Nursing and community rates of Mycobacterium tuberculosis infection among students in Harare, Zimbabwe.
BACKGROUND
African hospitals have experienced major increases in admissions for tuberculosis, but they are ill-equipped to prevent institutional transmission. We compared institutional rates and community rates of tuberculin skin test (TST) conversion in Harare, Zimbabwe.


METHODS
We conducted a cohort study of TST conversion 6, 12, and 18 months into training among 159 nursing and 195 polytechnic school students in Harare. Students had negative TST results (induration diameter, < or =9 mm) with 2-step testing at the start of training.


RESULTS
Nursing students experienced 19.3 TST conversions (increase in induration diameter, > or =10 mm) per 100 person-years (95% confidence interval [CI], 14.2-26.2 conversions per 100 person-years), and polytechnic school students experienced 6.0 (95% CI, 3.5-10.4) conversions per 100 person-years. The rate of difference was 13.2 conversions (95% CI, 6.5-20.0) per 100 person-years. With a more stringent definition of conversion (increase in the induration diameter of > or =10 mm to at least 15 mm), which is likely to increase specificity but decrease sensitivity, conversion rates were 12.5 and 2.8 conversions per 100 person-years in nursing and polytechnic school students, respectively (rate difference, 9.7 conversions per 100 person-years; 95% CI, 4.5-14.8 conversions per 100 person-years). Nursing students reportedly nursed 20,868 inpatients with tuberculosis during 315 person-years of training.


CONCLUSIONS
Both groups had high TST conversion rates, but the extremely high rates among nursing students imply high occupational exposure to Mycobacterium tuberculosis. Intense exposure to inpatients with tuberculosis was reported during training. Better prevention, surveillance, and management of institutional M. tuberculosis transmission need to be supported as part of the international response to the severe human immunodeficiency virus infection epidemic and health care worker crisis in Africa.
Corbett
Elizabeth L
EL
Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom. elc1@mweb.co.zw
Muzangwa
Joyce
J
Chaka
Kathryn
K
Dauya
Ethel
E
Cheung
Yin Bun
YB
Munyati
Shungu S
SS
Reid
Andrew
A
Hakim
James
J
Chandiwana
Steven
S
Mason
Peter R
PR
Butterworth
Anthony E
AE
Houston
Stan
S
D001500:BCG Vaccine / Q000276:immunology; D015331:Cohort Studies; D017714:Community-Acquired Infections / Q000453:epidemiology*; D003428:Cross Infection / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission; D015658:HIV Infections / Q000150:complications; D006801:Humans; D015994:Incidence; D017053:Infection Control / Q000706:statistics & numerical data; D017758:Infectious Disease Transmission, Patient-to-Professional; D016273:Occupational Exposure / Q000517:prevention & control / Q000706:statistics & numerical data*; D011446:Prospective Studies; D012111:Residence Characteristics; D013338:Students, Nursing; D014374:Tuberculin Test / Q000706:statistics & numerical data; D014376:Tuberculosis / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission*; D015030:Zimbabwe / Q000453:epidemiology
D001500:BCG Vaccine