States, the first human case in Australia and the first person infected with H5N2 in Mexico: In the space of a week, different sublineages of avian flu have caused concern by jumping from animal species to humans. Although these are not the same viruses nor do they involve the same public health issues, the World Health Organization (WHO) considers that in all cases "the current risk to the general population posed by this virus [is] low."
Nonetheless, warning signs are mounting and scientists are intensifying their calls to implement measures to prevent a catastrophic scenario. "I think the current circumstances justify sounding the alarm and mobilizing for vaccine production," Gregory Poland, director of the vaccine research group at the Mayo Clinic in Rochester, Minnesota, told Le Monde.
On Friday, June 7, a two-and-a-half-year-old Australian girl became the country's first official case of H5N1. She is believed to have been infected during a trip to India and developed symptoms when returning home. After more than two weeks in intensive care, she has now recovered. In Mexico, few details have yet emerged from the investigation into the first known human case linked to the H5N2 virus, announced on Wednesday by the WHO. The patient, a 59-year-old man, died a week after the onset of acute symptoms including fever, shortness of breath, diarrhea and nausea. His family and friends reported that he was already suffering from multiple comorbidities and the WHO considers his death to be "multifactorial." Over the past 20 years, it has been estimated that around half of all reported cases of avian flu have resulted in death from acute symptoms but in the absence of large-scale screening that takes into account asymptomatic cases, it is impossible to calculate a mortality rate.
Screening is the key issue in the current epizootic on dairy farms in the United States. With a new infection reported in Minnesota on Thursday, 81 farms in 11 US states are now affected by the virus. However, farmers are not currently required to test their animals except when transferring them from one state to another and they remain reluctant to conduct tests that could force them to quarantine or even cull their herds. At the end of May, it was found that one in five samples of milk marketed in the US contained remnants of the virus, suggesting that the epidemic is more widespread than previously thought.
Lack of screening
Three farm workers have already been infected. While the first two suffered only conjunctivitis after their eye mucosa came into contact with contaminated milk, the third man, identified on May 30 in Michigan, showed respiratory symptoms. This important development opens up new avenues for viral transmission. If the virus were to develop the ability to spread between humans, which has not yet been proven, it could circulate more easily. Here again, however, the lack of screening prevents us from grasping the full extent of the phenomenon.
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