Surveillance for foodborne disease outbreaks in China, 2003 to 2008.

Knowledge of implicated food vehicles and contributing factors derived from foodborne disease outbreak (FBDO) investigations allows consumers to be educated on decreasing high-risk behavior to reduce the risk of being affected by foodborne diseases. Food safety regulatory authorities also need summary of outbreak data, as these data indicate where the existing food supply system should be improved. To obtain information on epidemiology of FBDOs in China, FBDOs reported to the China National Foodborne Diseases Surveillance Network by 12 surveillance provinces that include 43% of the Chinese population was summarized. Between 2003 and 2008, 2795 FBDOs were reported, resulting in 62559 illnesses, 31261 hospitalizations, and 330 deaths. Outbreak size ranged from 2 to 464 cases, with a median of 14 cases. The outbreak rate had decreased from 1.37 per 1 million population in 2003 to 0.46 per 1 million population in 2008. Of the 2176 outbreaks with a single known etiology, bacteria (1051 outbreaks, 48%), man-made chemical hazards (550 outbreaks, 25%), and animal and plant toxins (536 outbreaks, 25%) were the main courses. Only one outbreak was caused by virus. Of the 1930 outbreaks with a single commodity, plant-based foods were the most common reported (930 outbreaks, 48%), followed by animal-based foods (590 outbreaks, 31%). Outbreaks most frequently occurred in private residences (32%), workplace cafeterias (21%), and restaurants (17%). The most common factor reported in the 2190 outbreaks with known contributing factors were improper cooking (510 outbreaks, 23%), contaminated ingredient (503 outbreaks, 23%), cross contamination (475 outbreaks, 22%) and improper storage (295 outbreaks, 13%). It is considered that FBDOs continue to be an important public health problem in China.

[Responses of Extracellular Enzymes to Nitrogen Application in Rice of Various Ages with Rhizosphere and Bulk Soil].

Ecological enzyme activities are closely relevant to the carbon and nitrogen decomposition and mineralization of paddy soils, which can reflect the growth and metabolism of microorganisms. In order to clarify the response to nitrogen application by different enzymes in the rhizosphere and bulk soil of rice, the rhizosphere and bulk soil were identified using a rhizosphere bag. In addition, the ß-1,4-glucosidase (BG) enzyme; ß-1,4-N-acetylglucosaminidase (NAG) enzyme; and the effects of the rhizosphere, nitrogen application, and growth period on soil enzyme activities were analyzed. The results showed that the activity of the BG enzyme decreased by 7.4-13.5 nmol·(g·h)-1 in the jointing stage and increased by 7.0-31.4 nmol·(g·h)-1 in the maturity stage, and the activity of the BG enzyme in the rhizosphere and bulk soil also changed with the growth period of rice.compared with no nitrogen fertilizer, nitrogen application increased NAG enzyme activity by 1.1 times and rhizosphere soil by 0.3 times in the bulk soil in the maturity stage. Nitrogen application and growth period had significant effects on soil BG enzyme activity, whereas the interaction within rice growth stage, nitrogen application, and rhizosphere effect had significant effects on NAG enzyme activity. The result of RDA showed that the soil microbial biomass carbon (MBC) and dissolved organic carbon (DOC) contents mainly affected the activity of extracellular enzymes in the rice rhizosphere soil, whereas the activities of enzymes in the rhizosphere soil were mainly affected by microbial biomass nitrogen (MBN) and NH4+-N. The relationships between soil enzyme activity and various factors are complex, and the effects of nitrogen addition on microbial community composition needs to be considered after accounting for plant physiological characteristics, soil enzyme activity, and soil characteristics.

[Input and Distribution of Photosynthesized Carbon in Soil-Rice System Affected by Water Management and Nitrogen Fertilization].

