With the help of my colleagues, I have been conducting epidemiological studies on biliary tract cancer (BTC), including gallbladder cancer (GBC) and extrahepatic bile duct cancer (BDC), in Japan and Chile for about 19 years. Clustered areas with high mortality rates, especially for female GBC were found to correspond with places or prefectures in Japan that were famous for rice production. The roles of known risk factors, such as gallstones and cholecystitis, were examined, but no single factor was implicated in the high mortality rates for GBC in these areas. A working hypothesis, called the “rice production hypothesis” was formulated; this initial hypothesis was replaced by a new multifactorial causation hypothesis: GBC is more likely to occur in individuals with a genetic susceptibility and a past history of gallstones or cholecystitis who are exposed to geographically specific environmental factors, such as agricultural chemicals. On the basis of various analytical studies, it is concluded that a certain agricultural chemical was responsible for the occurrence of GBC. At the time of writing, no evidence has been obtained to disprove our hypothesis. We have also conducted international collaborative studies in Chile, which has the highest mortality rate for GBC in the world. Bile from Chileans was found to have a higher mutagenic activity than that from Japanese subjects; Chileans with a history of constipation or a habit of consuming red chilli pepper had a high risk of developing GBC, if they also had gallstone(s). The presence of a regional difference in p53 mutagenesis was also observed.
seconds ; Gallstones ; Mortality Vital Statistics ; Cancer of Biliary Tract ; Spatial Distribution

Plague is a virulent infectious disease in China. In this study, '3S' technology was used to perform spatial autocorrelation analysis and spatial interpolation analysis for Spermophilus dauricus (S. Dauricus, a species of ground squirrel) captured in Manchuria City in 2015. The results were visually inspected. During the two-month (May to July) plague surveillance in 2015, 198 S. dauricus individuals were captured in the study area in Manchuria City (48 monitoring areas) by using a day-by-day catching method. Spatial autocorrelation was conducted using the ArcGIS software, and the following significantly different results were obtained: Moran's I=0.228472, Z-score=2.889126, and P<0.05. Thus, a spatial aggregation was observed. In 2015, the distribution of S. dauricus diminished from west to east and from north to south of Manchuria. Geo Detector software was used to analyze the habitat factors affecting the spatial distribution of S. dauricus. This highly clustered species mainly exists in suburban communities, construction sites, and areas surrounding factories. In future studies, plague surveillances should be performed in areas around Manchuria and Zhalainuoer.
Animal Distribution ; Animals ; China ; Disease Reservoirs ; statistics & numerical data ; Geographic Information Systems ; Humans ; Plague ; transmission ; Sciuridae ; physiology ; Spatial Analysis

Objective: To identify the spatial clustering and its temporal trends among newly detected female HIV/AIDS cases aged 15 years or older, in China from 2010 to 2016. Methods: Newly detected HIV/AIDS cases among aged 15 years or older women in China during 2010-2016 were collected, to describe their demographic characteristics, changing trends and spatial autocorrelation. This program was conducted at county level, using the ArcGIS 10.3. Results: The number of newly detected HIV/AIDS cases among aged 15 years or older women was increasing annually from 16 603 to 26 196 in 2010 and in 2016. As the main route proportion of heterosexual transmission increased from 84.25% (13 988/16 603) in 2010 to 96.29%(25 224/26 196) in 2016. Both the number and proportion of HIV/AIDS cases among elderly women ≥50 years of age increased significantly from 17.82%(2 959/16 603) to 38.10%(9 981/26 196) in 2016. Results from spatial analysis demonstrated a county-level clustered distribution of HIV/AIDS cases across the country with a rising global Moran's I value=0.55 over the years (Z=51.46, P<0.001), which was concentrating on western and southern China, covering 9 provinces/autonomous regions/municipalities (Yunnan, Guangxi, Sichuan, Xinjiang, Guizhou, Guangdong, Chongqing, Henan and Hunan). The temporal trends of hot spots differed by age groups, with the trend of epidemic shifting towards western border and southern coastal regions among women aged 15-49 years old, while the elderly women aged ≥50 years old were spreading northward from the southwestern regions. Conclusion: Our findings indicated that an increasing trend of clusters appeared on HIV epidemic among newly detected female HIV/AIDS cases aged 15 years or older in China, particularly in the western and southern regions. Prevention and intervention strategies should target on women according to their age distribution, particularly in regions with increasing trend of HIV epidemics.
Adolescent ; Adult ; Age Distribution ; Aged ; China/epidemiology* ; Epidemics ; Female ; HIV Infections/ethnology* ; Humans ; Middle Aged ; Spatial Analysis ; Young Adult

