Exploring the characteristics of Burkholderia gladioli pathovar cocovenenans: Growth, bongkrekic acid production, and potential risks of food contamination in wet rice noodles and vermicelli.

This research investigated the presence of Burkholderia gladioli pathovar cocovenenans (BGC) in wet rice and starch products, Tremella, and Auricularia auricula in Guangzhou, China. It examined BGC growth and bongkrekic acid (BA) production in wet rice noodles and vermicelli with varying rice flour, edible starch ratios, and oil concentrations. A qualitative analysis of 482 samples revealed a detection rate of 0.62%, with three positive for BGC. Rice flour-based wet rice noodles had BA concentrations of 13.67 ± 0.64 mg/kg, 2.92 times higher than 100% corn starch samples (4.68 ± 0.54 mg/kg). Wet rice noodles with 4% soybean oil had a BA concentration of 31.72 ± 9.41 mg/kg, 5.74 times higher than those without soybean oil (5.53 ± 1.23 mg/kg). The BA concentration correlated positively (r = 0.707, P < 0.05) with BGC contamination levels. Low temperatures (4 °C and -18 °C) inhibited BGC growth and BA production, while higher storage temperatures (26 °C and 32 °C) promoted BGC proliferation and increased BA production. Reducing edible oil use and increasing edible starch can mitigate the risk of BGC-related food poisoning in wet rice noodles and vermicelli production. Further research is needed to find alternative oils that do not enhance BA production. Strengthening prevention and control measures is crucial across the entire production chain to address BGC contamination and BA production.

Prediction of risk factors for scrub typhus from 2006 to 2019 based on random forest model in Guangzhou, China.

OBJECTIVES: Scrub typhus is an increasingly serious public health problem, which is becoming the most common vector-borne disease in Guangzhou. This study aimed to analyse the correlation between scrub typhus incidence and potential factors and rank the importance of influential factors. METHODS: We collected monthly scrub typhus cases, meteorological variables, rodent density (RD), Normalised Difference Vegetation Index (NDVI), and land use type in Guangzhou from 2006 to 2019. Correlation analysis and a random forest model were used to identify the risk factors for scrub typhus and predict the importance rank of influencing factors related to scrub typhus incidence. RESULTS: The epidemiological results of the scrub typhus cases in Guangzhou between 2006 and 2019 showed that the incidence rate was on the rise. The results of correlation analysis revealed that a positive relationship between scrub typhus incidence and meteorological factors of mean temperature (Tmean ), accumulative rainfall (RF), relative humidity (RH), sunshine hours (SH), and NDVI, RD, population density, and green land coverage area (all p < 0.001). Additionally, we tested the relationship between the incidence of scrub typhus and the lagging meteorological factors through cross-correlation function, and found that incidence was positively correlated with 1-month lag Tmean , 2-month lag RF, 2-month lag RH, and 6-month lag SH (all p < 0.001). Based on the random forest model, we found that the Tmean was the most important predictor among the influential factors, followed by NDVI. CONCLUSIONS: Meteorological factors, NDVI, RD, and land use type jointly affect the incidence of scrub typhus in Guangzhou. Our results provide a better understanding of the influential factors correlated with scrub typus, which can improve our capacity for biological monitoring and help public health authorities to formulate disease control strategies.

Malaria epidemiological characteristics and control in Guangzhou, China, 1950-2022.

