This article is taken from issue 957 of the monthly Science and Future, dated November 2026. This comes from our «Forum» section, which allows us to answer questions from our readers. Ask us yours on the Facebook page of Science and Future We regularly answer a selection of these questions. This one was asked by Jean-Christophe S.
In 2023, an unusual case shocked the scientific community: a fungus that usually attacks trees was identified in the trachea of a 61-year-old man. It was Chondrostereum purpureum, a species responsible for lead poisoning in fruit trees, and whose ability to infect humans had never been documented.
“ Several human illnesses can be caused by fungi that are responsible for plant diseases. «,” explains Laurence Lachaud, head of the parasitology-mycology department at the University Hospital of Montpellier, “for example, fungi of the genus Fusarium.
“ Most often, these fungi enter our bodies through the respiratory system, since we constantly breathe in their spores. » she remarks.
Read also Fungal infections: a growing threat
Different receptors depending on the species, an obstacle to infection
However, unlike fungi, whose mode of infection depends little on specific host recognition, bacteria and viruses must attach to receptors present on the surface of human cells in order to infect or replicate them. These cells do not possess the same receptors as plant cells.
In addition, a human body temperature that is too high for most of these agents to multiply is a factor. One of the few plant-derived viruses found in humans is the chili pepper mottle virus. This is not a true infection: the virus, ingested through food, passes through the body without replicating or causing illness.
On the bacterial side, we can cite the case of Pseudomonas aeruginosa, whose infections have been observed in immunocompromised individuals. Finally, it is important to distinguish these situations from diseases where the plant acts as a passive vector of transmission: liver fluke and echinococcosis («fox disease»), for example. These parasites of animal origin are generally contracted by consuming contaminated plants.
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