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Volume 10, Number 7—July 2004

Volume 10, Number 7—July 2004   PDF Version [PDF - 6.39 MB - 175 pages]

Perspective

  • Environmental and Occupational Health Response to SARS, Taiwan, 2003 PDF Version [PDF - 209 KB - 8 pages]
    E. J. Esswein et al.
        View Abstract

    The Taiwan Department of Health requested assistance from the Centers for Disease Control and Prevention (CDC) in controlling an outbreak of severe acute respiratory syndrome (SARS). The CDC SARS response team included industrial hygiene specialists from the National Institute for Occupational Safety and Health (NIOSH). Four NIOSH specialists visited hospitals and medical centers throughout Taiwan and assisted with designing and evaluating ventilation modifications for infection control, developed guidelines for converting hospital rooms into SARS patient isolation rooms, prepared designs for the rapid conversion of a vacated military facility into a SARS screening and observation facility, assessed environmental aspects of dedicated SARS hospitals, and worked in concert with the Taiwanese to develop hospital ventilation guidelines. We describe the environmental findings and observations from this response, including the rapid reconfiguration of medical facilities during a national health emergency, and discuss environmental challenges should SARS or a SARS-like virus emerge again.

  • Malaria Epidemics and Surveillance Systems in Canada PDF Version [PDF - 326 KB - 7 pages]
    J. D. MacLean et al.
        View Abstract

    In the past decade, fluctuations in numbers of imported malaria cases have been seen in Canada. In 1997–1998, malaria case numbers more than doubled before returning to normal. This increase was seen in no other industrialized country. The Canadian federal malaria surveillance system collects insufficient data to interpret these fluctuations. Using local (sentinel), provincial, federal, and international malaria surveillance data, we evaluate and interpret these fluctuations. Several epidemics are described. With an ever-increasing immigrant and refugee population of tropical origin, improved surveillance will be necessary to guide public health prevention policy and practice. The Canadian experience is likely to be generalizable to other industrialized countries where malaria is a reportable disease within a passive surveillance system.

  • Estimating Time and Size of Bioterror Attack PDF Version [PDF - 78 KB - 4 pages]
    J. Walden and E. H. Kaplan
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    Time and size of possible bioterror event estimated in real time.

        View Abstract

    In the event of a bioterror attack, rapidly estimating the size and time of attack enables short-run forecasts of the number of persons who will be symptomatic and require medical care. We present a Bayesian approach to this problem for use in real time and illustrate it with data from a simulated anthrax attack. The method is simple enough to be implemented in a spreadsheet.

Research

  • Detection of SARS-associated Coronavirus in Throat Wash and Saliva in Early Diagnosis PDF Version [PDF - 146 KB - 7 pages]
    W. Wang et al.
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    The severe acute respiratory syndrome–associated coronavirus (SARS-CoV) is thought to be transmitted primarily through dispersal of droplets, but little is known about the load of SARS-CoV in oral droplets. We examined oral specimens, including throat wash and saliva, and found large amounts of SARS-CoV RNA in both throat wash (9.58 x 102 to 5.93 x 106 copies/mL) and saliva (7.08 x 103 to 6.38 x 108 copies/mL) from all specimens of 17 consecutive probable SARS case-patients, supporting the possibility of transmission through oral droplets. Immunofluorescence study showed replication of SARS-CoV in the cells derived from throat wash, demonstrating the possibility of developing a convenient antigen detection assay. This finding, with the high detection rate a median of 4 days after disease onset and before the development of lung lesions in four cases, suggests that throat wash and saliva should be included in sample collection guidelines for SARS diagnosis.

  • Alert Threshold Algorithms and Malaria Epidemic Detection PDF Version [PDF - 173 KB - 7 pages]
    H. D. Teklehaimanot et al.
        View Abstract

    We describe a method for comparing the ability of different alert threshold algorithms to detect malaria epidemics and use it with a dataset consisting of weekly malaria cases collected from health facilities in 10 districts of Ethiopia from 1990 to 2000. Four types of alert threshold algorithms are compared: weekly percentile, weekly mean with standard deviation (simple, moving average, and log-transformed case numbers), slide positivity proportion, and slope of weekly cases on log scale. To compare dissimilar alert types on a single scale, a curve was plotted for each type of alert, which showed potentially prevented cases versus number of alerts triggered over 10 years. Simple weekly percentile cutoffs appear to be as good as more complex algorithms for detecting malaria epidemics in Ethiopia. The comparative method developed here may be useful for testing other proposed alert thresholds and for application in other populations.

