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Volume 12, Number 4—April 2006

Volume 12, Number 4—April 2006   PDF Version [PDF - 10.15 MB - 183 pages]

Archival of this issue is in progress. To receive a PDF of an article that appeared in this issue, please click here.


  • Negligible Risk for Epidemics after Geophysical Disasters PDF Version [PDF - 205 KB - 6 pages]
    N. Floret et al.
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    Short-term risk for epidemics after geophysical disasters is very low.

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    After geophysical disasters (i.e., earthquakes, volcanic eruptions, tsunamis), media reports almost always stress the risk for epidemics; whether this risk is genuine has been debated. We analyzed the medical literature and data from humanitarian agencies and the World Health Organization from 1985 to 2004. Of >600 geophysical disasters recorded, we found only 3 reported outbreaks related to these disasters: 1 of measles after the eruption of Pinatubo in Philippines, 1 of coccidioidomycosis after an earthquake in California, and 1 of Plasmodium vivax malaria in Costa Rica related to an earthquake and heavy rainfall. Even though the humanitarian response may play a role in preventing epidemics, our results lend support to the epidemiologic evidence that short-term risk for epidemics after a geophysical disaster is very low.

  • Potential Arbovirus Emergence and Implications for the United Kingdom PDF Version [PDF - 193 KB - 7 pages]
    E. Gould et al.
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    Climate change can cause arthropodborne diseases to emerge.

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    Arboviruses have evolved a number of strategies to survive environmental challenges. This review examines the factors that may determine arbovirus emergence, provides examples of arboviruses that have emerged into new habitats, reviews the arbovirus situation in western Europe in detail, discusses potential arthropod vectors, and attempts to predict the risk for arbovirus emergence in the United Kingdom. We conclude that climate change is probably the most important requirement for the emergence of arthropodborne diseases such as dengue fever, yellow fever, Rift Valley fever, Japanese encephalitis, Crimean-Congo hemorrhagic fever, bluetongue, and African horse sickness in the United Kingdom. While other arboviruses, such as West Nile virus, Sindbis virus, Tahyna virus, and Louping ill virus, apparently circulate in the United Kingdom, they do not appear to present an imminent threat to humans or animals.

  • Confronting Zoonoses, Linking Human and Veterinary Medicine PDF Version [PDF - 66 KB - 6 pages]
    L. H. Kahn
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    Greater collaboration is needed between human and veterinary medicine to better control zoonoses.

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    Many of the emerging infectious diseases, including those caused by bioterrorist agents, are zoonoses. Since zoonoses can infect both animals and humans, the medical and veterinary communities should work closely together in clinical, public health, and research settings. In the clinical setting, input from both professions would improve assessments of the risk-benefit ratios of pet ownership, particularly for pet owners who are immunocompromised. In public health, human and animal disease surveillance systems are important in tracking and controlling zoonoses such as avian influenza virus, West Nile virus, and foodborne pathogens. Comparative medicine is the study of disease processes across species, including humans. Physician and veterinarian comparative medicine research teams should be promoted and encouraged to study zoonotic agent-host interactions. These efforts would increase our understanding of how zoonoses expand their host range and would, ultimately, improve prevention and control strategies.

  • Human Influenza Surveillance: the Demand to Expand PDF Version [PDF - 134 KB - 7 pages]
    S. P. Layne
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    The potential of avian A/H5N1 to cause a global human pandemic is uncertain because it cannot be predicted with current knowledge.

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    The World Health Organization Influenza Program is one of the best developed and longest running infectious disease surveillance systems that exists. It maintains a worldwide watch of influenza's evolution to assist delivery of appropriately formulated vaccines in time to blunt seasonal epidemics and unpredictable pandemics. Despite the program's success, however, much more is possible with today's advanced technologies. This article summarizes ongoing human influenza surveillance activities worldwide. It shows that the technology to establish a high-throughput laboratory network that can process and test influenza viruses more quickly and more accurately is available. It also emphasizes the practical public health and scientific applications of such a network.

  • Prospects for Universal Influenza Virus Vaccine PDF Version [PDF - 62 KB - 6 pages]
    W. Gerhard et al.
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    The current vaccination strategy against influenza A and B viruses is vulnerable to the unanticipated emergence of epidemic strains that are poorly matched by the vaccine. A vaccine that is less sensitive to the antigenic evolution of the virus would be a major improvement. The general feasibility of this goal is supported by studies in animal models that show that immunologic activities directed against relatively invariant viral determinants can reduce illness and death. The most promising approaches are based on antibodies specific for the relatively conserved ectodomain of matrix protein 2 and the intersubunit region of hemagglutinin. However, additional conserved determinants for protective antibodies are likely to exist, and their identification should be encouraged. Most importantly, infection and current vaccines do not appear to effectively induce these antibodies in humans. This finding provides a powerful rationale for testing the protective activity of these relatively conserved viral components in humans.


