The impact of health communication and enhanced laboratory-based surveillance on detection of cyclosporiasis outbreaks in California.

We investigated the timing of diagnosis, influence of media information on testing for Cyclospora, and the method used to identify cases during eight cyclosporiasis outbreaks in California in spring of 1997. We found that Internet information, media reports, and enhanced laboratory surveillance improved detection of these outbreaks

Influence of host genetics on the severity of coccidioidomycosis.

Coccidioidomycosis, a mild flulike illness in approximately 40% of infected persons, progresses to severe pulmonary or disseminated disease in 1% to 10% of symptomatic cases. We examined host genetic influences on disease severity among class II HLA loci and the ABO blood group. Participants included African-American, Caucasian, and Hispanic persons with mild or severe disseminated coccidioidomycosis from Kern County, California. Among Hispanics, predisposition to symptomatic disease and severe disseminated disease is associated with blood types A and B, respectively. The HLA class II DRB1*1301 allele marks a pre-disposition to severe disseminated disease in each of the three groups. Reduced risk for severe disease is associated with DRB1*0301-DQB1*0201 among Caucasians and Hispanics and with DRB1*1501-DQB1*0602 among African-Americans. These data support the hypothesis that host genes, in particular HLA class II and the ABO blood group, influence susceptibility to severe coccidioidomycosis

Barriers to Creutzfeldt-Jakob Disease Autopsies, California

Creutzfeldt-Jakob disease (CJD) surveillance relies on autopsy and neuropathologic evaluation. The 1990–2000 CJD autopsy rate in California was 21%. Most neurologists were comfortable diagnosing CJD (83%), but few pathologists felt comfortable diagnosing CJD (35%) or performing autopsy (29%). Addressing obstacles to autopsy is necessary to improve CJD surveillance

Participant Blinding and Gastrointestinal Illness in a Randomized, Controlled Trial of an In-Home Drinking Water Intervention

We conducted a randomized, triple-blinded home drinking water intervention trial to determine if a large study could be undertaken while successfully blinding participants. Households were randomized 50:50 to use externally identical active or sham treatment devices. We measured the effectiveness of blinding of participants by using a published blinding index in which values >0.5 indicate successful blinding. The principal health outcome measured was “highly credible gastrointestinal illness” (HCGI). Participants (n=236) from 77 households were successfully blinded to their treatment assignment. At the end of the study, the blinding index was 0.64 (95% confidence interval 0.51-0.78). There were 103 episodes of HCGI during 10,790 person-days at risk in the sham group and 82 episodes during 11,380 person-days at risk in the active treatment group. The incidence rate ratio of disease (adjusted for the clustered sampling) was 1.32 (95% CI 0.75, 2.33) and the attributable risk was 0.24 (95% CI -0.33, 0.57). These data confirm that participants can be successfully blinded to treatment group assignment during a randomized trial of an in-home drinking water intervention

Geographic variations and temporal trends of Salmonella-associated hospitalization in the U.S. elderly, 1991-2004: A time series analysis of the impact of HACCP regulation

<p>Abstract</p> <p>Background</p> <p>About 1.4 million <it>Salmonella </it>infections, a common food-borne illness, occur in the U.S. annually; the elderly (aged 65 or above) are most susceptible. In 1997, the USDA introduced the Pathogen Reduction and Hazard Analysis and Critical Control Points Systems (PR/HACCP) which demands regular <it>Salmonella </it>testing in various establishments processing meat products, such as broiler chickens. Impact evaluations of PR/HACCP on hospitalizations related to <it>Salmonella </it>are lacking.</p> <p>Methods</p> <p>Hospitalization records of the U.S. elderly in 1991-2004 were obtained from the Centers of Medicare and Medicaid Services. Harmonic regression analyses were performed to evaluate the long-term trends of <it>Salmonella</it>-related hospitalizations in pre- and post-HACCP periods. Seasonal characteristics of the outcome in the nine Census divisions of the contiguous U.S. were also derived and contrasted.</p> <p>Results</p> <p>Predicted rates decreased in most divisions after 1997, except South Atlantic, East South Central, and West South Central. These three divisions also demonstrated higher overall hospitalization rates, pronounced seasonal patterns, and consistent times to peak at about 32^ndto 34^thweek of the year.</p> <p>Conclusion</p> <p>The impact of HACCP was geographically different. South Atlantic, East South Central, and West South Central divisions should be targeted in further <it>Salmonella </it>preventive programs. Further research is needed to identify the best program type and timing of implementation.</p

