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INVESTIGATION & CONTROL OF OUTBREAKSWATER BORNE DISEASES
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THE RISK OF WATER-BORNE DISEASES IS
HIGHER IN AREAS WITH:
Inadequate water supply
Poor quality of water and sewage pipelinesPoor sanitary conditions
Step wells and uncovered wells used as sources
of drinking water
Defecation in the open especially near sources
of drinking water
Poor system for the disposal of human waste.
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COMMON SOURCES OF INFECTION
DRINKING WATER
y Contaminated at itssource
y Contaminated druingsupply& storage
y Ice made fromcontaminated water
FOOD
y Contaminated during orafter preparation
y fruits and vegetables,
freshened withcontaminated water andeaten raw.
y Fruits and Vegetables.grown at or near ground
level and fertilized withnight soil or irrigated withwater contaminated withhuman waste, and eatenraw.
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Incidence of Water Borne DiseasesMay occur throughout the Year.
Seasonal increase is noted in the summer,
monsoon and post monsoon period.
The risk of large outbreaks of water-borne and
water related diseases increases following heavy
rains.
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. Water-Borne-Diseases of Public-Health Importance
Water borne diseases are considered to be publichealth importance for the following reasons:
Potential for causing large outbreaks
High disease burden due to the large number of cases and
deaths especially in young children.
In many states and districts, water-borne diseases are major
causes of pediatric indoor admissions and out-patient visits
to the hospitals and health facilities.
No specific treatment is available for some viral diseasessuch as hepatitis E. Increasing anti-microbial drug resistance
is being recorded for some bacterial diseases.
Potential for causing panic in the community and negative
media coverage.
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WATER BORNE
DISEASES
Acute watery diarrhoea
Cholera
Bacillary
Dysentery/Shigellosis
Typhoid fever/ Enteric fever/ Salmonellas
Viral hepatitis
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MANAGEMENT OF DEHYDRATION AND ELECTROLYTE
IMBALANCE DUE TO ACUTE WATERYDIARRHOEA.
Almost all cases of acute diarrhoea, including cholera, should
be treated with oral rehydration salt (ORS) solution. Patients with
global hypotonia, in hypovolaemic shock or otherwise unable totake fluids by mouth should be given intravenous fluids. ORS can
be started as soon as the condition improves. The signs of
dehydration and electrolyte imbalance are given below.
IV fluids should be used only for the initial rehydration of patients
with severe dehydration, including those who are in shock.Ringers lactate solution is the preferred fluid for intravenous
rehydration. Normal saline solution is less effective for intravenous
rehydration, but can be used if Ringers lactate solution is
unavailable. Plain glucose solutions are ineffective and should
not be used.
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Cholera
In a majority of the cases, the infection is mild with no
overt symptoms or only mild diarrhoea. However, in a
few cases the onset is rapid with severe waterydiarrhoea and vomiting, resulting in loss of large
amounts of fluids and electrolytes. Fluid therapy for
cholera is similar to that for acute watery diarrhoea.
Use of antibiotics for mild cases is notrecommended
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Laboratory Diagnosis
General principles
In an outbreak situation, laboratory examination of
specimens from the first few suspected cases is
important to identify the causative organism andtest its sensitivity to antibiotics. Once the presence
of cholera or other aetiological agent is confirmed, it
is not necessary to examine specimens from all
cases or contacts. n fact, this should be
discouraged since it places an unnecessary burden
on laboratory facilities and is not required for
effective treatment.
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CHOLERA AND DYSENTERY _ LAB
Stool specimens or rectal swabs should be sent to
the laboratory in a transport medium such as Cary-Blair medium (VR medium, alkaline Peptone Water
for Cholera). If a transport medium is not available,
cotton tipped rectal swab soaked in the liquid stool
should be placed in a sterile plastic bag and tightlysealed. Specimens should be collected before the
patient has received any antibiotics.
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Prevention and control of water-borne outbreaks
General principles
The primary purpose of outbreak investigations is to control
the outbreak, limit its spread to other areas and assess how
preventive strategies can be further strengthened to reduceor eliminate the risk of such outbreaks in the future.
The control measures are most effective if these are
appropriate and specific and applied early. It is important that
information of an outbreak is received in a timely manner andcontrol measures are initiated promptly. Treatment should be
accessible to prevent deaths.
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THE CONTROL OF WATER BORNE DISEASES
REQUIRES ESSENTIALLY:
Supply of safe drinking water
proper disposal of human excreta
Good food hygiene
Good personal hygiene
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CHLORINATION OF WATER
Chlorination of water sources renders water safe for
drinking. Standards have been laid down for minimum
chlorine levels which should be maintained.
Alternate arrangements for water supply, including tankers,should be arranged if immediate chlorination is not possible.
Chlorine releasing tablets are used for domestic use during
an outbreak.
Boiling is the safest method but is not practical as it requires
fuel which may be scarce or costly
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SANITATION
Sanitation is important to prevent faecal contamination of
water.
sanitary conditions should be checked and necessarymeasures taken for improving these conditions.
Stool of young children is as dangerous as of adults.
Human excreta should be disposed promptly and safely.
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CASE MANAGEMENT
Treatment of patients as per recommended guidelines is
important to reduce the risk of death.
Treatment facilities should be readily available and
accessible.
The community should be encouraged to seek treatment in a
timely manner as most deaths take place when patients are
brought late in terminal condition.
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PREPARATORY ACTION IN ANTICIPATION OF
AN OUTBREAK
Measures for the reduction of risks of outbreaks of water-
borne diseases are similar. Random monitoring of the water
quality for residual chlorine and for coli form organisms isimportant for identifying high risk pockets and for taking
preventive measures. IEC activities need to be stepped up
prior to the monsoon period regarding safe water,
environmental sanitation , personal and domestic hygienic
practices. A surveillance system should be in place so thatincrease in cases of diarrhoeal diseases or jaundice or
clustering of these cases is recognized early for timely
corrective measures.
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HEALTH EDUCATIONAL ACTIVITIES AND
COMMUNITY PARTICIPATION
Health education and public awareness and co-operation
are important to control an outbreak. If the community
knows how the outbreak spreads and what measures theycan take in their own families, the risks can be considerably
reduced. It is also important that the public should know that
treatment is simple and effective and there should be no
cause for panic. ORS packets should be widely accessible.
While the key messages will essentially remain the same for
all areas, the language and style may be adapted to local
needs