Tuberculosis burden in Vietnam increasing with contribution from low detection rates and increased drug resistance. There is a need to identify MDR-TB (MultiDrug Resistant Tuberculosis) among both notified TB cases and their contacts in the community. Traditional contact tracing often focuses on household contacts while strains of TB circulate in homes, schools, workplaces, and beyond. Social network Analysis (SNA) is a comprehensive approach which includes a set of persons and the connections among them used for analysis of structure of disease transmission.

In this study, SNA will be used to collect network data from 60 newly detected Rifampicin resistant TB patients including an expected 50 MDR-TB patients living in Hanoi, and to identify and test potential MDR-TB cases.

The study will identify and recruit 60 newly detected Rifampicin resistant TB patients including an expected 50 MDR-TB patients living in Hanoi (index cases) who will undergo SNA of contacts and places they have stayed during 3 months preceding their TB diagnosis including residence, travel history, places of social aggregation in relation with their risk behaviour.

Patients will be interviewed to investigate contacts before the confirmation of MDR-TB (for early contact detection and minimize the risk of information lost due to patient default during treatment). Data analysis will focus on MDR-TB social networks using Cytoscape software.

After the first two enrolled Rifampicin resistant MDR-TB cases, social network data will be analyzed to identify close contacts, mutual contacts, mutual places and high risk locations. The Social Network Questionnaire (SNQ) will be contextualized to the Vietnamese setting and validated in a pilot study. Eligible contacts and locations will undergo MDR-TB screening.

Approximately 720 contacts will undergo active screening (on 2 occasions per individual: at the time of contact identification and 6 months later). Contacts will include household contacts, close contacts, mutual contacts and symptomatic individuals with significant exposure to the index case at mutual locations within a closed environment.

Contact screening will involve clinical assessment, chest X-ray and sputum or gastric aspirate collection for TB culture, molecular techniques and microbiological identification.

If contacts are screened and detected as having Rifampicin resistant TB, they will be invited to be included in SNA for further analysis.

The number of MDR-TB detected by SNA will determine whether transmission of MDR-TB not otherwise detected by routine contact investigation (only household contact tracing) is important. While traditional contact tracing practices in Vietnam mainly focus on household contacts to detect secondary cases of TB, this SNA is expected not only to identify secondary cases of MDR-TB within an extended catchment but to also identify the source cases of MDR-TB patients to " turn off the tap" of MDR-TB transmission. Moreover, the places identified as the sources of sustained transmission will be targeted for case finding along with appropriate resource allocation.

In this study analysis will focus on the costs of contact tracing with Social Network Questionnaires, the proportion of MDR-TB among eligible contacts by subgroup, the proportion of MDR-TB among Rifampicin resistant TB patients and the genotyping pattern of MDR -TB patients.

Inclusion Criteria:

• PATIENTS: Newly detected rifampicin resistant TB or MDR-TB patients living in Hanoi for at least 3 months preceding a diagnosis made between 2013-2015.
• CONTACTS: During the 3 months before the patient's TB or MDR-TB diagnosis: all persons who spend an average of >4 hours per day in the same residence as the patient AND/OR any individual who has had frequent and prolonged contact with the patient AND/OR anyone who has spent time in a closed environment with an MDR-TB patient
• PATIENTS AND CONTACTS: All ages
• PATIENTS AND CONTACTS: Living in Hanoi during the study period.

Exclusion Criteria:

-PATIENTS AND CONTACTS: Lack of informed consent for participation.

Patients with newly detected rifampicin resistant TB or MDR-TB and their contacts