Jimin Sun

Time series analysis of dengue fever and weather in Guangzhou, China

BackgroundMonitoring and predicting dengue incidence facilitates early public health responses to minimize morbidity and mortality. Weather variables are potential predictors of dengue incidence. This study explored the impact of weather variability on the transmission of dengue fever in the subtropical city of Guangzhou, China.MethodsTime series Poisson regression analysis was performed using data on monthly weather variables and monthly notified cases of dengue fever in Guangzhou, China for the period of 2001-2006. Estimates of the Poisson model parameters was implemented using the Generalized Estimating Equation (GEE) approach; the quasi-likelihood based information criterion (QICu) was used to select the most parsimonious model.ResultsTwo best fitting models, with the smallest QICu values, are selected to characterize the relationship between monthly dengue incidence and weather variables. Minimum temperature and wind velocity are significant predictors of dengue incidence. Further inclusion of minimum humidity in the model provides a better fit.ConclusionMinimum temperature and minimum humidity, at a lag of one month, are positively associated with dengue incidence in the subtropical city of Guangzhou, China. Wind velocity is inversely associated with dengue incidence of the same month. These findings should be considered in the prediction of future patterns of dengue transmission.

Systematic review of severe fever with thrombocytopenia syndrome: virology, epidemiology, and clinical characteristics.

Severe fever with thrombocytopenia syndrome (SFTS) was firstly discovered in China in 2010, followed by several reports from many other countries worldwide. SFTS virus (SFTSV) has been identified as the causative agent of the disease and has been recognized as a public health threat. This novel Bunyavirus belongs to the Phlebovirus genus in the family Bunyaviridae. This review also describes the different aspects of virology, pathogenesis, epidemiology, and clinical symptoms on the basis of the published article surveillance data and phylogenetic analyses of viral sequences of large, medium, and small segments retrieved from database using mega 5.05, simplot 3.5.1, network 4.611, and epi information system 3.5.3 software. SFTS presents with fever, thrombocytopenia, leukocytopenia, and considerable changes in several serum biomarkers. The disease has 10u2009~u200915% mortality rate, commonly because of multiorgan dysfunction. SFTSV is mainly reported in the rural areas of Central and North‐Eastern China, with seasonal occurrence from May to September, mainly targeting those of ≥50u2009years of age. A wide range of domesticated animals, including sheep, goats, cattle, pigs, dogs, and chickens have been proven seropositive for SFTSV. Ticks, especially Haemaphysalis longicornis, are suspected to be the potential vector, which have a broad animal host range in the world. More studies are needed to elucidate the vector–animal–human ecological cycle, the pathogenic mechanisms in high level animal models and vaccine development.

Epidemiological, clinical and viral characteristics of fatal cases of human avian influenza A (H7N9) virus in Zhejiang Province, China

BACKGROUNDnThe high mortality of avian influenza H7N9 in humans is a cause of great concern in China.nnnMETHODSnWe compared epidemiological, clinical and viral features of H7N9 influenza of 10 fatal cases and 30 survivors.nnnRESULTSnIncreasing age (pxa0=xa00.021), smoking (pxa0=xa00.04), underlying medical background (pxa0=xa00.05) and chronic drug use (pxa0=xa00.042) had a strong relationship with death due to H7N9 infection. Serological inflammatory markers were higher in fatal cases compared to survivors. Acute respiratory distress syndrome (100%), respiratory failure (100%), co-infection with bacteria (60%), shock (50%) and congestive heart failure (50%) were the most common complications observed in fatal cases. The median time from onset of symptoms to antiviral therapy was 4.6 and 7.4 days in those who survived and those who died, respectively (pxa0=xa00.04). Viral HA, NA and MP nucleotide sequences of isolates from both study groups exhibited high molecular genetic homology.nnnCONCLUSIONSnAge along with a history of smoking, chronic lung disease, immuno-suppressive disorders, chronic drug use and delayed Oseltamivir treatment are risk factors which might contribute to fatal outcome in human H7N9 infection.

Dengue virus serotype 3 subtype III, Zhejiang Province, China.

