Browsing by Author "Quinn, Frederick"

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    Assessing a transmission network of Mycobacterium tuberculosis in an African city using single nucleotide polymorphism threshold analysis
    (MicrobiologyOpen, 2021) Yassine, Edriss; Galiwango, Ronald; Ssengooba, Willy; Ashaba, Fred; Joloba, Moses L.; Zalwango, Sarah; Whalen, Christopher C.; Quinn, Frederick
    Tuberculosis (TB) is the leading cause of death in humans by a single infectious agent worldwide with approximately two billion humans latently infected with the bacterium Mycobacterium tuberculosis. Currently, the accepted method for controlling the disease is Tuberculosis Directly Observed Treatment Shortcourse (TB-DOTS). This program is not preventative and individuals may transmit disease before diagnosis, thus better understanding of disease transmission is essential. Using whole-genome sequencing and single nucleotide polymorphism analysis, we analyzed genomes of 145 M. tuberculosis clinical isolates from active TB cases from the Rubaga Division of Kampala, Uganda. We established that these isolates grouped into M. tuberculosis complex (MTBC) lineages 1, 2, 3, and 4, with the most isolates grouping into lineage 4. Possible transmission pairs containing ≤12 SNPs were identified in lineages 1, 3, and 4 with the prevailing transmission in lineages 3 and 4. Furthermore, investigating DNA codon changes as a result of specific SNPs in prominent virulence genes including plcA and plcB could indicate potentially important modifications in protein function. Incorporating this analysis with corresponding epidemiological data may provide a blueprint for the integration of public health interventions to decrease TB transmission in a region.
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    Excess Risk of Tuberculosis Infection Among Extra-household Contacts of Tuberculosis Cases in an African City
    (Clinical Infectious Diseases, 2021) Kakaire, Robert; Kiwanuka, Noah; Zalwango, Sarah; Sekandi, Juliet N.; Quach, Trang Ho Thu; Castellanos, Maria Eugenia; Quinn, Frederick; Whalen, Christopher C.
    Although households of tuberculosis (TB) cases represent a setting for intense transmission of Mycobacterium tuberculosis, household exposure accounts for <20% of transmission within a community. The aim of this study was to estimate excess risk of M. tuberculosis infection among household and extra-household contacts of index cases. Methods. We performed a cross-sectional study in Kampala, Uganda, to delineate social networks of TB cases and matched controls without TB. We estimated the age-stratified prevalence difference of TB infection between case and control networks, partitioned as household and extra-household contacts. Results. We enrolled 123 index cases, 124 index controls, and 2415 first-degree network contacts. The prevalence of infection was highest among household contacts of cases (61.5%), lowest among household contacts of controls (25.2%), and intermediary among extra-household TB contacts (44.9%) and extra-household control contacts (41.2%). The age-adjusted prevalence difference between extra-household contacts of cases and their controls was 5.4%. The prevalence of infection was similar among the majority of extra-household case contacts and corresponding controls (47%). Conclusions. Most first-degree social network members of TB cases do not have adequate contact with the index case to experience additional risk for infection, but appear instead to acquire infection through unrecognized exposures with infectious cases in the community.
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    A prospective validation of a Clinical Algorithm to detect Tuberculosis in child contacts
    (American Thoracic Society, 2018) Zalwango, Sarah; Malone, LaShaunda; Stein, Catherine; Quinn, Frederick; Chakraburty, Srijita; Shen, Ye; Handel, Andreas; Martinez, Leonardo
    Over 60% of pediatric tuberculosis cases are undetected by healthcare services in low-income settings (1). Untreated children with tuberculosis have fatality rates of .20%, reaching above 40% in children ,5 years old (2). Specific, effective, and validated interventions to increase case detection in children are urgently needed.