Case Investigation

Case investigation is an integral part of infectious disease case management.  Case investigation takes place after a case has been identified.

While this training will not go into much detail about case investigation, thorough investigation is required to develop an effective individual plan of care (required as part of case management).

The goals of the investigation process are to interrupt the disease transmission, find and treat exposed individuals, and gather enough information to be able to develop an effective individual plan of care from which the case will be managed.

Have you had experience developing an individual plan of care? 

In order to develop an effective individual plan of care that ensures interruption of disease transmission, the case manager must consider the case presentation, his/her knowledge of the microorganism, and how the disease is transmitted.

  • Some infectious diseases may have a higher risk of transmission, depending on the mode of transmission (i.e., blood/body fluids, airborne, droplet)

The LBOH should consult with the state health department when faced with a disease that they are unfamiliar with. State level resources can guide the LBOH through a proper investigation and the creation of an appropriate care plan.


Review the examples below.



Those who present with pulmonary symptoms of active TB can be infectious.

  • TB is transmitted through the air; thus, people who shared the same breathing space with the individual during their infectious period must be identified and evaluated

Given that TB is an airborne disease, the case manager must identify where the individual has been during that time.

  • Exposure sites could include school or work, as well as many others  

Perinatal Hepatitis B

When a pregnant woman tests positive for Hepatitis B, she is entered into case management by MDPH nurses, by the MDPH Refugee and Immigrant Health Program, or by the Boston Public Health Commission (BPHC).

  • BPHC performs all components of perinatal Hepatitis B case management for Boston residents
  • LBOH in other parts of the state take part in case investigation by assessing household and sexual contacts for infection and vaccination status

Vaccinating contacts will prevent further transmission, especially to the newborn who will soon be coming into the household.


Interruption of Disease Transmission

To protect the community, LBOH must ensure proper actions are in place to interrupt disease transmission to others. The steps required vary significantly based on the disease and modes of transmission.

In some cases, it is necessary to determine who the patient has been in contact with prior to diagnosis. This is referred to as a contact investigation.

As part of disease containment, if it has been determined that a contact investigation needs to be performed based on communicability of the infecting microorganism, individuals prioritized for testing and referral will be identified by the infectious disease case manager.

Think about your setting. How would you go about evaluating and communicating with affected individuals?

The evaluation method for those who test positive depends on the mode of transmission and includes education about the disease.

  • Applying the public health practices below is instrumental to interrupting disease transmission



Review the examples below.



Contact investigations of those identified to have come into contact with suspected TB patients are managed in a variety of ways.

  • LBOH work collaboratively with the state health department and a variety of partners depending on the exposure site
  • Patient and community education is provided by the team, which may include the local public health nurse, state TB nurse, state epidemiologist, and community health worker team to ensure every contact is identified, tested, evaluated, and referred for follow-up care (if needed)
  • Diagnostic testing such as tuberculin skin test or blood assay for is arranged through this collaboration and done in a systematic fashion


Perinatal Hepatitis B

Hepatitis B is a liver infection caused by the Hepatitis B virus (HBV). Hepatitis B is transmitted when blood, semen, or other body fluids from a person infected with HBV enters the body of someone who is not infected and not immune.

This can happen through sexual contact, sharing of needles or syringes, or birth (from mother to baby).

For some people, Hepatitis B is an acute short-term illness, but, for others, it can become a long-term chronic infection. The risk for chronic infection is related to age at infection.

  • Approximately 90% of infected infants become chronically infected, compared to 2–6% of adults

Because of the high risk of becoming chronically infected with HBV if exposed at a young age, perinatal Hepatitis B case management plays an important role in protecting these infants against chronic Hepatitis B.

Chronic Hepatitis B can lead to serious health issues, like cirrhosis or liver cancer. The best way to prevent Hepatitis B is by getting vaccinated. (CDC 2015).