To the Editor: Beginning in July 2009, physicians in the city of Yiwu, Zhejiang Province, People’s Republic of China, noted an outbreak of illness characterized by rash, headache, subjective fever, itching, anorexia, and arthritis. We present the results of the investigation of this outbreak, which was caused by dengue virus (DENV) serotype 3 (DENV-3) subtype III. n nDENV-3 subtype III has been continuously circulating in the Indian subcontinent since the 1960s. The virus was first isolated from East Africa in 1985 in Mozambique and subsequently in Kenya (1991) and Somalia (1993) (1,2). Although dengue has occurred frequently in southern China, including Guangdong, Guangxi, Hainan, Fujian, and Zhejiang Provinces and in Taiwan (3–6), to our knowledge, DENV-3 subtype III has not been reported in China. n nYiwu is in the center of Zhejiang Province, southeastern China. This investigation included the entire town of Yiwu and towns that are part of the larger town of Yiting where the outbreak took place. We reviewed medical records and conducted prospective surveillance at all hospitals, health centers, and outpatient clinics in Yiwu to identify patients with suspected dengue fever (DF) during July 1 through October 31, 2009. According to the diagnostic criteria for DF (WS216–2008) enacted by the Chinese Ministry of Health, a patient with suspected disease had at least 2 of the following symptoms: acute onset of rash, headache, subjective fever, itching, anorexia, or arthralgia. Patients with suspected disease were asked to provide blood specimens during the acute phase (within 7 days after symptom onset). n nSerum samples were tested by ELISA for immunoglobulin (Ig) M against DENV by using the E-DEN01M kit (Panbio, Sinnamon Park, Queensland, Australia). Acute-phase serum samples were tested by real-time PCR for DENV RNA, according to the diagnostic criteria for dengue fever enacted by the Chinese Ministry of Health. Samples that were positive for DENV-3 by real-time PCR were inoculated into Aedes albopictus mosquito clone C6/36. Primers for reverse transcription–PCR and sequencing of the envelope gene of DENV isolates were used to identify DENV (4). n nWe considered a patient to have a confirmed case if DENV RNA was detected in the serum by real-time PCR or if IgM against DENV was present. A patient was considered to have a clinically diagnosed case if he or she had acute onset of rash, headache, subjective fever, itching, anorexia, and leukopenia, and lived in Qingsu, Fantianzhu, Xitian, or Shangzhai (4 adjoining villages in the area of the first confirmed case). n nThe sequences of isolates from case-patients were compared with published sequences by using the BLAST program (www.ncbi.nlm.nih.gov/BLAST/), and phylogenic analysis was calculated with PAUP 4.0 β 10 (7), which ran an unrooted tree with 1,000 bootstrap replicates. n nWe identified 196 cases of DF; 279 suspected cases were excluded, and no cases of dengue hemorrhagic fever or dengue shock syndrome were found. Of DF cases, 71 (36.2%) were confirmed and 125 (63.8%) were clinically diagnosed. Acute-phase serum samples were collected within 7 days after the onset of illness from 350 patients with suspected DF, and dengue virus RNA was detected in samples from 65 patients (18.6%). Six samples had IgM against DENV. n nTwenty-six samples positive for DENV RNA by real-time PCR were randomly selected to isolate viruses; 23 isolates were cultured. All isolates were amplified by reverse transcription–PCR, and amplicons were sequenced. The envelope gene sequences of all isolates were identical and 1,479 nt in length. All sequences had 99% similarity to 1 DENV serotype 3 partial envelope gene (GenBank accession no. {type:entrez-nucleotide,attrs:{text:AM746229,term_id:189086048}}AM746229), which had been detected in Jeddah, Saudi Arabia, in 2004. According to evolutionary analysis (Figure), sequences of our study were also most closely related to the isolate from Saudi Arabia, which suggests that the outbreak may have been initiated by imported cases from the Indian subcontinent or western Asia. n n n nFigure n nEvolutionary analysis of dengue virus isolates from this study (boldface) compared with established dengue virus serotype 3 subtypes, Zhejiang Province, People’s Republic of China, 2009. n n n nThe date of symptom onset among patients with confirmed or clinically diagnosed cases ranged from July 20 to October 4, 2009. Cases peaked in early September and subsided in early October. The median age of patients with confirmed or probable disease was 47.3 years (range 3–96 years). Infections occurred in all age groups, but most infections occurred among persons 41 to 65 years of age; 118 (60.2%) were women, and 172 were farm workers. n nConfirmed and clinically diagnosed cases occurred in 18 villages, which were part of 7 towns. Most cases (182) were reported in Yiting, where the first case was confirmed, and in particular, were in persons who lived in the villages of Qingsu, 100 cases; Fantianzhu, 49 cases; Xitian, 19 cases; Shangzhai, 4 cases; and Xiateng, 4 cases. n nThe outbreak shows that DENV-3 subtype III is easily transmitted among humans and mosquitoes and can adapt efficiently to a new area. Other countries where the climate is similar to that of Zhejiang Province (subtropical monsoon) should be aware of the risk for expansion of DENV-3 subtype III transmission. Clinical vigilance and strong epidemiologic and laboratory surveillance are essential.

