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A study of shigellosis in Tasmania


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Hunt, A L C(Alfred Leslie Clive) 1989 , 'A study of shigellosis in Tasmania', Coursework Master thesis, University of Tasmania.

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In a recent publication, Tasmania was designated as an area of
moderate or unknown status in regard to the overall problem of
diarrhoea (DuPont and Pickering, 1980). This impression seems
to be at least partly the fault of Tasmania itself. For example,
between the years 1976 to 1983, only eleven cases of Shigella
infection were reported, an average of 1.6 cases per year. This
not only made it appear that Tasmania had a very low incidence
of this infection in comparison with the rest of Australia, but
also in fact, with most of the rest of the world.
Considering that Tasmania is no longer isolated from the mainland
or the rest of the world, and also the fact that there is a
large movement of people in both directions, including many
tourists from countries with high incidence of diarrhoeal infections,
it would seem very unusual to have so few cases of Shigella
infections on record.
There could be a number of reasons for this situation, the main
ones being:
(a) that dysentery (including Shigella infections) are not
all being investigated and notified;
(b) that it is true there is a very low incidence which in
itself is interesting, and should be investigated further in
order to establish, if possible, the reasons for such a fortunate
(c) infections do occur but for reasons unknown, are not
detected, e.g. specimens are not being sent to the laboratories
for investigation, or the organisms are not being isolated by the
laboratories. This may involve the culture media presently
available or those being used by diagnostic laboratories not always recovering or isolating the organisms.
(d) The distance between the areas of collecting and the
diagnostic laboratory may cause delay in the investigation. This
could be significant as it is a well known fact that the Shigellae
need to be plated onto culture media almost immediately; even a
short delay can reduce considerably the chance of isolating the
Finally, there is a need to examine the possible introduction of
a more rapid method to overcome the problem of delay in isolating
Shigella infections combined with a more reliable method of
detecting positive cases than the recovery of the organisms on
culture media.
It was decided to combine the investigation of the alleged lack
of Shigella infections in Tasmania with an overall research project
as follows:
1. Research Protocol
To investigate the accuracy of presently available culture media
to detect Shigella organisms using known strains and stock cultures
of local strains to determine to what extent they can be recovered
on available culture media, both directly and in dilution.
2. Due to the close relationship between Escherichia coil (A - D)
(Alkalescens dlspar) and Shigella, this former group of organisms will
also be tested against the media as for Shigella.
3. To establish if Shigella infections are being missed, due to
the fact that patients with diarrhoea are not being investigated
by the laboratories, the cooperation of local doctors was obtained
to submit specimens from any diarrhoeal patient, even if only
having mild symptoms, and provided it was suspected the diarrhoea
was due to infection. Further, the co-operation of laboratories was obtained to submit
diarrhoeal specimens they had found to be either positive or
negative for microorganisms known to cause diarrhoea.
4. Having isolated suspected Shigella colonies, to establish
which biochemical methods are most satisfactory for their rapid
5. Due to the close relationship between Escherichiacoli and
Shigella, to investigate the frequency of toxigenic E. coil and
invasive E. coil by gene probe analysis in those specimens from
patients with diarrhoea in which no other possible pathogens
had been isolated. This has never been investigated in Tasmania.
6. To investigate the possibility of developing a more rapid
and accurate technique for the identification of shigella
infections in stool specimens, e.g. E.L.I.S.A. technique.

Item Type: Thesis - Coursework Master
Authors/Creators:Hunt, A L C(Alfred Leslie Clive)
Keywords: Shigellosis, Shigellosis
Copyright Holders: The Author
Copyright Information:

Copyright 1989 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (M.Med.Sc.)--University of Tasmania, 1989. Bibliography: p. 95-113

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