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Volume 12, Number 12—December 2006

Volume 12, Number 12—December 2006   PDF Version [PDF - 11.15 MB - 203 pages]

Perspective

  • International Attention for Zoonotic Infections PDF Version [PDF - 187 KB - 3 pages]
    N. Marano et al.
  • On the Question of Sporadic or Atypical Bovine Spongiform Encephalopathy and Creutzfeldt-Jakob Disease PDF Version [PDF - 177 KB - 6 pages]
    P. Brown et al.
    View Summary

    Atypical BSE is probably not sporadic and not related to sporadic Creutzfeldt-Jakob disease.

       View Abstract

    Strategies to investigate the possible existence of sporadic bovine spongiform encephalopathy (BSE) require systematic testing programs to identify cases in countries considered to have little or no risk of orally acquired disease or to detect a stable occurrence of atypical cases in countries in which orally acquired disease is disappearing. To achieve 95% statistical confidence that the prevalence for sporadic BSE is no greater than 1 per million (i.e., the annual incidence of sporadic Creutzfeldt-Jakob disease [CJD] in humans) would require negative tests in 3 million randomly selected older cattle. A link between BSE and sporadic CJD has been suggested on the basis of laboratory studies but is unsupported by epidemiologic observation. Such a link might yet be established by the discovery of a specific molecular marker or of particular combinations of trends over time of typical and atypical BSE and various subtypes of sporadic CJD, as their numbers are influenced by a continuation of current public health measures that exclude high-risk bovine tissues from the animal and human food chains.

  • Ecologic Niche Modeling and Spatial Patterns of Disease Transmission PDF Version [PDF - 187 KB - 5 pages]
    A. T. Peterson
    View Summary

    This technique can be used to study the geography and ecology of disease transmission.

       View Abstract

    Ecologic niche modeling (ENM) is a growing field with many potential applications to questions regarding the geography and ecology of disease transmission. Specifically, ENM has the potential to inform investigations concerned with the geography, or potential geography, of vectors, hosts, pathogens, or human cases, and it can achieve fine spatial resolution without the loss of information inherent in many other techniques. Potential applications and current frontiers and challenges are reviewed.

  • Qualitative Assessment of Risk for Monkeypox Associated with Domestic Trade in Certain Animal Species, United States
    S. M. Bernard and S. A. Anderson
    View Summary

    The probability of further human infection is low and the risk is further mitigated by rodent import restrictions.

       View Abstract

    In 2003, US officials identified several human monkeypox cases and traced the virus exposure to infected captive prairie dogs. The virus was likely introduced through a shipment of imported African rodents, which were kept with other mammals, including prairie dogs, in a pet distribution facility in the Midwest. To prevent the further introduction and spread of the virus, federal agencies restricted the importation of African rodents and restricted the domestic trade or movement of prairie dogs and certain other rodents. In this qualitative assessment of the risk for monkeypox associated with the 2003 outbreak, we conclude that the probability of further human infection is low; the risk is further mitigated by rodent import restrictions. Were this zoonotic disease to become established domestically, the public health effects could be substantial.

Synopses

  • Review of Bats and SARS PDF Version [PDF - 159 KB - 7 pages]
    L. Wang et al.
    View Summary

    The discovery of SARS-like coronaviruses in horseshoe bats highlights the possibility of future outbreaks caused by different coronaviruses of bat origin.

       View Abstract

    Bats have been identified as a natural reservoir for an increasing number of emerging zoonotic viruses, including henipaviruses and variants of rabies viruses. Recently, we and another group independently identified several horseshoe bat species (genus Rhinolophus) as the reservoir host for a large number of viruses that have a close genetic relationship with the coronavirus associated with severe acute respiratory syndrome (SARS). Our current research focused on the identification of the reservoir species for the progenitor virus of the SARS coronaviruses responsible for outbreaks during 2002–2003 and 2003–2004. In addition to SARS-like coronaviruses, many other novel bat coronaviruses, which belong to groups 1 and 2 of the 3 existing coronavirus groups, have been detected by PCR. The discovery of bat SARS-like coronaviruses and the great genetic diversity of coronaviruses in bats have shed new light on the origin and transmission of SARS coronaviruses.

