Case and Contact Investigation Training

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Case and Contact Investigation Training

• Public Health Seattle and King County

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(No Transcript)
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Objectives - Learner will know

• What a case investigation is
• What a contact investigation is
• What the steps in an investigation are
• The purpose of a contact investigation interview
• How to prioritize contacts
• How to decide when to expand and investigation
• How to evaluate a contact investigation

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What is a contact investigation?

• It is a procedure for identifying people exposed
  to someone with an infectious disease,
  determining their risk for becoming infected,
  evaluating them for disease and providing them
  with appropriate treatment.

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What is a case investigation?

• It is the process for identifying and confirming,
  through symptoms, laboratory test results and
  epidemiological evidence, who has a communicable,
  serious disease then treating this person and
  educating them on how to reduce the spread of
  their particular disease.

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Why are case and contact investigations done?

• To establish diagnosis
• To do lab testing
• To perform clinical evaluations
• To treat infected people
• To provide counseling to exposed people
  concerning disease control recommendations
• To prevent transmission to other people
• To prevent future outbreaks of disease

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When is a case and contact investigation done?

• It is done when someone with a serious and
  communicable infectious disease is reported to
  the health department. This report can come from
  a private health care provider, a laboratory,
  hospital, correctional facility or other
  institution where the patient is diagnosed.

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Definitions

• Contacts - people exposed to someone with an
  infectious disease, generally including household
  members, roommates or housemates, close friends,
  coworkers, classmates and others
• Types of contacts
• household or family
• social
• school
• work
• other

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Definitions continued

• Close contact - a person who has had prolonged,
  frequent or intense contact with a sick person
  while they were infectious resulting in increased
  risk for transmission of the infection
• Other than close contacts - contacts with less
  intense, less frequent or shorter durations of
  contact with the infected person corresponding to
  a lower risk for disease transmission

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Definitions continued

• High priority contacts - the contacts who are at
  most risk for serious disease and for the spread
  of disease to vulnerable populations
• Index patient - a person with suspected or
  confirmed disease who is the initial case
  identified by the health department

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Definitions continued

• Source case - a person with an infectious disease
  who is responsible for transmitting the disease
  to someone else
• Primary case - the person who introduces the
  disease into the population

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Definitions continued

• High risk contacts - contacts at particularly
  high risk of developing disease, young children,
  the elderly or immune compromised individuals or
  contacts that if they became infected would pose
  a significant risk to other vulnerable
  populations, (health care workers, teachers etc.)
  

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Definitions continued

• Infection rate - the percentage of persons who
  become ill out of all exposed people
• Period of infectiousness - the time period during
  which an ill person is capable of transmitting
  disease
• Transmission - The spread of an infectious agent
  from one person to another

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Definitions continued

• Field investigation - visiting the persons home,
  workplace and other places a case spent time.
  The purpose is to identify contacts and evaluate
  the environmental characteristics of the place in
  which exposure occurred.
• Exposure - The condition of being exposed to
  something that could have a harmful effect, such
  as an infectious agent.

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Steps in a case investigation

• Identify missing data pieces
• Conduct interviews with primary care providers
  and laboratories
• Track laboratory results
• Identify if the case needs to be isolated or
  quarantined
• Document the information you are gathering

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Steps in a case investigation continued

• Report and coordinate efforts with the state
  department of health
• Seek consultation from other health department
  employees, CDC, WHO etc.

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Steps in a contact investigation

• Establish the data collection tools that are
  going to be used
• Clarify rationale for contact investigation
• Set contact investigation priorities
• Conduct the patient interview
• Field investigation
• Risk assessment for transmission
• Decision about priority of contacts
• Evaluation of contacts

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Steps in a contact investigation continued

• Treatment and follow up for contacts
• Decision about whether or not to expand testing
• Evaluation of contact investigation activities

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Ensure prompt and accurate data intake and
assessment

• Establish forms and process as to how data is
  collected
• Ensure that all staff are aware of what
  information to gather and what to do with this
  data
• Arrange for any immediate care or isolation
  needed for identified patients and their contacts

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Ensure prompt and accurate data intake and
assessment continued

• Develop a system to follow up on missing or
  incomplete data
• Process data
• entry
• analysis

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Examples of Elements for Data Collection Forms
for Contact Investigations

• Index patient info.
• Name
• Address
• Phone (wk, home, cell)
• Date of Birth
• Employment or school
• Sex
• Race/ethnicity/language
• Disease onset, communicable period
• Symptoms

