Clinical pathology of foodborne diseases: notes on the patient with foodborne gastrointestinal illness

The symptoms and signs in persons with food- or waterborne infections provide clues to the nature of the infecting microbe. Proper treatment of the affected individual, and protection of those exposed to the same source, is dependent on time-honored methods of diagnosis: exposure history, and physical examination. Laboratory testing may help to identify the responsible agent. Spontaneous recovery is the most likely outcome once supportive measures such as fluid and electrolyte replacement are addressed. Antibiotics are often unnecessary and may prolong fecal excretion of certain microorganisms. In immunosuppressed persons or those weakened by marginal nutrition, foodborne infection can be more severe, mandating more specific therapy. Management requires knowing the level of tissue invasion and organ infected by each of the commonly encountered microbes. Some of the most life-threatening infections (cholera, for example) are associated with no visible tissue injury, yet they have a profound impact on gut function. In contrast, salmonellosis and shigellosis can cause severe gut injury, and when foodborne infections extend beyond the confines of the gut, skilled care is essential. Examples are hemolytic uremic syndrome of Escherichia coli infections, or listeriosis, both of which require urgent attention. Long-term consequences of gut infections such as the paralytic Guillain-Barre syndrome following Campylobacter infections illustrates the long-term problems sometimes encountered. Because it is unlikely that all infectious agents will ever be removed from food and water in any country, sound medical intervention tailored to the extent of illness will be the mainstay of handling such illnesses.     

Borrelia burgdorferi: another cause of foodborne illness?

Borrelia burgdorferi was identified as the etiological agent of Lyme disease in 1982. This Gram-negative spirochete is classified in the order Spirochaetales and the family Spirochaetaceae. The pathogen is fastidious, microaerophilic, mesophilic and metabolises glucose through the Embden-Meyerhof pathway. A generation time of 11 to 12 h at 37 degrees C in Barbour-Stoenner-Kelly medium has been reported. Lyme disease, named after Lyme in Connecticut, is distributed globally. It is the most commonly reported vector-borne disease in the United States, where the incidence is highest in the eastern and midwestern states. Since establishment of national surveillance in 1982, there has been a nine-fold increase in the number of cases reported to the U.S. Centers for Disease Control. The deer tick of the genus Ixodes is the primary vector of Lyme borreliosis. The tick may become infected with B. burgdorferi, by feeding on an infected host, at any point in its 2-year life cycle which involves larval, nymphal and adult stages. The infection rate in deer ticks may be as high as 40% in endemic areas. The primary vertebrate reservoirs for Ixodes are the white-footed mouse (Peromyscus leucopus) and the white-tailed deer (Odocopileus virginianus). Dairy cattle and other food animals can be infected with B. burgdorferi and hence some raw foods of animal origin might be contaminated with the pathogen. Recent findings indicate that the pathogen may be transmitted orally to laboratory animals, without an arthropod vector. Thus, the possibility exists that Lyme disease can be a food infection. In humans, the symptoms of Lyme disease, which manifest themselves days to years after the onset of infection, may involve the skin, cardiac, nervous and/or muscular systems, and so misdiagnosis can occur.     

Mass balance for mercury in the San Francisco Bay area

We have developed and illustrated a general regional multi-species model that describes the fate and transport of mercury in three forms, elemental, divalent, and methylated, in a generic regional environment including air, soil, vegetation, water, and sediment. The objectives of the model are to describe the fate of the three forms of mercury in the environment and to determine the dominant physical sinks that remove mercury from the system. Chemical transformations between the three groups of mercury species are modeled by assuming constant ratios of species concentrations in individual environmental media. We illustrate and evaluate the model with an application to describe the fate and transport of mercury in the San Francisco Bay Area of California. The model successfully rationalizes the identified sources with observed concentrations of total mercury and methyl mercury in the San Francisco Bay Estuary. The mass balance provided by the model indicates that continental and global background sources control mercury concentrations in the atmosphere but that loadings to water in the San Francisco Bay Estuary are dominated by runoff from the Central Valley catchment and remobilization of contaminated sediments deposited during past mining activities. The model suggests that the response time of mercury concentrations in the San Francisco Bay Estuary to changes in loadings is long, on the order of 50 years.     

