This pilot study found the collaborative approach was feasible and indicates transmission exists among the student population receiving TB treatment. The study estimated prevalence of 3.2% is similar to the pooled prevalence of active TB (all forms) among close contacts of 3.1% and 4.5% reported in two comprehensive meta-analyses, one of which included 95 contact investigation studies in resource-limited countries [10, 17]. Our estimated prevalence was higher than the reported prevalence of 1.2% among adults in India  and 1.5% reported in a comparative meta-analysis study in eleven high burden countries . It was however lower than the prevalence of 6% reported in a Ugandan study . The reported variation in yield of contact investigation studies could be influenced by factors such as background prevalence of TB or HIV infection, design, and implementation of studies which includes screening strategies to identify and trace contacts and diagnostics methods used.
The study observed that sharing a bed with an index case was associated with the risk of contracting TB. Similarly, a study of risk factors for TB among close contacts reported that sharing a bedroom with an index case increased exposure to TB perhaps due to enhanced contact during the night, shared airspace, and sharing of MTB aerosols . Our findings were also consistent with earlier studies where the risk of transmission was reported to be related to the duration and proximity of contact with the source case, being in an enclosed space with the source case and the infectivity of the source case [21–23]. Those who shared a bed likely spent the most time with the patient during their period of infectivity (usually weeks to months before diagnosis) hence at the highest risk of infection. One study showed that symptomatic contacts with diagnosed TB had a comparatively longer duration of symptoms and greater duration of contact with index cases . These findings suggest that the duration of symptoms and duration of contact with index cases could be important predictors for the risk of TB among symptomatic contacts. In the setting of this study students share an average of four continuous months in the same room (duration of one university semester). This cross-sectional study sampled the contacts at a single point within this period, potentially before subsequent transmission from index cases to contacts occurred. It is therefore plausible the transmission rate in this study is a gross underestimation of actual transmission in this population. Future research, including a well-powered prospective cohort study, may improve our understanding of disease transmission.
Understanding the global threat of the youth as an infection pool and therefore potentially transmission to the wider population is of paramount importance in the global response to infectious diseases like TB and COVID 19. Closure of learning institutions and debates on when and how to re-open universities in the absence of a vaccine at the forefront of the COVID 19 strategic plans. Despite the small-scale nature of this pilot study, students played a major role in TB transmission. This timely study contributes to the limited knowledge of contact investigation in the youth population. The resource-limited context of the study demonstrated the feasibility of identifying the youth in universities with airborne infectious diseases and their social contacts. Collaborating and strengthening existing health systems shown in this study promotes identifying youth with TB and facilitates contact tracing. This paper highlights the importance of contact tracing among index cases of infectious disease, similar to TB, among students and justifies further research on the magnitude of transmission of airborne diseases among university students.
Study Strengths and Limitations
The main strength of this study was the systematic TB testing of all the contacts using GeneXpert which was reported to have high sensitivity  to detect TB compared to other diagnostic methods, hence very few TB cases were likely to have been missed. Collaboration with the Kilifi County TB Control programme enabled investigators to work with clinicians who helped in the identification of index patients ensuring that no student TB case was missed. The investigators also worked with Community health volunteers (CHV) who helped navigate the community where students live and aided in the recruitment of index patients and student contacts residing off-campus.
It is possible some students were on TB treatment from other hospitals. Therefore, this study captures a limited proportion of students with TB infection on treatment at KCH and thus under-represents the magnitude of TB among students. The convenience and operational design of this study using routine hospital data missed a majority of students. The stigma of a TB diagnosis, partly due to the association with HIV in this context, and age group promotes the testing and management of the university population within the vibrant private sector in Kilifi County. This population is mobile and 80% come from outside the study setting where diagnosis and treatment occur. Inclusion of the private and out of town facilities was not pursued due to time and resource constraints to conduct a larger study.
Currently no TB screening of students, either on admission or at regular intervals during attendance, occurs in Pwani University despite the infection pool they provide. New Students do provide a chest X-ray on admission however the true population with TB infection is unknown.This pilot study underestimates both the magnitude and transmission of TB within the student population.
Lastly, this was an exploratory study and was not powered to test features associated with TB transmission. Furthermore, the investigators did not have the capacity to perform genome sequencing to confirm index case-contacts transmission.
Conclusion and Recommendations
Students sleeping in crowded hostels promote TB transmission within universities, informing national TB control interventions. Collaborating with existing national TB programme systems is a feasible approach to recruit people with active disease and their social contacts. Expansion of this approach to a larger population of students with TB infection may demonstrate the magnitude of TB transmission within universities and their wider communities.