High prevalence of pulmonary tuberculosis and inadequate case finding in rural western Kenya.
BACKGROUND
Limited information exists on the prevalence of tuberculosis and adequacy of case finding in African populations with high rates of HIV.


OBJECTIVE
To estimate the prevalence of bacteriologically confirmed pulmonary tuberculosis (PTB) and the fraction attributable to HIV, and to evaluate case detection.


METHODS
Residents aged 15 years and older, from 40 randomly sampled clusters, provided two sputum samples for microscopy; those with chest radiograph abnormalities or symptoms suggestive of PTB provided one additional sputum sample for culture.


RESULTS
PTB was defined by a culture positive for Mycobacterium tuberculosis or two positive smears. Persons with PTB were offered HIV testing and interviewed on care-seeking behavior. We estimated the population-attributable fraction of HIV on prevalent and notified PTB, the patient diagnostic rate, and case detection rate using provincial TB notification data. Among 20,566 participants, 123 had PTB. TB prevalence was 6.0/1,000 (95% confidence interval, 4.6-7.4) for all PTB and 2.5/1,000 (1.6-3.4) for smear-positive PTB. Of 101 prevalent TB cases tested, 52 (51%) were HIV infected, and 58 (64%) of 91 cases who were not on treatment and were interviewed had not sought care. Forty-eight percent of prevalent and 65% of notified PTB cases were attributable to HIV. For smear-positive and smear-negative PTB combined, the patient diagnostic rate was 1.4 cases detected per person-year among HIV-infected persons having PTB and 0.6 for those who were HIV uninfected, corresponding to case detection rates of 56 and 65%, respectively.


CONCLUSIONS
Undiagnosed PTB is common in this community. TB case finding needs improvement, for instance through intensified case finding with mobile smear microscopy services, rigorous HIV testing, and improved diagnosis of smear-negative TB.
Kenya Medical Research Institute, Kenya Medical Research Institute/Centers for Disease Control and Prevention Research and Public Health Collaboration, Kisumu, Kenya. a.h.vanthoog@amc.uva.nl
Anna H
AH
van't Hoog
Kayla F
KF
Laserson
Willie A
WA
Githui
Helen K
HK
Meme
Janet A
JA
Agaya
Lazarus O
LO
Odeny
Benson G
BG
Muchiri
Barbara J
BJ
Marston
Kevin M
KM
DeCock
Martien W
MW
Borgdorff
D000293:Adolescent; D000328:Adult; D015984:Causality; D016000:Cluster Analysis; D015897:Comorbidity; D005260:Female; D015658:HIV Infections / Q000453:epidemiology; D006801:Humans; D007630:Kenya / Q000453:epidemiology; D008297:Male; D009169:Mycobacterium tuberculosis; D015995:Prevalence; D012424:Rural Population / Q000706:statistics & numerical data; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000453:epidemiology*; D055815:Young Adult