Xiang Ren

The changing epidemiology of dengue in China, 1990-2014: a descriptive analysis of 25 years of nationwide surveillance data

BackgroundDengue has been a notifiable disease in China since 1 September 1989. Cases have been reported each year during the past 25 years of dramatic socio-economic changes in China, and reached a historical high in 2014. This study describes the changing epidemiology of dengue in China during this period, to identify high-risk areas and seasons and to inform dengue prevention and control activities.MethodsWe describe the incidence and distribution of dengue in mainland China using notifiable surveillance data from 1990-2014, which includes classification of imported and indigenous cases from 2005-2014.ResultsFrom 1990-2014, 69,321 cases of dengue including 11 deaths were reported in mainland China, equating to 2.2 cases per one million residents. The highest number was recorded in 2014 (47,056 cases). The number of provinces affected has increased, from a median of three provinces per year (range: 1 to 5 provinces) during 1990-2000 to a median of 14.5 provinces per year (range: 5 to 26 provinces) during 2001-2014. During 2005-2014, imported cases were reported almost every month and 28 provinces (90.3%) were affected. However, 99.8% of indigenous cases occurred between July and November. The regions reporting indigenous cases have expanded from the coastal provinces of southern China and provinces adjacent to Southeast Asia to the central part of China. Dengue virus serotypes 1, 2, 3, and 4 were all detected from 2009-2014.ConclusionsIn China, the area affected by dengue has expanded since 2000 and the incidence has increased steadily since 2012, for both imported and indigenous dengue. Surveillance and control strategies should be adjusted to account for these changes, and further research should explore the drivers of these trends.Please see related article: http://dx.doi.org/10.1186/s12916-015-0345-0

Global epidemiology of avian influenza A H5N1 virus infection in humans, 1997-2015: A systematic review of individual case data

SUMMARY Avian influenza viruses A(H5N1) have caused a large number of typically severe human infections since the first human case was reported in 1997. However, there is a lack of comprehensive epidemiological analysis of global human cases of H5N1 from 1997-2015. Moreover, few studies have examined in detail the changing epidemiology of human H5N1 cases in Egypt, especially given the most recent outbreaks since November 2014 which have the highest number of cases ever reported globally over a similar period. Data on individual cases were collated from different sources using a systematic approach to describe the global epidemiology of 907 human H5N1 cases between May 1997 and April 2015. The number of affected countries rose between 2003 and 2008, with expansion from East and Southeast Asia, then to West Asia and Africa. Most cases (67.2%) occurred from December to March, and the overall case fatality risk was 53.5% (483/903) which varied across geographical regions. Although the incidence in Egypt has increased dramatically since November 2014, compared to the cases beforehand there were no significant differences in the fatality risk , history of exposure to poultry, history of human case contact, and time from onset to hospitalization in the recent cases.

Differences in the epidemiology of human cases of avian influenza A(H7N9) and A(H5N1) viruses infection

BACKGROUNDnThe pandemic potential of avian influenza viruses A(H5N1) and A(H7N9) remains an unresolved but critically important question.nnnMETHODSnWe compared the characteristics of sporadic and clustered cases of human H5N1 and H7N9 infection, estimated the relative risk of infection in blood-related contacts, and the reproduction number (R).nnnRESULTSnWe assembled and analyzed data on 720 H5N1 cases and 460 H7N9 cases up to 2 November 2014. The severity and average age of sporadic/index cases of H7N9 was greater than secondary cases (71% requiring intensive care unit admission vs 33%, P = .007; median age 59 years vs 31, P < .001). We observed no significant differences in the age and severity between sporadic/index and secondary H5N1 cases. The upper limit of the 95% confidence interval (CI) for R was 0.12 for H5N1 and 0.27 for H7N9. A higher proportion of H5N1 infections occurred in clusters (20%) compared to H7N9 (8%). The relative risk of infection in blood-related contacts of cases compared to unrelated contacts was 8.96 for H5N1 (95% CI, 1.30, 61.86) and 0.80 for H7N9 (95% CI, .32, 1.97).nnnCONCLUSIONSnThe results are consistent with an ascertainment bias towards severe and older cases for sporadic H7N9 but not for H5N1. The lack of evidence for ascertainment bias in sporadic H5N1 cases, the more pronounced clustering of cases, and the higher risk of infection in blood-related contacts, support the hypothesis that susceptibility to H5N1 may be limited and familial. This analysis suggests the potential pandemic risk may be greater for H7N9 than H5N1.

