Epidemiology Of Q Fever In The South China Sea

Background and PurposeThe clinical manifestations of Q fever are not typical,with a high misdiagnosis rate.After developing into chronic infection,the treatment cycle is long and the harm is significant.There are few epidemiological surveys of Q fever in the south of China.Research shows that Q fever has a high incidence rate in tropical areas.South China is located in the tropics.Soldiers in this area have had fever of unknown origin for many times.Therefore,understanding the epidemiology of Q fever in the South China Sea is of great value in guiding the diagnosis and treatment of fever of unknown origin.MethodsFrom June 2020 to October 2022,go to Leizhou Peninsula,Hainan Island and South China Sea Islands to collect blood samples from soldiers stationed on the island.Collect blood samples of some wild animals and tick samples from South China Sea Islands.Collect blood samples from 5 domestic dogs on Hainan Island.Perform mNGS testing on collected blood samples and ticks.Perform Q fever serological testing on non febrile soldiers and soldiers who tested negative for mNGS in the South China Sea islands.Perform whole genome sequencing of the body of Coxiella burnetii.(1)The disease spectrum of fever of unknown origin in each island was counted,and the chi square test(SPSS 25.0 software)was used to compare whether there was any difference in the incidence rate of Q fever in each island;(2)Statistics on the infection rates of humans and animals in South China Sea Islands;(3)Comparison and tracing of the entire genome with Coxiella burnetii in Vietnam;(4)Statistics on the infection rate of domestic dogs on Hainan Island.ResultsA total of 206 blood samples were collected from soldiers,including 176 feverish soldiers(51 in Leizhou Peninsula,75 in Hainan Island,50 in South China Sea Islands),30 feverish free soldiers,and all feverish free soldiers were South China Sea Islands soldiers.In case of fever of unknown cause,7 cases(13.73%)of Q fever and 16 cases(31.37%)of tsutsugamushi disease were detected in Leizhou Peninsula,and 32 cases(54.9%)of pathogens were not detected;Among the soldiers with fever on Hainan Island,27 cases(36.00%)of Q fever,9 cases(12.00%)of scrub typhus,5 cases(6.67%)of melioidosis,1 case(1.33%)of leptospirosis,and 1 case(1.33%)of echinococcosis were detected,while 32 cases(42.67%)of pathogen were not detected;40 cases(80%)of Q fever were detected on the South China Sea Island,while the remaining 10 cases(20%)of mNGS did not detect pathogens.However,Q fever serology was positive,and all 30 non fever soldiers were positive.The infection rate of soldiers on the South China Sea Island was 100%.There are differences in the incidence rate of Q fever among the three islands.The incidence rate of the South China Sea island is the highest,followed by Hainan Island,and the incidence rate of Leizhou Peninsula is the lowest(P<0.05).The Q fever serological tests of non febrile soldiers on the South China Sea Island were all positive.All animals collected from the South China Sea island have detected the gene sequence of Coxiella burnetii,with an infection rate of 100%.Conclusions1.Q fever is an important cause of unexplained fever in the South China Sea;2.There are differences in the incidence rate of Q fever among the three islands.The incidence rate of the South China Sea Islands is the highest(80%),followed by Hainan Island(36.00%),and the incidence rate of Leizhou Peninsula is the lowest(13.73%);3.There is an epidemic of Q fever in the South China Sea Islands;4.Ticks may play a significant role in the transmission of Q fever,and insect borne bite transmission may be another important mode of Q fever transmission.