BACKGROUND: Malaria was once widespread in Guangzhou, China. However, a series of control measures have succeeded in eliminating local malaria infections. Based on the analysis of the characteristics of malaria epidemics in Guangzhou, China, from 1950 to 2022, the changes and effectiveness of malaria control strategies and surveillance management in Guangzhou from 1950 to 2022 are described. METHODS: Data on malaria prevention and treatment in Guangzhou from 1950 to 2022 were collected, and descriptive epidemiological methods were used to analyse the prevalence of malaria, preventive and control measures taken, and the effectiveness of prevention and treatment in different periods. Data on malaria cases were obtained from the Guangzhou Centre for Disease Control and Prevention (CDC) and the China Communicable Disease Reporting System. RESULTS: The development of the malaria control system in Guangzhou has gone through four periods: 1. High malaria prevalence (1950-1979), 2. Intensive prevention and control stage (1980-2000), 3. Consolidating gains in malaria control (2001-2008), and 4. Preventing reestablishment of transmission (2009-2022). During Period 1, only medical institutions at all levels and the local CDCs, the Guangzhou CDC participated in the malaria prevention and control system, establishing a three-tier health system on malaria prevention and control. During Period 2, other types of organizations, including the agricultural sector, schools and village committees, the construction department and street committee, are involved in the malaria control system. During Period 3, more and more organizations are joining forces to prevent and control malaria. A well-established multisectoral malaria control mechanism and an improved post-elimination surveillance management system are in place. Between 1950 and 2022, a total of 420,670 cases of malaria were reported. During Period 1, there was an epidemic of malaria in the early 1950s, with an annual incidence rate of more than 10,000/100,000, including a high rate of 2887.98/100,000 in 1954. In Period 2 malaria was gradually brought under control, with the average annual malaria incidence rate dropping to 3.14/100,000. During Period 3, the incidence rate was kept below 1/100,000, and by 2009 local malaria infections were eliminated. CONCLUSION: For decades, Guangzhou has adopted different malaria control strategies and measures at different epidemic stages. Increased collaboration among civil organizations in Guangzhou in malaria control has led to a significant decline in the number of malaria cases and the elimination of indigenous malaria infections by 2009.The experience of Guangzhou can guide the development of malaria control strategies in other cities experiencing similar malaria epidemics.

[Lead contamination status and assessment of potential risk to human health of commercial foods in Guangzhou City in 2017-2019].

OBJECTIVE: To investigate lead contamination in commercial foods in Guangzhou City, and to assess the health risk of dietary lead exposure in the residents. METHODS: Food samples were collected in 11 districts in Guangzhou City from 2017 to 2019.The samples were tested for lead by using inductively coupled plasma mass spectrometry. The dietary exposure to lead of residents of different age groups in Guangzhou was calculated in combination with the intake of foods from the food consumption survey of Guangzhou residents in 2011, and the margin of exposure(MOE) method was used to evaluate the health risk of the population. RESULTS: A todal of 3130 food samples of 15 categories were collected. The overall lead detection rate was 82.11%, the exceeding rate was 0.13%, and the average lead content was 0.031 mg/kg. The highest lead levels were found in bivalve, edible fungi and flour and flour products. Excessive levels of lead were found in bivalve, eggs and egg products, and flour and flour products. The average daily dietary intake of lead in people aged 3-6, 7-17, 18-59 and over 60 in Guangzhou were 0.368, 0.377, 0.326 and 0.337 µg/kg, respectively. Daily lead exposure of population with high consumption(P95) in various age groups through foods were 1.091, 1.079, 0.906 and 0.925 µg/kg, respectively. Brassica and leafy vegetables, rice and its products and meat were the main sources of dietary lead exposure, accounting for 53.28% of the total dietary lead exposure. The average MOE of lead in all age groups were greater than 1, but the P95 of MOE value of people aged 3-6 and 7-17 were 0.55 and 0.56, respectively, which presented certain health risks. CONCLUSION: There was a certain amount of lead exceeding the standard in commercial foods in Guangzhou. The average level of dietary lead exposure for residents of all ages posed a low risk to population health, but the dietary lead exposure risk of high-food consumers aged 3-6 and 7-17 posed certain health risks that deserve significant attention.

A Tentative Tamdy Orthonairovirus Related to Febrile Illness in Northwestern China.

