Investigation Epidemic

download Investigation Epidemic

of 26

  • date post

    08-Apr-2018
  • Category

    Documents

  • view

    219
  • download

    0

Embed Size (px)

Transcript of Investigation Epidemic

  • 8/7/2019 Investigation Epidemic

    1/26

    INVESTIGATION OF AN EPIDEMIC

  • 8/7/2019 Investigation Epidemic

    2/26

  • 8/7/2019 Investigation Epidemic

    3/26

    VERIFICATIONS OF DIAGNOSIS

    It is the first step ,do as quickly as possible. It is not

    necessary to examine all the cases to arrive at a

    diagnosis. clinical examination of a sample of cases

    may well suffice. Lab investigations are most usefulto confirm the diagnosis but the epidemiological

    investigations should not be delayed until the lab

    results are available

  • 8/7/2019 Investigation Epidemic

    4/26

    CONFIRMATION OF THE EXISTENCE

    OF AN EPIDEMIC

    Second step. Done by comparing the disease

    frequencies during the same period of previous

    years. An epidemic is said to be exist when the no.

    of cases is in excess of the expected frequency forthat population based on past experience

  • 8/7/2019 Investigation Epidemic

    5/26

    DEFINING THE POPULATION AT RISK

    A.Obtainig a map of the area.

    Before beginning the investigation it is necessary to havea detailed and current map of the area. It shouldcontain information concerning natural landmarks, roadsand location of all dwelling units in each road or inisolated areas. Area may be divided into segments,using natural landmarks as boundaries. This may againdivided into smaller sections. Within each section thedwelling units may be designated by numbers.

    B.Counting of the population

    A complete census of the population by age and sex byhouse to house visits(if the general population affected)

  • 8/7/2019 Investigation Epidemic

    6/26

  • 8/7/2019 Investigation Epidemic

    7/26

    RAPID SEARCH FOR ALL CASES AND

    THEIR CHARECTERISTICS

    B.Epidemiological case sheet

    This includes:

    Name,Age,Sex,Occupation,Socialclass,Travell,

    History of previous expossure,Time of onset ofdisease,Signs&Symptoms of illness,Personnel contact athome,work,school and other places,Special events suchas parties attended, Foods eaten, and exposure to

    common vehicles such as water, food and milk, visits outof the community, History of injections, or bloodproducts, attendance at large gatherings. If the outbreak is large-random sample.

  • 8/7/2019 Investigation Epidemic

    8/26

    RAPID SEARCH FOR ALL CASES AND

    THEIR CHARECTERISTICS

    C.Searching for more cases:

    Patient may be asked if he knew of other cases inthe home,family,neigbourhood,school,workplace,

    having an onset within the incubation period ofthe index case, cases admitted to local hospitalsshould also be taken into consideration. Searchshould be carried out every day till the area is

    declared free of epidemic. This period is usuallytaken as twice the incubation period of the diseasesince the occurrence of last case

  • 8/7/2019 Investigation Epidemic

    9/26

    DATA ANALYSIS

    A . Prepare a

    chronologicaldistribution ofdates of onsetand construct

    an epidemiccurve

  • 8/7/2019 Investigation Epidemic

    10/26

    DATA ANALYSIS

    B. Place

    prepare a spot map of cases(geographic distribution)

