Kira L. Newman

The impact of socioeconomic status on foodborne illness in high income countries: A systematic review

Foodborne illness is a major cause of morbidity and loss of productivity in developed nations. Although low socioeconomic status (SES) is generally associated with negative health outcomes, its impact on foodborne illness is poorly understood. We conducted a systematic review to examine the association between SES and laboratory-confirmed illness caused by eight important foodborne pathogens. We completed this systematic review using PubMed for all papers published between 1 January 1980 and 1 January 2013 that measured the association between foodborne illness and SES in highly developed countries and identified 16 studies covering four pathogens. The effect of SES varied across pathogens: the majority of identified studies for Campylobacter, salmonellosis, and E. coli infection showed an association between high SES and illness. The single study of listeriosis showed illness was associated with low SES. A reporting bias by SES could not be excluded. SES should be considered when targeting consumer-level public health interventions for foodborne pathogens.

Norovirus immunology: Of mice and mechanisms

Noroviruses (NoVs) are the most common cause of sporadic and epidemic gastroenteritis in the United States and Europe and are responsible for 20% of acute gastroenteritis worldwide. Over the past decade, the understanding of NoV immunology has grown immensely. Studies of the natural immune response to NoV in humans and animal models have laid the foundation for innovations in cell culture systems for NoV and development of new therapeutics. Evidence from animal models, NoV surrogates, observational human research, and human challenge studies suggest that the innate immune response is critical for limiting NoV infection but is insufficient for viral clearance. NoV may antagonize the innate immune response to establish or prolong infection. However, once a robust adaptive immune response is initiated, the immune system clears the infection through the action of T and B cells, simultaneously generating highly specific protective immunologic memory. We review here both the current knowledge on NoV immunity and exciting new developments, with a focus on ongoing vaccine development work, novel cell culture systems, and advances in understanding the role of the gut microbiome. These changes reinforce the need for a better understanding of the human immune response to NoV and suggest novel hypotheses.

Human norovirus infection and the acute serum cytokine response

Noroviruses (NoV) are the most common cause of epidemic gastroenteritis worldwide. The acute immune response to NoV in humans is poorly understood, hindering research on prevention and treatment. To elucidate the acute immune response and test for cytokine predictors of susceptibility to infection, serum samples from two human NoV challenge studies were tested for 16 cytokines. Subjects who became infected (n = 26) were age‐matched with subjects who remained uninfected following NoV challenge (n = 26). Samples were tested from prechallenge and days 1‐4 post‐challenge. Cytokine responses were compared between infected and uninfected groups. Overall, infected individuals exhibited an elevation in T helper type 1 (Th1) and Th2 cytokines, as well as chemokines interleukin (IL)‐8 and monocyte chemoattractant protein (MCP‐1), compared to uninfected individuals (all P < 0·05). Most cytokines peaked on day 2 post‐challenge in infected subjects, and tumour necrosis factor (TNF)‐α, IL‐8, and IL‐10 remained elevated to day 3. The only cytokine elevated significantly among infected subjects to day 4 post‐challenge was IL‐10 (P = 0·021). Prechallenge cytokine concentrations were not predictive of infection status post‐challenge. There were no significant changes in serum cytokines among NoV‐challenged subjects who remained uninfected. These results suggest that NoV infection elicits a Th1‐type response, with some Th2 activation. Persistent elevation of IL‐10 among infected subjects is consistent with activation of adaptive immune responses, such as B cell expansion, as well as down‐regulation of Th1 cytokines. This study presents the first comprehensive description of the acute cytokine response to GI.1 NoV in humans.

Fecal microbiota transplant for Clostridium difficile infection in older adults

Background: The objective of this study was to describe the safety of fecal microbiota transplant (FMT) for Clostridium difficile infection (CDI) among older adults. Methods: We performed a case review of all FMT recipients aged 65 or older treated at Emory University Hospital, a tertiary care and referral center for Georgia and surrounding states. Results: CDI resolved in 27 (87%) of 31 respondents, including three individuals who received multiple FMTs. Among four whose CDI was not resolved at follow up, three respondents did well initially before CDI recurred, and one individual never eradicated his CDI despite repeating FMT. During the study, five deaths and eight serious adverse events requiring hospitalization were reported within the study group during the follow-up period. Fecal transplant was not a causative factor in these events. The most common adverse event reported in 4 (13%) of 31 respondents was subjective worsening of arthritis. Conclusion: FMT is a generally safe and effective treatment option for older adults with CDI.

