Owing to limited evidence, the risk of and factors related to tuberculosis (TB) infection among care workers is not understood. We experienced an outbreak of TB with 2 cases of active TB (positive cultures) and 34 cases of latent TB infection at a care facility for the elderly. Using an epidemiological investigation of the outbreak, this study aimed to investigate the risk of and factors related to TB infection among care workers and to establish a system for TB control in care facilities for the elderly. The index patient (80-year-old woman; fever for 1.5 months) was diagnosed with TB [bI3: GAKKAI classification, sputum smear (3+)]. We investigated the contacts of the patient. On the basis of the epidemiological investigation, we conducted a contact examination of close contacts, including those of residents and care workers at the care facility and staff at the medical facility to which the patient was referred. Reviewing this information, we compared both the results of the QuantiFERON-TB Gold (QFT-GIT) test and the degree of contact in 10 care workers and 7 nurses who had close contact while providing care services to the patient. The QFT-GIT test was conducted twice: 3 weeks and 11-12 weeks after the last contact with the patient. The number of care workers who tested positive while providing care services to the patient were 3, 0, and 5 according to the contact time of < 20 h, 20 to < 40 h, and 40 to < 60 h, respectively. In addition, one equivocal result was found in the < 20 h group. Equivocal results were noted in 1, 1, and 0 nurses, respectively. Only care workers tested positive using the QFT-GIT test, and one developed active TB. Each of the care workers spent approximately 50 min daily in planned care service to the patient, while each of the nurses spent approximately 20 min for the same. Care workers provided daily care services such as feeding, changing the patient's posture, turning in bed, diaper changing, bathing, and providing a bed bath, and nurses provided services such as the measurement of vital signs, hydration, administration of medication, and exchange of cooling material for lowering body temperature. In addition, care workers had been in contact with the patient while providing care services before the patient developed fever, and nurses initiated contact with the patient for care after the fever developed. With regards to daily health monitoring, the staff of the care facility had not monitored the patient for fever, loss of appetite, and/or weight loss before the fever became apparent. On the basis of these results, we suggest that the risk of TB infection is higher in care workers than in nurses because they work in close proximity (with body contact) with the patient for a longer period of time during the infectious period, including the asymptomatic period. To reduce the risk of TB infection in care workers, it is important to establish early detection systems in care facility residents by improving compliance with TB preventive measures, including routinely conducting closer observation of these health conditions. The high rate of infection among care workers may have been related to the longer period of close contact while caring for the patient. To reduce such risks, it is important to establish an early detection system for TB preventive measures in care facilities for the elderly.
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Mar 6, 2019
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