Contact tracing and partner notification: finding, interviewing and following contacts

Safe practice

Contact tracing finds the people exposed to an infectious person, tells them, checks them and supports them so the chain of transmission breaks.

Updated Nov 13, 2026

Key points

Three tasks: identify and list contacts, notify them, and follow them up (symptoms, testing, prevention, referral).
WHO suggests active follow-up (home visits, calls, messages) over leaving contacts to report themselves; certainty is very low.
Contacts with the highest priority: household members, children, people with HIV or other immunosuppression, and long or close exposure in small, poorly ventilated rooms.
For HIV partners, the person chooses how partners are contacted and gets time to decide; where the person accepts, WHO prioritises provider-assisted referral.
Confidentiality is part of the method: the identity of the index case is never revealed to contacts without consent.
In Colombia, TB contacts are searched in the first week after the index case is detected and again at set times during treatment.

What it is

WHO defines contact tracing as the systematic process of identifying, assessing, managing and supporting the contacts of infectious people. It starts during the case investigation: the nurse interviews the person with the disease, lists everyone who was exposed in a way that makes transmission likely, notifies them and follows them up. Who counts as a contact depends on the mode of transmission, the duration and closeness of the exposure and how infectious the case was. In tuberculosis the search covers the household, work and school; for HIV and syphilis it covers sexual and drug-injecting partners and, for HIV, untested biological children. In Colombia the territorial health office leads the field visit, and the IPS and the EPS make sure contacts get tested without barriers.

What it requires

Training in interview methods, confidentiality and cultural competence before interviewing index cases.
A nominal list of contacts (in TB, the contact book) that allows follow-up and indicators.
The person's consent and a private place for the interview, in the person's own language or with an interpreter.
Agreement with laboratories and services so that contacts are tested and treated quickly and without fees or authorisations that block access.

Components

Case interview: where the person lived, worked, studied, travelled and sought care during the infectious period.
Listing: name, place, health status and type, frequency and duration of exposure of each contact.
Prioritisation: who is at highest risk of infection or of severe disease.
Notification and assessment: symptoms, risk conditions, tests and preventive measures offered.
Follow-up and closure: repeat checks, referral and recording of results.

How it is applied (and why)

Review the case record before the interview — the diagnosis, test results and dates set the infectious period to explore.
Interview the person in private, explain the purpose and guarantee confidentiality — trust is what brings out the names of contacts.
Ask where the person spent time and with whom during the infectious period — contacts outside the home are easy to forget.
Visit the home and other key sites when the protocol says so — the visit finds more contacts, especially children, and shows ventilation.
List and rank the contacts by closeness and length of exposure and by their own risk — children and immunosuppressed people come first.
Notify each contact without revealing the index case, unless the person agreed — notification protects; disclosure without consent harms.
Assess symptoms and refer for the tests and preventive measures of the protocol — early detection stops new chains of transmission.
Follow up actively by visit, phone or message on the dates of the protocol — passive follow-up loses contacts.
Record each contact's result and close the list with the team — the list feeds surveillance and programme indicators.

In nursing practice

Expect stigma, shame and fear of rejection: explain why tracing protects the person's family and community.
In HIV, offer the person options (provider-assisted referral, self-referral) and time to decide; never force notification.
Tracers need skills in interviewing, de-escalation, field safety, confidentiality and cultural competence.
A contact with symptoms is managed as a possible case: refer the same day according to the protocol.

Common mistakes

Revealing the name of the index case to contacts, or talking about it in front of neighbours.
Listing only the household and forgetting the workplace, school or sexual partners.
Notifying once and never following up, so tests are not done.
Pressuring the person: testing services rest on consent, and the person chooses how partners are contacted.

Test yourself

Think of the answer, then tap the question to see it.

How does WHO define contact tracing?

As the systematic process of identifying, assessing, managing and supporting the contacts of infectious people.

Which TB contacts get the highest priority?

Household and congregate-setting contacts, young children, people with HIV or other immunosuppression, and those with long or close exposure in small, poorly ventilated spaces.

What type of follow-up does WHO suggest for contacts?

Active follow-up, with home visits, calls or messages from the health service, rather than passive follow-up in which the contact must report on their own. The recommendation is conditional, with very low certainty.

Who decides how the partners of a person with HIV are contacted?

The person. They are offered options and time to decide; WHO prioritises provider-assisted referral when the person accepts it.

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Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.

Sources: WHO guideline on contact tracing (World Health Organization, 2024); Guidelines for the Investigation of Contacts of Persons with Infectious Tuberculosis (MMWR Recommendations and Reports 54(RR-15)) (Centers for Disease Control and Prevention (CDC), 2005); HIV testing services: partner services and social network-based testing (World Health Organization, 2024); Resolución 227 de 2020: lineamientos técnicos y operativos del Programa Nacional de Prevención y Control de la Tuberculosis (Ministerio de Salud y Protección Social, Colombia, 2020).

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