Shenlong Li

Epidemiologic Features of Severe Fever With Thrombocytopenia Syndrome in China, 2011–2012

Severe fever with thrombocytopenia syndrome (SFTS), an emerging vector-borne disease, is caused by a novel bunyavirus belonging to the genus Phlebovirus [1, 2]. SFTS infections can be life-threatening and are characterized by sudden onset of fever, thrombocytopenia, gastrointestinal symptoms, and leukocytopenia. The tick Haemaphysalis longicornis is generally considered to be the vector of SFTS, which is widely distributed in China [2]. Person-to-person transmission through direct contact with contaminated blood has also been reported as a possible means of SFTS transmission [3–5]. Currently, there is no specific treatment other than supportive care [6]...

Scrub typhus in mainland China, 2006-2012: the need for targeted public health interventions.

Scrub typhus is a vector-borne disease carried by the chigger mite. The aetiological agent is the rickettsia Orientia tsutsugamushi, which is endemic to several countries in the Asia-Pacific region, including China [1]. It is also a travel-associated disease [2] and of great importance among military personnel [3], [4]. During the Second World War, scrub typhus was associated with a higher case fatality ratio than any other infectious disease in the China-Burma-India theatre of operations 1,3. Clinical presentation in patients varies from asymptomatic to life-threatening disease [5], including acute hearing loss and multiple organ failure [6], [7]. To date, there is still no effective and reliable human vaccine against scrub typhus and no point-of-care diagnostics available [1].

Epidemiologic Characteristics of Cases for Influenza A(H7N9) Virus Infections in China

*Articles free to read on publisher website after 12 months back to Jan 1996 Abstract: Chinas National Health and Family Planning Commission announced 3 deaths caused by avian-origin influenza A(H7N9) virus in March, which was the first time that the H7N9 strain has been found in humans [1]. This is of major public health significance and raises urgent questions and global concerns [2, 3]. To explore epidemic characteristics of human infections with H7N9 virus, data on individual cases from 19 February 2013 (onset date of first case) to 14 April 2013 were collected from the China Information System for Disease Control and Prevention, which included information about sex; age; occupation; residential address; and day of symptom onset, diagnosis, and outcome for each case. The definition of an unconfirmed probable H7N9 case is a patient with epidemiologic evidence of contact …

Spatiotemporal patterns of Japanese encephalitis in China, 2002–2010

Objective The aim of the study is to examine the spatiotemporal pattern of Japanese Encephalitis (JE) in mainland China during 2002–2010. Specific objectives of the study were to quantify the temporal variation in incidence of JE cases, to determine if clustering of JE cases exists, to detect high risk spatiotemporal clusters of JE cases and to provide evidence-based preventive suggestions to relevant stakeholders. Methods Monthly JE cases at the county level in mainland China during 2002–2010 were obtained from the China Information System for Diseases Control and Prevention (CISDCP). For the purpose of the analysis, JE case counts for nine years were aggregated into four temporal periods (2002; 2003–2005; 2006; and 2007–2010). Local Indicators of Spatial Association and spatial scan statistics were performed to detect and evaluate local high risk space-time clusters. Results JE incidence showed a decreasing trend from 2002 to 2005 but peaked in 2006, then fluctuated over the study period. Spatial cluster analysis detected high value clusters, mainly located in Southwestern China. Similarly, we identified a primary spatiotemporal cluster of JE in Southwestern China between July and August, with the geographical range of JE transmission increasing over the past years. Conclusion JE in China is geographically clustered and its spatial extent dynamically changed during the last nine years in mainland China. This indicates that risk factors for JE infection are likely to be spatially heterogeneous. The results may assist national and local health authorities in the development/refinement of a better preventive strategy and increase the effectiveness of public health interventions against JE transmission.

Modeling the transmission dynamics of Ebola virus disease in Liberia

Ebola virus disease (EVD) has erupted many times in some zones since it was first found in 1976. The 2014 EVD outbreak in West Africa is the largest ever, which has caused a large number of deaths and the most serious country is Liberia during the outbreak period. Based on the data released by World Health Organization and the actual transmission situations, we investigate the impact of different transmission routes on the EVD outbreak in Liberia and estimate the basic reproduction number R0 = 2.012 in the absence of effective control measures. Through sensitivity and uncertainty analysis, we reveal that the transmission coefficients of suspected and probable cases have stronger correlations on the basic reproduction number. Furthermore, we study the influence of control measures (isolation and safe burial measures) on EVD outbreak. It is found that if combined control measures are taken, the basic reproduction number will be less than one and thus EVD in Liberia may be well contained. The obtained results may provide new guidance to prevent and control the spread of disease.