BACKGROUND: Many novel tick-borne viruses have been discovered by deep-sequencing technology in recent years; however, their medical significance is unknown. METHODS: We obtained clinical data of a patient from Xinjiang, China. Possible pathogens were detected by metagenomic analysis; the causative pathogen Tacheng tick virus 1 (TcTV-1) was found and further confirmed by reverse transcriptase-polymerase chain reaction, viral culture, and sequence analyses. Epidemiological investigation was conducted in the local human population, domestic animals, and ticks by serological/molecular methods. RESULTS: A 62-year-old woman with a history of tick bite in Qinghe, Xinjiang, presented with fever and rashes. These symptoms were relieved after clinical treatment. TcTV-1 (strain QH1) was isolated from the patient's cerebrospinal fluid, throat swabs, and urine on day 47 after illness onset. Although the blood and urine showed viral RNA positive on day 73 after illness onset, the virus was only isolated from urine. Serological detection revealed a virus neutralizing antibody titer of 1:40 and 1:80 on day 47 and 73 after illness onset, respectively. No coinfection with other pathogens was detected, suggesting TcTV-1 may be the potential causative pathogen. We detected anti-TcTV-1 antibodies (immunoglobulin G: 10.1%; immunoglobulin M: 4.8%) in the local human population. The viral RNA was also found in cattle (4.9%), sheep (9.2%), and ticks, including Dermacentor marginatus (14.3%), Dermacentor silvarum (11.8%), Dermacentor nuttalli (6.7%), and Hyalomma asiaticum (4.8%). CONCLUSIONS: TcTV-1 may be associated with a febrile illness syndrome, and epidemiological data of the virus in humans and animals necessitate disease surveillance of TcTV-1 infection in China.

Bacillus aerolatus sp. nov., a novel member of the genus Bacillus, isolated from bioaerosols in a school playground.

A Gram-positive, endospore-forming, rod-shaped bacterium with a single flagellum, and a motile strain, designated CX253, was isolated from bioaerosols. The isolate is facultatively anaerobic, is able to grow at 25-45 â„ƒ (optimum 37 â„ƒ) and pH 6.5-10.0 (optimum 7.5), and can tolerate up to 5.0% NaCl (w/v) under aerobic conditions. The diagnostic diamino acid in the cell wall of strain CX253T is meso-diaminopimelic acid, while major isoprenoid quinone is menaquinone 6 (MK-6) along with a smaller amount of MK-7 (20%). The polar lipid profile is composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phospholipids and glycolipids. The major cellular fatty acid is iso-C15:0 and anteiso-C15:0. Phylogenetic analysis based on 16S rRNA gene and genome sequence grouped strain CX253T into the genus Bacillus. The strain was most closely related to Bacillus thermotolerans CCTCC AB 2012108 T by comparison of 16S rRNA gene sequence (97.2% similarity) and to Bacillus wudalianchiensis CCTCC AB 2015266 T by comparison of gyrB gene sequence (80.1% similarity). The draft genome of strain CX253T comprised 3,929,195 bp with a G + C content of 43.3 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain CX253T and phylogenetically related Bacillus species were lower than 95% and 70%, respectively. Thus, the polyphasic evidence generated through phenotypic, chemotaxonomic and genomic methods confirmed that strain CX253T (= GDMCC 1.1608 T = KACC 21318 T) was a novel species of the genus Bacillus, for which the name Bacillus aerolatus sp. nov. is proposed.

Canine rabies control and human exposure 1951-2015, Guangzhou, China.

OBJECTIVE: To describe changes in rabies surveillance and management in Guangzhou, China between 1951 and 2015, and to analyse human rabies cases over that period. METHODS: Rabies control policies and strategies implemented by the Guangzhou government were reviewed for three periods: 1951 to 1978, 1979 to 2000 and 2001 to 2015. Data on human rabies deaths and exposure were obtained from Guangzhou and national health and disease records. The demographic characteristics of human cases are reported using descriptive statistics. FINDINGS: Between 1951 and 2015, the number of organizations cooperating on rabies control increased: there were two between 1951 and 1978, six between 1979 and 2000, and nine between 2001 and 2015. The number of human rabies cases reported in these periods was 331, 422 and 60, respectively. Organizations involved included city and district centres for disease control and prevention, rabies outpatient clinics, medical institutions and police. Overall, 88% (713/813) of cases occurred in rural districts, though, between 1951 and 2015, the distribution shifted from being predominantly rural to being both urban and rural. The number of people exposed to rabies increased annually. The biggest increases were among those injured by a pet dog or other animal: 3.26 and 4.75 times, respectively, between 2005 and 2015. CONCLUSION: Increased cooperation on rabies control between civil organizations in Guangzhou over decades was associated with a marked decrease in the number of human rabies cases. The Guangzhou experience could thereby provide guidance for other cities experiencing similar rabies epidemics.