Objective: To compare the time and spatial distribution of hepatitis C and HIV/AIDS cases and its correlation, in China from 2012 to 2017. Methods: Data on reported hepatitis C and HIV/AIDS cases was gathered from the Direct Reporting System of Infectious Diseases Information Network in China, 2012 to 2017 while annually collected provincial data was based on the date of review and current address. Correlation of the data was analyzed, using both simple correlation and linear regression methods. Results: The number of reported cases of hepatitis C remained stable in China, in 2012-2017, with the number of annual reported cases as 201 622, 203 155, 202 803, 207 897, 206 832 and 214 023, respectively. The number of reported cases on HIV/AIDS showed a steady growing trend, from 82 434, 90 119, 103 501, 115 465, 124 555 to 134 512. However, the numbers of hepatitis C and HIV/AIDS cases were in the same, top six provinces: Henan, Guangdong, Xinjiang, Guangxi, Hunan and Yunnan. Results from the simple correlation analysis indicated that there was a positive correlation (r>0.5, P<0.01) existed between the above-said two kinds of cases at the provincial level in China, in 2012-2017. Again, results from the linear regression analysis also showed that the correlation coefficient r(s) and year was strongly correlated (r=0.966) while r(s) had been linearly increasing with time. Conclusions: Our data showed that there were temporal and spatial correlations existed between the reported cases of hepatitis C and HIV/AIDS at the provincial level, suggesting that relevant prevention and control programs be carried out in areas with serious epidemics. Combination of the two strategies should be encouraged, especially on prevention and treatment measures related to blood transmission.
Age Distribution ; China/epidemiology* ; Epidemics ; HIV ; HIV Infections/ethnology* ; Hepatitis C/ethnology* ; Humans ; Linear Models ; Spatial Analysis ; Spatio-Temporal Analysis ; Young Adult

Spatial analytical techniques and models are often used in epidemiology to identify spatial anomalies (hotspots) in disease regions. These analytical approaches can be used to identify not only the location of such hotspots, but also their spatial patterns. We used spatial autocorrelation methodologies, including Global Moran's I and Local Getis-Ord statistics, to describe and map spatial clusters and areas in which nine malignant neoplasms are situated in Taiwan. In addition, we used a logistic regression model to test the characteristics of similarity and dissimilarity between males and females and to formulate the common spatial risk. The mean found by local spatial autocorrelation analysis was used to identify spatial cluster patterns. We found a significant relationship between the leading malignant neoplasms and well-documented spatial risk factors. For instance, in Taiwan, the geographic distribution of clusters where oral cavity cancer in males is prevalent was closely correspond to the locations in central Taiwan with serious metal pollution. In females, clusters of oral cavity cancer were closely related with aboriginal townships in eastern Taiwan, where cigarette smoking, alcohol drinking, and betel nut chewing are commonplace. The difference between males and females in the spatial distributions was stark. Furthermore, areas with a high morbidity of gastric cancer were clustered in aboriginal townships where the occurrence of Helicobacter pylori is frequent. Our results revealed a similarity between both males and females in spatial pattern. Cluster mapping clarified the spatial aspects of both internal and external correlations for the nine malignant neoplasms. In addition, using a method of logistic regression also enabled us to find differentiation between gender-specific spatial patterns.
Alcohol Drinking ; adverse effects ; Areca ; Cluster Analysis ; Environmental Pollution ; adverse effects ; Female ; Helicobacter Infections ; epidemiology ; Humans ; Logistic Models ; Male ; Mouth Neoplasms ; epidemiology ; etiology ; Neoplasms ; epidemiology ; etiology ; microbiology ; Risk Factors ; Sex Distribution ; Smoking ; adverse effects ; Spatial Analysis ; Stomach Neoplasms ; epidemiology ; microbiology ; Taiwan ; epidemiology