The Journal of Association of Chest Physicians

: 2014  |  Volume : 2  |  Issue : 1  |  Page : 31--32


Sourin Bhuniya 
 Department of Pulmonary Medicine, All India Institute of Medical Sciences, Bhubaneswar, Odisha, India

Correspondence Address:
Sourin Bhuniya
Department of Pulmonary Medicine, All India Institute of Medical Sciences, Sijua, Dumuduma, Bhubaneswar - 751 019, Odisha

How to cite this article:
Bhuniya S. Commentary.J Assoc Chest Physicians 2014;2:31-32

How to cite this URL:
Bhuniya S. Commentary. J Assoc Chest Physicians [serial online] 2014 [cited 2020 Aug 5 ];2:31-32
Available from:

Full Text

Tuberculosis (TB) remains a major global health challenge, affecting 8.8 million people each year, most of who live in the low and middle income countries. [1] Contact investigation involves the systematic evaluation of the contacts of known TB patients to identify active disease or latent TB infection (LTBI). Active case finding may be worthwhile in contacts of patients with TB because they are at higher risk of exposure to the causative organism than the members of the general population. [2] After exposure to airborne droplets containing Mycobacterium tuberculosis, some contacts will be infected and some of these will go on to develop the disease. The risk of a contact becoming infected relates to the infectiousness of the TB patient, the duration and proximity of the contact and susceptibility of the contact. [3],[4] The onset of disease may occur early, within 6 weeks or many years later. [5]

Such contact investigation has been standard practice for decades in high income countries, where the incidence of TB in general population is low. [6] Systematic evaluation of people who have been exposed to potentially infectious cases of TB can be an efficient, targeted approach to intensified TB case finding that is within the purview of TB control programs. There are, however, no comprehensive global recommendations for programs. World Health Organization (WHO), the International Union against Tuberculosis and Lung Disease (IUTLD), and the International Standards for Tuberculosis Care (ISTC) all recommend that children <5 years of age and persons living with human immunodeficiency virus (PLHIV) who are exposed to infectious cases of TB be evaluated for active TB and considered for treatment of LTBI if active TB is excluded. With these exceptions, there are no recommendations at global level to: [7]

Define the epidemiological and program conditions under which contact investigation is indicatedDescribe TB index patients on whom contact investigation should be focusedIdentify TB contacts who should be investigated (other than children <5 years of age and PLHIV) and recommend the procedures to be used for identifying, screening, and tracking TB contactsIn the study on active case finding in household contacts of infectious TB patients in Karachi, the authors have found a very high incidence of sputum positive TB among household contacts (11.7%), which is even higher than that found in India and China, which together share around one-third of global TB burden. There are reasons for caution when interpreting such results. The recruitment of contacts in contact investigations is almost always incomplete and is subject to selection bias. There is substantial risk of bias in the reported outcomes, owing to the observational design of such studies and the lack of suitably matched control population. Symptomatic contacts may be more likely than those without symptoms to comply with contact investigations. Hence, the measured prevalence of TB among contacts may overestimate the true prevalence of disease among contacts. HIV screening is a must in such a setting of high disease among household contacts even though HIV prevalence may be low in the general population. This is because due to many social, religious, and cultural practices; HIV may be underreported from such areas.

In the resource constraint countries of our subcontinent, with huge population and TB burden both, the issues of trained human resources and financial implications to carry out active case finding in all parts of the country play a vital role in deciding the cost effectiveness of such a strategy. If effective treatment with quality assured drugs and patient compliance to treatment are not given due importance, then giving priority only to active case finding will never bear the desired results. In a country with high illiteracy rate and population density, lack of basic health facilities like Bacillus Calmette-Guιrin (BCG) vaccination and where only 8% of TB cases have access to directly observed treatment, short-course (DOTS; WHO report 2010), resources should better be targeted to improve upon these basic needs. Increasing awareness among people with proper education and access to basic health care facilities will reap much more benefits in the long-term than active case finding in such a scenario.

A Cochrane review to determine whether systematic screening all the direct contacts of people with proven TB disease increases the early detection of TB, found that there are not currently any suitable randomized controlled trials or quasi-randomized controlled trials to answer this question. There is insufficient evidence to show whether screening programs for TB will improve the rate of diagnosis among contacts of known TB patients or reduce the rate of TB in the community. [8]

Therefore, TB control programs in all countries need to consider the effectiveness and cost implications of any contact investigation policy carefully. While observational studies show that contacts have a higher risk of developing TB than the general population, further research is needed to determine whether active case finding among contacts significantly increases case detection rates.


1World Health Organization. Global tuberculosis control 2011. Geneva: WHO, 2011.
2Greenaway C, Palayew M, Menzies D. Yield of casual contact investigation by the hour. Int J Tuberc Lung Dis 2003;7 (Suppl 3):S479-85.
3Fok A, Numata Y, Schulzer M, FitzGerald MJ. Risk factors for clustering of tuberculosis cases: A systematic review of population based molecular epidemiology studies. Int J Tuberc Lung Dis 2008;12:480-92.
4Yim JJ, Selvaraj P. Genetic susceptibility in tuberculosis. Respirology 2010;15:241-56.
5Marks SM, Taylor Z, Qualls NL, Shrestha-Kuwahara RJ, Wilce MA, Nquyen CH. Outcomes of contact investigations of infectious tuberculosis patients. Am J Respir Crit Care Med 2000;162:2033-8.
6Control and prevention of tuberculosis in the United Kingdom: Code of practice 2000. Joint Tuberculosis Committee of the British Thoracic Society. Thora×2000;55:887-901.
7World Health Organization. Recommendations for investigating contacts of persons with infectious tuberculosis in low- and middle-income countries. Geneva: WHO, 2012.
8Fox GJ, Dobler CC, Marks GB. Active case finding in contacts of people with tuberculosis. Cochrane Database Syst Rev 2011;CD008477.