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International Scientific Forum on Home Hygiene
Infectious
Intestinal Disease
in the home- it’s
not all foodborne!
What is IID?
The
definition of infectious intestinal disease
is when
a person experiences diarrhoea or significant vomiting lasting less than 2
weeks, preceded by a symptom-free period of at least 3 weeks in the absence
of a known non-infectious cause. Vomiting is considered significant if
occurs more than once in a 24-hour period, incapacitates the person or is
accompanied by other symptoms such as cramps or fever.
IID
diagnoses include intestinal infections resulting from bacteria and viruses,
salmonellosis, shigellosis, food poisoning, amoebiasis, other protozoal
intestinal diseases, cholera, typhoid and paratyphoid fevers.
Infections intestinal disease can be caused by
the consumption of contaminated food and water or it may be transmitted from
person-to-person either directly or indirectly. Examples of indirect
transmission are via hands, environmental surfaces or the airborne route
(e.g. inhalation of aerosols from vomit).
How is IID
transmitted in the home?
Some IID is
attributable to the consumption of contaminated food and poor food hygiene.
Indications are that a significant proportion of cases occurring in the
community is transmitted by other means. Surveillance studies together with
the community IID study (discussed below) suggest that alternative routes of
spread are particularly important for viral infections, which represent the
major component of IID in the community.
The WHO report that,
of IID outbreaks in Europe during 1999 and 2000, 60% and 69% respectively
were due to person-to-person spread.
From surveillance
data of IID outbreaks in England and Wales from 1992-1998 it is estimated
that
·
19% of
Salmonella outbreaks are transmitted by other means
·
less than
half of E. coli O157 outbreaks are foodborne
·
only 3% of
reported NV outbreaks are foodborne; the remainder are due to
person-to-person spread.
In Scotland,
person-to-person spread was main mode of transmission in 76% of Norovirus
IID outbreaks in 2002.
Food-borne IID can
arise by consumption of food that has become contaminated during preparation
for sale, or the food can become contaminated by an infected person in the
home who handles and prepares food for the family
Person-to-person
spread can occur by a number of means including direct contact between
infected and uninfected family members or by inhalation of infected aerosol
particles produced e.g. by vomiting. For person-to-person spread of
infection, hands and other surfaces can also play a significant part and
these infections are preventable by good hygiene.
·
Carpets can harbour NV serving as reservoirs of infection. Two carpet
fitters became ill after removing a carpet from a hospital ward 13 days
after the last case in outbreak. Routine vacuuming every day since the
outbreak had not removed the virus.
·
During
a prolonged outbreak of NV gastroenteritis in a hotel, NV was detected on
environmental sites such as carpets and toilet areas.
·
For
E. coli 0157, the household secondary transmission rate from an index
case is estimated at 4-14%.
·
In an
investigation of 50 homes in the US in which children under 4 years were
known to be infected with Salmonella spp., Salmonella was recovered
from 38% of homes. In all but 2 homes, the same serotype was isolated from
the environment, another family member, or pets in the home. The study
indicated that other risk factors were significant for development of
salmonellosis in children other than contaminated foods.
IID reports in England and
Wales during 2001
|
Organism |
Number of reports |
|
Campylobacter |
56420 |
|
|
16465 |
|
Rotavirus |
16345 |
|
Cryptosporidium |
3680 |
|
Norovirus (NV) |
1604 |
|
Escherichia coli |
768 |
|
Astrovirus |
116 |
Other causes include
Staphylococcus aureus, Bacillus spp., Shigella spp.,
Giardia spp. and adenovirus.
Reported General
Outbreaks of IID
Note:
a general outbreak is an outbreak that affects members of more than one
household, or residents of an institution.
Country
|
1998
|
1999
|
2000
|
2001
|
2002
|
|
England and Wales |
570 |
|
|
|
|
|
Scotland |
71 |
130 |
|
|
292 |
|
Ireland |
39 |
28 |
36 |
56 |
|
It is calculated
that of the total reported outbreaks of IID in England and Wales:
·
25% due to
bacteria
·
38% due to
viruses
·
36% unknown
cause (although half suspected as viral)
Data from community
IID study
A study involving
460,000 participants was carried out in England and Wales to evaluate IID
cases in the community and presenting to general practice. The study
indicated that:
·
As many as 1
in 5 people in the general population develop IID each year
·
This gives an
estimated 9.4 million cases each year
·
For every one
IID case detected by surveillance, another 136 cases occur in the community.
·
Only 1 in 6
patients consults a doctor.
·
It is not
possible to determine exactly what proportion of these cases originate in
the home
The ratio of
unreported cases in the community to cases reported to national surveillance
was estimated:
·
For every 1
case of Campylobacter reported, another 7.6 cases occur in the community
·
For every 1
case of Salmonella reported, 3.2 cases occur in the community
·
For every 1
case of Rotavirus reported, 35 cases occur in the community
·
For every 1
case of NV reported, 1562 cases occur in the community
What this means
for England and Wales is that, using the figures above for “reported” IID
cases in 2001:
|
Organism |
Number of reported faecal isolates in 2001 |
Ratio of actual: reported cases |
Estimated number of cases in the community |
|
Campylobacter |
56,420 |
7.6 |
428,792 |
|
Salmonella |
16,465 |
3.2 |
52,688 |
|
Rotavirus |
16,345 |
35 |
572,075 |
|
Norovirus |
1604 |
1562 |
2,505,448 |
Consequences and
costs of IID
·
Each year IID
causes over 300 deaths and 35000 hospital admissions in England and Wales.
·
The cost of
IID to the health sector in UK has been estimated at 226 million Euros. This
includes GP visits, laboratory tests, prescriptions and hospital stays.
·
Additional
societal costs such as lost productivity, travel and death amounts to almost
2 billion Euros as well as 13 million days sick leave.
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