Data from all reported cases of 2009 pandemic influenza A (H1N1) were obtained from the China Information System for Disease Control and Prevention. The spatiotemporal distribution patterns of cases were characterized through spatial analysis. The impact of travel-related risk factors on invasion of the disease was analyzed using survival analysis, and climatic factors related to local transmission were identified using multilevel Poisson regression, both at the county level. The results showed that the epidemic spanned a large geographic area, with the most affected areas being in western China. Significant differences in incidence were found among age groups, with incidences peaking in school-age children. Overall, the epidemic spread from southeast to northwest. Proximity to airports and being intersected by national highways or freeways but not railways were variables associated with the presence of the disease in a county. Lower temperature and lower relative humidity were the climatic factors facilitating local transmission after correction for the effects of school summer vacation and public holidays, as well as population density and the density of medical facilities. These findings indicate that interventions focused on domestic travel, population density, and climatic factors could play a role in mitigating the public health impact of future influenza pandemics.
China; disease outbreaks; disease transmission, infectious; influenza, human; invasion process; pandemics
Anaplasma phagocytophilum; ticks; bacteria; China; Russia; border; letter
The outbreak of human infections with an emerging avian influenza A (H7N9) virus occurred in China in early 2013. It remains unknown what and how the underlying risk factors were involved in the bird-to-human cross-species transmission. To illustrate the dynamics of viral spread, we created a thematic map displaying the distribution of affected counties and plotted epidemic curves for the three most affected provinces and the whole country. We then collected data of agro-ecological, environmental and meteorological factors at the county level, and used boosted regression tree (BRT) models to examine the relative contribution of each factor and map the probability of occurrence of human H7N9 infection. We found that live poultry markets, human population density, irrigated croplands, built-up land, relative humidity and temperature significantly contributed to the occurrence of human infection with H7N9 virus. The discriminatory ability of the model was up to 97.4%. A map showing the areas with high risk for human H7N9 infection was created based on the model. These findings could be used to inform targeted surveillance and control efforts in both human and animal populations to reduce the risk of future human infections.
Eschars can be used for genetic characterization of O. tsutsugamushi during the convalescent phase.
To verify the value of eschars for the diagnosis of scrub typhus and to characterize genotypes of Orientia tsutsugamushi in patients, we examined eschars and blood specimens of 7 patients from Shandong Province, People's Republic of China, for O. tsutsugamushi by polymerase chain reaction targeting the Sta56 gene. All 7 eschars and acute-phase blood samples were positive, while no specific DNA amplicons were obtained from the 7 convalescent-phase blood samples collected after antimicrobial drug therapy. The findings indicate that patients' eschars can be used for detection and genetic characterization of O. tsutsugamushi during the convalescent phase.
Scrub typhus; eschar; Orientia tsutsugamushi
A total of 420 rodents in China were examined for Francisella tularensis by polymerase chain reaction. The infection rates were 4.76% in total, and 11.65%, 10.00%, 6.56%, 1.77%, and 0% in Jilin, Xinjiang, Heilongjiang, Inner Mongolia, and Zhejiang, respectively. Sequence analysis showed that all the detected agents belonged to F. tularensis subsp. holarctica.
Francisella tularensis; tularemia; PCR; rodents; China; dispatch
SARS; People’s Republic of China; pulmonary tuberculosis; letter
We report here the genome sequence of Borrelia afzelii strain HLJ01, isolated from a patient with Lyme disease in China. It is the first report of the whole genome of a B. burgdorferi sensu lato isolate from a human in China.
We detected Bartonella quintana in 48.6% of captive rhesus macaques from an animal facility in Beijing, China. Prevalence of infection increased over the period of observation. Our findings suggest that macaques may serve as reservoir hosts for B. quintana and that Pedicinus obtusus lice might act as efficient vectors.
Bartonella quintana; rhesus macaques; reservoir host; lice; transmission; China; vector-borne infections; Bartonella
To identify Candidatus Neoehrlichia mikurensis infection in northeastern China, we tested blood samples from 622 febrile patients. We identified in 7 infected patients and natural foci for this bacterium. Field surveys showed that 1.6% of ticks and 3.8% of rodents collected from residences of patients were also infected.