Evaluation of a statewide foodborne illness complaint surveillance system in Minnesota, 2000 through 2006

Foodborne outbreaks are detected by recognition of similar illnesses among persons with a common exposure or by identification of case clusters through pathogen-specific surveillance. PulseNet USA has created a national framework for pathogen-specific surveillance, but no comparable effort has been made to improve surveillance of consumer complaints of suspected foodborne illness. The purpose of this study was to characterize the complaint surveillance system in Minnesota and to evaluate its use for detecting outbreaks. Minnesota Department of Health foodborne illness surveillance data from 2000 through 2006 were analyzed for this study. During this period, consumer complaint surveillance led to detection of 79% of confirmed foodborne outbreaks. Most norovirus infection outbreaks were detected through complaints. Complaint surveillance also directly led or contributed to detection of 25% of salmonellosis outbreaks. Eighty-one percent of complainants did not seek medical attention. The number of ill persons in a complainant's party was significantly associated with a complaint ultimately resulting in identification of a foodborne outbreak. Outbreak confirmation was related to a complainant's ability to identify a common exposure and was likely related to the process by which the Minnesota Department of Health chooses complaints to investigate. A significant difference (P < 0.001) was found in incubation periods between complaints that were outbreak associated (median, 27 h) and those that were not outbreak associated (median, 6 h). Complaint systems can be used to detect outbreaks caused by a variety of pathogens. Case detection for foodborne disease surveillance in Minnesota happens through a multitude of mechanisms. The ability to integrate these mechanisms and carry out rapid investigations leads to improved outbreak detection.     

对食源性疾病病例定义确定原则的探讨

为提高食源性疾病的诊断水平，通过对国内外制定食源性疾病病例定义的具体实践的研究，提出了确定食源性疾病病例定义的5项原则：1．要全面考虑病例定义的基本要素和基本内容，综合分析流行病学资料、潜伏期和临床表现、现场卫生学调查情况和实验室检验结果；2．要以客观临床体征和实验室检验指标为主，但要考虑实际情况；3．要注意精神诱导因素和伪装“发病”，不能轻信主观症状，及时予以排除；4．对中毒或感染餐次不明或肇事单位不明的食源性疾病事件，要确定最初病例定义和最终病例定义，一旦通过流行病学调查确定了中毒或感染餐次或肇事单位，则排除确实未在最终确定的中毒或感染餐次或肇事单位进食的发病；5．要事先考虑、科学解释可能出现的不符合工作假设和最终病例定义的发病情况。     

Biological oxygen demand dynamics in the lower San Joaquin River, California

Dissolved oxygen less than 5 mg L(-1) (U. S. EPA advisory level) commonly occurs in the lower San Joaquin River (SJR), California. Most acute episodes typically occur in late summer and fall. The oxygen deficit can stress and kill aquatic organisms, often inhibiting the upstream migration of Chinook salmon (Oncorhynchus tshawytscha). This 5 year study examined watershed-scale spatial and temporal biological oxygen demand (BOD) loads and the primary components believed to contribute to BOD: ammonium, algal biomass, nonalgal particulate organic carbon, dissolved organic carbon, and dissolved organic nitrogen. Samples were collected bimonthly at 15 sites during the summers of 2000 and 2001 and from three lower mainstem sites from May 2002 to March 2005. BOD loads showed a downstream increase in parallel with increasing algal biomass loads resulting primarily from in-stream growth. BOD loads from measured tributaries and drains accounted for 28% and 39% of the BOD load at the downstream Vernalis site in 2000 and 2001, respectively. Algal C was positively correlated (r=0.80) with BOD, explaining 64% of BOD variance for data collected from 2001 to 2005. Less than 20% of BOD was found in the dissolved fraction (<0.45 microm). We conclude that algal biomass is the primary contributor to BOD loads in the lower SJR, upstream of Mossdale.     