Effect of Live Poultry Market Closure on Avian Influenza A(H7N9) Virus Activity in Guangzhou, China, 2014.

We assessed the effect of closing live poultry markets in China on influenza A(H7N9) virus detection and viability. Intensive sampling was carried out before, during, and after a 2-week citywide market closure; the markets were cleaned and disinfected at the beginning of the closure period. Swab samples were collected at different sites within the markets and tested for H7N9 by real-time reverse transcription PCR and culture. During the closure, H7N9 viral RNA detection and isolation rates in retail markets decreased by 79% (95% CI 64%-88%) and 92% (95% CI 58%-98%), respectively. However, viable H7N9 virus could be cultured from wastewater samples collected up to 2 days after the market closure began. Our findings indicates that poultry workers and the general population are constantly exposed to H7N9 virus at these markets and that market closure and disinfection rapidly reduces the amount of viable virus.

One Health responses to prevent the occurrence of rabies due to attacks by a rabid stray dog.

BACKGROUND: The number of human rabies cases caused by pet dogs in Guangzhou has been decreasing after years of comprehensive interventions. Consequently, attacks by stray dogs become a major issue in rabies control. OBJECTIVES: To share our experience of successfully dealing with rabies to provide some inspiration for prevention and control in countries and regions affected by it. METHODS: A multidisciplinary One Health response was initiated to control this outbreak. Rabies virus was detected by PCR in the brain tissue of the associated stray dog. The sequences were aligned with reference sequences downloaded from GenBank using ClustalX. The maximum likelihood method implemented in MEGA 5.0 software package was used in a phylogenetic analysis of the aligned sequences. RESULTS: Twelve patients with exposure to the stray dog were identified in the field investigation. Rabies vaccines and immunoglobulin were administered to all patients within 48 h. After 1 year of follow-up, no exposed patients showed symptoms. Maximum likelihood analysis of the nucleotide sequences obtained from the PCR products indicated that the rabies virus in the dog was closely related to isolates from neighbouring provinces of Guangdong as well as those from surrounding countries of China. CONCLUSIONS: Multidisciplinary One Health intervention is effective not only in the control of rabies but also in rapid emergency responses to attacks by rabid stray dogs.

Characteristics of leptospirosis cases, prevention and control managements 1955-2020, Guangzhou, China.

Background: Leptospirosis, which is an easily overlooked zoonotic disease, was once widespread in Guangzhou, China. However, due to the implementation of control measures, the number of cases is decreasing. Based on the characteristics of leptospirosis cases in Guangzhou, China, between 1955 and 2020, we describe the changes and achievements in prevention and control management strategies over that period. Methods: The development of the leptospirosis control system in Guangzhou occurred over three periods: Period I: 1955-1978; Period II: 1979-2000; and Period III: 2001-2020. Data about leptospirosis cases were obtained from the Guangzhou Center for Disease Control and Prevention (CDC) and national health departments. The demographic characteristics of leptospirosis patients were analyzed using descriptive statistics. Results: During Period I, only the Guangzhou CDC and medical institutions at every level participated in the leptospirosis control system. During Period II, additional types of organizations, including local CDCs, countryside committees, community committees, and the Patriotic Health Movement Commission, were involved in the control system. Additionally, strong links were established between different organizations. After entering Period III, an increasing number of departments joined the cooperation, and the management of human patients was expanded to include the management of host animals, and thus, the prevalence of leptospirosis was monitored and controlled in various ways. The leptospirosis control system in Guangzhou has been further improved. From 1955 to 2020, a total of 2501 leptospirosis cases were recorded in Guangzhou, and the number of cases decreased significantly over time, from 1608 (Period I) to 744 (Period II) and then to 149 (Period III). Conclusion: The improvements of the leptospirosis control system in Guangzhou that occurred over decades were associated with a marked decrease in the number of leptospirosis cases. Guangzhou's experience can provide guidance for other countries or cities around the world facing similar challenges.

