Prototypes virus of hand, foot and mouth disease infections and severe cases in Gansu, China: a spatial and temporal analysis.

BACKGROUND: Little research has been conducted on the spatio-temporal relationship between the severe cases and the enteroviruses infections of hand, foot and mouth disease (HFMD). This study aimed to investigate epidemic features and spatial clusters of HFMD incidence rates and assess the relationship between Enterovirus 71 (EV71) and Coxsackievirus A16 (CoxA16) and severe cases of HMFD in Gansu province, China. METHODS: Weekly county-specific data on HFMD between 1st January and 31st December 2018 were collected from the China Infectious Disease Information System (CIDIS), including enterovirus type (EV71 and CoxA16), severe and non-severe cases in Gansu province, China. Temporal risk [frequency index (α), duration index (ß) and intensity index (γ)] and spatial cluster analysis were used to assess epidemic features and identify high-risk areas for HFMD. Time-series cross-correlation function and regression model were used to explore the relationship between the ratios of two types of viruses (i.e. EV71/Cox16) (EC) and severe cases index (i.e. severe cases/non-severe cases) (SI) of HFMD. RESULTS: Some counties in Dingxi City, Gansu were identified as a hot spot for the temporal risk indices. Time-series cross-correlation analysis showed that SI was significantly associated with EC (r = 0.417, P < 0.05) over a 4-week time lag. The regression analysis showed that SI was positively associated with EC (ß = 0.04, 95% confidence interval (CI) 0.02-0.06). CONCLUSION: The spatial patterns of HFMD incidence were associated with enteroviruses in Gansu. The research suggested that the EC could be considered a potential early warning sign for predicting severe cases of HFMD in Gansu province.

Different responses of weather factors on hand, foot and mouth disease in three different climate areas of Gansu, China.

BACKGROUND: To determine the linear and non-linear interacting relationships between weather factors and hand, foot and mouth disease (HFMD) in children in Gansu, China, and gain further traction as an early warning signal based on weather variability for HFMD transmission. METHOD: Weekly HFMD cases aged less than 15 and meteorological information from 2010 to 2014 in Jiuquan, Lanzhou and Tianshu, Gansu, China were collected. Generalized linear regression models (GLM) with Poisson link and classification and regression trees (CART) were employed to determine the combined and interactive relationship of weather factors and HFMD in both linear and non-linear ways. RESULTS: GLM suggested an increase in weekly HFMD of 5.9% [95% confidence interval (CI): 5.4%, 6.5%] in Tianshui, 2.8% [2.5%, 3.1%] in Lanzhou and 1.8% [1.4%, 2.2%] in Jiuquan in association with a 1 °C increase in average temperature, respectively. And 1% increase of relative humidity could increase weekly HFMD of 2.47% [2.23%, 2.71%] in Lanzhou and 1.11% [0.72%, 1.51%] in Tianshui. CART revealed that average temperature and relative humidity were the first two important determinants, and their threshold values for average temperature deceased from 20 °C of Jiuquan to 16 °C in Tianshui; and for relative humidity, threshold values increased from 38% of Jiuquan to 65% of Tianshui. CONCLUSION: Average temperature was the primary weather factor in three areas, more sensitive in southeast Tianshui, compared with northwest Jiuquan; Relative humidity's effect on HFMD showed a non-linear interacting relationship with average temperature.

Socio-ecological factors and hand, foot and mouth disease in dry climate regions: a Bayesian spatial approach in Gansu, China.

The influence of socio-ecological factors on hand, foot and mouth disease (HFMD) were explored in this study using Bayesian spatial modeling and spatial patterns identified in dry regions of Gansu, China. Notified HFMD cases and socio-ecological data were obtained from the China Information System for Disease Control and Prevention, Gansu Yearbook and Gansu Meteorological Bureau. A Bayesian spatial conditional autoregressive model was used to quantify the effects of socio-ecological factors on the HFMD and explore spatial patterns, with the consideration of its socio-ecological effects. Our non-spatial model suggests temperature (relative risk (RR) 1.15, 95 % CI 1.01-1.31), GDP per capita (RR 1.19, 95 % CI 1.01-1.39) and population density (RR 1.98, 95 % CI 1.19-3.17) to have a significant effect on HFMD transmission. However, after controlling for spatial random effects, only temperature (RR 1.25, 95 % CI 1.04-1.53) showed significant association with HFMD. The spatial model demonstrates temperature to play a major role in the transmission of HFMD in dry regions. Estimated residual variation after taking into account the socio-ecological variables indicated that high incidences of HFMD were mainly clustered in the northwest of Gansu. And, spatial structure showed a unique distribution after taking account of socio-ecological effects.

