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Volume 19, Number 2—February 2013

Dispatch

High Seroprevalence for Typhus Group Rickettsiae, Southwestern Tanzania

Tatjana Dill1, Gerhard Dobler1, Elmar Saathoff, Petra Clowes, Inge Kroidl, Elias Ntinginya, Harun Machibya, Leonard Maboko, Thomas Löscher, Michael Hoelscher, and Norbert HeinrichComments to Author 
Author affiliations: Author affiliations: Medical Centre of the University of Munich, Munich, Germany (T. Dill, E. Saathoff, P. Clowes, I. Kroidl, T. Löscher, M. Hoelscher, N. Heinrich); DZIF German Centre for Infection Research–Ludwig Maximilian University of Munich, Munich (G. Dobler, E. Saathoff, M. Hoelscher, N. Heinrich); Bundeswehr Institute of Microbiology, Munich (G. Dobler); NIMR-Mbeya Medical Research Centre, Mbeya, Tanzania (P. Clowes, I. Kroidl, E. Ntinginya, L. Maboko, M. Hoelscher); Regional Medical Office, Mbeya (H. Machibya)

Main Article

Table

Covariates associated with seropositivity for typhus group rickettsiae, Mbeya region, southwestern Tanzania, 2007*

Covariate/stratum No. specimens (% positive) Univariable†‡
Multivariable†§
PR (95% CI)
p value
PR (95% CI)
p value
Age, y
5–<13.6 245 (5.3) 1 1 (–)
13.6–<27.7 245 (6.5) 1.23 (0.60–2.51) 0.568 1.28 (0.63–2.58) 0.495
27.8–<42.1 243 (12.3) 2.33 (1.23–4.39) 0.009 2.40 (1.28–4.49) 0.006
42.1–55.2 248 (14.9) 2.81 (1.53–5.18) 0.001 2.73 (1.49–4.99) 0.001
>55.2
246 (7.3)
1.38 (0.69–2.76)
0.365

1.41 (0.71–2.80)
0.331
Distance to nearest highway, km 1,227 (9.3) 0.96 (0.94–0.99) 0.012 0.97 (0–0.99) 0.011
Enhanced vegetation index, per 0.1 units 1,227 (9.3) 0.58 (0.44–0.76) <0.001 0.60 (0.46–0.79) <0.001
Persons/km2, per 1,000 persons
1,227 (9.3)
1.08 (1.04–1.12)
<0.001



Sex
F 672 (8.6) 1
M 544 (9.9) 1.15 (0.81–1.63) 0.430
Unknown
11 (18.2)
2.11 (0.59–7.58)
0.254



SES rank, per unit¶
1,227 (9.3)
1.08 (1.02–1.15)
0.008



Cattle/km2, per 100 cattle 1,227 (9.3) 1.28 (1.05–1.56) 0.017
No. cows owned 1,227 (9.3) 0.96 (0.84–1.09) 0.526
No. goats owned
1,227 (9.3)
0.94 (0.83–1.07)
0.367



Dogs owned
No 820 (8.8) 1
Yes 191 (8.4) 0.95 (0.54–1.67) 0.869
No information
216 (12.0)
1.37 (0.89–2.11)
0.150



Minimum ambient temperature, °C 1,227 (9.3) 0.92 (0.87–0.97) 0.004
Average day land surface temperature, °C 1,227 (9.3) 1.37 (0.71–2.63) 0.351
Average night land surface temperature, °C
1,227 (9.3)
0.61 (0.38–0.99)
0.044



Elevation, per 100 m 1,227 (9.3) 1.04 (1.00–1.08) 0.025
Rainfall, per 1,000 mm 1,227 (9.3) 0.53 (0.30–0.92) 0.025

*PR, prevalence ratio; SES, socioeconomic status. Blank cells indicate that the variables were not included in the multivariable analyses due to lack of multivariable significance.
†Results of univariable and multivariable Poisson regression adjusted for household clustering by using robust variance estimates.
‡Results of separate models for each of the covariates below.
§Multivariable model, including only age, distance to nearest highway, and enhanced vegetation index as covariates.
¶SES rank, rank (from 0 [lowest] to 10 [highest]), according to socioeconomic score.

Main Article

1These authors contributed equally to this article.

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