Norovirus in symptomatic and asymptomatic individuals: cytokines and viral shedding

Noroviruses (NoV) are the most common cause of epidemic gastroenteritis world‐wide. NoV infections are often asymptomatic, although individuals still shed large amounts of NoV in their stool. Understanding the differences between asymptomatic and symptomatic individuals would help in elucidating mechanisms of NoV pathogenesis. Our goal was to compare the serum cytokine responses and faecal viral RNA titres of asymptomatic and symptomatic NoV‐infected individuals. We tested serum samples from infected subjects (n = 26; 19 symptomatic, seven asymptomatic) from two human challenge studies of GI.1 NoV for 16 cytokines. Samples from prechallenge and days 1‐4 post‐challenge were tested for these cytokines. Cytokine levels were compared to stool NoV RNA titres quantified previously by reverse transcription–polymerase chain reaction (RT–qPCR). While both symptomatic and asymptomatic groups had similar patterns of cytokine responses, the symptomatic group generally exhibited a greater elevation of T helper type 1 (Th1) and Th2 cytokines and IL‐8 post‐challenge compared to the asymptomatic group (all P < 0·01). Daily viral RNA titre was associated positively with daily IL‐6 concentration and negatively with daily IL‐12p40 concentration (all P < 0·05). Symptoms were not associated significantly with daily viral RNA titre, duration of viral shedding or cumulative shedding. Symptomatic individuals, compared to asymptomatic, have greater immune system activation, as measured by serum cytokines, but they do not have greater viral burden, as measured by titre and shedding, suggesting that symptoms may be immune‐mediated in NoV infection.

Immunocompetent Adults from Human Norovirus Challenge Studies do not Exhibit Norovirus Viremia

Noroviruses (NoV) are among the leading causes of acute gastroenteritis worldwide ([1][1]). There is also limited knowledge of the pathogenesis of human NoV infection. Children, immunocompromised adults, and gnotobiotic pigs and calves used as models of human NoV infection all can develop NoV

Low Prevalence of Human Pathogens on Fresh Produce on Farms and in Packing Facilities: A Systematic Review

Foodborne illness burdens individuals around the world and may be caused by consuming fresh produce contaminated with bacterial, parasite, and viral pathogens. Pathogen contamination on produce may originate at the farm and packing facility. This research aimed to determine the prevalence of human pathogens (bacteria, parasites, and viruses) on fresh produce (fruits, herbs, and vegetables) on farms and in packing facilities worldwide through a systematic review of 38 peer-reviewed articles. The median and range of the prevalence was calculated, and Kruskal–Wallis tests and logistic regression were performed to compare prevalence among pooled samples of produce groups, pathogen types, and sampling locations. Results indicated a low median percentage of fresh produce contaminated with pathogens (0%). Both viruses (p-value = 0.017) and parasites (p-value = 0.033), on fresh produce, exhibited higher prevalence than bacteria. No significant differences between fresh produce types or between farm and packing facility were observed. These results may help to better quantify produce contamination in the production environment and inform strategies to prevent future foodborne illness.

Estimating occupational illness, injury, and mortality in food production in the united states: a farm-to-table analysis

Objectives: The study provides a novel model and more comprehensive estimates of the burden of occupational morbidity and mortality in food-related industries, using a farm-to-table approach. Methods: The authors analyzed 2008 to 2010 US Bureau of Labor Statistics data for private industries in the different stages of the farm-to-table model (production, processing, distribution and storage, and retail and preparation). Results: The morbidity rate for food system industries was significantly higher than the morbidity rate for nonfood system industries (rate ratio = 1.62; 95% confidence interval = 1.30 to 2.01). Furthermore, the occupational mortality rate for food system industries was significantly higher than the national nonfood occupational mortality rate (rate ratio = 9.51; 95% confidence interval = 2.47 to 36.58). Conclusions: This is the first use of the farm-to-table model to assess occupational morbidity and mortality, and these findings highlighting specific workplace hazards across food system industries.