Probabilistic risk assessment of dietary exposure to pentachlorophenol in Guangzhou, China.

Pentachlorophenol (PCP) is a ubiquitous environmental contaminant commonly existing as its sodium salt (NaPCP), which enters the human body primarily through long term but low-level dietary exposure. PCP contributes to chemical carcinogenesis and teratogenesis. In this study, the probabilistic risk of dietary exposure to PCP in Guangzhou citizens was investigated. In total, 923 food samples in the categories of pork, livestock (beef and lamb), poultry, offal, eggs, and freshwater fish (considered to be relatively susceptible to PCP contamination) were collected from various markets in Guangzhou and tested for PCP. Probabilistic risk assessment model calculations for PCP dietary exposure and margin of exposure (MOE) values were performed using @RISK software, based on a Monte Carlo simulation with 10,000 iterations. The overall detection rate of PCP (above 1 µg kg-1, the detection limit) was 19.9% (184/923), with an average of 7.9 µg kg-1. The highest rate of PCP detection, 28.2%, was in livestock (beef and lamb). The MOE value for dietary PCP exposure in general Guangzhou residents averaged 400, which was far below 5,000 (the borderline for judging a health risk). The lowest MOE value, 190, was observed in the 3- to-6-year old population and indicates a significant risk. In conclusion, this study suggests that PCP exposure in Guangzhou residents is of considerable health risk, especially for the pre-school young children.

Preparation of cationic hierarchical porous covalent organic frameworks for rapid and effective enrichment of perfluorinated substances in dairy products.

Perfluorinated substances (PFASs) are harmful pollutants that have environmental persistence and high bioaccumulation. Effective sample pretreatment must be performed to detect trace or even ultra-trace PFASs in actual samples because of their extremely low contents in complex samples. In this study, a cationic hierarchical porous covalent organic frameworks (C-H-COF) were customized via a template-assisted strategy using polystyrene spheres (PS) as sacrificial materials and a post-synthetic modification method. C-H-COF showed good adsorption selectivity for PFASs owing to the dual effects of the full utilization of the internal adsorption sites and electrostatic interaction. The key role of electrostatic attraction in the extraction of PFASs using C-H-COF was further proven by density functional theory (DFT) calculations. The maximum adsorption capacity of the C-H-COF for perfluorooctanoic acid (PFOA) was 400 mg·g⁻1, which was superior to that of microporous COFs (M-COF) and hierarchical porous COFs without cationic functionalization (H-COF). Accordingly, an analytical method for sensitively detecting five PFASs was established by employing C-H-COF as a dispersive solid phase extraction (DSPE) adsorbent combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and the limits of detection were 0.011‒0.29 ng·L⁻1. Moreover, the hierarchical porous structure of the C-H-COF accelerated the mass transfer of analytes so that the extraction process could be completed within 10 min. This method was employed to analyze PFASs in dairy products, in which the ultra-trace levels of analytes were quickly determined with spiked recoveries of 80.1‒112.6%. This work not only provides a rational synthetic strategy for novel ionic hierarchical porous COFs but also helps to expand the application of COFs in sample pretreatment.

Associations Between Household Pesticide Exposure, Smoking and Hypertension.