Ultra-Fast and Sensitive Detection of Non-Typhoidal Salmonella Using Microwave-Accelerated Metal-Enhanced Fluorescence (“MAMEF”)

Certain serovars of Salmonella enterica subsp. enterica cause invasive disease (e.g., enteric fever, bacteremia, septicemia, meningitis, etc.) in humans and constitute a global public health problem. A rapid, sensitive diagnostic test is needed to allow prompt initiation of therapy in individual patients and for measuring disease burden at the population level. An innovative and promising new rapid diagnostic technique is microwave-accelerated metal-enhanced fluorescence (MAMEF). We have adapted this assay platform to detect the chromosomal oriC locus common to all Salmonella enterica subsp. enterica serovars. We have shown efficient lysis of biologically relevant concentrations of Salmonella spp. suspended in bacteriological media using microwave-induced lysis. Following lysis and DNA release, as little as 1 CFU of Salmonella in 1 ml of medium can be detected in <30 seconds. Furthermore the assay is sensitive and specific: it can detect oriC from Salmonella serovars Typhi, Paratyphi A, Paratyphi B, Paratyphi C, Typhimurium, Enteritidis and Choleraesuis but does not detect Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae, Haemophilus influenzae or Acinetobacter baumanii. We have also performed preliminary experiments using a synthetic Salmonella oriC oligonucleotide suspended in whole human blood and observed rapid detection when the sample was diluted 1∶1 with PBS. These pre-clinical data encourage progress to the next step to detect Salmonella in blood (and other ordinarily sterile, clinically relevant body fluids)

Evolution of Salmonella enterica Virulence via Point Mutations in the Fimbrial Adhesin

Whereas the majority of pathogenic Salmonella serovars are capable of infecting many different animal species, typically producing a self-limited gastroenteritis, serovars with narrow host-specificity exhibit increased virulence and their infections frequently result in fatal systemic diseases. In our study, a genetic and functional analysis of the mannose-specific type 1 fimbrial adhesin FimH from a variety of serovars of Salmonella enterica revealed that specific mutant variants of FimH are common in host-adapted (systemically invasive) serovars. We have found that while the low-binding shear-dependent phenotype of the adhesin is preserved in broad host-range (usually systemically non-invasive) Salmonella, the majority of host-adapted serovars express FimH variants with one of two alternative phenotypes: a significantly increased binding to mannose (as in S. Typhi, S. Paratyphi C, S. Dublin and some isolates of S. Choleraesuis), or complete loss of the mannose-binding activity (as in S. Paratyphi B, S. Choleraesuis and S. Gallinarum). The functional diversification of FimH in host-adapted Salmonella results from recently acquired structural mutations. Many of the mutations are of a convergent nature indicative of strong positive selection. The high-binding phenotype of FimH that leads to increased bacterial adhesiveness to and invasiveness of epithelial cells and macrophages usually precedes acquisition of the non-binding phenotype. Collectively these observations suggest that activation or inactivation of mannose-specific adhesive properties in different systemically invasive serovars of Salmonella reflects their dynamic trajectories of adaptation to a life style in specific hosts. In conclusion, our study demonstrates that point mutations are the target of positive selection and, in addition to horizontal gene transfer and genome degradation events, can contribute to the differential pathoadaptive evolution of Salmonella