An outbreak of enterovirus 71 in metropolitan Sydney: enhanced surveillance and lessons learnt

OBJECTIVE

To report the findings of the enhanced surveillance set up in New South Wales in response to the recent outbreak of human enterovirus 71 (EV71) infection.

DESIGN AND SETTING

A two-armed enhanced public health surveillance system including statewide emergency department surveillance and clinical surveillance at the Sydney Children's Hospitals Network.

PARTICIPANTS

Children aged less than 10 years with suspected or confirmed enterovirus infection.

MAIN OUTCOME MEASURES

Epidemiology of the outbreak, including weekly case counts, demographic information, geographic spread of the outbreak, and clinical presentation and progression.

RESULTS

Statewide weekly case counts indicate that an epidemic of EV71 infection occurred in NSW from December 2012 until May 2013. Around 119 children were reported with disease severe enough to warrant admission to a tertiary Sydney children's hospital. Cases were spread throughout the Sydney metropolitan area and there is some evidence of geographic migration of the outbreak. Presenting features included fever, lethargy, myoclonus and skin rash. Only 24% of cases presented with classical hand, foot and mouth disease.

CONCLUSIONS

EV71 infection is likely to continue to be a public health problem in Australia. Surveillance of routinely collected emergency department data can provide a useful indication of its activity in the community.

Methylation-capture and Next-Generation Sequencing of free circulating DNA from human plasma

BACKGROUND

Free circulating DNA (fcDNA) has many potential clinical applications, due to the non-invasive way in which it is collected. However, because of the low concentration of fcDNA in blood, genome-wide analysis carries many technical challenges that must be overcome before fcDNA studies can reach their full potential. There are currently no definitive standards for fcDNA collection, processing and whole-genome sequencing. We report novel detailed methodology for the capture of high-quality methylated fcDNA, library preparation and downstream genome-wide Next-Generation Sequencing. We also describe the effects of sample storage, processing and scaling on fcDNA recovery and quality.

RESULTS

Use of serum versus plasma, and storage of blood prior to separation resulted in genomic DNA contamination, likely due to leukocyte lysis. Methylated fcDNA fragments were isolated from 5 donors using a methyl-binding protein-based protocol and appear as a discrete band of ~180 bases. This discrete band allows minimal sample loss at the size restriction step in library preparation for Next-Generation Sequencing, allowing for high-quality sequencing from minimal amounts of fcDNA. Following sequencing, we obtained 37 × 10(6)-86 × 10(6) unique mappable reads, representing more than 50% of total mappable reads. The methylation status of 9 genomic regions as determined by DNA capture and sequencing was independently validated by clonal bisulphite sequencing.

CONCLUSIONS

Our optimized methods provide high-quality methylated fcDNA suitable for whole-genome sequencing, and allow good library complexity and accurate sequencing, despite using less than half of the recommended minimum input DNA.

Disparities in tuberculosis between Asian/Pacific Islanders and non-Hispanic Whites, United States, 1993-2006

SETTING

The United States (US) National Tuberculosis Surveillance System (NTSS), including 50 states, District of Columbia, and New York City.

OBJECTIVE

To examine disparities in characteristics and rates of Asian/Pacific Islander (API) and non-Hispanic White tuberculosis (TB) patients.

DESIGN

Descriptive analysis and logistic regression of selected 1993-2006 NTSS data. US Census Bureau Zip Code Tabulation Areas and geographic information system were used to compare API and non-Hispanic White TB patients by population density.

RESULT

Of 253,299 TB cases, 19.8% were APIs and 23.2% were Whites; 94.2% APIs and 11.9% Whites were foreign-born. Factors that were most often associated with APIs were being female, age 15-24 years, extra-pulmonary TB, and drug resistance. APIs were less likely than Whites to be human immunodeficiency virus (HIV) positive, homeless, substance abusers, or on directly observed therapy. From 1993 to 2006, the API TB case rate declined by 42.9% vs. 66.6% in Whites (P < 0.01). Being foreign-born was the strongest risk factor for TB, regardless of population densities, but APIs were more likely to have TB than foreign-born Whites at lower population densities.

CONCLUSION

Disparities in TB exist among US APIs and non-Hispanic Whites. TB program officials should allocate programs appropriately for foreign-born APIs in lower population density areas.

