A new emerging pandemic of severe fever with thrombocytopenia syndrome (SFTS)

摘要

The aim of this study is to make aware every one of the deadliest diseases named severe fever with thrombocytopenia syndrome (SFTS). It has become the worldwide pandemic in recent few years. It is a kind of haemorrhagic fever, caused by SFTS virus (SFTSV), a novel phlebovirus of family Bunyaviridae. This syndrome is also a tick-borne zoonosis that means the virus transmitted from tick bite (having virus) into human body, i.e. infection spread from animals to humans and also transmitted from human to human. Epidemiological data of SFTS was collected to know the nature/symptoms of SFTSV. First case of this disease has been reported in China, followed by Japan, South korea, Taiwan, USA and many other countries. Vertebrates are the host of this disease and tick functions as a vector, where the virus can undergo brisk changes using gene mutation, homologous recombination and reassortments. The major symptoms of hemorrhagic fever are fever, thrombocytopenia, leucopenia and gastrointestinal abnormalities. Sometimes in very severe cases, full body organ failure may also take place and average death rate in humans is nearly 10?%. Old aged peoples are more prone to SFTSV infection. Apart from the fact of increasing SFTSV related health problems to humans, the pathogenesis of SFTS virus in human is not entirely understood and no treatment to this virus is still available. The simplest way to protect our self from this infection is to refrain from tick bite. Therefore, this disease has evolved to produce serious health issues to humans in various countries of world including china. This review discussing about causative agent, epidemiology, pathogenesis, diagnosis and treatment of SFTS. In order to control the spread of SFTSV, we have to stop the viral transmission or to protect the easily vulnerable population from tick bites, avoiding direct contact of infectious and also to use personal protective devices for SFTS patients. So, the weather conditions, mode of transmission and creation of new therapeutics like vaccines and drugs are the main areas of forthcoming research. Keywords: SFTS (SFTSV), Tick bite, Phlebovirus, Hemorrhagic fever, Epidemiology, PathogenesisIntroductionDuring 2006–2007, various patients have been reported with the symptoms of having fever, stomach ache, gastrointestinal disorders, nausea, bloating, vomiting and thrombocytopenia in various regions of china [1, 2]. The first human case of severe fever with thrombocytopenia syndrome (SFTS), was also found in shaanxi province of western china and the patient was 66?years old man with high fever, chills, pharyngeal pain, nausea and vomiting [3]. The causative agent of this disease is SFTS virus, which was identified as a phlebovirus of family Bunyaviridae. In the initial days, it was suspected that this disease caused by Anaplasma phagocytophilum bacterium, but the pathogen was not isolated from the patients, till the isolation of SFTSV from the blood of human granulocytic anaplasmosis patient in 2009 from henan province. Like other phleoviruses, genome of SFTSV also consist of large, medium and small segments. Two non-overlapping open reading frames (ORFs) of small segment are encoding the nucleocapsid and non-structural proteins. The medium and large segments encode the RNA-dependent RNA polymerase and Gn-Gc envelope glycoproteins, respectively [4]. After complete sequencing of SFTSV, it shows close resemblance with Uukuniemi virus and sequences can also be found in GenBank. The infection is transmitted from infected tick and viral sequences obtained from these ticks on animal are closely related to those collected from human (zoonotic transmission) [5], but various reports are also available showing human to human transmission of infection [6–8]. In china, during 2013 to 2016, total 7419 cases of human have been confirmed with 355 deaths [9], SFTS has been also found in Henan, Hubei, Anhui, Shandong, Jiangsu, Zhejiang, Liaoning, Yunnan, Guangxi, Jiangxi and Shannxi [10]. After an epidemiological survey, SFTS have been also reported in Japan [11, 12], South Korea [13–15], USA [16] and Taiwan [9, 17]. So, due to the worldwide spread of SFTSV, high mortality rate and human communicable nature of virus, it poses a great menace globally.Besides from the fact of increasing SFTSV related health problems to humans, the pathogenesis of SFTS virus in human is not entirely understood and no treatment to this virus is still available. The simple way to protect our self from this infection is to refrain from tick bite. Therefore, this disease has evolved to produce serious health issues to humans in various countries of world including china. All review articles available in literature are deficient in clinical, epidemiological and research related description of SFTS [18–20, 9]. So, this review is the systematic presentation of SFTS cases, SFTSV and detailed summary of research. This review discussing about causative agent, epidemiology, pathogenesis, diagn