# The Role of Casual Contact and Migration in XDR TB Transmission in South Africa: a Geospatial, Genomic and Social Network Study

> **NIH NIH R01** · EMORY UNIVERSITY · 2021 · $715,301

## Abstract

Tuberculosis (TB) is the leading infectious disease killer globally and is largely driven by transmission in
high incidence settings. Studies to date, however, have not been able to identify where the majority of
transmission is occurring. TB transmission has traditionally been attributed to prolonged, close contact, but
numerous studies have shown that only 9–30% of genotypically linked cases can be attributed to close
contact. A compelling alternative hypothesis is that the remaining 70% of transmission occurs due to casual
contact in the community, but this has never been verified. A better understanding of where transmission
occurs will enable the design of more effective interventions to curb TB incidence.
 In the Transmission of HIV-Associated XDR TB (TRAX) study in KwaZulu-Natal province, South Africa, we
demonstrated that extensively drug-resistant (XDR) TB is primarily driven by transmission, rather than acquired
resistance, overturning the prevailing belief. However, similar to drug-susceptible TB, less than one-third of
drug-resistant TB cases could be linked through close contact. Drug-resistant TB provides a unique opportunity
to study transmission due to casual contact, as the limited caseload allows for comprehensive genotyping to
identify transmission links between individuals who may name each other in a contact investigation.
 In the proposed study, we will test a novel hypothesis that casual contact and migration are fueling TB
transmission in high incidence settings. Rising rates of urbanization and migration throughout Asia and Africa
have created favorable conditions for TB transmission. Yet, to date, no studies have comprehensively studied
how migration may facilitate the spread of TB from urban to rural settings. In Aim 1, we will determine the
proportion of XDR TB that develops through casual contact and identify locations where transmission occurs
using genomic, social network, and geospatial analyses. In Aim 2, we will characterize migration patterns
among persons diagnosed with XDR TB in Durban to determine how migration creates opportunities for XDR
TB dissemination. In Aim 3, we will quantify the proportion of XDR TB cases from throughout KwaZulu-Natal
province that are genomically linked to cases in Durban using whole genome sequencing.
 The aims proposed in the CONTEXT (Casual Contact and Migration in the Transmission of XDR TB)
study build upon our established research infrastructure and successful track record of combining state-of-the-
art methodologies to gain insight into TB transmission. New knowledge from this study will be essential for
informing evidence-based interventions to halt TB transmission and reduce drug-susceptible and drug-resistant
TB incidence. This will include near real-time data on genomically linked TB cases, as well as the identification
of locations that will be highest yield for targeting interventions to decrease airborne transmission. Together,
the knowledge and integrated methodology...

## Key facts

- **NIH application ID:** 10079465
- **Project number:** 5R01AI138646-04
- **Recipient organization:** EMORY UNIVERSITY
- **Principal Investigator:** Kogieleum Naidoo
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $715,301
- **Award type:** 5
- **Project period:** 2018-01-17 → 2022-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10079465

## Citation

> US National Institutes of Health, RePORTER application 10079465, The Role of Casual Contact and Migration in XDR TB Transmission in South Africa: a Geospatial, Genomic and Social Network Study (5R01AI138646-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10079465. Licensed CC0.

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