Research

  • Risk Factors for Human Infection with Avian Influenza A H5N1, Vietnam, 2004 PDF Version [PDF - 170 KB - 7 pages]
    P. N. Dinh et al.
    View Summary

    Risk factors include direct or household contact with sick or dead poultry and absence of an indoor water source.

       View Abstract

    To evaluate risk factors for human infection with influenza A subtype H5N1, we performed a matched case-control study in Vietnam. We enrolled 28 case-patients who had laboratory-confirmed H5N1 infection during 2004 and 106 age-, sex-, and location-matched control-respondents. Data were analyzed by matched-pair analysis and multivariate conditional logistic regression. Factors that were independently associated with H5N1 infection were preparing sick or dead poultry for consumption <7 days before illness onset (matched odds ratio [OR] 8.99, 95% confidence interval [CI] 0.98–81.99, p = 0.05), having sick or dead poultry in the household <7 days before illness onset (matched OR 4.94, 95% CI 1.21–20.20, p = 0.03), and lack of an indoor water source (matched OR 6.46, 95% CI 1.20–34.81, p = 0.03). Factors not significantly associated with infection were raising healthy poultry, preparing healthy poultry for consumption, and exposure to persons with an acute respiratory illness.

  • Salmonella Enteritidis in Broiler Chickens, United States, 2000–2005 PDF Version [PDF - 198 KB - 5 pages]
    S. F. Altekruse et al.
    View Summary

    Greater sampling and monitoring efforts are needed to reverse a significant increase in prevalence.

       View Abstract

    US Department of Agriculture Food Safety and Inspection Service (FSIS) data on Salmonella enterica serotype Enteritidis in broiler chicken carcass rinses collected from 2000 through 2005 showed the annual number of isolates increased >4-fold and the proportion of establishments with Salmonella Enteritidis–positive rinses increased nearly 3-fold (test for trend, p<0.0001). The number of states with Salmonella Enteritidis in broiler rinses increased from 14 to 24. The predominant phage types (PT) were PT 13 and PT 8, 2 strains that a recent Foodborne Diseases Active Surveillance Network (FoodNet) case-control study associated with eating chicken. FSIS is directing more sampling resources toward plants with marginal Salmonella control to reduce prevalence in products including broilers. The policy targets establishments with common Salmonella serotypes of human illness, including Salmonella Enteritidis. Voluntary interventions should be implemented by industry.

  • Human Metapneumovirus in Turkey Poults PDF Version [PDF - 423 KB - 7 pages]
    B. T. Velayudhan et al.
    View Summary

    Human metapneumovirus causes clinical signs in turkey poults.

       View Abstract

    This study was conducted to reexamine the hypothesis that human metapneumovirus (hMPV) will not infect turkeys. Six groups of 2-week-old turkeys (20 per group) were inoculated oculonasally with 1 of the following: noninfected cell suspension; hMPV genotype A1, A2, B1, or B2; or avian metapneumovirus (aMPV) subtype C. Poults inoculated with hMPV showed nasal discharge days 4–9 postexposure. Specific viral RNA and antigen were detected by reverse-transcription PCR and immunohistochemical evaluation, respectively, in nasal turbinates of birds exposed to hMPV. Nasal turbinates of hMPV-infected turkeys showed inflammatory changes and mucus accumulation. Each of the 4 hMPV genotypes caused a transient infection in turkeys as evidenced by clinical signs, detection of hMPV in turbinates, and histopathologic examination. Detailed investigation of cross-species pathogenicity of hMPV and aMPV and its importance for human and animal health is needed.

  • Distinct Transmission Cycles of Leishmania tropica in 2 Adjacent Foci, Northern Israel PDF Version [PDF - 472 KB - 9 pages]
    M. Svobodova et al.
    View Summary

    Infection with Leishmania tropica is emerging because of encroachment of rock hyraxes and transmission by multiple vector species.

