Typhoid fever acquired in the United States, 1999-2010: epidemiology, microbiology, and use of a space-time scan statistic for outbreak detection.

Although rare, typhoid fever cases acquired in the United States continue to be reported. Detection and investigation of outbreaks in these domestically acquired cases offer opportunities to identify chronic carriers. We searched surveillance and laboratory databases for domestically acquired typhoid fever cases, used a space-time scan statistic to identify clusters, and classified clusters as outbreaks or non-outbreaks. From 1999 to 2010, domestically acquired cases accounted for 18% of 3373 reported typhoid fever cases; their isolates were less often multidrug-resistant (2% vs. 15%) compared to isolates from travel-associated cases. We identified 28 outbreaks and two possible outbreaks within 45 space-time clusters of ⩾2 domestically acquired cases, including three outbreaks involving ⩾2 molecular subtypes. The approach detected seven of the ten outbreaks published in the literature or reported to CDC. Although this approach did not definitively identify any previously unrecognized outbreaks, it showed the potential to detect outbreaks of typhoid fever that may escape detection by routine analysis of surveillance data. Sixteen outbreaks had been linked to a carrier. Every case of typhoid fever acquired in a non-endemic country warrants thorough investigation. Space-time scan statistics, together with shoe-leather epidemiology and molecular subtyping, may improve outbreak detection.

Sequencing and phylogenetic analysis of the coding region of six common rotavirus strains: evidence for intragenogroup reassortment among co-circulating G1P[8] and G2P[4] strains from the United States.

The segmented genome of rotaviruses provides an opportunity for rotavirus strains to generate a large genetic diversity through reassortment; however, this mechanism is considered to play little role in the generation of mosaic gene constellations between Wa-like and DS-1-like strains in genes other than the neutralization antigens. A pilot study was undertaken to analyze these two epidemiologically important strains at the genomic level in order to (i) identify intergenogroup reassortment and (ii) to make available additional reference genome sequences of G1P[8] and G2P[4] for future genomics analyses. The full or nearly complete coding region of all 11 genes for 3 G1P[8] (LB2719, LB2758, and LB2771) and 3 G2P[4] (LB2744, LB2764, and LB2772) strains isolated from children hospitalized with severe diarrhea in Long Beach, California, where these strains were circulating at comparable rates during 2005-2006 are described in this study. Based on the full-genome classification system, all G1P[8] strains had a conserved genomic constellation: G1-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-E1-H1 and were mostly identical to the few Wa-like strains whose genome sequences have already been determined. Similarly, the genome sequences of the 3 G2P[4] strains were highly conserved: G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-E2-H2 and displayed an overall lesser genetic divergence with reference DS-1-like strains. While intergenogroup reassortment was not seen between the G1P[8] and G2P[4] strains studied here, evidence for intragenogroup reassortment events was identified. Similar studies in the post-rotavirus genomic era will help uncover whether intergenogroup reassortment affecting the backbone genes could play a significant role in any potential vaccine breakthrough events by evading immunity of vaccinated children.

Phylogenetic analysis of novel G12 rotaviruses in the United States: A molecular search for the origin of a new strain.

Rotavirus serotype G12 was initially identified in the Philippines in 1987 and was not described again until it reemerged more than 13 years later. G12 strains were first detected in the United States in 2002 and have recently assumed a worldwide distribution. The high similarity between the sequence of the major outer capsid VP7 gene of human G12 strains and the single porcine G12 isolate raised the prospect that human strains may have arisen through reassortment with porcine strains or, alternatively, that the porcine strain originally came from humans. We sequenced portions of the remaining 10 segments of two human G12 strains (G12P[8] and G12P[6]) and a currently circulating common strain (G1P[8]) identified during the 2005-2006 surveillance season and compared the sequences with those of strains available through GenBank. By comparison, the three strains were all Wa-like and not porcine-like. A newly outlined classification system proposed genotypes for each gene segment based on nucleotide similarity. Using this approach, gene segments VP1-3, VP6 and NSP1-5 grouped within the same genotype, indicating that the three strains analyzed were closely related. These results suggest that the novel G12P[8] strain could have been formed by the solitary introduction of a VP7 gene into a globally common rotavirus strain, G1P[8]. Classifying rotavirus strains based only on VP7 (G) and VP4 (P) genotype potentially underestimates diversity and sequence analysis of the other segments is required to assess the complete genetic relationships between strains.

