School and household tuberculosis contact investigations in Swaziland: Active TB case finding in a high HIV/TB burden setting

Abstract

BackgroundInvestigation of household contacts exposed to infectious tuberculosis (TB) is widely recommended by international guidelines to identify secondary cases of TB and limit spread. There is little data to guide the use of contact investigations outside of the household, despite strong evidence that most TB infections occur outside of the home in TB high burden settings. In older adolescents, the majority of infections are estimated to occur in school. Therefore, as part of a project to increase active case finding in Swaziland, we performed school contact investigations following the identification of a student with infectious TB.MethodsThe Butimba Project identified 7 adolescent TB index cases (age 10–20) with microbiologically confirmed disease attending 6 different schools between June 2014 and March 2015. In addition to household contact investigations, Butimba Project staff worked with the Swaziland School Health Programme (SHP) to perform school contact investigations. At 6 school TB screening events, between May and October 2015, selected students underwent voluntary TB screening and those with positive symptom screens provided sputum for TB testing.ResultsAmong 2015 student contacts tested, 177 (9%) screened positive for TB symptoms, 132 (75%) produced a sputum sample, of which zero tested positive for TB. Household contact investigations of the same index cases yielded 40 contacts; 24 (60%) screened positive for symptoms; 19 produced a sputum sample, of which one case was confirmed positive for TB. The odds ratio of developing TB following household vs. school contact exposure was significantly lower (OR 0.0, 95% CI 0.0 to 0.18, P = 0.02) after exposure in school.ConclusionSchool-based contact investigations require further research to establish best practices in TB high burden settings. In this case, a symptom-based screening approach did not identify additional cases of tuberculosis. In comparison, household contact investigations yielded a higher percentage of contacts with positive TB screens and an additional tuberculosis case.

Tuberculosis Transmission in Households and Classrooms of Adolescent Cases Compared to the Community in China

“…In fact, our zero detection rate in 200 household members has 95% CI (0%, 1.83%). This fraction is not significantly different from the detection of the 1 of 40 household contact in Swaziland [10] ( p -value = 0.167 by Fisher Exact testing). Moreover, a report from United States detected one genito-urinary TB case among five household contacts from a student during a TB contact investigation [11].…”

“…Adolescent active TB case detection rates in school outbreak settings have been reported to be 2.9% in Korea [4], 4.1% in China [5], and 6% in the United Kingdom [6], suggesting TB is actively transmitted in school [5,7,8], particularly in students who share classes with the index case patient [9]. However, in most school TB outbreak investigations, contact investigation is usually confined to the school, while household transmission is often overlooked and neglected [10,11], and where potential household contacts with active disease may be identified. It has been well documented that household exposure to a known TB case is the primary risk factor for TB [12], especially for children [13].…”

Distinct Risk Factors for Clinical and Bacteriologically Confirmed Tuberculosis among Child Household Contacts in a High-Burden Setting

“…BUTIMBA, "The Royal Hunt" in siSwati, was an active case finding and household contact-tracing project implemented between 2013 and 2015 in three of Eswatini's four regions. 18,19 Seven TB basic management units (BMUs), including national and district hospitals, referral clinics, and a rural health center, participated in the program. Study staff at each BMU were trained to identify index cases beginning anti-TB treatment (ATT) and perform household contact tracing and evaluation using a novel family mapping tool.…”

“…This cross-sectional analysis focuses on child household contacts of adult index cases; results considering all agegroups are reported elsewhere. 18,19 Univariate and multivariate regression analyses were conducted to determine risk factors associated with any child TB diagnosis and bacteriologically confirmed child TB. Final models were determined using a purposive variable selection strategy; P-values less than 0.05 were considered significant.…”

Quality matters: Redefining child TB care with an emphasis on quality

“…Reframing child TB care from a ‘specialized’ service to a ‘routine, simplified standard-of-care’ service will allow clinicians across the spectrum to be empowered to accurately identify, diagnose and confidently treat child TB, including referrals within the health system when needed. Further, combined with robust active case finding in the community, a successful shift of child TB care from central to peripheral settings promises to dramatically narrow the abysmally large child TB detection gap of nearly 63% and enhance the quality of services [66], [67], [68], [69].…”