Molecular characterization of Vibrio parahaemolyticus strains associated with foodborne illness in Florida

Vibrio parahaemolyticus is the leading cause of bacterial seafood-based illness in the United States. Real-time PCR, pandemic group-specific PCR, ribotyping, and multilocus sequence typing were used to characterize 30 strains of V. parahaemolyticus including 11 strains associated with foodborne outbreaks in Florida and 6 known pandemic strains. Thirteen strains were positive for four pandemic group-specific PCR markers, including 5 strains associated with outbreaks in Florida. Molecular typing methods were used to further define the pandemic status of these strains because the current PCR markers are not sufficient to identify pandemic isolates. Nine of the Florida strains clustered with a majority of the known pandemic strains, based on ribotyping patterns using PvuII, but no isolated pandemic branch was formed. Using multilocus sequence typing, it was determined that 14 strains possess a previously determined pandemic sequence type. This study identified 13 novel sequence types and seven to nine novel alleles for each locus. Furthermore, the results indicate that seven of the strains from recent foodborne outbreaks in Florida are pandemic strains, and that multilocus sequence typing was the most accurate molecular method to identify these strains.     

地区性食源性疾病病例实时监测系统的开发与实现

开发区域性食源性疾病病例监测系统,并提供接口等解决方案在三类医院中应用,实现食源性疾病病例实时监测,提高工作效率和质量。方法 调查分析各医院的食源性疾病监测流程找出共性点,开发多客户端的B/S结构的区域性食源性疾病病例监测系统。结果 食源性疾病监测可分为病例信息采集和粪便标本采集检验和现场流调3个阶段,医院食源性疾病监测可分为2种模式和3个环节。完成3种客户端口的区域性食源性疾病病例监测系统开发,为医院提供软件接口等对接解决方案,实现食源性疾病病例实时监测。医院实际应用中效果明显。结论 区域性食源性疾病病例监测系统和提供的接口等解决方案能有效提高监测工作效率与质量。     

Atmospheric concentrations and fluxes of organic compounds in the northern San Francisco Estuary

A study was conducted to measure atmospheric concentrations of PAHs and PCBs and estimate their fluxes between air and water in the northern San Francisco Estuary. Ambient air samples were collected once every 12 days at a single sampling site in Concord, CA, from June to November 2000, using a modified high-volume air-sampling device equipped with glass fiber filters and polyurethane foam. Concentrations of total PAHs and PCBs ranged from 5.7 to 56 and 0.17 to 0.32 ng/m3, respectively. PAHs and PCBs in the ambient air were predominantly in the vapor phase (83-99%). Gaseous fluxes of PAHs in the estuary showed high seasonal variation, ranging from 110 ng x m(-2) x day(-1) efflux in August to 1,050 ng x m(-2) x day(-1) influx in November. Gaseous PCBs showed consistent net volatilization 12.2-24 ng x m(-1) x day(-1)) for this period. Particle settling contributed estimated net deposition fluxes of 45-960 ng x m(-2) day(-1) for PAHs and 0.39-2.1 ng x m(m(-2) x day(-1) for PCBs. Combining these fluxes, PAHs were either deposited to or lost from the estuary via the atmosphere, depending on the month. In contrast, there consistently was net emission of PCBs from the estuary to the atmosphere.     

Decadal trends of silver and lead contamination in San Francisco Bay surface waters

Over the past decade, San Francisco Bay surface waters have remained enriched with dissolved (<0.45 microm) silver and lead concentrations (decadal means of 5.7 ng kg(-1) Ag[filtered] and 31 ng kg(-1) Pb[filtered]) compared with those (0.26 ng kg(-1) Ag[filtered] and 2.7 ng kg(-1) Pb[filtered]) of adjacent oceanic surface waters of the northeast Pacific, despite efforts to reduce pollutant loadings to the Bay during that period. While time series models show that there has been a 40% decline in total lead concentrations in the southern reach of the estuarine system between 1989 and 1999, the filtered lead fraction has not changed significantly during that time. That persistence is attributed to (i) the ongoing input from previous atmospheric depositions and industrial lead to its drainage basin, which are slowly being advected into the estuary and (ii) the internal recycling of lead between the surface sediments and the water column within the Bay. In contrast, both filtered and total silver concentrations in the southern reach have declined by 70% and 40%, respectively, within the past decade. These temporal declines are attributed to a 2-fold decrease in silver loadings from publicly owned treatment works and a comparable decline in the silver concentration of surficial sediments within that region during the past decade. In the northern reach, silver and lead concentrations have remained essentially constant between 1989 and 1999, reflecting invariable anthropogenic input of these elements to this embayment over that decade.     