       View Abstract

    Transmission of Leishmania tropica was studied in 2 adjacent foci in Israel where vector populations differ. Only Phlebotomus sergenti was found infected with L. tropica in the southern focus; P. arabicus was the main vector in the northern focus. Rock hyraxes (Procavia capensis) were incriminated as reservoir hosts in both foci. L. tropica strains from the northern focus isolated from sand flies, cutaneous leishmaniasis cases, and rock hyraxes were antigenically similar to L. major, and strains from the southern focus were typically L. tropica. Laboratory studies showed that P. arabicus is a competent vector of L. tropica, and P. sergenti is essentially refractory to L. tropica from the northern focus. Susceptibility of P. arabicus may be mediated by O glycoproteins on the luminal surface of its midgut. The 2 foci differ with respect to parasites and vectors, but increasing peridomestic rock hyrax populations are probably responsible for emergence of cutaneous leishmaniasis in both foci.

  • Bartonella quintana Endocarditis in Dogs PDF Version [PDF - 105 KB - 4 pages]
    P. Kelly et al.
    View Summary

    PCR and sequencing provide the first evidence that B. quintana can be pathogenic in dogs.

       View Abstract

    We provide the first evidence that Bartonella quintana can infect dogs and cause typical signs of endocarditis. Using PCR and sequencing, we identified B. quintana in the blood of a dog from the United States with aortic valve endocarditis and probably also in the mitral valve of a dog from New Zealand with endocarditis.

  • Serologic Evidence of Widespread Everglades Virus Activity in Dogs, Florida PDF Version [PDF - 259 KB - 7 pages]
    L. L. Coffey et al.
    View Summary

    A serosurvey showed that this virus is widespread in dogs.

       View Abstract

    Everglades virus (EVEV), an alphavirus in the Venezuelan equine encephalitis complex, circulates among rodents and vector mosquitoes in Florida and occasionally infects humans. It causes febrile disease, sometimes accompanied by neurologic manifestations. Although previous surveys showed high seroprevalence in humans, EVEV infections may be underdiagnosed because the disease is not severe enough to warrant a clinic visit or the undifferentiated presentations complicate diagnosis. Documented EVEV activity, as recent as 1993, was limited to south Florida. Using dogs as sentinels, a serosurvey was conducted to evaluate whether EVEV circulated recently in Florida and whether EVEV's spatial distribution parallels that of the mosquito vector, Culex cedecei. Four percent of dog sera contained neutralizing EVEV antibodies, and many seropositive animals lived farther north than both recorded EVEV activity and the principal vector. These results indicate that EVEV is widespread in Florida and may be an important, unrecognized cause of human illness.

  • Influenza, Campylobacter and Mycoplasma Infections, and Hospital Admissions for Guillain-Barré Syndrome, England
    C. C. Tam et al.
    View Summary

    Campylobacter, Mycoplasma pneumoniae, and influenza (or influenza vaccination) act as infectious triggers for Guillain-Barré syndrome.

       View Abstract

    Guillain-Barré syndrome (GBS) is the most common cause of acute flaccid paralysis in polio-free regions. Considerable evidence links Campylobacter infection with GBS, but evidence that implicates other pathogens as triggers remains scarce. We conducted a time-series analysis to investigate short-term correlations between weekly laboratory-confirmed reports of putative triggering pathogens and weekly hospitalizations for GBS in England from 1993 through 2002. We found a positive association between the numbers of reports of laboratory-confirmed influenza A in any given week and GBS hospitalizations in the same week. Different pathogens may trigger GBS in persons of different ages; among those <35 years, numbers of weekly GBS hospitalizations were associated with weekly Campylobacter and Mycoplasma pneumoniae reports, whereas among those >35 years, positive associations were with influenza. Further studies should estimate the relative contribution of different pathogens to GBS incidence, overall and by age group, and determine whether influenza is a real trigger for GBS or a marker for influenza vaccination.

  • Foodborne Transmission of Nipah Virus, Bangladesh PDF Version [PDF - 191 KB - 7 pages]
    S. P. Luby et al.
    View Summary

    Nipah virus was likely transmitted from fruit bats to humans by drinking fresh date palm sap.