Toxoplasma gondii infection in the United States: seroprevalence and risk factors

Infection with Toxoplasma gondii can cause severe illness when the organism is contracted congenitally or when it is reactivated in immune-suppressed persons. To determine the prevalence of T. gondii infection in a representative sample of the US population, the authors tested sera from participants in the Third National Health and Nutrition Examination Survey (1988-1994) for immunoglobulin G antibodies to T. gondii. Of 27,145 persons aged > or =12 years, 17,658 (65%) had sera tested. The overall age-adjusted seroprevalence was 22.5% (95% confidence interval (CI): 21.1, 23.9); among women aged 15-44 years, seroprevalence was 15.0% (95% CI: 13.2, 17.0). Age-adjusted seroprevalence was higher in the Northeast (29.2%) than in the South (22.8%), Midwest (20.5%), or West (17.5%) (p < 0.05). In multivariate analysis, risk for T. gondii infection increased with age and was higher among persons who were foreign-born, persons with a lower educational level, those who lived in crowded conditions, and those who worked in soil-related occupations, although in subset analyses risk categories varied by race/ethnicity. Nearly one quarter of adults and adolescents in the United States have been infected with T. gondii. Most women of childbearing age in the United States are susceptible to acute infection and should be educated about ways to minimize exposure to T. gondii.

Detection by an immunofluorescence test of Encephalitozoon intestinalis spores in routinely formalin-fixed stool samples stored at room temperature

Of the several microsporidia that infect humans, Enterocytozoon bieneusi is known to cause a gastrointestinal disease whereas Encephalitozoon intestinalis causes both a disseminated and an intestinal disease. Although several different staining techniques, including the chromotrope technique and its modifications, Uvitex 2B, and the quick-hot Gram-chromotrope procedure, detect microsporidian spores in fecal smears and other clinical samples, they do not identify the species of microsporidia. A need for an easily performed test therefore exists. We reevaluated 120 stool samples that had been found positive for microsporidia previously, using the quick-hot Gram-chromotrope technique, and segregated them into two groups on the basis of spore size. We also screened the smears by immunofluorescence microscopy, using a polyclonal rabbit anti-E. intestinalis serum at a dilution of 1:400. Spores in 29 (24.1%) of the 120 samples fluoresced brightly, indicating that they were E. intestinalis spores. No intense background or cross-reactivity with bacteria, yeasts, or other structures in the stool samples was seen. Additionally, the numbers of spores that fluoresced in seven of these samples were substantially smaller than the numbers of spores that were present in the stained smears, indicating that these samples were probably derived from patients with mixed infections of Enterocytozoon bieneusi and E. intestinalis. Because a 1:400 dilution of this serum does not react with culture-grown Encephalitozoon hellem, Encephalitozoon cuniculi, or Vittaforma corneae or with Enterocytozoon bieneusi spores in feces, we concluded that an immunofluorescence test using this serum is a good alternative for the specific identification of E. intestinalis infections.

Carnitine transport in isolated adult rat heart myocytes and the effect of 7,8-diOH chlorpromazine

We studied the carnitine transport system in isolated adult rat heart myocytes able to tolerate physiological concentrations of calcium. Carnitine uptake occurred against a concentration gradient and was inhibited by 2,4-dinitrophenol (2,4-DNP). The transport system had a Km of 60 microM and a Vmax of 110 pmol/mg protein per hour. The carnitine precursor deoxycarnitine, acetylcarnitine, and both the D and L isomers were effective inhibitors of uptake. The transport of carnitine was not dependent on sodium ions, but was stimulated by decreasing concentrations of calcium ions. Decreased uptake was observed in the presence of beta-adrenergic agonists and antagonists, dibutyrl cyclic AMP, local anesthetics, and ouabain. No significant alteration of uptake was effected by atropine, carbachol or a variety of tricyclic agents. The auto-oxidation product of 7,8-dihydroxychlorpromazine (7,8-diOH CPZ) decreased carnitine efflux from myocytes, which were highly permeable to low molecular weight compounds. We found that this effect was not substrate specific, and is discussed as possibly resulting from a change in the arrangement or state of polymerization of subcellular structural components.