Azit et al. BMC Public Health (2019) 19:1432 https://doi.org/10.1186/s12889-019-7814-x RESEARCH ARTICLE Open Access Factors associated with tuberculosis disease among children who are household contacts of tuberculosis cases in an urban setting in Malaysia Noor Atika Azit1, Aniza Ismail1*, Norfazilah Ahmad1, Rohani Ismail2 and Shuhaily Ishak2 Abstract Background: With the rise in prevalence of childhood tuberculosis (TB) globally, contact tracing should be a powerful strategy for early diagnosis and management, especially in children who are household contacts of active TB cases. Here, we aimed to determine the prevalence and factors associated with TB disease in children who are household contacts of TB cases. Methods: We used a cross-sectional study with data from the Malaysian TB Information System (TBIS) recorded from 1 January 2014 to 31 December 2017. All children aged 0–14 years who were registered in the TBIS with at least one household contact of TB cases were included in the study. Multiple logistic regression analysis was performed to calculate the adjusted odds ratio (adj. OR) and for adjusting the confounding factors. Results: A total of 2793 children were included in the study. The prevalence of active TB was 1.5% (95% confidence interval [CI]: 1.31, 1.77%). Children aged < 5 years [adj. OR 9.48 (95% CI: 3.41, 26.36) p < 0.001] with positive tuberculin skin test [adj. OR 395.73 (95% CI: 134.17, 1167.13), p < 0.001] and investigation period of > 6 weeks [adj. OR 7.48 (95% CI: 2.88, 19.43), p < 0.001] had significantly higher odds for TB disease. Conclusions: The prevalence of TB disease in children who were household contacts of TB cases is relatively low. However, contact tracing programmes should not only focus on children aged < 5 years and with positive tuberculin skin test results, but also be empowered to reduce the investigation period. Keywords: Childhood tuberculosis, Active case finding, Urban setting, Active tuberculosis, Household contact Background is acquired through the inhalation of aerosol droplets Until recent years, the diagnosis of tuberculosis (TB) dis- containing bacilli expectorated by an active TB patient, ease in children has remained challenging. The majority especially in smear-positive pulmonary TB [3]. There- of studies conducted globally have revealed that child- fore, the likelihood of infection is higher when children hood TB remains under-recognised and underdiagnosed are close contacts of TB cases [4]. [1]. This is due to the non-specific presentation of the According to the WHO, close contact is defined as a cases and the paucibacillary characteristics of the smear person ‘living in the same household or in frequent con- finding. The World Health Organization (WHO) classi- tact with the source case’ [5]. The source case is a TB fies childhood TB as children aged 0–14 years with case that results in infection among their contacts [5]. Mycobacterium tuberculosis infection [2]. The infection The definition of household contact commonly used in TB contact tracing programmes is ‘a person or group of people, related or unrelated to each other, who live to- * Correspondence: [email protected]; [email protected] gether in the same dwelling unit and share a common 1Department of Community Health, Universiti Kebangsaan Malaysia Medical Centre (UKMMC), Jalan Yaacob Latif, Bandar Tun Razak, Cheras, 56000 Kuala source of food’ [1]. To improve the detection of TB Lumpur, Malaysia cases, the WHO and the International Union Against Full list of author information is available at the end of the article © The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Azit et al. BMC Public Health (2019) 19:1432 Page 2 of 6 TB and Lung Disease recommend that contact tracing conduct a case investigation and identify the contacts be included in national TB programmes (NTP) [5]. This through interviews and a home visit. All contacts will be is because, in childhood TB, early detection is one of the referred to the nearest health clinic for TB screening. To fundamental aspects of reducing morbidity and mortality ensure that the contacts follow the referral, a written no- [6]. Most childhood TB cases are related to close contact tice is issued to the contacts and to the TB team in- with TB disease [1, 5]. A meta-analysis found that chil- charge at the nearest clinic. At the clinic, the contacts dren who were household contacts had four times will be screened by trained medical personnel, and all higher chances of acquiring infection compared to non– necessary contact information will be recorded in the household contact children [7]. Malaysian TB Information