  • Recombinant Viruses and Early Global HIV-1 Epidemic PDF Version [PDF - 409 KB - 8 pages]
    M. L. Kalish et al.
        View Abstract

    Central Africa was the epicenter of the HIV type 1 (HIV-1) pandemic. Understanding the early epidemic in the Democratic Republic of the Congo, formerly Zaire, could provide insight into how HIV evolved and assist vaccine design and intervention efforts. Using enzyme immunosorbent assay, we tested 3,988 serum samples collected in Kinshasa in the mid-1980s and confirmed seroreactivity by Western blot. Polymerase chain reaction of gag p17, env C2V3C3, and/or gp41; DNA sequencing; and genetic analyses were performed. Gene regions representing all the HIV-1 group M clades and unclassifiable sequences were found. From two or three short gene regions, 37% of the strains represented recombinant viruses, multiple infections, or both, which suggests that if whole genome sequences were available, most of these strains would have mosaic genomes. We propose that the HIV epidemic was established in Central Africa by the early 1980s and that some recombinant viruses most likely seeded the early global epidemic.

  • Molecular Analysis of Plasmodium ovale Variants PDF Version [PDF - 242 KB - 6 pages]
    T. T. Win et al.
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    Complete DNA sequences of the small subunit ribosomal RNA (SSUrRNA) gene and partial sequences of three other loci were obtained from three variant-type and three classic-type Plasmodium ovale isolates from Southeast Asia and compared with GenBank-available data. Three different SSUrRNA sequences (Pov 1–3) were found in each variant-type isolate, and two different SSUrRNA sequences (Poc 1–2) in each classic-type isolate. Pov 1–3 were closer to sequences previously found in the Cameroon and MAL/MAI isolates, whereas Poc 1–2 were closer to sequences previously found in two clones of the Nigerian I/CDC strain. The 3′ half of Pov 1–3 was identical to the partial sequence of the SSUrRNA gene from the London School (LS) strain. Results support grouping P. ovale into two groups, the classic type (including the Nigerian I/CDC strain) and the variant type (Cameroon, MAL/MAI, and LS isolates).

  • Sporadic Cryptosporidiosis Case-Control Study with Genotyping PDF Version [PDF - 288 KB - 9 pages]
    P. R. Hunter et al.
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    We report a case-control study of sporadic cryptosporidiosis with genotyping of isolates from case-patients. A postal questionnaire was completed by 427 patients and 427 controls. We obtained genotyping data on isolates from 191patients; 115 were Cryptosporidium hominis, and 76 were C. parvum. When all cryptosporidiosis cases were analyzed, three variables were strongly associated with illness: travel outside the United Kingdom, contact with another person with diarrhea, and touching cattle. Eating ice cream and eating raw vegetables were both strongly negatively associated with illness. Helping a child <5 years of age to use the toilet and the number of glasses of tap water drunk at home each day were also independently positively associated with risk. Eating tomatoes was negatively associated. For C. hominis infections, the strongly significant risk factors were travel abroad and changing diapers of children <5 years of age. For C. parvum, eating raw vegetables and eating tomatoes were strongly negatively associated with illness; touching any farm animals was associated with illness.

  • Fluoroquinolone and Other Antimicrobial Resistance in Invasive Pneumococci, Hong Kong, 1995–2001 PDF Version [PDF - 236 KB - 8 pages]
    P. Ho et al.
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    We determined the susceptibilities of 265 invasive isolates of pneumococci obtained during 1995 to 2001 in Hong Kong to 11 antimicrobial agents and their serotypes. Overall, 62.6% isolates were susceptible to penicillin, 20% were intermediately resistant, and 17.4% were resistant. The overall prevalence of levofloxacin resistance (MIC >8 μg/mL) was 3.8% but increased to 15.2% among the penicillin-resistant isolates. All levofloxacin-resistant isolates were clonally related; had reduced susceptibility to penicillin, cefotaxime, and clarithromycin; and were derived from adults >50 years of age. Of the penicillin-nonsusceptible pneumococci, 90% were from children <5 years of age, and 54.8% from persons of all ages are of serotypes that are included in the 7-valent pneumococcal conjugate vaccine; 93.5% from children <5 years of age and 93% from persons of all ages are of serotypes that are included in the 23-valent polysaccharide vaccine.

  • Model Parameters and Outbreak Control for SARS PDF Version [PDF - 275 KB - 6 pages]
    G. Chowell et al.
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    Tool for estimating basic reproductive number for the SARS outbreak suggests need for multiple methods of control.