Coinfection with Four Genera of Bacteria (Borrelia, Bartonella, Anaplasma, and Ehrlichia) in Haemaphysalis longicornis and Ixodes sinensis Ticks from China

We studied coinfection with four genera of bacteria--Borrelia, Bartonella, Anaplasma, and Ehrlichia--in ticks collected between December 2005 and November 2006 from Zhejiang Province and Liaoning Province. Four hundred fifty Haemaphysalis longicornis and 86 Ixodes sinensis ticks were collected and divided into 236 groups. Polymerase chain reaction (PCR) or nested PCR was used to detect the bacteria. The amplicons were sequenced and compared to published sequences. Phylogenic analysis was performed with MEGA3.1 and the data were analyzed using SPSS 11.0. Borrelia, Bartonella, Anaplasma, and Ehrlichia positive rates were 30.1% (71/236), 28.8% (68/236), 1.3% (3/236), and 0.8% (2/236), respectively. One tick was coinfected with all four bacteria (Borrelia, Bartonella, Anaplasma, and Ehrlichia) and another group was coinfected with three bacteria, Borrelia, Bartonella, and Ehrlichia. Statistical analysis showed most coinfections were significant, indicating that once a tick was infected with one bacteria, there was a greater chance to be infected with another bacteria.

Epidemiology of the avian influenza A (H7N9) outbreak in Zhejiang Province, China

BackgroundA novel influenza A virus infection was identified on March 31, 2013 in China and a total of 134 cases were identified in 12 provinces of China between March 25 and September 31, 2013. Of these, 46 cases occurred in Zhejiang Province and the number of patients is the largest in China.MethodsField investigations were conducted for each confirmed H7N9 case. A standardized questionnaire was used to collect information about demographics, exposure history, clinical signs and symptoms, timelines of medical visits and care after onset of illness, and close contacts. Descriptive statistics were used to analyze the epidemiological and clinical characteristics. Samples from the patients were collected and tested by real time reverse transcriptase-polymerase chain reaction and viral culture.ResultsA total of 46 laboratory confirmed cases of H7N9 influenza infection were identified in the Zhejiang province between March 31 and September 31, 2013 of which 29 were male and 17 were female. The median age of patients was 61.5xa0years and 76.09% of cases occurred in persons aged ≥50xa0years old. Unlike other province, 34.78% of cases in Zhejiang Province were rural residents. Among 11 deaths, 9 were male, 10 were older than 60xa0years old, and 10 had underlying diseases. 30 of 38 cases with available data had a recent history of poultry exposures and 8 cases had multi-exposure history. The estimated median incubation period was two days which was shorter than corresponding data in other provinces. All cases were hospitalized and the median time from illness onset to hospitalization was 5xa0days. Symptoms at the onset of the illness included fever, cough, expectoration, shivering, fatigue, muscular aches, nausea, vomiting. Only 4.91% contacts developed respiratory symptoms, but their samples were tested negative for H7N9 virus designating lack of human-to-human transmission of the virus.ConclusionsAll cases were sporadic and there was no evidence of an epidemiologic link between them. Control measures including closing affected poultry and slaughtering backyard poultry are needed not only in urban areas but also in rural areas to reduce human H7N9 infection risk.

Epidemiological characteristics of severe fever with thrombocytopenia syndrome in Zhejiang Province, China

OBJECTIVESnTo summarize the epidemiological characteristics of severe fever with thrombocytopenia syndrome (SFTS) in Zhejiang Province, China.nnnMETHODSnA standardized questionnaire was used to collect information on demographic features, exposure history, clinical symptoms, and timelines of medical visits. Descriptive statistics were used to analyze the characteristics of SFTS.nnnRESULTSnA total of 65 cases of SFTS were identified in Zhejiang Province from 2011 to 2013, of whom 34 were male and 31 were female. The median age was 66 years and 60 cases occurred in persons aged ≥ 50 years. The majority (91%) of SFTS cases occurred between May and August. With regard to exposure history, patients had pursued outdoor activities (63%), had a history of exposure to a tick (68%) or tick bite (29%), bred domestic animals (31%), or had a history of exposure to a mouse (57%), and some patients had a multi-exposure history. Approximately 98.46% of patients were hospitalized, and symptoms of the illness included fever (98%), fatigue (71%), chills (51%), etc. Two family clusters occurred, although there was no person-to-person transmission.nnnCONCLUSIONSnIn Zhejiang Province, SFTS is prevalent between May and August among elderly persons who live in hilly areas, and clinical features are not specific. More emphasis should be given to this disease and further training of medical personnel should be carried out to prevent misdiagnosis.