This analysis aims to investigate the association between household pesticide exposure and hypertension risk, and to determine whether smoking plays a role in this association. We used data from the National Health and Nutrition Examination Survey (NHANES) for the years 1999-2014, including a total of 32,309 U.S. adult participants who were 20 years or older. Smoking status and pesticide exposure were self-reported. Blood pressure was measured by trained personnel using a mercury sphygmomanometer, according to a standardized protocol. We observed an increased risk of hypertension (OR [odds ratio] = 1.10, 95% confidence intervals [CI]: 1.01-1.18) in participants with exposure to household pesticides. Moreover, a significant interaction between smoking status and pesticide exposure on hypertension was observed (P = 0.022). Stratified analysis showed that household pesticide exposure was associated with a 29% higher risk of hypertension (OR = 1.29, 95% CI: 1.08-1.53) in smokers. However, for non-smokers, this association was not significant. Similar trends were found for systolic and diastolic blood pressures. In addition, we investigated the associations between pesticide metabolites in urine/serum and hypertension and found that several metabolites of dioxins, furans, and coplanar polychlorinated biphenyls were significantly associated with a higher risk of hypertension. This study suggests that household pesticide exposure is associated with an elevated risk of hypertension. We also report that smoking may accentuate the effect of pesticide exposure on hypertension.

Probabilistic Risk Assessment of Dietary Exposure to Cadmium in Residents of Guangzhou, China-Young Children Potentially at a Health Risk.

Cadmium (Cd) and its compounds are hazardous environmental pollutants with renal toxicity and human carcinogenicity, with ingestion of contaminated foods representing the major mode of exposure. There have been a number of reports evaluating the Cd content in various foods; however, regarding the actual risk posed by dietary cadmium exposure, only a few reports are available in which single point evaluation (less accurate than multiple point evaluation) was employed. In this study, we used a margin of exposure (MOE) model and @RISK software (for multiple evaluation) to evaluate Cd-related health risk in the local Guangzhou residents at varying ages, through a comparison between the estimated monthly exposures and the provisional tolerable monthly intake (0.025 mg/kg body weight (b.w.)), based on the Cd contents in various food categories available locally (a total of 3964 food samples were collected from each of the 13 districts of Guangzhou between 2015 and 2019), which were determined by using inductively coupled plasma mass spectrometry. In this study, Cd was detected in 69.6% of the samples (averaged 0.120 mg/kg), and rice and its products, leafy vegetables, bivalves, and shrimp and crabs contributed most to Cd exposure (8.63, 3.18, 2.79, and 1.48 ng/kg b.w./day, respectively). The MOE values demonstrated the following tendency: the younger age group, the lower MOE, and its 95% confidence range for the (youngest) 3~6 year old group started from 0.92, indicating a health risk of young children, while that for the other age groups were all above 1.0. Our preliminary findings warrant further clarification using biomarker assays in the relevant population.

Probabilistic Risk Assessment of Dietary Exposure to Chloramphenicol in Guangzhou, China.

Chloramphenicol has been used in veterinary medicine, where its residues can remain in food of animal origin, thus potentially causing adverse health effects. This facilitated the ban for its use in food-producing animals globally, but its residues have remained ubiquitous. In this study, food commodities possibly contaminated with chloramphenicol, including livestock meat, poultry, edible viscera, fish, shrimp and crab, molluscs, milk, and eggs, were collected from domestic retail shops in all the 11 districts of Guangzhou and tested for its residue. Probabilistic risk assessment model calculations for its dietary exposure, and the margin of exposure (displayed as mean values and 5th percentile to 95th percentile ranges) were performed by using @RISK software based on a Monte Carlo simulation with 10,000 iterations. The results indicated the detection of chloramphenicol in 248 out of 1454 samples (17.1%), which averaged to a level of 29.1 µg/kg. The highest average value was observed in molluscs (148.2 µg/kg, with the top value as 8196 µg/kg); meanwhile, based on the dietary structure of a typical Cantonese, pond fish, pork, and poultry meat contributed most (about 80%) to the residents' dietary exposure to chloramphenicol. The margin of exposure for dietary chloramphenicol exposure in Guangzhou residents was 2489, which was apparently below 5000 (the borderline for judging a health risk), particularly low in preschool children (2094, suggesting an increased risk). In conclusion, the study suggests that chloramphenicol exposure in Guangzhou residents is considerable, and its relevant health hazard, especially for preschool children, is worthy of further investigation.

Representative Genotyping, Recombination and Evolutionary Dynamics Analysis of TSA56 Gene Segment of Orientia tsutsugamushi.