Human brucellosis, a heterogeneously distributed, delayed, and misdiagnosed disease in china.

TO THE EDITOR—Brucellosis is a common zoonotic disease worldwide [1]. The epidemiology of human brucellosis has drastically changed owing to changing sanitary and socioeconomic conditions, and the substantial increase in international travel. New foci of human brucellosis have emerged or reemerged, with brucellosis becoming a travel-related disease, particularly in nonendemic areas [2–4]. Awareness of the geographic distribution and characteristics of brucellosis is valuable not only for the disease control in endemic areas, but also for preventing and diagnosing travel-associated disease in nonendemic areas [5, 6]. To investigate the geographic distribution of the human brucellosis epidemic in China, data were extracted from the National Notifiable Disease Surveillance System and analyzed. From December 2004 to July 2010, 141 604 laboratoryconfirmed cases were reported. A geographic distribution analysis showed that brucellosis is mainly distributed in some of the northern provinces of China. The 5 provinces with the highest incidence include Inner Mongolia (45.83%), Shanxi (13.94%), Heilongjiang (13.82%), Jilin (10.29%), and Hebei (6.31%); these provinces accounted for >90% of the reported cases. Nationwide, the annual incidence, at a county level, ranged from 0.00 to 1395.84 per 100 000 (Figure 1). Timely diagnosis is important for treating brucellosis and preventing chronic infections [7]. We examined the case data for possible contributing factors to delayed diagnoses. Of these 141 604 confirmed cases, only 26.98% were diagnosed within 7 days of symptom onset, 43.83% within 14 days, and 2.39% longer than 6 months, indicating that a large proportion of the cases had a delayed diagnosis. Further analysis showed that the average diagnosis delay was shorter in the high-incidence areas than in the low-incidence areas (35 vs 59 days, P < .001), and shorter in urban areas than in villages (32.55 vs 40.62 days, P < .001). In addition, patients who traveled or migrated across provinces had longer delays than did patients residing within an area (43.54 vs 36.82 days, P < .001). These data indicated that diagnosis delays were multifactorial and may have contributed to the chronicity of brucellosis in some population segments. Epidemiological information regarding 2060 cases were collected from brucellosis clinics and analyzed to investigate the reasons for the delays in diagnosis. Surprisingly, 57.62% of the patients had been misdiagnosed or suspected of having other diseases with similar clinical symptoms. Approximately 24.34% of the “delayed diagnosis” patients had traveled to or migrated from a high-risk area. All the patients had experienceddirect contactwith animals and/or consumed contaminated animal products prior to disease onset. The absence of characteristic symptoms and a general unawareness of epidemiological information contributed to the misdiagnoses. The lackof typical clinicalmanifestations makes it difficult to diagnose brucellosis, primarily contributing to the misdiagnosis and delay. The availability of additional information regarding the geographic

Association between hemorrhagic fever with renal syndrome epidemic and climate factors in Heilongjiang Province, China.

The purpose of this study was to quantify the relationship between climate variation and transmission of hemorrhagic fever with renal syndrome (HFRS) in Heilongjiang Province, a highly endemic area for HFRS in China. Monthly notified HFRS cases and climatic data for 2001-2009 in Heilongjiang Province were collected. Using a seasonal autoregressive integrated moving average model, we found that relative humidity with a one-month lag (β = -0.010, P = 0.003) and a three-month lag (β = 0.008, P = 0.003), maximum temperature with a two-month lag (β = 0.082, P = 0.028), and southern oscillation index with a two-month lag (β = -0.048, P = 0.019) were significantly associated with HFRS transmission. Our study also showed that predicted values expected under the seasonal autoregressive integrated moving average model were highly consistent with observed values (Adjusted R(2) = 83%, root mean squared error = 108). Thus, findings may help add to the knowledge gap of the role of climate factors in HFRS transmission in China and also assist national local health authorities in the development/refinement of a better strategy to prevent HFRS transmission.