  • Domestic Ducks and H5N1 Influenza Epidemic, Thailand PDF Version [PDF - 552 KB - 7 pages]
    T. Songserm et al.
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    Traditional methods of raising ducks in Southeast Asia must be modified.

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    In addition to causing 12 human deaths and 17 cases of human infection, the 2004 outbreak of H5N1 influenza virus in Thailand resulted in the death or slaughter of 60 million domestic fowl and the disruption of poultry production and trade. After domestic ducks were recognized as silent carriers of H5N1 influenza virus, government teams went into every village to cull flocks in which virus was detected; these team efforts markedly reduced H5N1 infection. Here we examine the pathobiology and epidemiology of H5N1 influenza virus in the 4 systems of duck raising used in Thailand in 2004. No influenza viruses were detected in ducks raised in "closed" houses with high biosecurity. However, H5N1 influenza virus was prevalent among ducks raised in "open" houses, free-ranging (grazing) ducks, and backyard ducks.


  • Recently Acquired Toxoplasma gondii Infection, Brazil PDF Version [PDF - 176 KB - 6 pages]
    J. L. Jones et al.
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    Soil exposure, eating undercooked meat, and having children are risk factors for acute infection and high rate of eye disease.

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    The city of Erechim, Brazil, has a 17% prevalence of ocular toxoplasmosis, and type 1 Toxoplasma gondii predominates. To examine risk factors for acute T. gondii infection in this area, we administered a questionnaire to recently infected persons (n = 131) and seronegative controls (n = 110). Eating undercooked meat; having a garden; working in the garden or yard more than once per week; eating rare meat; eating cured, dried, or smoked meat; eating frozen lamb; and being male increased risk for T. gondii infection in univariate analysis. Risk factors independently associated with acute T. gondii infection in multivariate analysis were working in the garden (odds ratio [OR] 2.35, 95% confidence interval [CI] 1.27–4.33) and eating frozen lamb (OR 2.06, 95% CI 1.15–3.67). Among women (n = 86), having had children markedly increased the risk for T. gondii infection (OR 14.94, 95% CI 3.68–60.73).

  • Reducing Legionella Colonization of Water Systems with Monochloramine PDF Version [PDF - 515 KB - 9 pages]
    B. Flannery et al.
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    Monochloramine reduced colonization in building hot water systems.

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    Monochloramine disinfection of municipal water supplies is associated with decreased risk for Legionnaires' disease. We conducted a 2-year, prospective, environmental study to evaluate whether converting from chlorine to monochloramine for water disinfection would decrease Legionella colonization of hot water systems. Water and biofilm samples from 53 buildings were collected for Legionella culture during 6 intervals. Prevalence ratios (PRs) comparing Legionella colonization before and after monochloramine disinfection were adjusted for water system characteristics. Legionella colonized 60% of the hot water systems before monochloramine versus 4% after conversion (PR 0.07, 95% confidence interval 0.03–0.16). The median number of colonized sites per building decreased with monochloramine disinfection. Increased prevalence of Legionella colonization was associated with water heater temperatures <50°C, buildings taller than 10 stories, and interruptions in water service. Increasing use of monochloramine in water supplies throughout the United States may reduce Legionella transmission and incidence of Legionnaires' disease.

  • Atypical Enteropathogenic Escherichia coli Infection and Prolonged Diarrhea in Children PDF Version [PDF - 113 KB - 7 pages]
    R. N. Nguyen et al.
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    Infection of children with atypical EPEC is associated with prolonged diarrhea.

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    Some clinical isolates of enteropathogenic Escherichia coli (EPEC) lack bundle-forming pili and are termed atypical EPEC. The aim of this study was to determine if atypical EPEC are pathogens by comparing the clinical features of patients infected with atypical EPEC with those of children infected with other causative agents of diarrhea. Fecal samples obtained from children attending the Royal Children's Hospital in Melbourne for investigation of diarrhea were examined for adenovirus, rotavirus, Campylobacter spp., Salmonella spp., protozoa, and pathogenic E. coli. Clinical data were obtained by using a standardized pro forma and analyzed separately. Patients infected with atypical EPEC experienced mild, nondehydrating, and noninflammatory diarrhea that was not particularly associated with fever, vomiting, or abdominal pain. However, the duration of diarrhea in patients infected with atypical EPEC was significantly longer than that caused by the other species or where no pathogens were identified. Infection with atypical EPEC is associated with prolonged diarrhea.