Candidatus Neoehrlichia mikurensis; bacteria; human infection; ticks; rodents; vector-borne infections; China
Using retrospective hemorrhagic fever with renal syndrome (HFRS) cases in China, we determined that although the incidence of HFRS was higher among males, case fatality rates were higher among females and were age-dependent.
Background. Differences between male and female individuals in response to infectious diseases are an overlooked global health problem.
Methods. The relationship between sex and disease outcome was examined in populations of patients with hemorrhagic fever with renal syndrome (HFRS) in mainland China, where most cases of hantavirus exposure occur. HFRS in China is diagnosed on the basis of symptoms and is confirmed with serological testing. The geographical distribution, incidence, and case fatality rates (CFRs) of HFRS in China were estimated and compared by patient sex and age. In a subset of patients with HFRS, clinical manifestations of HFRS were assessed using latent class analysis and compared by sex.
Results. There were 80,671 HFRS cases reported during the period 2004–2008, with a majority of HFRS cases (39.2%) occurring among individuals 20–39 years of age. The incidence of HFRS was higher among male patients than among female patients for all individuals >10 years of age. There were 945 deaths (CFR, 1.17%) due to HFRS in China during the period 2004–2008. CFRs were higher among women than among men between the ages of 20–39 and ≥50 years of age. There were no sex differences in the geographical distribution of HFRS cases or deaths. Although the prevalence of each clinical marker did not differ by sex, 2 profiles of clinical markers were identified that were related to both severity of disease and sex.
Conclusions. These data illustrate a paradox in which the incidence of disease is greater for males, but the severity of disease outcome is worse for females. Several behavioral, societal, and biological factors are hypothesized to be involved.
Hemorrhagic fever with renal syndrome (HFRS) is an important public health problem in Shandong Province, China. In this study, we combined ecologic niche modeling with geographic information systems (GIS) and remote sensing techniques to identify the risk factors and affected areas of hantavirus infections in rodent hosts. Land cover and elevation were found to be closely associated with the presence of hantavirus-infected rodent hosts. The averaged area under the receiver operating characteristic curve was 0.864, implying good performance. The predicted risk maps based on the model were validated both by the hantavirus-infected rodents' distribution and HFRS human case localities with a good fit. These findings have the applications for targeting control and prevention efforts.
The multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) has emerged as a global threat. Xinjiang is a multi-ethnic region and suffered second highest incidence of TB in China. However, epidemiological information on MDR and XDR TB is scarcely investigated.
A prospective study was conducted to analyze the prevalence of MDR and XDR TB and the differences of drug resistance TB between Chinese Han and other nationalities population at Chest Hospital of Xinjiang Uygur Autonomous Region, China. We performed in vitro drug susceptibility testing of Mycobacterium tuberculosis to first- and second-line anti-tuberculosis drugs for all 1893 culture confirmed positive TB cases that were diagnosed between June 2009 and June 2011. Totally 1117 (59.0%, 95% CI, 56.8%–61.2%) clinical isolates were resistant to ≥1 first-line drugs; the prevalence of MDR TB was 13.2% (95% CI, 11.7%–14.7%), of which, 77 (30.8%; 95% CI, 25.0%–36.6%) and 31 (12.8%; 95% CI, 8.6%–17.0%) isolates were pre-XDR and XDR TB respectively. Among the MDR/XDR TB, Chinese Han patients were significantly less likely to be younger with an odds ratio 0.42 for age 20–29 years and 0.52 for age 40–49 years; Ptrend = 0.004), and Chinese Han patients has a lower prevalence of XDR TB (9.6%) than all the other nationality (14.9%).
The burden of drug resistance TB cases is sizeable, which highlights an urgent need to reinforce the control, detection and treatment strategies for drug resistance TB. However, the difference of MDR and XDR TB between Chinese Han and other nationalities was not observed.
