Abstract
Background: Knowledge gaps exist on risk factors for spotted fever group rickettsioses (SFGR) in sub-Saharan Africa. We sought to identify SFGR risk factors in Kilimanjaro Region, Tanzania.
Methods: We recruited febrile patients presenting at two hospitals in Moshi from February 2012 through May 2014. Standardised clinical and risk factor questionnaires were administered. SFGR exposure was defined as a Rickettsia africae immunofluorescence antibody reciprocal titer ≥64, and acute SFGR as a ≥four-fold rise between paired sera. Logistitic regression was used to identify associations.
Results: Of 1,190 participants providing ≥1 serum sample, median (range) age was 21.8 (0.3, 100.2) years, 545 (54.3%) were female, and 650 (54.6%) had SFGR exposure. Of 731 participants with paired sera, 67 (9.2%) had acute SFGR. On multivariable analysis, odds of acute SFGR were higher in age group 0-2 years (adjusted odds ratios [aOR] for older age groups <0.36, p<0.011), rural residence (aOR 4.1, p=0.007), and areas with maximum daily temperature <26°C (aORs for higher temperature groups <0.42, p-values<0.035). Odds of SFGR exposure were higher in those working in the garden (aOR 1.8, p=0.010), and seeing a dog (aOR 1.5, p=0.010). Odds of SFGR exposure were lower in age group 0-2 years (aORs for older age groups >1.5, p<0.026), female sex (aOR 0.62, p<0.001), and being from Chaga tribe (aOR 0.68, p=0.003).
Conclusion: Those aged <2 years, rural residents, and persons residing in areas with cooler temperatures had increased odds of SFGR. Our results identify groups for further research on tick exposure and for targeted prevention interventions.