       View Abstract

    We investigated an outbreak of encephalitis in Tangail District, Bangladesh. We defined case-patients as persons from the outbreak area in whom fever developed with new onset of seizures or altered mental status from December 15, 2004, through January 31, 2005. Twelve persons met the definition; 11 (92%) died. Serum specimens were available from 3; 2 had immunoglobulin M antibodies against Nipah virus by capture enzyme immunoassay. We enrolled 11 case-patients and 33 neighborhood controls in a case-control study. The only exposure significantly associated with illness was drinking raw date palm sap (64% among case-patients vs. 18% among controls, odds ratio [OR] 7.9, p = 0.01). Fruit bats (Pteropus giganteus) are a nuisance to date palm sap collectors because the bats drink from the clay pots used to collect the sap at night. This investigation suggests that Nipah virus was transmitted from P. giganteus to persons through drinking fresh date palm sap.

  • Borrelia lusitaniae and Green Lizards (Lacerta viridis), Karst Region, Slovakia PDF Version [PDF - 142 KB - 7 pages]
    V. Majláthová et al.
    View Summary

    The green lizard is implicated in the transmission cycle of B. lusitaniae.

       View Abstract

    In Europe, spirochetes within the Borrelia burgdorferi sensu lato complex are transmitted by Ixodes ricinus ticks. Specific associations are described between reservoir hosts and individual genospecies. We focused on green lizard (Lacerta viridis) as a host for ticks and potential host for borreliae. In 2004 and 2005, a total of 146 green lizards infested by ticks were captured, and 469 I. ricinus ticks were removed. Borrelial infection was detected in 16.6% of ticks from lizards. Of 102 skin biopsy specimens collected from lizards, 18.6% tested positive. The most frequently detected genospecies was B. lusitaniae (77.9%–94.7%). More than 19% of questing I. ricinus collected in areas where lizards were sampled tested positive for borreliae. B. garinii was the dominant species, and B. lusitaniae represented 11.1%. The presence of B. lusitaniae in skin biopsy specimens and in ticks that had fed on green lizards implicates this species in the transmission cycle of B. lusitaniae.

  • Transmission of Human and Macaque Plasmodium spp. to Ex-Captive Orangutans in Kalimantan, Indonesia PDF Version [PDF - 165 KB - 7 pages]
    M. J. Reid et al.
    View Summary

    We identified 4 discrete Plasmodium spp. sequences from the blood of orangutans, including 1 of P. vivax, which has implications for human residents and orangutan rehabilitation programs.

       View Abstract

    Data are lacking on the specific diseases to which great apes are susceptible and the transmission dynamics and overall impact of these diseases. We examined the prevalence of Plasmodium spp. infections in semicaptive orangutans housed at the Orangutan Care Center and Quarantine, Central Kalimantan, Indonesia, by using a combination of microscopic and DNA molecular techniques to identify the Plasmodium spp. in each animal. Previous studies indicated 2 orangutan-specific Plasmodium spp., but our data show 4 Plasmodium spp. These findings provide evidence for P. vivax transmission between humans and orangutans and for P. cynomolgi transmission between macaques and orangutans. These data have potential implications for the conservation of orangutans and also for the bidirectional transmission of parasites between orangutans and humans visiting or living in the region.

  • Borrelia garinii in Seabird Ticks (Ixodes uriae), Atlantic Coast, North America PDF Version [PDF - 152 KB - 4 pages]
    R. P. Smith et al.
    View Summary

    The primary agent of neurotropic Lyme disease in Eurasia was found in seabird ticks in northeastern North America.

       View Abstract

    Borrelia garinii is the most neurotropic of the genospecies of B. burgdorferi sensu lato that cause Lyme disease in Europe, where it is transmitted to avian and mammalian reservoir hosts and to humans by Ixodes ricinus. B. garinii is also maintained in an enzootic cycle in seabirds by I. uriae, a tick found at high latitudes in both the Northern and Southern Hemispheres. To determine whether B. garinii is present in seabird ticks on the Atlantic Coast of North America, we examined 261 I. uriae ticks by polyclonal antiborrelial fluorescent antibody. Ten of 61 ticks from Gull Island, Newfoundland, were positive for borreliae by this screen. Amplicons of DNA obtained by PCR that targeted the B. garinii rrs-rrla intergenic spacer were sequenced and matched to GenBank sequences for B. garinii. The potential for introduction of this agent into the North American Lyme disease enzootic is unknown.

