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Volume 15, Number 3—March 2009

Volume 15, Number 3—March 2009   PDF Version [PDF - 5.95 MB - 159 pages]

Perspective

  • Meeting the Challenge of Influenza Pandemic Preparedness in Developing Countries PDF Version [PDF - 196 KB - 7 pages]
    D. S. Fedson
        View Abstract

    Developing countries face unique difficulties preparing for an influenza pandemic. Our current top-down approach will not provide these countries with adequate supplies of vaccines and antiviral agents. Consequently, they will have to use a bottom-up approach based on inexpensive generic agents that either modify the host response to influenza virus or act as antiviral agents. Several of these agents have shown promise, and many are currently produced in developing countries. Investigators must primarily identify agents for managing infection in populations and not simply seek explanations for how they work. They must determine in which countries these agents are produced and define patterns of distribution and costs. Because prepandemic research cannot establish whether these agents will be effective in a pandemic, randomized controlled trials must begin immediately after a new pandemic virus has emerged. Without this research, industrialized and developing countries could face an unprecedented health crisis.

Research

  • Shiga Toxin–producing Escherichia coli Strains Negative for Locus of Enterocyte Effacement PDF Version [PDF - 317 KB - 9 pages]
    H. J. Newton et al.
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    Most Shiga toxin–producing Escherichia coli (STEC) infections that are associated with severe sequelae such as hemolytic uremic syndrome (HUS) are caused by attaching and effacing pathogens that carry the locus of enterocyte effacement (LEE). However, a proportion of STEC isolates that do not carry LEE have been associated with HUS. To clarify the emergence of LEE-negative STEC, we compared the genetic composition of the virulence plasmids pO113 and pO157 from LEE-negative and LEE-positive STEC, respectively. The complete nucleotide sequence of pO113 showed that several plasmid genes were shared by STEC O157:H7. In addition, allelic profiling of the ehxA gene demonstrated that pO113 belongs to a different evolutionary lineage than pO157 and that the virulence plasmids of LEE-negative STEC strains were highly related. In contrast, multilocus sequence typing of 17 LEE-negative STEC isolates showed several clonal groups, suggesting that pathogenic LEE-negative STEC has emerged several times throughout its evolution.

  • Sources of Hepatitis E Virus Genotype 3 in the Netherlands PDF Version [PDF - 207 KB - 7 pages]
    S. A. Rutjes et al.
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    Non–travel-related hepatitis E virus (HEV) genotype 3 infections in persons in the Netherlands may have a zoonotic, foodborne, or water-borne origin. Possible reservoirs for HEV transmission by water, food, and animals were studied. HEV genotype 3/open reading frame 2 sequences were detected in 53% of pig farms, 4% of wild boar feces, and 17% of surface water samples. HEV sequences grouped within 4 genotype 3 clusters, of which 1 is so far unique to the Netherlands. The 2 largest clusters contained 35% and 43% of the animal and environmental sequences and 75% and 6%, respectively, of human HEV sequences obtained from a study on Dutch hepatitis E patients. This finding suggests that infection risk may be also dependent on transmission routes other than the ones currently studied. Besides the route of exposure, virus characteristics may be an important determinant for HEV disease in humans.

  • Integron-mediated Multidrug Resistance in a Global Collection of Nontyphoidal Salmonella enterica Isolates PDF Version [PDF - 359 KB - 9 pages]
    M. G. Krauland et al.
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    Salmonella enterica bacteria have become increasingly resistant to antimicrobial agents, partly as a result of genes carried on integrons. Clonal expansion and horizontal gene transfer may contribute to the spread of antimicrobial drug–resistance integrons in these organisms. We investigated this resistance and integron carriage among 90 isolates with the ACSSuT phenotype (resistance to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline) in a global collection of S. enterica isolates. Four integrons, dfrA12/orfF/aadA2, dfrA1/aadA1, dfrA7, and arr2/blaOXA30/cmlA5/aadA2, were found in genetically unrelated isolates from 8 countries on 4 continents, which supports a role for horizontal gene transfer in the global dissemination of S. enterica multidrug resistance. Serovar Typhimurium isolates containing identical integrons with the gene cassettes blaPSE1 and aadA2 were found in 4 countries on 3 continents, which supports the role of clonal expansion. This study demonstrates that clonal expansion and horizontal gene transfer contribute to the global dissemination of antimicrobial drug resistance in S. enterica.

