Way this question’s phrased makes me interpret it as two questions in one.
- One, humans as transporters of plant disease, on their clothes, shoes, etc.
- Two, common disease agents of humans and plants.
- There is more compelling evidence for the former, less for the latter, with the caveat that there are many more studies exploring the potential of plants and plant products as sources of human diseases. Far fewer the other way around.
Part one. Humans as transporters of plant disease? Yes, there’s some evidence.
- Process by which humans can spread diseases to plants is through fomites, i.e. carrying plant disease-causing agents on their person and depositing them on the plants which, if susceptible, could develop disease.
- This is a well-known mechanism of inter-species and/or -kingdom transfer of disease agents. For example, in research institutes that use animals, entry is limited to restricted personnel who need to wear (PPE) before they enter areas where animals are housed. This is to minimize spread of human-to-animal diseases and vice-versa. Same procedure is in place in plant research stations.
- Wheat rust is an example of humans spreading plant disease. Since 1970, human-borne rust has been implicated as the source in at least two outbreaks of in Australia (1).
Part two. Common disease agents of humans and plants? Yes, but not yet for transfer of human-to-plant disease.
- is a filamentous fungus found the world over.
- Species within it are designated FSSC for Fusarium solani species complex.
- Within this complex, FSSC 1 is unique since it includes examples that cause diseases in both humans and plants (2, 3, 4).
- FSSC 1 can infect most fruits (squash, pumpkin, etc), with reports of infected fruits from California and Ohio in USA, and New Zealand and Japan (5).
- Similarly, Klebsiella species that cause diseases in humans have been shown capable of growing on plant tissues. For example, on the surface of potatoes and lettuce (6)
However, no evidence yet that infected humans transmit same disease to plants, making them ‘sick’ in turn (7).
- Hodson, D. P. “Shifting boundaries: challenges for rust monitoring.” Euphytica 179.1 (2011): 93-104.
- Chang, Douglas C., et al. “Multistate outbreak of Fusarium keratitis associated with use of a contact lens solution.” Jama 296.8 (2006): 953-963.
- Zhang, Ning, et al. “Members of the Fusarium solani species complex that cause infections in both humans and plants are common in the environment.” Journal of Clinical Microbiology 44.6 (2006): 2186-2190.
- O’Donnell, Kerry, et al. “Phylogenetic diversity and microsphere array-based genotyping of human pathogenic fusaria, including isolates from the multistate contact lens-associated US keratitis outbreaks of 2005 and 2006.” Journal of clinical microbiology 45.7 (2007): 2235-2248.
- Mehl, H. L., and Lynn Epstein. “Sewage and community shower drains are environmental reservoirs of Fusarium solani species complex group 1, a human and plant pathogen.” Environmental microbiology 10.1 (2008): 219-227.
- Knittel, Martin D., et al. “Colonization of the botanical environment by Klebsiella isolates of pathogenic origin.” Applied and environmental Microbiology 34.5 (1977): 557-563.
- Melotto, Maeli, Shweta Panchal, and Debanjana Roy. “Plant innate immunity against human bacterial pathogens.” Frontiers in microbiology 5 (2014).