To elucidate the importance of the norovirus and other enteric viruses, and the difference of the genetic relatedness on norovirus between the outbreak and sporadic cases, a total of 557 stool samples, consisting of 503 sporadic cases and 54 samples of 4 outbreaks were collected and tested for norovirus and other enteric viruses in Beijing, China, July 2007–June 2008. The data showed norovirus, rotavirus, astrovirus, and sapovirus, were detected in 26.6%, 6.1%, 1.8%, and 0.5%, respectively. Norovirus was detected almost throughout the surveillance period, norovirus co-infecting with rotavirus, astrovirus, and sapovirus, respectively, were identified both in outbreak and the sporadic cases. GII.4/2006 was identified as the predominant strain circulating both in outbreak and sporadic cases. The results showed that norovirus was rather the important agent than other enteric viruses affected adults with acute gastroenteritis; no significant genetic relatedness of the dominant strains was found between the outbreak and sporadic cases.
Brucellosis; Brucella spp.; China; bacteria; zoonoses; letter
The transmission of hemorrhagic fever with renal syndrome (HFRS) is influenced by climatic variables. However, few studies have examined the quantitative relationship between climate variation and HFRS transmission.
We examined the potential impact of climate variability on HFRS transmission and developed climate-based forecasting models for HFRS in northeastern China.
We obtained data on monthly counts of reported HFRS cases in Elunchun and Molidawahaner counties for 1997–2007 from the Inner Mongolia Center for Disease Control and Prevention and climate data from the Chinese Bureau of Meteorology. Cross-correlations assessed crude associations between climate variables, including rainfall, land surface temperature (LST), relative humidity (RH), and the multivariate El Niño Southern Oscillation (ENSO) index (MEI) and monthly HFRS cases over a range of lags. We used time-series Poisson regression models to examine the independent contribution of climatic variables to HFRS transmission.
Cross-correlation analyses showed that rainfall, LST, RH, and MEI were significantly associated with monthly HFRS cases with lags of 3–5 months in both study areas. The results of Poisson regression indicated that after controlling for the autocorrelation, seasonality, and long-term trend, rainfall, LST, RH, and MEI with lags of 3–5 months were associated with HFRS in both study areas. The final model had good accuracy in forecasting the occurrence of HFRS.
Climate variability plays a significant role in HFRS transmission in northeastern China. The model developed in this study has implications for HFRS control and prevention.
China; cross-correlation; forecast; hemorrhagic fever with renal syndrome; risk factors; time-series Poisson regression
Roseomonas; bacteria; ticks; Dermacentor nuttalli; China; letter
Three strains were isolated and characterized.
To characterize the strains of Anaplasma phagocytophilum in wild and domestic animals in China, we isolated the organism from rodents and sheep in northeastern China. We isolated 3 strains (2 from rodents and 1 from sick sheep) through propagation in BALB/c mice and then cell culture in HL60 cells. The 3 isolates were identified by Wright-Giemsa staining, immunofluorescence, and electronic microscopy and were characterized by sequence analyses of the 16S rRNA gene, partial citrate synthase gene, major surface protein 4 gene, and heat shock protein gene. The multiple sequences of the 3 isolates were identical to each other but different from all known strains from other countries. The public health and veterinary relevance of the isolates deserves further investigation.
Anaplasma phagocytophilum; isolation; rodents; sheep; China; rickettsia; research
Influenza; seasonal pattern; surveillance; viruses; letter
Many rodent species may be involved in the enzootic maintenance of these agents.
A total of 705 rodents from 6 provinces and autonomous regions of mainland People’s Republic of China were tested by PCRs for tick-borne agents (Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato, spotted fever group rickettsiae, and Francisella tularensis). Infection rates were 5.5%, 6.7%, 9.1% and 5.0%, respectively. Eighteen (2.6%) rodents of 10 species were positive for 2 or 3 agents. Sequence analysis of PCR products confirmed the presence and genotypes of detected agents. These findings demonstrate that these tick-borne agents cocirculate and that a variety of rodent species may be involved in their enzootic maintenance.
Anaplasma phagocytophilum; Borrelia burgdorferi sensu lato; spotted fever group rickettsiae; Francisella tularensis; rodents; coexistence; China; research
By using multilocus sequence analysis, five Borrelia valaisiana-related strains isolated from rodents and ticks in southwestern China were eventually classified as a new genospecies of B. burgdorferi sensu lato rather than B. valaisiana. The finding explained the differences in transmission cycle and phenotype between B. valaisiana strains from Europe and B. valaisiana-related strains from eastern Asia.