Fertilizer and water management are two key factors for rice growth. A better understanding of the carbon (C) cycling in paddy soil requires investigation into the input characteristics and distribution dynamics of photosynthesized carbon in rice-soil system. We grew rice (Zhongzao 39) in PVC pots and used the 13 C-CO2 continuous labeling method to quantify the allocation of photosynthesized carbon in rice-soil system under two regimes(Drying-rewetting vs. continuous watering) and N fertilization (250 mg·kg-1vs. no addition). The results showed that nitrogen fertilizer application increased rice shoot biomass and the amount of C and N, but had no significant influence on rice root biomass. Thus, nitrogen fertilizer application decreased rice biomass root/shoot ratio significantly. Drying-rewetting with N fertilizer treatment resulted in higher total C and N amount by 22% and 33%, respectively, in the shoot, and by 36% and 44%, respectively in the root than continuous watering with nitrogen fertilizer treatment. These results indicated that nitrogen fertilizer application promoted the growth of rice shoot. Nitrogen fertilizer application significantly increased the 13 C content in rice shoot by 32%-83% over the control without N addition. Nitrogen fertilizer application also increased the 13 C recovery in rice shoot by 6%-32%, but decreased that in the root by 18%-59%. Pertaining to water effect, drying-rewetting with N application increased the amount of 13 C in rice shoot and root. However, without N addition, the amount and the recovery of 13 C in shoot dropped by 10.3 mg·pot-1 and 12%, respectively, compared with the continuous watering treatment. The root, on the other hand, recorded increases in both the amount and the recovery of 13 C by 1.9 mg·pot-1 and 57%, respectively. Furthermore, the deposition of assimilated C into rhizosphere-soil increased by both the individual and the interactive effects of N fertilizer application and drying-rewetting treatment. Thus, combining N fertilizer and drying-rewetting water management led to more increased allocation and deposition of photosynthesized carbon in soil-rice system compared with combined continuous flooding and N application. This study was able to quantify the partitioning and allocation of rice photosynthesized carbon into different plant and soil pools under different water and N fertilizer treatments, and can serve as a useful guide for better water and nutrient management practices in paddy-rice production that can achieve both sustainable high yield and sequestration of more C within the paddy soil system.

Risk factors for measles in children younger than age 8 months: A case-control study during an outbreak in Guangxi, China, 2013.

BACKGROUND: Following a period (2009-2012) during which zero measles cases were reported, a measles outbreak occurred in 2013 in Bama County, Guangxi, China, that involved more than 100 children younger than age 8 months. We aimed to identify the pitfalls and risk factors while implementing the control measures. METHODS: An outbreak investigation and a case-control study was conducted among children younger than age 8 months. The serum specimens of the study subjects and their mothers were tested for measles immunoglobulin M and immunoglobulin G. RESULTS: The attack rate was 2.3/1,000 population. The median (interquartile range) age was 18.6 months (7.9-52.8 months). The coverage of 2-dose measles-containing vaccine was only 34%. The case-control study revealed 2 independent risk factors: low education level of main caregiver (odds ratio [OR], 2.86; 95% confidence interval [CI], 1.31-6.22) and visiting a hospital 7-21 days before the date of symptoms onset (OR, 9.84; 95% CI, 4.27-22.67). The population attributable fraction of the latter was 52.8%. The mothers of the cases had nonsignificantly higher levels of immunoglobulin M and were significantly more likely to have protective levels of immunoglobulin G than those of the controls. This suggests a reactive rather than protective role of the antibody to the child's infection. CONCLUSIONS: In a near-elimination but low measles-containing vaccine coverage community, supplementary immunization activities should be emphasized for children and women who are potential future mothers. The minimum age of measles-containing vaccine should be further reduced. Hospital measles transmission must also be strictly prevented.

[Investigation on the risk factors for HIV infection among elderly male clients of the commercial female sex-workers in Guangxi Zhuang Autonomous Region, in 2012].

OBJECTIVE: To monitor the current HIV prevalence, related risk behaviors and factors for HIV infection among the elderly male clients of the commercial female sex-workers (CFSW)in Guangxi. METHODS: Face to face interview on male clients aged ≥40 years old was carried out in April to July, 2012. Information on demography, awareness of HIV prevention, related risk behaviors, history on HIV testing etc. were collected, with 3-5 ml full blood collected for testing on HIV. Data was analyzed by SPSS 18.0 software. RESULTS: 4260 clients were surveyed at 14 surveillance sites in which 82.1% had received secondary or lower education, 72.0% experienced commercial sex in places with low-class sex trade. HIV awareness rate of clients was 74.2% in which the rate of clients who were HIV positive was 65.8%. Among all the clients, 73 were detected as HIV positive, with the HIV positive rate as 1.40% . Samples from voluntary counseling and testing sites showed higher risk to HIV infection than from other sources (OR = 23.672, 95%CI:4.984-112.434). Samples from middle class population showed lower risk to HIV infection than those at low class (OR = 0.410, 95%CI:0.190-0.885). Among those who were syphilis negative (OR = 0.255, 95%CI: 0.132-0.491) or hepatitis C virus (HCV)negative (OR = 0.154, 95% CI:0.059-0.401), the risk of getting HIV infected seemed to be low. Rate on condom use was low for clients among all of the sex-related behaviors regardless of the marriage status. In those lower-class sex trade places, lower rate on the condom use was seen. Rate for previous HIV testing for clients was only 4.6% . Among 41 clients who had received CD4 testing, 80.5% of them showed CD4 under 350 cell/µl, 61.0% were under 200 cell/µl. CONCLUSION: The HIV positive rate for elderly male clients of the CFSWs was high in Guangxi. Unprotective sexual contact with low class sex workers was the most important risk factor for HIV infection.