Considering uncertainty in comparing the burden of illness due to foodborne microbial pathogens

The uncertainty attendant to burden-of-illness estimates should be taken into account in comparing the public health impact of different foodborne pathogens. In this paper, decision analysis concepts are applied to the comparisons of pathogen-specific burden-of-illness estimates. In situations wherein the magnitude of uncertainty varies, the rank order of pathogen-specific burden-of-illness estimates is sensitive to the decisional criteria applied. To illustrate the magnitude of attendant uncertainty in pathogen-specific foodborne-illness estimates, probabilistic risk assessment methods are used to characterize the uncertainty regarding the burden of illness due to Escherichia coli O157:H7. The magnitude of uncertainty about the burden of food-related illness due to E. coli O157:H7 is substantial, ranging from less than 50,000 to more than 120,000 cases/year. This example underscores the importance of considering the uncertainty attendant to burden-of-illness estimates in comparing the public health impacts of different pathogens. Although some would argue that the expected value of the number of illnesses provides the "best estimate" for decision-making, this merely reflects a decision-making rule of convention and not a scientific truism.     

In situ measurement of polychlorinated biphenyls in the waters of San Diego Bay,California

Sediments of San Diego Bay (SDB) are known to contain elevated levels of polychlorinated biphenyls (PCBs). While numerous efforts have been made to monitor the spatial or temporal trends of contamination in SDB, no studies have been directed toward measurements of water column contamination. We measured PCB concentrations in the water column of SDB with an in situ sampling system. Except for one sample collected near the bay mouth, all other samples contained higher PCB concentrations than the 30-day average discharge limit established by the California Ocean Plan. The highest concentrations of water column PCBs occurred in the Central Bay, consistent with the previous findings that sediments in the Central Bay contained higher PCB levels than those in the North and South Bays. Based on the water volume of 2.2 x 10(8) cm3 at a lower water level, it was estimated that approximately 1,000 g of PCBs is transported out of SDB via tidal exchange annually. This indicates that water column transport driven by tidal exchange is a viable mechanism reducing PCB contamination within SDB.     

Watershed sources of disinfection byproduct precursors in the Sacramento and San Joaquin Rivers, California

High levels of dissolved organic carbon (DOC) and bromide (Br) in the Sacramento and San Joaquin River waterways are of concern because DOC and Br are organic and inorganic precursors, respectively, of carcinogenic and mutagenic disinfection byproducts (DBPs). The Sacramento and San Joaquin Rivers are the two major rivers supplying water to the San Francisco Bay Delta, but sources and loads of DBP precursors into the Delta are still uncertain. The major objectives of this study were to evaluate both the quantity (DOC and Br fluxes) and the quality (reactivity in forming DBPs) of DBP precursors from the Sacramento and San Joaquin watersheds. Water samples were collected every 2 weeks at up to 35 locations along the Sacramento and San Joaquin Rivers and selected tributaries and analyzed for DOC (4 years), Br (1 year), and ultraviolet absorbance at 254 nm (1 year). Selected water samples were also tested for THM formation potential. Estimated fluxes for the Sacramento River were 39 000 +/- 12 000 Mg DOC year(-1) and 59 Mg of Br year(-1) as compared to 9000 +/- 5000 Mg of DOC year(-1) and 1302 Mg of Br year(-1) for the San Joaquin River. The THM formation potential was higher in the San Joaquin River (441 +/- 49 microg L(-1)) than the Sacramento River (176 +/- 20 microg L(-1)) because of higher concentrations of both organic (DOC = 3.62 +/- 0.14 vs 1.92 +/- 0.09 mg L(-1)) and inorganic DBP (Br = 0.80 +/- 0.07 vs < 0.03 +/- 0.01 mg L(-1)) precursors. The Sacramento River's greater DOC load despite lower DOC concentrations is due to its discharge being about 5 times greater than the San Joaquin River (50 x 10(9) vs 10 x 10(9) L day(-1)). The DOC concentration was significantly correlated with several land-cover types, including agriculture; however, no relationship was found between DOC quality and land-cover at the watershed scale.     

