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8/6/2019 Add Outbreak Investigation

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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

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