Scrub typhus, a disease with increasing threat in Guangdong

【作者】 吴德； 寇婧； 张欢；

【机构】 广东省疾病预防控制中心病原微生物检验所；

【摘要】 There has been a rapid increase in the number of scrub typhus cases in Guangdong, China. An epidemiologic study was conducted to understand the characteristics of scrub typhus epidemics in Guangdong. Human cases typically occur in the months of May and November each year with a huge peak composing of two peaks of cases observed in most years. The increasing incidence in humans from 0.4321 to 3.5917 per 100,000 was observed during the period of 2006-13. To detect the prevalence of Orientia tsutsugamush among suspected human cases and rodents, we performed ELISA tests of IgM/IgG and nest PCR tests on 42 whole blood samples from the suspected human cases and 112 spleen samples from rodents. 72.1%(31/42) of suspected cases and 59.5%(25/42) of rodents tested positive for anti-O.tsutsugamushi IgM and IgG, respectively; 11.9%(5/42) of blood samples and 13.4%(15/112) of spleen samples were positive for the 56-kDa antigen genes, respectively. Phylogenetic analysis revealed that there were four definable clusters among the 20 nucleotide sequences of the 56-kDa antigen genes: 40% Karp(8/20), 30% Gillima(6/20), 20% Kato(4/20) and 10% TA763(2/20). The high infection rate of O. tsutsugamush among rodents highlights the increasing incidence in humans, multiple genotypes of O. tustusgamushi co-circulating play a key role in the highly intensive prevalence of scrub typhus in the Guangdong area.更多还原

【Abstract】 There has been a rapid increase in the number of scrub typhus cases in Guangdong, China. An epidemiologic study was conducted to understand the characteristics of scrub typhus epidemics in Guangdong. Human cases typically occur in the months of May and November each year with a huge peak composing of two peaks of cases observed in most years. The increasing incidence in humans from 0.4321 to 3.5917 per 100,000 was observed during the period of 2006-13. To detect the prevalence of Orientia tsutsugamush among suspected human cases and rodents, we performed ELISA tests of IgM/IgG and nest PCR tests on 42 whole blood samples from the suspected human cases and 112 spleen samples from rodents. 72.1%(31/42) of suspected cases and 59.5%(25/42) of rodents tested positive for anti-O.tsutsugamushi IgM and IgG, respectively; 11.9%(5/42) of blood samples and 13.4%(15/112) of spleen samples were positive for the 56-kDa antigen genes, respectively. Phylogenetic analysis revealed that there were four definable clusters among the 20 nucleotide sequences of the 56-kDa antigen genes: 40% Karp(8/20), 30% Gillima(6/20), 20% Kato(4/20) and 10% TA763(2/20). The high infection rate of O. tsutsugamush among rodents highlights the increasing incidence in humans, multiple genotypes of O. tustusgamushi co-circulating play a key role in the highly intensive prevalence of scrub typhus in the Guangdong area.更多还原