Changing epidemiology of human brucellosis, China, 1955–2014

Brucellosis, a zoonotic disease, was made statutorily notifiable in China in 1955. We analyzed the incidence and spatial–temporal distribution of human brucellosis during 1955–2014 in China using notifiable surveillance data: aggregated data for 1955–2003 and individual case data for 2004–2014. A total of 513,034 brucellosis cases were recorded, of which 99.3% were reported in northern China during 1955–2014, and 69.1% (258, 462/374, 141) occurred during February–July in 1990–2014. Incidence remained high during 1955–1978 (interquartile range 0.42–1.0 cases/100,000 residents), then decreased dramatically in 1979–1994. However, brucellosis has reemerged since 1995 (interquartile range 0.11–0.23 in 1995–2003 and 1.48–2.89 in 2004–2014); the historical high occurred in 2014, and the affected area expanded from northern pastureland provinces to the adjacent grassland and agricultural areas, then to southern coastal and southwestern areas. Control strategies in China should be adjusted to account for these changes by adopting a One Health approach.

Malaria imported from Ghana by returning gold miners, China, 2013.

During May-August 2013, a malaria outbreak comprising 874 persons in Shanglin County, China, was detected among 4,052 persons returning from overseas. Ghana was the predominant destination country, and 92.3% of malarial infections occurred in gold miners. Preventive measures should be enhanced for persons in high-risk occupations traveling to malaria-endemic countries.

Changing epidemiology of hepatitis A and hepatitis E viruses in China, 1990-2014

We compared the epidemiology of hepatitis A and hepatitis E cases in China from 1990-2014 to better inform policy and prevention efforts. The incidence of hepatitis A cases declined dramatically, while hepatitis E incidence increased. During 2004-2014, hepatitis E mortality rates surpassed those of hepatitis A.

Epidemiology of human anthrax in China, 1955-2014

Using national surveillance data for 120,111 human anthrax cases recorded during 1955−2014, we analyzed the temporal, seasonal, geographic, and demographic distribution of this disease in China. After 1978, incidence decreased until 2013, when it reached a low of 0.014 cases/100,000 population. The case-fatality rate, cumulatively 3.6% during the study period, has also decreased since 1990. Cases occurred throughout the year, peaking in August. Geographic distribution decreased overall from west to east, but the cumulative number of affected counties increased during 2005−2014. The disease has shifted from industrial to agricultural workers; 86.7% of cases occurred in farmers and herdsmen. Most (97.7%) reported cases were the cutaneous form. Although progress has been made in reducing incidence, this study highlights areas that need improvement. Adequate laboratory diagnosis is lacking; only 7.6% of cases received laboratory confirmation. Geographic expansion of the disease indicates that livestock control programs will be essential in eradicating anthrax.

Assessing potential airlines and the risk of Ebolavirus importation from west African countries into China

A public health emergency of international concern regarding the 2014 West African Ebola epidemic was declared by the World Health Organization on August 8, 2014, in view of its potential for further international spread. Based on historic traveller flight itinerary data between October and December 2013 from the International Air Transport Association, we assessed the potential risk of Ebola virus exportation from three West African Countries, Guinea, Liberia, and Sierra Leone, into China via commercial air travel between October 1, 2014 and December 31, 2014. We found 107,113 passengers departed from the three affected countries during the fourth quarter of 2013, with 3167 people (3.0%) arriving in mainland China after transfers at the international airports of eight countries, including France, Belgium, and the U.A.E. The primary airports of entry into China for travelers from Guinea, Liberia, and Sierra Leone are located in Beijing, Guangzhou, Shanghai, Hangzhou, Wuhan, Chongqing, and Dalian, whereas the main final destinations in China include Beijing, Guangzhou, Chongqing, Wuhan, Shanghai, Hangzhou, and Wenzhou. With the assumption that travel behavior and mobility in the fourth quarter of 2014 will be the same as that of 2013, an average of 2235 international travellers would need to be screened at the points of entry into China to capture one traveler with potential exposure to Ebola virus in the three West African countries. In total, our model projects only 0.54 travellers infected with Ebola virus departing the above three countries entering China via commercial flights from October to December 2014 (0.35 infected travellers from Liberia, 0.16 from Sierra Leone, and 0.03 from Guinea). If the incidence of Ebola virus disease increases or the number of travellers to China decreases, the number of travellers with Ebola virus infection would fluctuate accordingly. This study shows that the risk of Ebola imported from West Africa to China via commercial air travel exists, although it is very low. China could support screening of departing international travellers from West Africa for the early detection of individuals with Ebola virus disease, screen high-risk traveller populations at the primary points of entry into China, and heighten surveillance in Chinas leading destination cities.

Assessing the risk of MERS importation from South Korea into cities of China: a retrospective study

On May 20th, 2015, the Republic of Korea reported its first laboratory-confirmed case of Middle East respiratory syndrome coronavirus (MERS-CoV) infection, followed by the largest outbreak of MERS-CoV outside of the Middle East, which included a case imported from South Korea into China.