Environmental Engineering Reference
In-Depth Information
Mitigating Exposure to Infection
a population of 1028), although these cases would
generally be relatively mild and short-lived (as the
bulk of cases are attributable to viral infection).
The combined DALY score of 0.069 can be placed
in context by considering the annual burden of
illness resulting from campylobacteriosis in Eng-
land and Wales from all causes. Analysis based on
an estimated annual incidence of 8.7/1000 popu-
lation (Adak et al. 2002), and expressing this as an
annual burden of illness in the case study popu-
lation, results in a DALY score of approximately
0.025 - less than half the score predicted from the
flood clean-up process.
Although the estimated number of cases of
illness is relatively high, it is likely that many
would not be picked up by the routine surveillance
system and an elevation in cases of enteric illness
due to flooding may not be identified. Under the
circumstances it is likely that many people would
not visit their GP, or the GP may choose not to
take a faecal sample from those reporting, partic-
ularly if the worse symptoms have passed. Also,
where a sample is taken, the clinical laboratory
may not isolate the pathogen causing the reported
symptoms. Unless all of these stages are complet-
ed the illness will not be entered onto the surveil-
lance system records. Additionally, because of the
population dispersion due to flooding, as those
affected move out of the area to stay in temporary
accommodation or with friends and family, cau-
tion is prudent in the interpretation of the partial
surveillance data available.
The exploratory QMRA was essentially quite
conservative for the type of flooding scenario
described, in that no account was taken of people
mitigating their exposure (see following section)
by wearing gloves, nor was any reduction in path-
ogen concentration allowed for (i.e. pathogen
levels were assumed to stay constant from the
point of flooding to the time when the clean-up
was conducted). In reality, many pathogen levels
decrease relatively rapidly in flood water and so
the pathogen concentrations towhich peoplewere
assumed to be exposed are likely to be a significant
overestimate. It does, however, illustrate the po-
tential for a notable burden of gastrointestinal
illness associated with flooding.
In the UK, the Health Protection Agency
(HPA 2008) has issued guidelines on the public
health impacts of flooding, including general
advice on protecting against infection. Contact
with flood waters and sediments may be mini-
mized by the use of protective clothing (water-
proof boots and gloves) during the clean-up
process. Infection risk may also be reduced by
taking general hygiene precautions such as thor-
ough hand washing after contact with either flood
waters, sewage or sediments, or items contami-
nated by these. The risk of wound infection
during flooding and remediation can be reduced
by keeping open cuts and sores clean and dry
where possible, avoiding contact with flood
waters, and wearing waterproof plasters.
The risk of exposure of children to flood-asso-
ciated pathogens (inside and outside the home) can
be mitigated by keeping them away from flooded
areas and contaminated items, including toys and
bedding, until the areas and objects can be thor-
oughly cleaned, disinfected, dried and returned to
their normal condition. Clothes worn during
clean-up activities should be washed in hot water,
separate from any uncontaminated clothes and
linen.
Attention should be paid especially to all areas
of the kitchen while cleaning up, to ensure that
pathogens are removed from objects and surfaces
where food is stored, prepared or served. Food
contaminated by flood water should be discarded.
Hands should bewashed before eating or preparing
food.
Conclusions
The estimate derived from the QMRA suggests
a significant level of mild gastrointestinal illness
(46 cases from a hypothetical population of 1028)
as a result of the post-flood clean-up process,
especially in relation to the estimated risk of
infection from the evacuation process of only two
cases of illness (data not shown; see Fewtrell
et al. 2008a). The results from QMRA are clearly