Scrub typhus is a zoonotic disease caused by Orientia tsutsugamushi (O. tsutsugamushi). Orientia tsutsugamushi has various genotypes and more new strains with difference in sequences increasingly appeared. Whether the accurateness of one special nested PCR method which amplifies segment instead of entire open reading frame (ORF) sequence meets the current work of identifying new strains and classifying genotypes remains to be confirmed. And the origins and evolution of this organism have not been thoroughly elucidated. Accordingly, in this study, segments and the entire ORF of the 56-kDa type-specific antigen (TSA56) gene of O. tsutsugamushi were collected, including 209 clinically isolated strains in Guangzhou, China from 2012 to 2016 and 139 reference strains worldwide. By performing phylogenetic analysis, we proved that the accurateness of the particular PCR method which almost met detection need. This re-grouping result showed that segments perfectly represented and identified strains of Karp, Boryong, Gilliam, TA763, Kawasaki and part of Kato genotype, and this accuracy is not restricted by region and time. Sequence diversification of Shimokoshi and some Kato strains made their genotyping need to consider entire ORF sequences, but their weak recognition might not be due to recombination. The frequent genetic recombination and high point mutations contributed to genetic diversification of the TSA56 gene. Major overlapping regions of most recombination events occurred between strains of the same genotype, especially Karp and Kato genotype. And cross-genotype overlapping events occurred between Karp and Boryong/Gilliam/TA763/Kato, Kato and Kawasaki/Gilliam/TA686, Boryong and TA686, and Gilliam and Kawasaki. But Segment has quite low recombination frequency and stable mutation trend from 1943 to 2016. So segment is a relatively conserved part of the TSA56 ORF as for its stable trend of genetic diversity, and it may anchor and represent the entire TSA56 ORF gene. And genetic diversity is rejected as one potential reason for the increased incidence of scrub typhus. But an occasional recombination event created an unrecognized genotype which might be due to the breakage of VD II and AD II. Additionally, strains in Guangzhou were homologous and Karp genotype was detected as a dominant.

The impact of discharge reduction activities on the occurrence of contaminants of emerging concern in surface water from the Pearl River.

"Swimming across the Pearl River" is an annual large-scale sporting event with great popularity in Guangzhou. To reduce the risk of swimmers' exposure to various contaminants in the Pearl River during swimming activities, the local government limits direct sewage and effluent discharge from urban channels during the event. However, the impact of discharge reduction on some contaminants of emerging concern (CECs), such as organophosphorus flame retardants (OPFRs), bisphenol analogues (BPs), and triclosan remains unknown. In the present study, the concentrations of CECs, as well as ammonia-nitrogen (NH3-N), dissolved organic carbon, and chemical oxygen demand, were measured in aqueous and suspended particulate matter (SPM) from the Guangzhou reaches of the Pearl River. The concentration ranges of sixteen OPFRs, eight BPs, and triclosan were 21.2-91.0, 8.46-37.3, and 1.47-5.62 ng/L, respectively, in aqueous samples, and 25.2-492, 14.0-86.3, and 0.69-17.5 ng/g, respectively, in SPM samples. Hydrophobic and π-π interactions could be contributing to the distribution of CECs. Principal component analysis indicated that consumer materials, manufacturing, and domestic sewage might be the main sources of the CECs. In addition, our study showed that the concentrations of CECs did not change considerably before or after discharge reduction activities, although NH3-N showed a substantial decrease following pollution control measure. The results demonstrated that temporary reductions of contaminant discharges to the Pearl River had only limited effect on the levels of CECs. Further research is needed to investigate the distributions and potential health risks of CECs in the Pearl River.

Probabilistic risk assessment of dietary exposure to aflatoxin B1 in Guangzhou, China.

