Scientists now believe that not only are insects the carriers of some existing diseases but they are also the vehicle where recently emerging highly infectious diseases, such as the plague that killed millions in the 14th and 17th centuries, evolve.

Writing in the October edition of Nature Reviews: Microbiology, the researchers point to the large reservoir of diseases in invertebrates, such as fleas and nematode worms, which are currently harmless to humans, but which could evolve quickly into a range of new diseases.

As part of their research, Dr Nick Waterfield and Professor Richard ffrench-Constant (correct) from the University of Bath, and Professor Brendan Wren, from the London School of Hygiene and Tropical Medicine, are studying a new disease-causing (pathogenic) bacterium that has been identified in about a dozen people in the USA and Australia.

Their study looked at the bioluminescent bacterium, Photorhabdus asymbiotica, which cause pustulent sores to appear on parts of sufferers' bodies. The researchers suspect that this new bacterium evolved recently from a well-known bacterium, Photorhabdus luminescens, which kills insects with the help of nematode worms.

This family of bacteria are known as Photorhabdus (glowing rods) because they are the only terrestrial bioluminescent bacteria. The bodies of insects killed by Photorhabdus luminescens infection are left luminous.

Genome studies have found close similarities between the plague-causing bacterium, Yersinia pestis, and its ancestor, Yersinia psuedotuberculosis, which has been shown to be capable of causing disease insects, at least in the laboratory. Evidence suggests that the plague could have evolved from a close insect-pathogenic ancestor as little as 1,500 years ago, an eye blink in evolutionary time, suggesting that similar scenari
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Contact: Andrew McLaughlin
a.mclaughlin@bath.ac.uk
44-122-538-6883
University of Bath
25-Oct-2004