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Insects and other invertebrates are the arena for the
evolution of new infectious diseases in humans, new research
shows.
Dr Nick Waterfield and Professor Richard ffrench-Constant
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.
The bioluminescent bacterium, Photorhabdus asymbiotica,
which causes pustulent sores. 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 genus is called Photorhabdus (glowing rods)
because they are the only terrestrial bioluminescent bacteria.
The bodies of insects killed by Photorhabdus luminescens
infection are left luminous.
Infections by Photorhabdus luminescens are naturally
resistant to several antibiotics but the relapsing infection can
be combated using repeated administration of certain drugs.
Failure of automated hospital diagnostic machines to
recognize this unusual bacterium means that many more cases of
this new infection may exist. This is likely to be particularly
true for the developing world, where doctors may diagnose the
sore as a bad ulcer and treat immediately with antibiotics. Now
that researchers are actively looking for Photorhabdus
asymbiotica infection, they are beginning to find cases in
countries in Asia. |