  • Epidemic Spread of Lyme Borreliosis, Northeastern United States PDF Version [PDF - 216 KB - 8 pages]
    K. Hanincová et al.
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    Host specialization is a key issue in infectious disease research because patterns of cross-species transmission affect parasite dispersal.

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    We examined the degree of host specialization of different strains of Borrelia burgdorferi, the tickborne pathogen that causes Lyme borreliosis in the northeastern United States. We first assessed the genetic population structures of B. burgdorferi in ticks obtained from different mammalian host species and in questing ticks sampled in a woodland ecosystem in Connecticut. By comparing the patterns found in our study with data from another cross-sectional study, we demonstrate that B. burgdorferi is a generalist microparasite and conclude that efficient cross-species transmission of B. burgdorferi is a key feature that has allowed the rapid spread of Lyme borreliosis across the northeastern United States.

  • Emerging Pediatric HIV Epidemic Related to Migration PDF Version [PDF - 60 KB - 6 pages]
    D. W. MacPherson et al.
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    Imported HIV infection is an emerging epidemic in countries with low HIV incidence.

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    In 2002, Canada introduced routine, mandatory HIV antibody screening for all residency applicants, including selected children. We report screening results from January 2002 to February 2005. Thirty-six pediatric HIV cases were detected (14/100,000 applicants); 94% of infected children were eligible to arrive in Canada. Thirty-two of the affected children were from Africa, and maternal infection was the main risk factor. Only 4 (11%) of the children had received antiretroviral therapy. In countries of low HIV incidence, migration-related imported infection in children may be an emerging epidemic. The early identification of HIV-infected immigrant women permits intervention to prevent mother-to-child HIV transmission. Routine HIV testing as a component of the medical examination of immigrants has national and international health policy and programmatic implications.

  • Lineage 1 and 2 Strains of Encephalitic West Nile Virus, Central Europe PDF Version [PDF - 91 KB - 6 pages]
    T. Bakonyi et al.
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    An encephalitic lineage 2 strain of WNV is observed for the first time outside Africa.

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    Two different West Nile virus (WNV) strains caused lethal encephalitis in a flock of geese and a goshawk in southeastern Hungary in 2003 and 2004, respectively. During the outbreak in geese, 14 confirmed human cases of WNV encephalitis and meningitis were reported in the same area. Sequencing of complete genomes of both WNV strains and phylogenetic analyses showed that the goose-derived strain exhibits closest genetic relationship to strains isolated in 1998 in Israel and to the strain that emerged in 1999 in the United States. WNV derived from the goshawk showed the highest identity to WNV strains of lineage 2 isolated in central Africa. The same strain reemerged in 2005 in the same location, which suggests that the virus may have overwintered in Europe. The emergence of an exotic WNV strain in Hungary emphasizes the role of migrating birds in introducing new viruses to Europe.

  • Human Trypanosoma cruzi Infection and Seropositivity in Dogs, Mexico PDF Version [PDF - 239 KB - 7 pages]
    J. G. Estrada-Franco et al.
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    Seroanalysis of parasite circulation in dogs can help identify T. cruzi infection in humans.

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    We used 5 diagnostic tests in a cross-sectional investigation of the prevalence of Trypanosoma cruzi in Tejupilco municipality, State of Mexico, Mexico. Our findings showed a substantial prevalence of immunoglobulin G (IgG) and IgM antibodies to T. cruzi in human (n = 293, IgG 2.05%, IgM 5.5%, both 7.1%) and dog (n = 114, IgG 15.8%, IgM 11.4%, both 21%) populations. We also found antibodies to T. cruzi (n = 80, IgG 10%, IgM 15%, both 17.5%) in dogs from Toluca, an area previously considered free of T. cruzi. Our data demonstrate the need for active epidemiologic surveillance programs in these regions. A direct correlation (r2 = 0.955) of seropositivity between humans and dogs suggests that seroanalysis in dogs may help identify the human prevalence of T. cruzi infection in these areas.

  • Contrasting Pediatric and Adult Methicillin-resistant Staphylococcus aureus Isolates PDF Version [PDF - 250 KB - 7 pages]
    M. Z. David et al.
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    Children may share a reservoir of MRSA strains that have an antimicrobial drug resistance profile distinct from that of adults.

