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Volume 6, Number 2—April 2000

Volume 6, Number 2—April 2000   PDF Version [PDF - 2.55 MB - 125 pages]

Perspective

  • Rumors of Disease in the Global Village: Outbreak Verification PDF Version [PDF - 280 KB - 6 pages]
    T. W. Grein et al.
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    Emerging infectious diseases and the growth of information technology have produced new demands and possibilities for disease surveillance and response. Increasing numbers of outbreak reports must be assessed rapidly so that control efforts can be initiated and unsubstantiated reports can be identified to protect countries from unnecessary economic damage. The World Health Organization has set up a process for timely outbreak verification to convert large amounts of data into accurate information for suitable action. We describe the context and processes of outbreak verification and information dissemination.

  • Malaria on the Move: Human Population Movement and Malaria Transmission PDF Version [PDF - 227 KB - 7 pages]
    P. Martens and L. Hall
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    Reports of malaria are increasing in many countries and in areas thought free of the disease. One of the factors contributing to the reemergence of malaria is human migration. People move for a number of reasons, including environmental deterioration, economic necessity, conflicts, and natural disasters. These factors are most likely to affect the poor, many of whom live in or near malarious areas. Identifying and understanding the influence of these population movements can improve prevention measures and malaria control programs.

Synopses

  • The bdr Gene Families of the Lyme Disease and Relapsing Fever Spirochetes: Potential Influence on Biology, Pathogenesis, and Evolution PDF Version [PDF - 880 KB - 14 pages]
    D. M. Roberts et al.
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    Species of the genus Borrelia cause human and animal infections, including Lyme disease, relapsing fever, and epizootic bovine abortion. The borrelial genome is unique among bacterial genomes in that it is composed of a linear chromosome and a series of linear and circular plasmids. The plasmids exhibit significant genetic redundancy and carry 175 paralogous gene families, most of of unknown function. Homologous alleles on different plasmids could influence the organization and evolution of the Borrelia genome by serving as foci for interplasmid homologous recombination. The plasmid-carried Borrelia direct repeat (bdr) gene family encodes polymorphic, acidic proteins with putative phosphorylation sites and transmembrane domains. These proteins may play regulatory roles in Borrelia. We describe recent progress in the characterization of the Borrelia bdr genes and discuss the possible influence of this gene family on the biology, pathogenesis, and evolution of the Borrelia genome.

  • Vaccines for Mucosal Immunity to Combat Emerging Infectious Diseases PDF Version [PDF - 223 KB - 10 pages]
    F. W. van Ginkel et al.
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    The mucosal immune system consists of molecules, cells, and organized lymphoid structures intended to provide immunity to pathogens that impinge upon mucosal surfaces. Mucosal infection by intracellular pathogens results in the induction of cell-mediated immunity, as manifested by CD4-positive (CD4+) T helper-type 1 cells, as well as CD8+ cytotoxic T-lymphocytes. These responses are normally accompanied by the synthesis of secretory immunoglobulin A (S-IgA) antibodies, which provide an important first line of defense against invasion of deeper tissues by these pathogens. New-generation live, attenuated viral vaccines, such as the cold-adapted, recombinant nasal influenza and oral rotavirus vaccines, optimize this form of mucosal immune protection. Despite these advances, new and reemerging infectious diseases are tipping the balance in favor of the parasite; continued mucosal vaccine development will be needed to effectively combat these new threats.

Research

  • Competence of American Robins as Reservoir Hosts for Lyme Disease Spirochetes PDF Version [PDF - 244 KB - 6 pages]
    D. Richter et al.
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    To explore the competence of American robins as a reservoir for Lyme disease spirochetes, we determined the susceptibility of these birds to tickborne spirochetes and their subsequent infectivity for larval vector ticks. Robins acquired infection and became infectious to almost all xenodiagnostic ticks soon after exposure to infected nymphal ticks. Although infectivity waned after 2 months, the robins remained susceptible to reinfection, became infectious again, and permitted repeated feeding by vector ticks. In addition, spirochetes passaged through birds retained infectivity for mammalian hosts. American robins become as infectious for vector ticks as do reservoir mice, but infectivity in robins wanes more rapidly.