        View Abstract

    Control of the 2002–2003 severe acute respiratory syndrome (SARS) outbreak was based on rapid diagnosis coupled with effective patient isolation. We used uncertainty and sensitivity analysis of the basic reproductive number R0 to assess the role that model parameters play in outbreak control. The transmission rate and isolation effectiveness have the largest fractional effect on R0. We estimated the distribution of the reproductive number R0 under perfect isolation conditions. The distribution lies in the interquartile range 0.19–1.08, with a median of 0.49. Even though the median of R0 is <1, we found that 25% of our R0 distribution lies at R0 > 1, even with perfect isolation. This implies the need to simultaneously apply more than one method of control.

  • Wind in November, Q fever in December PDF Version [PDF - 179 KB - 6 pages]
    H. Tissot-Dupont et al.
        View Abstract

    Q fever, a worldwide zoonosis caused by Coxiella burnetii, can be transmitted from animal reservoirs to humans by the inhalation of infected aerosols. We investigated the epidemiology of Q fever in the Bouches-du-Rhone district of southern France, particularly the role of wind and rainfall in C. burnetii transmission. During the winter of 1998 to 1999, an unexpected number of cases were diagnosed in the area. This statistically higher incidence was associated with an increased frequency of the mistral 1 month before onset of disease, i.e., shortly after the main lambing season. These data confirm that wind plays a role in C. burnetii transmission, a factor that can be monitored but not prevented. Further studies are needed to identify and confirm preventable individual behavioral risk factors for Q fever.

  • Rapid Assessment Tool for Haemophilus influenzae type b Disease in Developing Countries PDF Version [PDF - 164 KB - 7 pages]
    D. R. Feikin et al.
        View Abstract

    Haemophilus influenzae type b (Hib) still causes a substantial number of deaths among children in developing countries, despite the availability of effective conjugate vaccines. A major obstacle in developing a Hib vaccine has been limited awareness about the impact of Hib disease. A tool was developed to estimate the national rates of Hib meningitis and pneumonia by assessing retrospective local data over 7 to 10 days. Data from 11 countries in Africa, the Middle East, and Asia were studied and showed rates of Hib meningitis from >50 cases per 100,000 children >5 years in Ghana and Uganda to <15 per 100,000 in Iran, Jordan, and Uzbekistan. Results were affected by the quality of available data. The Hib rapid assessment tool can be useful to countries that desire a timely assessment of Hib disease rates.

  • Nosocomial Infection with Vancomycin-dependent Enterococci PDF Version [PDF - 209 KB - 5 pages]
    P. A. Tambyah et al.
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    We report three patients infected with unique strains of vancomycin-dependent enterococci. Two were first infected by genetically identical strains of vancomycin-resistant enterococci (VRE). All three patients had much greater exposure to vancomycin and third-generation cephalosporins than did two control groups (patients infected with VRE and hospitalized patients without enterococcal infections). While antimicrobial pressure promotes nosocomial colonization by VRE, prolonged exposure to vancomycin may foster the transition from vancomycin resistance to dependence.

  • Q Fever Outbreak in Industrial Setting PDF Version [PDF - 122 KB - 8 pages]
    H. C. van Woerden et al.
        View Abstract

    An outbreak of Q fever occurred in South Wales, United Kingdom, from July 15 through September 30, 2002. To investigate the outbreak a cohort and nested case-control study of persons who had worked at a cardboard manufacturing plant was conducted. The cohort included 282 employees and subcontractors, of whom 253 (90%) provided blood samples and 214 (76%) completed questionnaires. Ninety-five cases of acute Q fever were identified. The epidemic curve and other data suggested an outbreak source likely occurred August 5–9, 2002. Employees in the factory’s offices were at greatest risk for infection (odds ratio 3.46; 95% confidence interval 1.38–9.06). The offices were undergoing renovation work around the time of likely exposure and contained straw board that had repeatedly been drilled. The outbreak may have been caused by aerosolization of Coxiella burnetii spore-like forms during drilling into contaminated straw board.

  • Collecting Data To Assess SARS Interventions PDF Version [PDF - 74 KB - 3 pages]
    R. Scott et al.
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    With cases of severe acute respiratory syndrome (SARS) occurring across geographic regions, data collection on the effectiveness of intervention strategies should be standardized to facilitate analysis. We propose a minimum dataset to capture data needed to examine the basic reproduction rate, case status and criteria, symptoms, and outcomes of SARS.

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