An outbreak of endemic typhus in Baoshan city, Yunnan province / 中华流行病学杂志

ABSTRACT

Objective To understand the epidemiologic characteristics of endemic typhus in Baoshan city. Methods Epidemiological data were collected and characteristics were analyzed. IgG antibody(Ab) of Rickettsia mooseri and Orientia tsutsuganushi in serum of patients were tested using both Weil-Felix and IFA method. The Rickettsia mooseri gltA gene, Rickettsia prowazekii gltA gene,Orientia tsutsugamushi 56 kDa protein gene, SFGR ompA gene, Ehrlichia sp. 16S rRNA gene and Anaplasma sp. 16S rRNA gene in spleen of mice were examined by PCR. Results Fifty- eight endemic typhus cases were found in Longyang district of Baoshan city, during July to August, 2009.Among them, 48 cases were confirmed by clinical diagnosis and 10 cases by laboratory tests. The Ab of Orientia tsutsugamushi Karp serotype was detected in 3 cases from laboratory diagnosis. The spleen samples from 85 Rattns flavipectus were tested using PCR. Of them, 3 samples for Rickettsia mooseri gltA gene showed positive (positive rate was 3.5% ), and the homology of 3 Rickettsia mooseri and Rickettsia mooseri Wilmington strain (GenBank U59714.1) was 100% through comparing gene sequence. The results of PCR for detecting Rickettsia prowazekii, Orientia tsutsugamushi, SFGR,Anaplasma sp. and Ehrlichia. sp were all negative. Conclusion The outbreak of endemic typhus was confirmed in Longyang district of Baoshan city through epidemiological data, clinical diagnosis and laboratory tests. Rickettsia mooseri DNA was detected in the dominant Raw flavipectus, suggesting that endemic typhus did exist in the local areas.