  • Vibrio cholerae O139 in Calcutta, 1992-1998: Incidence, Antibiograms, and Genotypes PDF Version [PDF - 367 KB - 9 pages]
    A. Basu et al.
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    We report results of surveillance for cholera caused by Vibrio cholerae O139 from September 1992, when it was first identified, to December 1998. V. cholerae O139 dominated as the causative agent of cholera in Calcutta during 1992-93 and 1996-97, while the O1 strains dominated during the rest of the period. Dramatic shifts in patterns of resistance to cotrimoxazole, neomycin, and streptomycin were observed. Molecular epidemiologic studies showed clonal diversity among the O139 strains and continuous emergence of new epidemic clones, reflected by changes in the structure, organization, and location of the CTX prophages in the V. cholerae O139 chromosome.

  • Multivariate Markovian Modeling of Tuberculosis: Forecast for the United States PDF Version [PDF - 286 KB - 10 pages]
    S. M. Debanne et al.
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    We have developed a computer-implemented, multivariate Markov chain model to project tuberculosis (TB) incidence in the United States from 1980 to 2010 in disaggregated demographic groups. Uncertainty in model parameters and in the projections is represented by fuzzy numbers. Projections are made under the assumption that current TB control measures will remain unchanged for the projection period. The projections of the model demonstrate an intermediate increase in national TB incidence (similar to that which actually occurred) followed by continuing decline. The rate of decline depends strongly on geographic, racial, and ethnic characteristics. The model predicts that the rate of decline in the number of cases among Hispanics will be slower than among white non-Hispanics and black non-Hispanics--a prediction supported by the most recent data.

  • Serologic Response to Culture Filtrate Antigens of Mycobacterium ulcerans during Buruli Ulcer Disease PDF Version [PDF - 286 KB - 7 pages]
    K. M. Dobos et al.
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    Buruli ulcer (BU) is an emerging necrotic skin disease caused by Mycobacterium ulcerans. To assess the potential for a serodiagnostic test, we measured the humoral immune response of BU patients to M. ulcerans antigens and compared this response with delayed-type hypersensitivity responses to both Burulin and PPD. The delayed-type hypersensitivity response generally supported the diagnosis of BU, with overall reactivity to Burulin in 28 (71.8%) of 39 patients tested, compared with 3 (14%) of 21 healthy controls. However, this positive skin test response was observed primarily in patients with healed or active disease, and rarely in patients with early disease (p=0.009). When tested for a serologic response to M. ulcerans culture filtrate, 43 (70.5%) of 61 BU patients had antibodies to these antigens, compared with 10 (37.0%) of 27 controls and 4 (30.8%) of 13 tuberculosis patients. There was no correlation between disease stage and the onset of this serum antibody response. Our findings suggest that serologic testing may be useful in the diagnosis and surveillance of BU.

  • Haemophilus influenzae Type B and Streptococcus pneumoniae as Causes of Pneumonia among Children in Beijing, China PDF Version [PDF - 211 KB - 6 pages]
    O. S. Levine et al.
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    To determine if Haemophilus influenzae type b (Hib) and S. pneumoniae could be identified more often from the nasopharynx of patients with pneumonia than from control patients, we obtained nasopharyngeal swab specimens from 96 patients with chest x-ray-confirmed pneumonia and 214 age-matched control patients with diarrhea or dermatitis from the outpatient department at Beijing Children's Hospital. Pneumonia patients were more likely to be colonized with Hib and S. pneumoniae than control patients, even after the data were adjusted for possible confounding factors such as day-care attendance, the presence of other children in the household, and recent antibiotic use. In China, where blood cultures from pneumonia patients are rarely positive, the results of these nasopharyngeal cultures provide supporting evidence for the role of Hib and S. pneumoniae as causes of childhood pneumonia.

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