Aflatoxin B1 (AFB1) contamination in foods is an important health challenge for low-and middle-income countries in subtropical regions. AFB1 has been detected in a variety of foodsin Guangzhou, while the risk of dietary exposure is unknown. This study aimed to assess the probabilistic risk of dietary exposure to AFB1 contamination in food stuffs in Guangzhou by using margin of exposure (MOE) and quantitative liver cancer risk approaches. A total of1854 AFB1-contaminated foodstuffs were sampled in supermarkets, agricultural markets, retail shops, and family workshops from 11 districts of Guangzhou, and AFB1 content was determined by HPLC-fluorescence detector. In total, 9.9% (184/1854) of the test samples had AFB1 concentrations above the limit of detection. Home-made peanut oil had the highest AFB1 concentration, with a mean value of 38.74 ± 47.45 µg kg-1. The average MOE levels of Guangzhou residents ranged from 100 to 1000. The risk of liver cancer was 0.0264 cancers (100,000 population year)-1. The health risks of suburban people were higher than those of urban people, and home-made peanut oil was the main contributorto dietary exposure to AFB1 among suburban residents in Guangzhou. The production of home-made peanut oil should be supervised to reduce the risk of AFB1 exposure.

Dietary Lead Exposure and Associated Health Risks in Guangzhou, China.

Lead exposure is associated with a wide range of adverse effects on human health. The principal exposure route in the general population is through the diet. In this study, we estimate the dietary lead intake and associated health risks among the residents of Guangzhou, China. Data on lead concentrations were derived from the food safety risk monitoring system, which included 6339 samples from 27 food categories collected in 2014-2017. Food consumption data were taken from a 2011 dietary survey of 2960 Guangzhou residents from 998 households. Dietary lead intake was estimated by age group (3-6, 7-17, 18-59, and ≥60 years), and relevant health risks were assessed using the margin of exposure (MOE) method. The mean and 95th percentiles (P95) of dietary lead intake were respectively 0.7466 and 2.4525 µg/kg body weight per day for preschool children aged 3-6 years; 0.4739 and 1.5522 µg/kg bw/day for school children aged 7-17 years; 0.3759 and 1.1832 µg/kg bw/day for adults aged 18-59 years; and 0.4031 and 1.3589 µg/kg bw/day for adults aged ≥60 years. The MOE value was less than 1 for preschool children at the mean exposure level and for all age groups at the P95 exposure level. Rice and its products, leafy vegetables, and wheat flour and its products were found to be the primary food sources of lead exposure. Our findings suggest that the health risk from dietary lead exposure is low for Guangzhou residents overall, but that young children and consumers of certain foods may be at increased risk. Continued efforts are needed to reduce the dietary lead exposure in Guangzhou.

Microbiological Contamination of Strawberries from U-Pick Farms in Guangzhou, China.

This study quantified the association of rodent fruit damage and the microbiological quality of irrigation water on the risk of microbiological contamination of strawberries collected from 18 U-pick farms across five different districts in the Guangzhou metropolitan region of southern China. Fifty-four composite strawberries samples, with or without evidence of rodent or avian foraging damage (i.e., bitten), along with 16 irrigation water samples, were collected during the spring of 2014 and winter of 2015 from our cohort of 18 farms. Composite strawberry samples and irrigation water were analyzed for total coliforms, E. coli, Salmonella, E. coli O157, Giardia, and Cryptosporidium. Total coliforms and E. coli were detected in 100% and ~90% of irrigation water samples, respectively. In contrast, Cryptosporidium was detected in only two water samples, while Salmonella, E. coli O157, and Giardia were not detected in any water samples. Strawberries with signs of being bitten by wildlife had significantly higher concentrations of total coliforms and E. coli, compared to strawberries with no physical evidence of rodent damage (p < 0.001). Similarly, Cryptosporidium was detected in 7/18 (39%) of bitten, 4/18 (22%) of edge, and 5/18 (28%) of central strawberry samples, respectively. Concentration of E. coli on strawberries (p < 0.001), air temperature (p = 0.025), and presence of Cryptosporidium in irrigation water (p < 0.001) were all associated with the risk of Cryptosporidium contamination on strawberries. Salmonella and Giardia were detected in <4% strawberry samples and E. coli O157 was not detected in any samples. These results indicate the potential food safety and public health risks of consuming unwashed strawberries from U-pick farms, and the need for improved rodent biosecurity of U-pick strawberry fields and enhanced microbiological quality of irrigation water used at these facilities.