Recurrent multistate outbreak of Salmonella Newport associated with tomatoes from contaminated fields, 2005

Salmonella Newport causes more than an estimated 100,000 infections annually in the United States. In 2002, tomatoes grown and packed on the eastern shore of Virginia contaminated with a pan-susceptible S. Newport strain caused illness in 510 patients in 26 states. In July-November 2005, the same strain caused illness in at least 72 patients in 16 states. We conducted a case-control study during the 2005 outbreak, enrolling 29 cases and 140 matched neighbourhood controls. Infection was associated with eating tomatoes (matched odds ratio 9.7, 95% confidence interval 3.3-34.9). Tomatoes were traced back to the eastern shore of Virginia, where the outbreak strain was isolated from pond water used to irrigate tomato fields. Two multistate outbreaks caused by one rare strain, and identification of that strain in irrigation ponds 2 years apart, suggest persistent contamination of tomato fields. Further efforts are needed to prevent produce contamination on farms and throughout the food supply chain.

Blood glucose levels in children with Type 1 diabetes attending a residential diabetes camp: a 2-year review

AIMS

The objective of this retrospective analysis of blood glucose values at a week-long residential summer camp for children with Type 1 diabetes was to provide experiential data to reinforce current summer camp guidelines and to determine if specific interventions implemented between 2009 and 2010 were effective in lowering average blood glucose among our campers without increasing risk of hypoglycaemia.

METHODS

Blood glucose records were obtained from a random selection of children who attended six 1-week camp sessions, three each in 2009 and 2010. Five values per day: pre-meal breakfast, lunch and dinner, pre-evening snack and midnight values were analysed.

RESULTS

A total of 13,267 blood glucose values were included. There were no severe hypoglycaemic episodes, seizures or need for full-dose glucagon or intravenous glucose in either year. Mean blood glucose was significantly lower in 2010 compared with 2009 (9.22 vs. 10.06 mmol/l, P < 0.001). Older age and camp year were associated with lower mean blood glucose, even when controlling for gender and duration of diabetes.

CONCLUSIONS

This analysis is the largest so far conducted at a residential diabetes camp. Mean blood glucose levels were lower than other published studies. Although we cannot attribute a cause-and-effect relationship between our interventions and the improvement in blood glucose between 2009 and 2010, the use of pre-meal insulin bolus doses, low glycaemic meals and highlighting blood glucose levels in logs before being reviewed by endocrinologists are strongly encouraged. From this study we hope to establish benchmarks for comparison among camps and begin to identify best practices.

Evolution of the uniquely adaptable lentiviral envelope in a natural reservoir host

Background

The ability of emerging pathogens to infect new species is likely related to the diversity of pathogen variants present in existing reservoirs and their degree of genomic plasticity, which determines their ability to adapt to new environments. Certain simian immunodeficiency viruses (SIVcpz, SIVsm) have demonstrated tremendous success in infecting new species, including humans, resulting in the HIV-1 and HIV-2 epidemics. Although SIV diversification has been studied on a population level, the essential substrates for cross-species transmission, namely SIV sequence diversity and the types and extent of viral diversification present in individual reservoir animals have not been elucidated. To characterize this intra-host SIV diversity, we performed sequence analyses of clonal viral envelope (env) V1V2 and gag p27 variants present in individual SIVsm-infected sooty mangabeys over time.

Results

SIVsm demonstrated extensive intra-animal V1V2 length variation and amino acid diversity (le38%), and continual variation in V1V2 N-linked glycosylation consensus sequence frequency and location. Positive selection was the predominant evolutionary force. Temporal sequence shifts suggested continual selection, likely due to evolving antibody responses. In contrast, gag p27 was predominantly under purifying selection. SIVsm V1V2 sequence diversification is at least as great as that in HIV-1 infected humans, indicating that extensive viral diversification in and of itself does not inevitably lead to AIDS.

Conclusion

Positive diversifying selection in this natural reservoir host is the engine that has driven the evolution of the uniquely adaptable SIV/HIV envelope protein. These studies emphasize the importance of retroviral diversification within individual host reservoir animals as a critical substrate in facilitating cross-species transmission.