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Volume 7, Number 3—June 2001

Volume 7, Number 3—June 2001   PDF Version [PDF - 2.42 MB - 129 pages]

Perspective

  • Seasonal Variation in Host Susceptibility and Cycles of Certain Infectious Diseases PDF Version [PDF - 69 KB - 6 pages]
    S. F. Dowell
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    Seasonal cycles of infectious diseases have been variously attributed to changes in atmospheric conditions, the prevalence or virulence of the pathogen, or the behavior of the host. Some observations about seasonality are difficult to reconcile with these explanations. These include the simultaneous appearance of outbreaks across widespread geographic regions of the same latitude; the detection of pathogens in the off-season without epidemic spread; and the consistency of seasonal changes, despite wide variations in weather and human behavior. In contrast, an increase in susceptibility of the host population, perhaps linked to the annual light/dark cycle and mediated by the pattern of melatonin secretion, might account for many heretofore unexplained features of infectious disease seasonality. Ample evidence indicates that photoperiod-driven physiologic changes are typical in mammalian species, including some in humans. If such physiologic changes underlie human resistance to infectious diseases for large portions of the year and the changes can be identified and modified, the therapeutic and preventive implications may be considerable.

Synopses

  • Cryptococcus neoformans Infection in Organ Transplant Recipients: Variables Influencing Clinical Characteristics and Outcome PDF Version [PDF - 69 KB - 7 pages]
    S. Husain et al.
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    Unique clinical characteristics and other variables influencing the outcome of Cryptococcus neoformans infection in organ transplant recipients have not been well defined. From a review of published reports, we found that C. neoformans infection was documented in 2.8% of organ transplant recipients (overall death rate 42%). The type of primary immunosuppressive agent used in transplantation influenced the predominant clinical manifestation of cryptococcosis. Patients receiving tacrolimus were significantly less likely to have central nervous system involvement (78% versus 11%, p =0.001) and more likely to have skin, soft-tissue, and osteoarticular involvement (66% versus 21%, p = 0.006) than patients receiving nontacrolimus-based immunosuppression. Renal failure at admission was the only independently significant predictor of death in these patients (odds ratio 16.4, 95% CI 1.9 - 143, p = 0.004). Hypotheses based on these data may elucidate the pathogenesis and may ultimately guide the management of C. neoformans infection in organ transplant recipients.

  • PulseNet: The Molecular Subtyping Network for Foodborne Bacterial Disease Surveillance, United States PDF Version [PDF - 129 KB - 8 pages]
    B. Swaminathan et al.
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    PulseNet, the national molecular subtyping network for foodborne disease surveillance, was established by the Centers for Disease Control and Prevention and several state health department laboratories to facilitate subtyping bacterial foodborne pathogens for epidemiologic purposes. PulseNet, which began in 1996 with 10 laboratories typing a single pathogen (Escherichia coli O157:H7), now includes 46 state and 2 local public health laboratories and the food safety laboratories of the U.S. Food and Drug Administration and the U.S. Department of Agriculture. Four foodborne pathogens (E. coli O157:H7; nontyphoidal Salmonella serotypes, Listeria monocytogenes and Shigella) are being subtyped, and other

  • Spoligotype Database of Mycobacterium tuberculosis: Biogeographic Distribution of Shared Types and Epidemiologic and Phylogenetic Perspectives PDF Version [PDF - 102 KB - 7 pages]
    C. Sola et al.
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    We give an update on the worldwide spoligotype database, which now contains 3,319 spoligotype patterns of Mycobacterium tuberculosis in 47 countries, with 259 shared types, i.e., identical spoligotypes shared by two or more patient isolates. The 259 shared types contained a total of 2,779 (84%) of all the isolates. Seven major genetic groups represented 37% of all clustered isolates. Two types (119 and 137) were found almost exclusively in the USA and accounted for 9% of clustered isolates. The remaining 1,517 isolates were scattered into 252 different spoligotypes. This database constitutes a tool for pattern comparison of M. tuberculosis clinical isolates for global epidemiologic studies and phylogenetic purposes.

Research

  • Transmission of an Arenavirus in White-Throated Woodrats (Neotoma albigula), Southeastern Colorado, 1995-1999 PDF Version [PDF - 74 KB - 6 pages]
    C. H. Calisher et al.
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    From 1995 to 1999, we conducted longitudinal studies of white-throated woodrats (Neotoma albigula) in southeastern Colorado. Forty-five (42.9%) of 105 female and 15 (26.8%) of 56 male N. albigula had antibodies against Whitewater Arroyo virus (WWAV). Sixteen female and three male N. albigula seroconverted during the study period, most of them during July-November, when population densities are highest. Analyses of longevity data, minimum numbers alive and infected, movements, and weight data suggest that the dominant mode of WWAV transmission among white-throated woodrats in Colorado is direct contact. WWAV was recently reported to cause fatal infection in humans. Our findings will lead to better assessment of the public health threat posed by infected woodrats and may be useful in predicting periods of increased risk for human infection.

  • Geographic Distribution and Genetic Diversity of Whitewater Arroyo Virus in the Southwestern United States PDF Version [PDF - 86 KB - 5 pages]
    C. F. Fulhorst et al.
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    The purpose of this study was to extend our knowledge of the geographic distribution and genetic diversity of the arenavirus(es) associated with Neotoma species (woodrats) in the southwestern United States. Infectious arenavirus was recovered from 14 (3.3%) of 425 woodrats. The virus-positive species included N. albigula in New Mexico and Oklahoma, N. cinerea in Utah, N. mexicana in New Mexico and Utah, and N. micropus in Texas. Analyses of viral nucleocapsid protein gene sequence data indicated that all the isolates were strains of Whitewater Arroyo virus, an arenavirus previously known only from northwestern New Mexico. Analyses of the sequence data also indicated that there can be substantial genetic diversity among strains of Whitewater Arroyo virus from conspecific woodrats collected from different localities and substantial genetic diversity among strains from different woodrat species collected from the same locality.