Exaggerated proinflammatory and Th1 responses in the absence of gamma/delta T cells after infection with Listeria monocytogenes.

While gamma/delta T cells are involved in host defense and immunopathology in a variety of infectious diseases, their precise role is not yet clearly defined. In the absence of gamma/delta T cells, mice die after infection with a dose of Listeria monocytogenes that is not lethal in immunologically intact animals. Morbidity might result from insufficient levels of cytokines normally produced by gamma/delta T cells or conversely from an excess of cytokines due to a lack of down-regulation of the inflammatory response in the absence of gamma/delta T cells. Consistent with a regulatory role, we found that systemic levels of proinflammatory cytokines (interleukin-6 [IL-6], IL-12, and gamma interferon [IFN-gamma]) were significantly higher in the absence of gamma/delta T cells during the innate phase of the response. Using combinations of genetically altered and immunodepleted mice, we found evidence for gamma/delta T-cell-mediated regulation of IFN-gamma production by multiple cell types of both lymphoid and myeloid lineages. The antigen-specific alpha/beta T-cell response that followed the exaggerated innate response was also increased in gamma/delta T-cell-deficient mice. These findings are consistent with an emerging picture from a variety of immune response models of a critical role for gamma/delta T cells in down-modulation of the immune response.

Preliminary assessment of nutrients in daily diets of a sample of Belcher Island Inuit adults.

In order to describe daily food patterns and nutrient intakes of adults in the Inuit community of Sanikiluaq, 48 adults (young and older men and women, 12 per group, randomly selected from all individuals within their age and sex group) provided two 24-hour recalls of food consumption, once each in two seasons (February/March, October/November). The most frequent Inuit foods were reindeer, seal, and arctic char, while the most frequent market foods were tea, sugar, and bannock. On average 799 grams of Inuit food were consumed per day, providing 47% of daily energy and 65-92% of daily protein, iron, zinc, phosphorus, thiamin, riboflavin, and niacin. Inuit foods are primary sources of many nutrients for the Belcher Island Inuit.

Inuvialuit food use and food preferences in Aklavik, Northwest Territories, Canada.

Annual frequency of use of 32 species of mammals, fish, birds and plants was examined among 36 (43% of all) Inuvialuit households in Aklavik, NWT. Degree of preference for each of 34 traditional and 12 store-bought foods was examined among 36 adults and 35 (83% of all) Inuvialuit school children ages 10-16 years, using a Likert-type scale. Traditional foods were used on average 676 +/- 464 (mean +/- S.D.) times per year, the most frequent being caribou (145, mean), beluga whale (74), hares (35), muskrat (26), whitefish (52), cisco (39), burbot (38), inconnu (37), Arctic charr (31), geese (44) ducks (19), ptamigan (18), cloudberries (22), cranberries (20) and blueberries (18). Traditional foods were well-linked, especially caribou, bannock, charr, beluga, muskrat, geese, ducks, and hare. For 31 of 34 traditional foods, there were no statistically significant differences (p < 0.05, t-test) in children's vs adult's preference ratings; however, children rated 8 of 12 store-bought foods higher (p < 0.05) than adults did. Reasons given for the selection of favourite foods included the role of caribou as the dietary staple, the food's traditional nature, its origin in nature, its association with home and childhood, as well as organoleptic and convenience considerations. Overall, traditional foods are frequently consumed and highly preferred by contemporary Inuvialuit of Aklavik.