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A Suspiro1, L Menezes2
1 Public Health
Doctor, Health Authority
2 Public Health
Doctor
From: Saùde em nùmeros, 1996;
(11) 1: 5-7
The introduction of shigella into a child care centre
carries a high risk of secondary spread from person to person within the
centre (1). We report an outbreak of shigellosis in early 1995 that affected
99 children, 17 of their relations, and seven workers in a day care institution
for children under 10 years of age. The health authority closed the institution
for five days to control the outbreak and all the families at risk were
contacted in order to give an appropriate antimicrobial drug to all those
affected.
The outbreak occurred in late February and early
March. Those who became ill suffered diarrhoea with blood, mucus, and
pus and high fever, cramps, and malaise. Three patients were admitted
to hospital. Shigella sonnei was isolated from the stools of nine
cases tested at random and the three children admitted to hospital. The
strain isolated in each case was resistant to tetracycline and co-trimoxazole.
The outbreak occurred in two waves (figure). In the
first wave 65 cases were reported in five days. The attack rate differed
with age: two out of 48 kindergarten children (aged less than 3 years)
became ill (4.1%) and 65 out of 222 older children and adults (28.4%).
It seemed likely that a common source of infection was responsible (figure).
The children and adults had eaten lettuce and home made mayonnaise prepared
with raw eggs, but no leftover food was available for testing.
In the second wave of the outbreak 41 cases occurred
in a pattern compatible with spread through faecal oral transmission from
convalescent cases to susceptible people in the institution.
It appeared that co-trimoxazole, with which cases
had been treated in the early phase, had not prevented the second wave
of infection. At this point the institution was closed for five days during
which 82 cases were given antibiotic treatment, mostly amoxycillin to
which the organism was sensitive. Subsequently a random sample of 43 patients
submitted faecal specimens, all of which were negative. In addition to
these two measures, asymptomatic carriers were excluded among foodhandlers.
No control groups from the institution or the community
were investigated and no analytical study was conducted to investigate
the possibility that the first wave of cases was associated with a food
vehicle. The investigation of this outbreak highlighted the risk of secondary
transmission after a foodborne infection if hygiene is neglected. Although
shigellosis is usually a self limiting disease, when it occurs in an institution
for very young children or others unable to manage their own personal
hygiene, special care should be taken both with hygiene measures and the
administration of antimicrobial drugs to patients. It is likely that the
organism's resistance to common antibiotics and the initial failure to
exclude convalescent cases from the institution contributed to the spread
of infection (2).
References
(1) Benenson AS. Control of Communicable Disease
in Man. 15th edition, 1990, American Public Heath Association.
(2) Tauxe RV, Johnson KE, Boase JC et al. Control of day care shigellosis:
a trial of convalescent day care in isolation. American Journal of
Public Health. 1986, 76(6):627-30.
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