DETECTION OF BARTONELLA SPECIES IN SMALL MAMMALS FROM ZHEJIANG PROVINCE, CHINA

To estimate the prevalence of Bartonella in small mammals of different species, during different seasons, and at different study sites, and to provide baseline data for the risk assessment of human Bartonella infection, we captured small mammals using snap traps in Zhejiang Province, China. Bartonella species were detected in small-mammal samples by polymerase chain reaction and positive amplicons were sequenced. Bartonella DNA was detected in 47% (90/192) of Apodemus agrarius, 31% (14/45) of Rattus losea, 16% (7/43) of Rattus norvegicus, 24% (9/37) of Eothenomys melanogaster, 4% (1/28) of Niviventer confucianus, 30% (7/23) of Suncus murinus, 22% (2/9) of Microtus fortis, 27% (2/7) of Rattus tanezumi, and 29% (2/7) of Apodemus peninsulae. No Bartonella DNA was detected in 27 unidentified Soricidae or nine Mus musculus. This is the first report of Bartonella DNA detected in E. melanogaster and N. confucianus. The prevalence of Bartonella DNA varied among small-mammal species, study sites, and seasons; the prevalence of Bartonella DNA between genders did not vary significantly within a species. The sequences we report were most similar to Bartonella grahamii.

Seroprevalence of Bartonella in Eastern China and analysis of risk factors

BackgroundBartonella infections are emerging in the Zhejiang Province of China. However, there has been no effort to date to explore the epidemiology of these infections in this region, nor to identify risk factors associated with exposure to Bartonella. The aim of this study was to investigate the seroprevalence of Bartonella in both patients bitten by dogs and blood donors (for control) in Eastern China, and to identify risk factors associated with exposure to Bartonella. As no previous data for this region have been published, this study will provide baseline data useful for Bartonella infection surveillance, control, and prevention.MethodsBlood samples were collected from industrial rabies clinic attendees and blood donors living in eight areas of the Zhejiang Province of China, between December 2005 and November 2006. An indirect immunofluorescent antibody test was used to determine the presence of Bartonella in these samples. Risk factors associated with Bartonella exposure were explored using Chi-square tests and logistic regression analysis of epidemiological data relating to the studys participants.ResultsBartonella antibodies were detected in 19.60% (109/556) of blood samples. Seroprevalence varied among the eight areas surveys, ranging from over 32% in Hangzhou to only 2% in Jiangshan (X2 = 28.22, P < 0.001). We detected a significantly higher prevalence of Bartonella antibodies in people who had been bitten by dogs than in blood donors (X2 = 13.86, P < 0.001). Seroprevalence of Bartonella was similar among males (18.61%, n = 317) and females (20.92%, n = 239).ConclusionsBartonella antibodies were encountered in people living across Zhejiang Province and the seropositivity rate among those exposed to dog bites was significantly higher than that among blood donors, indicating that dog bites may be a risk factor for Bartonella infection.

Detection of spotted fever group Rickettsiae in ticks from Zhejiang Province, China

AbstractnTick species distribution and prevalence of spotted fever group Rickettsiae (SFGR) in ticks were investigated in Zhejiang Province, China in 2010 and 2011. PCR was used to detect SFGR and positive amplicons were sequenced, compared to published sequences and phylogenic analysis was performed using MEGA 4.0. A total of 292 adult ticks of ten species were captured and 7.5xa0% (22/292) of the ticks were PCR-positive for SFG Rickettsia. The PCR-positive rates were 5.5xa0% (6/110) for Haemaphysalis longicornis, 3.6xa0% (1/28) for Amblyomma testudinarium and 16xa0% (15/94) for Ixodes sinensis, respectively. Phylogenetic analyses of gltA genes detected in ticks indicated that there are two dominating groups of SFGR. Sequences of group one were closely related to Rickettsia monacensis, whereas sequences of group two were closest related to Rickettsia heilongjiangensis and Rickettsia japonica, which are human pathogens. Our findings underline the importance of these ticks in public health surveillance in Zhejiang Province, China.n