    and if possible their relation to possible sources of

    infection eg:water supply, air pollution, foods eaten,

    occupation etc.Clustering of cases may indicate a

    common source of infection

  • 8/7/2019 Investigation Epidemic

    11/26

    DATA ANALYSIS

    C.Person

    Analyze the data by age,sex,occupation and other

    possible risk factors. Determine the attack rate/

    case fatality rate

  • 8/7/2019 Investigation Epidemic

    12/26

    FORMULATION HYPOTHESES

    On the basis of time-place-person/agent-host-

    environment model, formulate hypotheses to explain

    the epidemic in terms of

    A. Possible source

    B. Causative agent

    C. Possible mode of spread and

    D. The environmental factors which enabled it to occur

  • 8/7/2019 Investigation Epidemic

    13/26

    TESTING OF HYPOTHESES

    All possible hypotheses need to be considered and

    weighed by comparing the attack rates in various

    groups for those exposed, those not exposed to

    each suspected factor

  • 8/7/2019 Investigation Epidemic

    14/26

    EVALUATION OF ECOLOGICAL

    FACTORS

    Evaluation of the circumstances involved should be

    carried out to undertake appropriate measures to

    prevent further transmission

    Sanitary status of eating establishments, water and

    milk supply, breakdown in the water supply system,

    movements of the human population, atmospheric

    changes such as temp.,humidity and air pollution,population dynamics of insects, and animal reservoir

    Source-reservoir-modes of transmission

  • 8/7/2019 Investigation Epidemic

    15/26

    FURTHER INVESTIGATION OF

    POPULATION AT RISK

    Medical examination, Screening tests, examination of

    suspected food,faeces or blood samples,

    biochemical studies,assesment of immunity status

  • 8/7/2019 Investigation Epidemic

    16/26

    The report should be complete and

    convincing.

    WRITING THE REPORTS

  • 8/7/2019 Investigation Epidemic

    17/26

    CONTENTS OF REPORT

    1. Back ground

    2. Historical data

    3.

    Methodology of investigation4. Analysis of data (clinical data,Epideiological

    data, modes of transmission, Lab data,

    Interpretation of data)

    5. Control measures

    6. Evaluation

    7. Preventive measures

  • 8/7/2019 Investigation Epidemic

    18/26

    BACK GROUND

    Geographical location

    Climatic conditions

    Demographic status(Population pyramid) Socio-economic situation

    Organization of health services

    Surveillance&early warning systems

    Normal disease prevalence

  • 8/7/2019 Investigation Epidemic

    19/26

    HISTORICAL DATA

    Previous occurrence of epidemics

    1.Of the same disease

    2.Locally or elsewhereOccurrence of related diseases if any

    In the given area

    In other area

    Discovery of first case of the present outbreak.

  • 8/7/2019 Investigation Epidemic

    20/26

    METHODOLOGY OF INVESTIGATION

    Case definition,

    Questionnaire used in epidemiological investigation

    Survey teamsa. House to house

    b. Retrospective

    c. Prospective

    Collection of Lab. Specimens

    Lab techniques

  • 8/7/2019 Investigation Epidemic

    21/26

    ANALYSIS OF DATA

    A. Clinical data

    1.Frequency of signs&symptoms

    2. Course of disease

    3. Different diagnosis

    4. Death or sequelae rates

    B.Epidemiological data

    1.Mode of occurrence2. In time

    3.By place

    4. By population groups

  • 8/7/2019 Investigation Epidemic

    22/26

    ANALYSIS OF DATA

    C. Modes of transmission

    1. Source of infection

    2.

    Route of excretion and portal of entry3. Factors influencing transmission

    D. Lab data

    1. Isolation of agents

    2. Serological confirmation

    3. Significance of results

  • 8/7/2019 Investigation Epidemic

    23/26

    ANALYSIS OF DATA

    E. Interpretation of data

    1. Comprehensive picture of the outbreak

    2.

    Hypotheses on causes3. Formation and testing hypotheses by statistical

    analysis

  • 8/7/2019 Investigation Epidemic

    24/26

    CONTROL MEASURES

    Definitions of strategies and methodology of

    implementation

    Constraints

    Results

  • 8/7/2019 Investigation Epidemic

    25/26

    EVALUATION

    Significance of results

    Cost/Effectiveness

    Preventive measures

  • 8/7/2019 Investigation Epidemic

    26/26

    THANK YOU

    SUGUNAN.KR

    HEALTH INSPECTOR

    PHC PINDIMANA&PUNNEKKAD

    MOB:9446024671