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Volume 24, Number 3—March 2018
Research

Prospective Observational Study of Incidence and Preventable Burden of Childhood Tuberculosis, Kenya

Andrew J. BrentComments to Author , Christopher Nyundo, Joyce Langat, Caroline Mulunda, Joshua Wambua, Evasius Bauni, Joyce Sande, Kate Park, Thomas N. Williams, Charles R.J. Newton, Michael Levin, J. Anthony G. Scott, on behalf of the KIDS TB Study Group
Author affiliations: KEMRI–Wellcome Trust Research Programme, Kilifi, Kenya (A.J. Brent, C. Nyundo, J. Langat, C. Mulunda, J. Wambua, E. Bauni, T.N. Williams, C.R.J. Newton, J.A.G. Scott); Oxford University Hospitals NHS Foundation Trust, Oxford, UK (A.J. Brent, K. Park); University of Oxford, Oxford (A.J. Brent, C.R.J. Newton, J.A.G. Scott); Imperial College London, London, UK (A.J. Brent, M. Levin); Aga Khan University, Nairobi, Kenya (J. Sande); London School of Hygiene and Tropical Medicine, London (J.A.G. Scott)

Main Article

Table 1

Baseline characteristics of children with and without TB examined at Kilifi County Hospital and Coast Provincial General Hospital, Kenya, August 2009–July 2011*

Characteristic
Confirmed TB, n = 73
Highly probable TB, n = 83
Treated for possible TB, n = 141
Not TB/TB excluded, n = 1,320
Not classifiable, n = 425
Case ascertainment
Passive case detection 71 (97) 79 (95) 141 (100) 1,237 (94) 410 (96)
Active case detection (contact tracing)
2 (3)
4 (5)
0 (0)
83 (6)
15 (4)
Patient demographics
Median age (interquartile range), mo 52 (16–114) 32 (13–70) 17 (10–64) 17 (10–41) 17 (9–44)
0–4 y 38 (55) 59 (71) 99 (70) 1,119 (85) 345 (81)
5–9 y 17 (25) 15 (18) 27 (19) 140 (11) 56 (13)
10–14 y 18 (25) 9 (11) 15 (11) 61 (4) 24 (6)
Sex
M 39 (53) 43 (52) 70 (50) 696 (53) 224 (53)
F
32 (47)
40 (48)
71 (50)
624 (47)
201 (47)
Risk factors for TB
HIV infected 17 (23) 21 (25) 42 (30) 160 (12) 112 (26)
Severely malnourished 30 (41) 37 (45) 58 (41) 457 (35) 162 (38)
BCG vaccination scar 65 (89) 86 (71) 128 (91) 1,172 (89) 338 (80)
Close TB contact
36 (49)
33 (40)
27 (19)
246 (19)
78 (18)
Clinical features of suspected TB
Cough >2 wks 48 (66) 48 (58) 95 (67) 572 (43) 225 (53)
Fever >2 wks 45 (62) 30 (36) 92 (65) 502 (38) 196 (46)
Weight loss or failure to thrive >4 wks 42 (58) 39 (47) 77 (55) 575 (44) 208 (49)
Pneumonia not responding to 1st-line ABX
27 (37)
25 (30)
42 (30)
308 (23)
159 (37)
TB clinical syndrome
Smear-positive pulmonary TB 20 (27) 4 (5) 0
Smear-negative pulmonary TB 40 (55) 69 (83) 108 (77)
All pulmonary TB† 60 (82) 73 (88) 108 (77)
Extrapulmonary TB† 30 (41) 17 (20) 46 (33)
Miliary TB 6 (8) 3 (4) 5 (4)
TB meningitis 8 (11) 2 (2) 12 (9)
Pleural TB 6 (9) 2 (2) 7 (5)
TB lymphadenitis 6 (8) 6 (7) 6 (4)
Osteoarticular TB 2 (3) 3 (4) 1 (1)
Abdominal TB 9 (12) 2 (2) 10 (7)
Persistent fever without a focus
0
1 (1)
13 (9)


Drug resistance
Isoniazid monoresistance 0
Multidrug-resistant TB 1 (1.4)

*Values are no. (%) unless otherwise indicated. ABX, antibiotics; BCG, bacillus Calmette-Guérin; TB, tuberculosis.
†Some children had >1 focus of infection, including some with pulmonary TB and extrapulmonary TB. Among children with confirmed TB, microbiologic confirmation was required from >1 site; diagnosis of other sites of disease were based on the definitions of highly probable TB (online Technical Appendix Table 1, https://wwwnc.cdc.gov/EID/article/24/3/17-0785-Techapp1.pdf).

Main Article

1The following members of the Kilifi Improving Diagnosis and Surveillance of Childhood TB (KIDS TB) Study Group also contributed to patient recruitment, investigation, and management: Victor Bandika, Jay Berkley, Kath Maitland, Susan Morpeth, Daisy Mugo, Robert Musyimi, Agnes Mutiso, John Paul Odhiambo, Monica Toroitich, and Hemed Twahir.

Prospective data on childhood tuberculosis (TB) incidence and case detection rates (CDRs) are scant, and the preventable burden of childhood TB has not been measured in prospective studies. We investigated 2,042 children (<15 years of age) with suspected TB by using enhanced surveillance and linked hospital, demographic, notification, and verbal autopsy data to estimate the incidence, CDR, risk factors, and preventable burden of TB among children in Kenya. Estimated TB incidence was 53 cases/100,000 children/year locally and 95 cases/100,000 children/year nationally. The estimated CDR was 0.20–0.35. Among children <5 years of age, 49% of cases were attributable to a known household contact with TB. This study provides much needed empiric data on TB CDRs in children to inform national and global incidence estimates. Moreover, our findings indicate that nearly half of TB cases in young children might be prevented by implementing existing guidelines for TB contact tracing and chemoprophylaxis.

Page created: February 15, 2018
Page updated: February 15, 2018
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