[Spatial clustering of hand-foot-mouth disease in Gansu, 2012].

OBJECTIVE: The purpose of this study was to explore the spatial distribution and spatial clustering of hand-foot-mouth disease (HFMD) in Gansu, 2012. METHODS: Spatial autocorrelation and Spatial scanning analysis were used to conduct spatial statistical analyses for the HFMD at the county/district level. RESULTS: HFMD cases did not show a random distribution but with significant spatial aggregation. When Local Autocorrelation analysis was applied at the county/district level, with nine hot spot areas as Jiayuguan, Yumen, Dunhuang, Jinta, Suzhou, Chengguan, Anning, Xigu and Gaolan, were discovered. Four statistically significant HFMD clusters were identified by spatial scan statistics. CONCLUSION: HFMD was noticed geographically clustered in Gansu in 2012. Results from this study indicated that the spatial autocorrelation and spatial scanning analysis could effectively detect the areas which presenting significant clusters. Cluster Detection System (CDS) could provide evidence for the development of an effective measure concerning the prevention and control of HFMD.

[Epidemiological features and pathogenic characteristics of hand, foot and mouth disease in Gansu Province, China during 2008-2012].

This study aims to analyze the epidemiological features and pathogenic characteristics of hand, foot and mouth disease (HFMD) in Gansu Province, China and to provide a basis for the development of effective prevention and control measures. The descriptive epidemiological analysis was used to analyse the data of HFMD cases in Gansu. The specimens collected from hospitals were subjected to RT-PCR or real-time PCR to detect human enterovirus (HEV) nucleic acid, and HEV strains were isolated using human rhabdomyosarcoma cells and human laryngeal carcinoma cells. The complete VP1-encoding region of several identified enterovirus A71 (EV71) and coxsackievirus A16 (CVA16) was subjected to full-length amplification by RT-PCR and then to sequencing and analysis. A total of 52 550 HFMD cases were reported in Gansu from 2008 to 2012, including 205 severe cases and 27 deaths. The incidence rates in the whole province from 2008 to 2012 were 22.42/10(5), 49.29/10(5), 47.20/10(5), 27.27/10(5), and 55.84/10(5), respectively. There were cases in all the 14 cities or prefectures in Gansu, and Lanzhou had the largest number of cases (16 001 cases), accounting for 30.45% of all cases in the province. HFMD cases were mostly reported during May to July, accounting for 51.69% of all cases throughout the year. The male-to-female ratio was 1.69:1. Of all the cases, 87.59% were under the age of five. Of the 5 416 cases for laboratory tests, 3 322 (61.34%) were positive for HEV nucleic acid, including EV71 (46.96%), CVA16 (41.57%), and other HEVs (11.47%). Among the 186 severe cases, 114 (61.29%) were positive for HEV nucleic acid, and 82.46% of the positive cases for EV71. All the 25 dead cases were infected with EV71. A total of 402 strains were isolated from 3 111 specimens collected from hospitals (2 123 throat swab specimens, 705 stool specimens, and 705 herpes specimens), including EV71 (70.15%), CVA16 (27.11), other coxsackievirus A (3.98%), coxsackievirus B (2.49%), echovirus (1.74%), and adenovirus (1.99%). The genotyping of VP1- encoding region showed that all the 194 EV71 strains isolated during 2008-2012 belonged to the C4a evolutionary branch of C4 subtype; among the 45 CVA16 strains, 12 belonged to the Bla evolutionary branch of B1 subtype and 33 to the B1b evolutionary branch, and B1b became the predominant subtype in 2012. In conclusion, in Gansu Province, HFMD occurs mostly in children under the age of five; EV71 and CVA16 are the main pathogens of this disease, and the two are predominant alternately from 2008 to 2012; the severe and dead cases of HFMD are closely related to infection with EV71; the types of pathogens varied across different regions in the same year during 2008-2012.