System (TBIS). This process Currently, contact tracing is widely practised in low–TB is monitored and verified regularly by the district health burden countries [8]. In Malaysia, it is routinely per- officers in charge. The TBIS contains data for TB sur- formed after an active TB case is detected and notified to veillance system in Malaysia. Data from the district will the health department. According to the Malaysian Clin- be analysed at the state level by the state TB organizer ical Practice Guidelines for TB, a child contact must be before compilation at the national level. The Kuala Lum- screened within 6 weeks of diagnosis of the index case [9]. pur Federal Health Office (JKWPKL) is responsible for However, previous studies conducted in Malaysia have re- TB disease surveillance in Kuala Lumpur, and monitors vealed that most diagnosed TB cases remain heavily TB data from four districts: Titiwangsa, Cheras, Lembah dependent on passive case detection, where patients have Pantai and Kepong. already developed sufficiently significant symptoms spur- ring them to seek medical treatment [10]. This is an un- Study setting desirable outcome for any NTP, as TB is still prevalent in In 2016, the estimated population of Kuala Lumpur was the country. The WHO reported that childhood TB inci- 1.78 million. The city has achieved 100% urbanisation dence had increased to 1 million cases worldwide in 2016 and is the most densely populated state in Malaysia. In [11]. Regionally, the WHO Western Pacific Region has 2016, the population density was 6891 persons per also shown a 6% increase in total childhood TB compared square kilometre. The estimated population aged 0–14 to the previous report in 2015 [12]. years was 368,600, which accounts for 20.6% of the total A similar pattern has surfaced in Malaysia, with the es- population in the city [13]. timated incidence increasing from 2800 cases to 3700 cases in the latest available report [11]. Even though Malaysia is classified as an intermediate–TB burden Study design and population country by the WHO, TB nevertheless poses a great This research adopted a cross-sectional study utilising threat, as the neighbouring countries are high–TB bur- TBIS data for the JKWPKL. All children registered in den countries, e.g. Indonesia and Thailand [11]. More- the TBIS from 1 January 2014 to 31 December 2017, over, Malaysia, particularly the capital city of Kuala aged 0–14 years and with at least one household active Lumpur, receives an influx of immigrants from other TB case (index case), were included in the study. The high–TB burden countries from time to time. Therefore, operational definition for household contact was the contact tracing plays an important role in the TB pre- children and their index case sharing the same residen- vention and control, apart from high-risk groups screen- tial address. The minimum sample size was calculated ing in the community. This situation indicates a further based on the formula for cross-sectional studies by Fleiss need to explore the predictors of TB disease in children (with reference to Narayanan et al. [2007]), with power who are household contacts to aid health authorities in of 80% and a confidence interval (CI) of 95% [14, 15]. A developing a more strategic and efficient TB control and minimum of 240 samples were obtained. prevention programme. Hence, the present study aimed to identify the prevalence and the factors associated with Study tools TB disease in children who are household contacts of The JKWPKL TBIS was used. This system contains in- active TB cases to improve understanding of this issue. formation on all TB contacts and the index cases. Methods Background of contact tracing in Malaysia Ethical approval In Malaysia, TB is a mandatory notifiable disease under Approval for this study was obtained from the Medical the Prevention and Control of Infectious Disease Act Research and Ethics Committee of the Malaysian Minis- 1988 [9]. The district health office will receive a notifica- try of Health (NMRR-18-642-39,752) and the National tion from the treating doctors within 1 week after a TB University of Malaysia Faculty of Medicine Ethics Com- case is diagnosed. The district health officers will then mittee (UKM PPI/111/8/JEP-2018-572). Azit et al. BMC Public Health (2019) 19:1432 Page 3 of 6 Outcome variables and most were from the main ethnic group, i.e. the The primary outcome was TB disease in children and Malays (74.4%). Clinically, 95.3% (n = 41) had TB symp- was defined as children who were identified as con- toms, 48.8% (n = 21) had positive TST, 86.0% (n = 37) firmed TB cases in the TBIS.