Economic burden from health losses due to foodborne illness in the United States

The Centers for Disease Control and Prevention (CDC) recently revised their estimates for the annual number of foodborne illnesses; 48 million Americans suffer from domestically acquired foodborne illness associated with 31 identified pathogens and a broad category of unspecified agents. Consequently, economic studies based on the previous estimates are now obsolete. This study was conducted to provide improved and updated estimates of the cost of foodborne illness by adding a replication of the 2011 CDC model to existing cost-of-illness models. The basic cost-of-illness model includes economic estimates for medical costs, productivity losses, and illness-related mortality (based on hedonic value-of-statistical-life studies). The enhanced cost-of-illness model replaces the productivity loss estimates with a more inclusive pain, suffering, and functional disability measure based on monetized quality-adjusted life year estimates. Costs are estimated for each pathogen and a broader class of unknown pathogens. The addition of updated cost data and improvements to methodology enhanced the performance of each existing economic model. Uncertainty in these models was characterized using Monte Carlo simulations in @Risk version 5.5. With this model, the average cost per case of foodborne illness was $1,626 (90% credible interval [CI], $607 to $3,073) for the enhanced cost-of-illness model and $1,068 (90% CI, $683 to $1,646) for the basic model. The resulting aggregated annual cost of illness was $77.7 billion (90% CI, $28.6 to $144.6 billion) and $51.0 billion (90% CI, $31.2 to $76.1 billion) for the enhanced and basic models, respectively.     

Levels and distribution of polybrominated diphenyl ethers in water, surface sediments, and bivalves from the San Francisco Estuary

Polybrominated diphenyl ethers (PBDEs) were found in water, surface sediments, and bivalve samples that were collected from the San Francisco Estuary in 2002. sigmaPBDE concentrations in water samples ranged from 3 to 513 pg/ L, with the highest concentrations found in the Lower South Bay (range 103-513 pg/L) region, which receives approximately 26% of the Estuary's wastewater treatment plant effluents. The sigmaPBDEs in sediments ranged from below detection limits to 212 ng/g dry wt, with the highest concentration found at a South Bay station (212 ng/g dry wt), which was up to 3 orders of magnitude higher than other stations. The sigmaPBDE concentrations ranged from 9 to 64 ng/g dry wt in oysters (Crassostrea gigas), from 13 to 47 ng/g dry wt in mussels (Mytilus californianus), and from 85 to 106 ng/g dry wt in clams (Corbicula fluminea). Only three PBDE congeners were detected in bivalves, BDE-47, BDE-99, and BOE-100; these are the most bioaccumulative congeners from the commercial Penta-BDE mixture.     

1998—2017年南平市食源性疾病事件流行病学特征分析

目的 分析南平市食源性疾病事件的流行病学特征和规律,为制定食源性疾病事件的预防控制策略提供依据。方法 收集1998—2017年南平市所辖10个县(市、区)上报的食源性疾病事件,对事件归因变量进行统计,回顾性的描述性分析。结果 20年间,南平市共报告食源性疾病事件184起,发病人数2 871人,死亡人数40人,年均发病率5.12人/10万,病死率为1.39%。食源性疾病事件的高发期为第三季度,8月份事件起数和死亡人数最多。报告事件起数和发病人数最多的为致病微生物事件,分别为80起(43.48%,80/184)和1 862人(64.86%,1 862/2 871);其次为有毒植物性事件,分别为66起(35.87%,66/184)和310人(10.80%,310/2 871)。引发事件的致病因子中,误食毒蕈共55起(29.89%,55/184),副溶血性弧菌污染共23起(12.50%,23/184);毒蕈为主要致死因子,死亡人数为35人(87.50%,35/40)。事件发生场所以家庭为主(39.13%,72/184),其中有毒植物性事件占66.67%(48/72);其次为宾馆饭店(22.28%,41/184),其中致病微生物事件占80.49%(33/41)。结论 南平市食源性疾病事件的控制策略应针对高发时段、多发地区、易发场所和高危致病因子实施重点监管,建立有效的预警、监测及政府监管机制,进一步遏制食源性疾病事件的发生。     

国内外急性胃肠炎和食源性疾病负担研究进展

食源性疾病是全球重要的公共卫生问题,也是中国最大的食品安全问题.急性胃肠炎人群负担的评估是食源性疾病负担评估的一个中心问题,许多国家已开展急性胃肠炎和食源性疾病负担评估研究,我国于2010-2011年在部分省份开展了研究疾病负担的试点工作.本文对急性胃肠炎和食源性疾病负担评估国内外研究进展进行综述.