[Application of cluster randomization method on typhoid Vi vaccine trails].

OBJECTIVE: To describe the design and application of cluster randomized controlled method on typhoid Vi vaccine trial, and to assess the effect of implementation. METHODS: Simple size calculation of cluster-randomized trial was used to determine the sample size of the two groups and a vaccination campaign was conducted. The study group was given typhoid Vi vaccine and the control group was given meningococcal A vaccine. RESULTS: According to sample size calculation, a total sample of 96,121 participants was required and the study areas were divided into 108 clusters. In practice, 53 study clusters with 44,054 participants and 54 control clusters with 48,422 participants were stratified and matched according to size, location (urban or rural), characteristics (school, department, factory, demography) were randomized respectively. Confounding factors of two groups including age, sex, resident area, income, level of education were compared. It was found that the ratio of all confounding factors between the two groups were comparable and balanced. CONCLUSION: Confounding factors can be better controlled between study group and the control group by applying cluster-randomized method on vaccine trail which enabled the intervention to be more scientifically evaluated; The implementation of cluster randomization trial was simple and easy to be accepted.

A mass vaccination campaign targeting adults and children to prevent typhoid fever in Hechi; expanding the use of Vi polysaccharide vaccine in southeast China: a cluster-randomized trial.

BACKGROUND: One of the goals of this study was to learn the coverage, safety and logistics of a mass vaccination campaign against typhoid fever in children and adults using locally produced typhoid Vi polysaccharide (PS) and group A meningococcal PS vaccines in southern China. METHODS: The vaccination campaign targeted 118,588 persons in Hechi, Guangxi Province, aged between 5 to 60 years, in 2003. The study area was divided into 107 geographic clusters, which were randomly allocated to receive one of the single-dose parenteral vaccines. All aspects regarding vaccination logistics, feasibility and safety were documented and systematically recorded. Results of the logistics, feasibility and safety are reported. RESULTS: The campaign lasted 5 weeks and the overall vaccination coverage was 78%. On average, the 30 vaccine teams gave immunizations on 23 days. Vaccine rates were higher in those aged < or = 15 years (90%) than in adolescents and young adults (70%). Planned mop-up activities increased the coverage by 17%. The overall vaccine wastage was 11%. The cold chain was maintained and documented. 66 individuals reported of adverse events out of all vaccinees, where fever (21%), malaise (19%) and local redness (19%) were the major symptoms; no life-threatening event occurred. Three needle-sharp events were reported. CONCLUSION: The mass immunization proved feasible and safe, and vaccine coverage was high. Emphasis should be placed on: injection safety measures, community involvement and incorporation of mop-up strategies into any vaccination campaign. School-based and all-age Vi mass immunizations programs are potentially important public health strategies for prevention of typhoid fever in high-risk populations in southern China.

[Epidemiologic surveillance for bacterial meningitis in 140 000 children under 5 years of age in Nanning district, Guangxi province].

OBJECTIVE: To characterize the incidence, epidemiologic features, etiologic agents and sequelae of bacterial meningitis in children under 5 years of age in Nanning, Guangxi. METHODS: A population-based surveillance was conducted to evaluate children with signs and symptoms of meningitis. All hospitals, township health centers and village clinics in the surveillance area were structured to participate in the case referral and evaluation. Cerebrospinal fluid (CSF) and blood specimens were obtained and processed using standardized microbiologic methods. RESULTS: During the 26-month surveillance period, among the children under 5 years old, a total of 1272 cases who met the screening criteria of meningitis were studied. 265 of 1272 cases were identified as clinically diagnosed meningitis, with an incidence rate of 86.36 per 100 000 population. The annual incidence rate under the 38 cases of confirmed bacterial meningitis appeared to be 12.38/100 000. Staphylococcus species accounted for the largest proportion of laboratory-confirmed bacterial meningitis, followed by E. coli and S. pneumoniae. The highest attack rate occurred in neonates < 1 month, followed by children aged 1 - 12 months in the confirmed patients. Meningitis caused by Sp and Hi mainly occurred in children aged 1 - 12 months. All cases of meningitis due to Hi and Sp were children aged 1 - 24 months. 13.16% and 0.00% of the cases survived with complications and sequelae, and the case-fatality rate was 18.42%. 40 bacterial isolates were identified from 1193 blood cultures and 23 from 1211 cerebrospinal fluid samples, but no Neisseria meningitidis was found. CONCLUSION: Meningitis due to Hi was first confirmed in Guangxi with the incidence of 0.98 per 100 000 population. The annual incidence rate of confirmed bacterial meningitis was 12.38 per 100 000, which was considered an important public health problem in children. Staphylococci was the predominant pathogen in confirmed bacterial meningitis.