Transmission network analysis to complement routine tuberculosis contact investigations.

Area of Science:

• Public Health
• Epidemiology
• Infectious Disease Control

Background:

• Tuberculosis (TB) outbreaks require effective contact investigations to prevent further transmission.
• Traditional contact tracing methods may not efficiently identify all transmission pathways or prioritize high-risk contacts.

Purpose of the Study:

• To assess the feasibility and value of using network analysis to augment standard TB contact investigation protocols.
• To determine if network analysis can improve the prioritization of contacts for TB screening and evaluation.

Main Methods:

• Reviewed medical records and interviewed TB patients to gather data on secondary cases and contacts.
• Genotyped Mycobacterium tuberculosis isolates to identify transmission clusters.
• Evaluated contacts for latent TB infection (LTBI) and active TB, analyzing tuberculin skin test (TST) results.
• Applied network analysis visualizations and metrics (reach, degree, betweenness) to characterize outbreak dynamics.

Main Results:

• The study involved secondary TB patients and over 1200 contacts, with genotyping revealing a specific strain W variant.
• Contacts prioritized using network analysis demonstrated a significantly higher likelihood of having LTBI (OR=7.8).
• Network analysis effectively identified central individuals driving the outbreak and facilitated targeted contact evaluation.

Conclusions:

• A network-informed strategy offers a novel method for analyzing complex TB contact investigation data.
• This approach enhances the focus and efficiency of TB control efforts by prioritizing key individuals and contacts.