Rapid Increase in Scrub Typhus Incidence in Mainland China, 2006–2014

Scrub typhus is a vector-borne disease, which has recently reemerged in China. In this study, we describe the distribution and incidence of scrub typhus cases in China from 2006 to 2014 and quantify differences in scrub typhus cases with respect to sex, age, and occupation. The results of our study indicate that the annual incidence of scrub typhus has increased during the study period. The number of cases peaked in 2014, which was 12.8 times greater than the number of cases reported in 2006. Most (77.97%) of the cases were reported in five provinces (Guangdong, Yunnan, Anhui, Fujian, and Shandong). Our study also demonstrates that the incidence rate of scrub typhus was significantly higher in females compared to males (P < 0.001) and was highest in the 60-69 year age group, and that farmers had a higher incidence rate than nonfarmers (P < 0.001). Different seasonal trends were identified in the number of reported cases between the northern and southern provinces of China. These findings not only demonstrate that China has experienced a large increase in scrub typhus incidence, but also document an expansion in the geographic distribution throughout the country.

The role of environmental factors in the spatial distribution of Japanese encephalitis in mainland China

Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public health concern in the Asia-Pacific region, particularly in China where 50% of global cases are notified. To explore the association between environmental factors and human JE cases and identify the high risk areas for JE transmission in China, we used annual notified data on JE cases at the center of administrative township and environmental variables with a pixel resolution of 1 km×1 km from 2005 to 2011 to construct models using ecological niche modeling (ENM) approaches based on maximum entropy. These models were then validated by overlaying reported human JE case localities from 2006 to 2012 onto each prediction map. ENMs had good discriminatory ability with the area under the curve (AUC) of the receiver operating curve (ROC) of 0.82-0.91, and low extrinsic omission rate of 5.44-7.42%. Resulting maps showed JE being presented extensively throughout southwestern and central China, with local spatial variations in probability influenced by minimum temperatures, human population density, mean temperatures, and elevation, with contribution of 17.94%-38.37%, 15.47%-21.82%, 3.86%-21.22%, and 12.05%-16.02%, respectively. Approximately 60% of JE cases occurred in predicted high risk areas, which covered less than 6% of areas in mainland China. Our findings will help inform optimal geographical allocation of the limited resources available for JE prevention and control in China, find hidden high-risk areas, and increase the effectiveness of public health interventions against JE transmission.

High-Risk Regions of Human Brucellosis in China: Implications for Prevention and Early Diagnosis of Travel Related Infections

TO THE EDITOR—Human brucellosis is caused by transmission of Brucella from animal reservoirs to humans by direct contact with infected animals or consumption of raw animal products such as unpasteurized milk or cheese. In many countries, brucellosis is underreported, and thus, official statistics reflect only a fraction of its true incidence [1]. Although its true incidence in China remains largely unknown, the incidence of human brucellosis is estimated to vary from <0.03 to >160 individuals per 100 000 population [2, 3]. Various sanitary, socioeconomic, and political factors have led the epidemiology of human brucellosis to change drastically over the past 2 decades [4, 5]. One important factor has been increased domestic and international travel [6]. This, together with the lack of awareness of brucellosis in lowincidence areas, impeded its recognition in these areas. Such initial lack of recognition typically results in delayed diagnosis and treatment, which may lead to chronic infection, and thus great economic and health problems for sufferers [2]. Increasing awareness of brucellosis and its distribution is important for both clinicians and travelers for achieving prevention, early diagnosis, and treatment. To assist in these endeavors, this study analyzed the spatial and time distribution of human brucellosis cases in China to identify high-risk regions. Information of the cases reported from January 2004 to December 2010 from the national surveillance system was collected. The geographic data for each case were extracted and a spatial incidence database was constructed. The incidence for each county was calculated, and space and time distribution and cluster identification were analyzed by using SaTScan and ArcGIS software as described previously [7]. As shown in Figure 1, 2 clusters were identified: a primary cluster (cluster I) and a secondary cluster (cluster II). Cluster I includes a total of 117 counties distributed at the junctions of Inner Mongolia, Hebei, Liaoning, Jilin, and Heilongjiang provinces, which were inhabited by 37 416 402 residents and reported 61 067 cases during the study period. Analysis of the data revealed the relative risk to be 40.093 and the log-likelihood ratio to be 151 573 (P < .001). Cluster II includes 331 counties at the junctions of Hebei, Shanxi, Inner Mongolia, Henan, Shanxi, and Ningxia provinces, which were inhabited by 104 103 364 residents and reported 29 595 cases during the study period. The relative risk and log-likelihood ratio were 5.236 and 23 130 (P < .001), respectively. The relative risk of transmission in cluster I is approximately 7.6 times that of cluster II. Investigation of high-risk factors for human brucellosis in 5 counties in cluster I identified animal contact and consumption of products from infected animals as the most significant factors. The diagnosis of human brucellosis in cluster I is relatively timely compared with that in other regions (P < .001). Because treatment within 3 months is generally efficacious [8], we recommend that clinicians and travelers remain aware