Abstract
In a prospective cohort study of febrile patients in northern Tanzania, Q fever and spotted fever group rickettsiosis were common but were not diagnosed by physicians in the absence of specific clinical features and local diagnostic methods.
Background.
The importance of Q fever, spotted fever group rickettsiosis (SFGR), and typhus group rickettsiosis (TGR) as causes of febrile illness in sub-Saharan Africa is unknown; the putative role of Q fever as a human immunodeficiency virus (HIV) coinfection is unclear.
Methods.
We identified febrile inpatients in Moshi, Tanzania, from September 2007 through August 2008 and collected acute- and convalescent-phase serum samples. A ≥4-fold increase in immunoglobulin (Ig) G immunfluorescence assay (IFA) titer to
Coxiella burnetii
phase II antigen defined acute Q fever. A ≥4-fold increase in IgG IFA titer to
Rickettsia
conorii
or
Rickettsia
typhi
antigen defined SFGR and TGR, respectively.
Results.
Among 870 patients, 483 (55.5%) were tested for acute Q fever, and 450 (51.7%) were tested for acute SFGR and TGR. Results suggested acute Q fever in 24 (5.0%) patients and SFGR and TGR in 36 (8.0%) and 2 (0.5%) patients, respectively. Acute Q fever was associated with hepato- or splenomegaly (odds ratio [OR], 3.1;
P
= .028), anemia (OR, 3.0;
P
= .009), leukopenia (OR, 3.9;
P
= .013), jaundice (OR, 7.1
; P
= .007), and onset during the dry season (OR, 2.7
; P
= .021). HIV infection was not associated with acute Q fever (OR, 1.7
; P
= .231). Acute SFGR was associated with leukopenia (OR, 4.1
; P
= .003) and with evidence of other zoonoses (OR, 2.2
; P
= .045).
Conclusions.
Despite being common causes of febrile illness in northern Tanzania, Q fever and SFGR are not diagnosed or managed with targeted antimicrobials.
C. burnetii
does not appear to be an HIV-associated co-infection.