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    We performed a prospective study of all inpatient and outpatient methicillin-resistant Staphylococcus aureus (MRSA) isolates identified at the University of Chicago Hospitals from November 2003 through November 2004. Differences in resistance to non–β-lactam antimicrobial drugs were determined after stratification of the 578 MRSA isolates into 4 groups by patient age (pediatric vs. adult) and onset location (community vs. hospital). Non–β-lactam resistance was significantly greater among the 288 adult than the 177 pediatric community-associated isolates for erythromycin (93.2 vs. 87.0%, p = 0.03), clindamycin (51.8 vs. 7.3%, p<0.001), ciprofloxacin (62.1 vs. 10.7%, p<0.001), gentamicin (11.1 vs. 1.1%, p<0.001), and tetracycline (19.9 vs. 6.4%, p<0.001). In contrast, hospital-associated MRSA isolates from children and adults had similar rates of non–β-lactam antimicrobial drug resistance. In our region, clindamycin is an appropriate empiric therapy of community-associated MRSA infection in children but should be used with caution in adults.

  • Identifying Influenza Viruses with Resequencing Microarrays PDF Version [PDF - 285 KB - 9 pages]
    Z. Wang et al.
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    Resequencing microarrays rapidly identify influenza viruses.

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    Identification of genetic variations of influenza viruses is essential for epidemic and pandemic outbreak surveillance and determination of vaccine strain selection. In this study, we combined a random amplification strategy with high-density resequencing microarray technology to demonstrate simultaneous detection and sequence-based typing of 25 geographically distributed human influenza virus strains collected in 2004 and 2005. In addition to identification, this method provided primary sequence information, which suggested that distinct lineages of influenza viruses co-circulated during the 2004–2005 season, and simultaneously identified and typed all component strains of the trivalent FluMist intranasal vaccine. The results demonstrate a novel, timely, and unbiased method for the molecular epidemiologic surveillance of influenza viruses.

  • Animals as Sentinels of Bioterrorism Agents PDF Version [PDF - 75 KB - 6 pages]
    P. Rabinowitz et al.
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    Pets, wildlife, or livestock could provide early warning.

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    We conducted a systematic review of the scientific literature from 1966 to 2005 to determine whether animals could provide early warning of a bioterrorism attack, serve as markers for ongoing exposure risk, and amplify or propagate a bioterrorism outbreak. We found evidence that, for certain bioterrorism agents, pets, wildlife, or livestock could provide early warning and that for other agents, humans would likely manifest symptoms before illness could be detected in animals. After an acute attack, active surveillance of wild or domestic animal populations could help identify many ongoing exposure risks. If certain bioterrorism agents found their way into animal populations, they could spread widely through animal-to-animal transmission and prove difficult to control. The public health infrastructure must look beyond passive surveillance of acute animal disease events to build capacity for active surveillance and intervention efforts to detect and control ongoing outbreaks of disease in domestic and wild animal populations.

  • Economic Impact of Lyme Disease PDF Version [PDF - 326 KB - 8 pages]
    X. Zhang et al.
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    Since 1975, Lyme disease has become the most common vectorborne inflammatory disease in the United States.

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    To assess the economic impact of Lyme disease (LD), the most common vectorborne inflammatory disease in the United States, cost data were collected in 5 counties of the Maryland Eastern Shore from 1997 to 2000. Patients were divided into 5 diagnosis groups, clinically defined early-stage LD, clinically defined late-stage LD, suspected LD, tick bite, and other related complaints. From 1997 to 2000, the mean per patient direct medical cost of early-stage LD decreased from $1,609 to $464 (p<0.05), and the mean per patient direct medical cost of late-stage LD decreased from $4,240 to $1,380 (p<0.05). The expected median of all costs (direct medical cost, indirect medical cost, nonmedical cost, and productivity loss), aggregated across all diagnosis groups of patients, was ≈$281 per patient. These findings will help assess the economics of current and future prevention and control efforts.

  • 1951 Influenza Epidemic, England and Wales, Canada, and the United States PDF Version [PDF - 605 KB - 8 pages]
    C. Viboud et al.
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    Death rates were substantially higher for England and Canada than for the United States.

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    Influenza poses a continuing public health threat in epidemic and pandemic seasons. The 1951 influenza epidemic (A/H1N1) caused an unusually high death toll in England; in particular, weekly deaths in Liverpool even surpassed those of the 1918 pandemic. We further quantified the death rate of the 1951 epidemic in 3 countries. In England and Canada, we found that excess death rates from pneumonia and influenza and all causes were substantially higher for the 1951 epidemic than for the 1957 and 1968 pandemics (by >50%). The age-specific pattern of deaths in 1951 was consistent with that of other interpandemic seasons; no age shift to younger age groups, reminiscent of pandemics, occurred in the death rate. In contrast to England and Canada, the 1951 epidemic was not particularly severe in the United States. Why this epidemic was so severe in some areas but not others remains unknown and highlights major gaps in our understanding of interpandemic influenza.



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