  • Is High Prevalence of Echinococcus multilocularis in Wild and Domestic Animals Associated with Disease Incidence in Humans? PDF Version [PDF - 159 KB - 5 pages]
    B. Gottstein et al.
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    We investigated a focus of highly endemic Echinococcus multilocularis infection to assess persistence of high endemicity in rural rodents, explore potential for parasite transmission to domestic carnivores, and assess (serologically) putative exposure versus infection frequency in inhabitants of the region. From spring 1993 to spring 1998, the prevalence of E. multilocularis in rodents was 9% to 39% for Arvicola terrestris and 10% to 21% for Microtus arvalis. From June 1996 to October 1997, 6 (7%) of 86 feral dogs and 1 of 33 cats living close to the region tested positive for intestinal E. multilocularis infection. Testing included egg detection by coproscopy, antigen detection by enzyme-linked immunosorbent assay (ELISA), and specific parasite DNA amplification by polymerase chain reaction. Thus, the presence of infected domestic carnivores can increase E. multilocularis exposure risk in humans. A seroepidemiologic survey of 2,943 blood donors in the area used specific Em2-ELISA. Comparative statistical analyses of seroprevalence and clinical incidence showed an increase in Em2-seroprevalence from 1986 and 1996-97 but no increase in clinical incidence of alveolar hydatid disease.

  • Goat-Associated Q Fever: A New Disease in Newfoundland PDF Version [PDF - 151 KB - 7 pages]
    T. F. Hatchette et al.
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    In the spring of 1999 in rural Newfoundland, abortions in goats were associated with illness in goat workers. An epidemiologic investigation and a serologic survey were conducted in April 1999 to determine the number of infections, nature of illness, and risk factors for infection. Thirty seven percent of the outbreak cohort had antibody titers to phase II Coxiella burnetii antigen >1:64, suggesting recent infection. The predominant clinical manifestation of Q fever was an acute febrile illness. Independent risk factors for infection included contact with goat placenta, smoking tobacco, and eating cheese made from pasteurized goat milk. This outbreak raises questions about management of such outbreaks, interprovincial sale and movement of domestic ungulates, and the need for discussion between public health practitioners and the dairy industry on control of this highly infectious organism.

  • Molecular Epidemiology of Serogroup A Meningitis in Moscow, 1969 to 1997 PDF Version [PDF - 130 KB - 8 pages]
    M. Achtman et al.
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    Molecular analysis of 103 serogroup A Neisseria meningitidis strains isolated in Moscow from 1969 to 1997 showed that four independent clonal groupings were responsible for successive waves of meningococcal disease. An epidemic from 1969 to the mid-1970s was caused by genocloud 2 of subgroup III, possibly imported from China. Subsequent endemic disease through the early 1990s was caused by subgroup X and then by subgroup VI, which has also caused endemic disease elsewhere in Eastern Europe. A 1996 epidemic was part of the pandemic spread from Asia of genocloud 8 of subgroup III. Recent genocloud 8 epidemic disease in Moscow may represent an early warning for spread of these bacteria to other countries in Europe.

  • Melioidosis: An Emerging Infection in Taiwan? PDF Version [PDF - 122 KB - 6 pages]
    P. Hsueh et al.
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    From January 1982 to May 2000, 17 infections caused by Burkholderia pseudomallei were diagnosed in 15 patients in Taiwan; almost all the infections were diagnosed from 1994 to May 2000. Of the 15 patients, 9 (60%) had underlying diseases, and 10 (67%) had bacteremic pneumonia. Thirteen (76%) episodes of infection were considered indigenous. Four patients died of melioidosis. Seventeen B. pseudomallei isolates, recovered from eight patients from November 1996 to May 2000, were analyzed to determine their in vitro susceptibilities to 14 antimicrobial agents, cellular fatty acid and biochemical reaction profiles, and randomly amplified polymorphic DNA patterns. Eight strains (highly related isolates) were identified. All isolates were arabinose non-assimilators and were susceptible to amoxicillin-clavulanate, piperacillin-tazobactam, imipenem, and meropenem. No spread of the strain was documented.

  • Outbreak of Human Monkeypox, Democratic Republic of Congo, 1996 to 1997 PDF Version [PDF - 65 KB - 5 pages]
    Y. Hutin et al.
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    Human monkeypox is a zoonotic smallpox-like disease caused by an orthopoxvirus of interhuman transmissibility too low to sustain spread in susceptible populations. In February 1997, 88 cases of febrile pustular rash were identified for the previous 12 months in 12 villages of the Katako-Kombe Health Zone, Democratic Republic of Congo (attack rate = 22 per 1,000, case-fatality rate = 3.7%). Seven were active cases confirmed by virus isolation. Orthopoxvirus-neutralizing antibodies were detected in 54% of 72 patients who provided serum and 25% of 59 wild-caught animals, mainly squirrels. Hemagglutination-inhibition assays and Western blotting detected antibodies in 68% and 73% of patients, respectively. Vaccinia vaccination, which protects against monkeypox, ceased by 1983 after global smallpox eradication, leading to an increase in the proportion of susceptible people.

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