  • Coccidioidal Pneumonia, Phoenix, Arizona, USA, 2000–2004 PDF Version [PDF - 177 KB - 5 pages]
    M. M. Kim et al.
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    Community-acquired pneumonia (CAP) often results in severe illness and death. In large, geographically defined areas where Coccidioides spp. are endemic, coccidioidomycosis is a recognized cause of CAP, but its frequency has not been studied extensively. To determine the frequency of patients with coccidioidomycosis, we conducted a prospective evaluation of 59 patients with CAP in the Phoenix, Arizona, area. Of 35 for whom paired coccidioidal serologic testing was performed, 6 (17%) had evidence of acute coccidioidomycosis. Coccidioidal pneumonia was more likely than noncoccidioidal CAP to produce rash. The following were not found to be risk factors or reliable predictors of infection: demographic features, underlying medical conditions, duration of time spent in disease-endemic areas, occupational and recreational activities, initial laboratory studies, and chest radiography findings. Coccidioidomycosis is a common cause of CAP in our patient population. In the absence of distinguishing clinical features, coccidioidal pneumonia can be identified only with appropriate laboratory studies.

  • Characterization of Avian Influenza Viruses A (H5N1) from Wild Birds, Hong Kong, 2004–2008 PDF Version [PDF - 201 KB - 6 pages]
    G. J. Smith et al.
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    From January 2004 through June 2008, surveillance of dead wild birds in Hong Kong, People’s Republic of China, periodically detected highly pathogenic avian influenza (HPAI) viruses (H5N1) in individual birds from different species. During this period, no viruses of subtype H5N1 were detected in poultry on farms and in markets in Hong Kong despite intensive surveillance. Thus, these findings in wild birds demonstrate the potential for wild birds to disseminate HPAI viruses (H5N1) to areas otherwise free from the viruses. Genetic and antigenic characterization of 47 HPAI (H5N1) viruses isolated from dead wild birds in Hong Kong showed that these isolates belonged to 2 antigenically distinct virus groups: clades 2.3.4 and 2.3.2. Although research has shown that clade 2.3.4 viruses are established in poultry in Asia, the emergence of clade 2.3.2 viruses in nonpasserine birds from Hong Kong, Japan, and Russia raises the possibility that this virus lineage may have become established in wild birds.

  • Prevalence and Seasonality of Influenza-like Illness in Children, Nicaragua, 2005–2007 PDF Version [PDF - 156 KB - 7 pages]
    A. Gordon et al.
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    Although information about seasonality and prevalence of influenza is crucial for development of effective prevention and control strategies, limited data exist on the epidemiology of influenza in tropical countries. To better understand influenza in Nicaragua, we performed a prospective 2-year cohort study of influenza-like illness (ILI) involving 4,276 children, 2–11 years of age, in Managua, during April 2005–April 2007. One peak of ILI activity occurred during 2005, in June–July; 2 peaks occurred during 2006, in June–July and November–December. The rate of ILI was 34.8/100 person-years. A household risk factor survey administered to a subset (61%) of participants identified the following risk factors: young age, asthma, and increasing person density in the household. Influenza virus circulation was confirmed during each ILI peak by laboratory testing of a subset of samples. Our findings demonstrate a high rate of ILI, with seasonal peaks, in children in Nicaragua.

  • Medscape CME Activity
    Clinical Risk Factors for Severe Clostridium difficile–associated Disease PDF Version [PDF - 228 KB - 8 pages]
    T. J. Henrich et al.
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    Identifying patients who are at high risk for severe Clostridium difficile–associated disease (CDAD) early in the course of their infection may help clinicians improve outcomes. Therefore, we compared clinical features associated with severe versus nonsevere CDAD by retrospectively reviewing records of hospitalized patients whose fecal assays were positive for C. difficile toxin. Of 336 patients, 12.2% had severe disease and 10.1% died from all causes. Regression modeling showed the following to be significantly associated with severe CDAD (p<0.05): age >70 years (odds ratio [OR] 3.35), maximum leukocyte count >20,000 cells/mL (OR 2.77), minimum albumin level <2.5 g/dL (OR 3.44), maximum creatinine level >2 mg/dL (OR 2.47), small bowel obstruction or ileus (OR 3.06), and computed tomography scan showing colorectal inflammation (OR 13.54). These clinical and laboratory markers for severe disease may be useful for identifying patients at risk for serious outcomes or death.

  • Capacity of Thailand to Contain an Emerging Influenza Pandemic PDF Version [PDF - 1.45 MB - 10 pages]
    W. Putthasri et al.
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    Southeast Asia will likely be the epicenter of the next influenza pandemic. To determine whether health system resources in Thailand are sufficient to contain an emerging pandemic, we mapped health system resources in 76 provinces. We used 3 prepandemic scenarios of clustered cases and determined resource needs, availability, and gaps. We extended this analysis to a scenario of a modest pandemic and assumed that the same standards of clinical care would be required. We found that gaps exist in many resource categories, even under scenarios in which few cases occur. Such gaps are likely to be profound if a severe pandemic occurs. These gaps exist in infrastructure, personnel and materials, and surveillance capacity. Policy makers must determine whether such resource gaps can realistically be closed, ideally before a pandemic occurs. Alternatively, explicit assumptions must be made regarding allocation of scarce resources, standards of care, and priority setting during a pandemic.

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