Tularemia was reported in China over 50 years ago, however, many epidemical characteristics remain unclear. In the present study, the prevalence of Francisella tularensis in ticks was investigated during an epidemiological surveillance in China and then we measured their genetic diversity by conducting multiple-locus variable- number tandem repeat analysis (MLVA).
1670 ticks from 2 endemic areas (Inner Mongolia Autonomous Region and Heilongjiang Province) and 2 non-endemic areas (Jilin and Fujian Provinces) were collected and tested for evidence of tularemia by nested PCR. The prevalence of Francisella tularensis in ticks averaged 1.98%. The positive rates were significantly different among tick species, with Dermacentor silvarum and Ixodes persulatus responsible for all positive numbers. All F. tularensis that were detected in ticks belonged to F. tularensis subsp. holarctica and MLVA disclosed genetic diversity. One subtype was identified in 17 of 33 positive tick samples in three different study areas. Another subtype belonging to F. tularensis subsp. holarctica genotype was described for the first time in the current study.
The study showed two tick species, D. silvarum and I. persulatus harboring the pathogen of tularemia in natural environment, indicating these two tick species might have a role in tularemia existence in China. MLVA results disclosed the genetic diversity F. tularensis and identified one genotype as the most prevalent among the investigated ticks in China.
Population fluctuation is a risk factor for TB in Beijing.
To determine the role of the migrant population in the transmission of tuberculosis (TB), we investigated the distribution and magnitude of TB in permanent residents and migrant populations of Beijing, People’s Republic of China, from 2000 through 2006. An exploratory spatial data analysis was applied to detect the “hot spots” of TB among the 2 populations. Results, using the data obtained from 2004–2006, showed that people who migrated from the western, middle, and eastern zones of China had a significantly higher risk of having TB than did permanent residents. These findings indicate that population fluctuations have affected the rate of TB prevalence in Beijing, and interventions to control TB should include the migrant population.
pulmonary tuberculosis; migrant population; spatial analysis; Extra Poisson model; research
Hemorrhagic fever with renal syndrome (HFRS) is an important public health problem in the People’s Republic of China, accounting for 90% of human cases reported globally. In this study, a landscape epidemiologic approach, combined with geographic information system and remote sensing techniques, was applied to increase our understanding of HFRS due to Hantaan virus and its relationship with landscape elements in China. The landscape elements considered were elevation, normalized difference vegetation index (NDVI), precipitation, annual cumulative air temperature, land surface temperature, soil type, and land use. Multivariate logistic regression analysis showed that HFRS incidence was remarkably associated with elevation, NDVI, precipitation, annual cumulative air temperature, semihydromorphic soils, timber forests, and orchards. These findings have important applications for targeting HFRS interventions in mainland China.
Landscape elements; hemorrhagic fever with renal syndrome (Apodemus type); remote sensing; GIS; research
Viral adaptation to the host may be occurring under selective immune pressure.
Single nucleotide variations (SNVs) at 5 loci (17564, 21721, 22222, 23823, and 27827) were used to define the molecular epidemiologic characteristics of severe acute respiratory syndrome–associated coronavirus (SARS-CoV) from Beijing patients. Five fragments targeted at the SNV loci were amplified directly from clinical samples by using reverse transcription–polymerase chain reaction (RT-PCR), before sequencing the amplified products. Analyses of 45 sequences obtained from 29 patients showed that the GGCTC motif dominated among samples collected from March to early April 2003; the TGTTT motif predominanted afterwards. The switch from GGCTC to TGTTT was observed among patients belonging to the same cluster, which ruled out the possibility of the coincidental superposition of 2 epidemics running in parallel in Beijing. The Beijing isolates underwent the same change pattern reported from Guangdong Province. The same series of mutations occurring in separate geographic locations and at different times suggests a dominant process of viral adaptation to the host.
severe acute respiratory syndrome; molecular epidemiology; single nucleotide variation; RT-PCR, research
This study investigated the long-term excretion of severe acute respiratory syndrome–associated coronavirus in sputum and stool specimens from 56 infected patients. The median (range) duration of virus excretion in sputa and stools was 21 (14–52) and 27 (16–126) days, respectively. Coexisting illness or conditions were associated with longer viral excretion in stools.
Dispatch; Severe acute respiratory syndrome; epidemiology; cohort; transmission; diagnosis; RT-PCR