[An outbreak of foot pain syndrome among students from a senior high school in Foshan, Guangdong province, 2014].

OBJECTIVE: To identify the cause of an outbreak of foot pain syndrome among students from a senior high school in Foshan. METHODS: We defined a suspect case as onset of foot pain/numbness with unknown reason among students and teachers in a school of Foshan city, from February 10 to March 16, 2014. A suspect case was noticed as having both food pain and numbness. All the cases were searched through reviewing medical records in the nearby hospitals and school's clinic, also the records of absenteeism in school. Clinical information was collected from all the students, using a standardized questionnaire. Daily temperature was collected from all the students, between January 1 and March 31, 2014. A 1 : 2 individual matched case-control study was conducted to identify related risk factors on this epidemic. We interviewed all the cases and controls on their diet, physical activities and measures used for warming. RESULTS: A total of 407 case-students were identified, with an attack rate (AR) as 26.5%. The AR was 37.3% in girls, compared to 12.9% in boys. The difference was statistically significant (χ² = 115.1, P < 0.01). Boarding students had a higher AR (31.8%) than the commuting students (16.2%). The difference was statistically significant (χ² = 43.2, P < 0.01). In girls, boarding students had higher AR (46.1%) than those commuting students (18.5%). The difference was statistically significant (χ² = 61.4, P < 0.01). No statistically significant difference was found between boarding or commuting students in boys. Outdoor temperature was coming down from 23 °C on February 6 to 6 °C on February 13, but gradually rose to 23 °C on February 28. There was a positive relationship (r = 0.65, P = 0.002) noticed between daily maximum temperature and the number of cases during February 13-28. Results from this case-control study showed that factors as lacking physical activities (OR = 2.8, 95% CI: 1.5-5.6), feeling cold in bed (OR = 3.0, 95% CI: 1.3-7.0) and having experienced similar symptoms (OR = 3.4, 95% CI: 1.1-11.0) could increase the risk of this disease. CONCLUSION: This outbreak was possibly caused by the abrupt fluctuation of temperature within a short period.

Early detection of an epidemic erythromelalgia outbreak using Baidu search data.

Dozens of epidemic erythromelalgia (EM) outbreaks have been reported in China since the mid-twentieth century, and the most recent happened in Foshan City, Guangdong Province early 2014. This study compared the daily case counts of this recent epidemic EM outbreak from February 11 to March 3 with Baidu search data for the same period. After keyword selection, filtering and composition, the most correlated lag of the EM Search Index was used for comparison and linear regression model development. This study also explored the spatial distribution of epidemic EM in China during this period based on EM Search Index. The EM Search Index at lag 2 was most significantly associated with daily case counts in Foshan (ρ = 0.863, P < 0.001). It captured an upward trend in the outbreak about one week ahead of official report and the linear regression analysis indicated that every 1.071 increase in the EM Search Index reflected a rise of 1 EM cases 2 days earlier. The spatial analysis found that the number of EM Search Indexes increased in the middle of Guangdong Province and South China during the outbreak period. The EM Search Index may be a good early indicator of an epidemic EM outbreak.