People can be infected by bacteria, viruses, fungi and animal parasites, but are any human or animal diseases caused by plants? Is it possible to suffer a moss infection, come down with a bad case of the ferns, or contract wisteria? If not, why have no plants taken advantage of us in this way? (Continued)
鈥� True plants may not have evolved into infectious disease agents, but one of humanity鈥檚 greatest scourges, the malaria parasite, evolved from a kind of single-celled alga.
鈥淥ne of humanity鈥檚 great scourges, the malaria parasite, evolved from a single-celled alga鈥�
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The plasmodium parasite that causes malaria has a structure in its cells, called the apicoplast, that is a remnant of a once used for photosynthesising. It鈥檚 not understood what it does, but the parasite cannot survive without it.
Plasmodium is just one member of a large group, the Apicomplexa, whose ancestor gave up photosynthesis and turned to parasitism more than half a billion years ago. They are responsible for a wide range of diseases. Other examples include Toxoplasma gondii, which infects a third of the world鈥檚 population and has been linked to a higher chance of accidents, and Cryptosporidium.
Michael Le Page, London, UK