US health officials have confirmed a human case of bird flu in a patient that had no immediately known animal exposure.
The patient, in the state of Missouri, was treated in hospital and has since recovered, the Centers for Disease Control and Prevention (CDC) said.
It is the 14th human case of bird flu in the US in 2024 and the first without a known occupational exposure to infected animals, according to the CDC.
The same relationship of the cost of high virulence hurting the fitness of a pathogen may not apply if hosts are kept in proximity that a fast death doesn’t necessarily mean the pathogen cannot find a new host.
It may have been how the 1918 flu pandemic was so deadly yet still successful at spreading to new hosts; being spread amongst soldiers in trenches and infirmaries and troop ships compared.
Plus, there are evolutionary pressures on pathogens to become more virulent; using less resources by the host only leads to being outcompeted by more virulent pathogens. While mortality is a limiting factor, there is a temporary benefit to strategies that select for virulence until that limit is reached.