• Contact info.
• Name
• Address
• Date of birth
• Phone
• Relationship to patient
• Setting of exposure
• Days of exposure
• Hours of exposure
• Close/casual contact
• Symptoms

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Purpose of Contact Investigation Interview

• To find out more about the cases symptoms to
  help determine period of infectiousness
• To find out the places where the case spent time
  while they were infectious

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Purpose of Contact Investigation Interview
continued

• To identify the cases contacts, get locating
  information for them and find out how long the
  contacts were exposed to the patient while they
  were infectious
• To describe the nature of the contact including
  the date of exposure and the type of contact

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Symptoms

• Does the contact have symptoms
• How long have they had symptoms for
• Contacts may be able to relate these symptoms to
  dates such as holidays or birthdays
• With the patients approval family members or
  friends can also be interviewed to determine when
  symptoms began, (approval is not required but is
  nice to get if possible)

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Potential barriers to performing good contact
investigations

• Nearly everyone has contact with someone but it
  can be difficult to identify who these people are
• Patients may be reluctant to identify their
  contacts. For example they may be hesitant to
  identify people with whom they use illegal drugs,
  people who are here illegally or they simply may
  not want friends or family to know they are sick.

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Barriers continued

• The interviewer should be sensitive to their
  fears, explain the importance of evaluating the
  contacts and assure the patient that
  confidentiality will be maintained to the fullest
  extent of the law, (i.e. if child abuse is
  occurring this must be reported to authorities
  etc.)
• A good contact investigation form can help in
  obtaining consistent, accurate information.

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Places

• Have case or contact go over their daily routine
• People spend most of their time at home, work
  or school or in leisure or recreational
  environments
• Case should also be asked the characteristics of
  each place, including the size of the place, the
  amount of time spent there and what kind of
  ventilation was present and how much crowding
  there was in the area

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Environmental assessment

• For airborne diseases assess for
• circulation of air
• length of time in the environment
• size of the airspace
• location of the index case and each contact in
  the air space
• proximity and duration of contact
• did the contact have physical contact with the
  cases saliva

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Environmental assessment continued

• For food borne illnesses
• food history
• food storage and handling
• types of foods

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Environmental assessment continued

• For water borne illnesses
• water sources
• amount of water consumed
• type of exposure to water

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How to prioritize contacts

• To use time and resources well the investigation
  should be focused on the high priority contacts
  or the people most at risk for developing and/or
  transmitting severe disease.

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How to prioritize contacts continued

• Whether transmission occurs or not depends on how
  infectious the case is, how susceptible the
  contact is, the nature of the exposure between
  the case and the contact and what kind of
  environment the interaction between case and
  contact occurs in.

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Contacts most likely to be infected

• People with lower immunity
• elderly
• children under the age of four
• HIV positive people
• other immunosuppressed individuals

• People who have had
• close
• regular
• prolonged contact

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Concentric circle testing

• This is a method of testing contacts in order of
  risk for infection based on exposure time and
  circumstances. First the closest circle to the
  patient is evaluated then if they are positive
  the next circle is tested and so on until
  evaluation is deemed no longer necessary.

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How to decide whether or not to expand testing

• Evaluate the highest risk priority group for
  infection
• Look at the infection rate amongst these
  individuals
• If significant infection has occurred amongst the
  first group of close contacts then the
  investigation should be expanded

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Contact Investigation Evaluation

• Were the appropriate of contacts identified?
• Were the highest priority contacts identified and
  tested?
• Was the investigation performed in all applicable
  settings?
• Was the investigation expanded appropriately?

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Contact Investigation Evaluation continued

• Were contacts completely evaluated and where
  appropriate, given treatment?
• Did identified contacts complete, where
  appropriate, treatment regime?
• Did identified cases, where appropriate,
  treatment regime?

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Contact Investigation Evaluation continued

• Program evaluation is a critical component of
  every program. Evaluation of performance is
  important to ensure that resources and priorities
  are being used effectively on the highest
  priority activities.

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Review

• Today we learned.

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Sources of information for this presentation

• Dr. Jeff Duchin, Chief of Communicable Disease
  and Epidemiology, Public Health Seattle and King
  County
• Janice Boase, Assistant Chief of Communicable
  Disease and Epidemiology, Public Health Seattle
  and King County
• CDC Self Study Modules on Tuberculosis, Case and
  Contact Investigations