  • Isolation of Lagos Bat Virus from Water Mongoose PDF Version [PDF - 310 KB - 6 pages]
    W. Markotter et al.
    View Summary

    Lagos bat virus from water mongoose showed strong sequence homology with other Lagos bat virus isolates from South Africa.

       View Abstract

    A genotype 2 lyssavirus, Lagos bat virus (LBV), was isolated from a terrestrial wildlife species (water mongoose) in August 2004 in the Durban area of the KwaZulu-Natal Province of South Africa. The virus isolate was confirmed as LBV by antigenic and genetic characterization, and the mongoose was identified as Atilax paludinosus by mitochondrial cytochrome b sequence analysis. Phylogenetic analysis demonstrated sequence homology with previous LBV isolates from South African bats. Studies performed in mice indicated that the peripheral pathogenicity of LBV had been underestimated in previous studies. Surveillance strategies for LBV in Africa must be improved to better understand the epidemiology of this virus and to make informed decisions on future vaccine strategies because evidence is insufficent that current rabies vaccines provide protection against LBV.

  • Modulatory Effect of Cattle on Risk for Lyme Disease PDF Version [PDF - 166 KB - 5 pages]
    D. Richter and F. Matuschka
    View Summary

    Low-intensity cattle grazing limits Borrelia burgdorferi s.l., but not B. miyamotoi, in vector ticks.

       View Abstract

    To determine the effect of cattle on the risk for Lyme disease, we compared the prevalence of spirochete infection in questing vector ticks collected from a pasture with low-intensity cattle grazing with the prevalence in those collected from a site on which no cattle grazed. The presence of cattle limited the prevalence of Borrelia burgdorferi s.l., but not B. miyamotoi, in vector ticks. The reintroduction of traditional, nonintensive agriculture in central Europe may help reduce risk for Lyme disease.

  • Long-term Psychological and Occupational Effects of Providing Hospital Healthcare during SARS Outbreak PDF Version [PDF - 203 KB - 9 pages]
    R. G. Maunder et al.
    View Summary

    Healthcare workers in hospitals affected by SARS experience increased psychological stress 1–2 years after the outbreak.

       View Abstract

    Healthcare workers (HCWs) found the 2003 outbreak of severe acute respiratory syndrome (SARS) to be stressful, but the long-term impact is not known. From 13 to 26 months after the SARS outbreak, 769 HCWs at 9 Toronto hospitals that treated SARS patients and 4 Hamilton hospitals that did not treat SARS patients completed a survey of several adverse outcomes. Toronto HCWs reported significantly higher levels of burnout (p = 0.019), psychological distress (p<0.001), and posttraumatic stress (p<0.001). Toronto workers were more likely to have reduced patient contact and work hours and to report behavioral consequences of stress. Variance in adverse outcomes was explained by a protective effect of the perceived adequacy of training and support and by a provocative effect of maladaptive coping style and other individual factors. The results reinforce the value of effective staff support and training in preparation for future outbreaks.

  • Methicillin-resistant Staphylococcus aureus Colonization in Veterinary Personnel PDF Version [PDF - 144 KB - 6 pages]
    B. A. Hanselman et al.
    View Summary

    Prevalence of colonization was 6.5%, and employment within a large-animal practice was a significant risk factor.

       View Abstract

    Methicillin-resistant Staphylococcus aureus (MRSA) was isolated from nares of 27/417 (6.5%) attendees at an international veterinary conference: 23/345 (7.0%) veterinarians, 4/34 (12.0%) technicians, and 0/38 others. Colonization was more common for large-animal (15/96, 15.6%) than small-animal personnel (12/271, 4.4%) or those with no animal patient contact (0/50) (p<0.001). Large-animal practice was the only variable significantly associated with colonization (odds ratio 2.9; 95% confidence interval 1.2–6.6). Pulsed-field gel electrophoresis identified 2 predominant clones with similar distribution among veterinarians as previously reported for horses and companion animals. Canadian epidemic MRSA-2 (CMRSA) was isolated from 11 small-animal and 2 large-animal personnel from the United States (n = 12) and Germany (n = 1). In contrast, CMRSA-5 was isolated exclusively from large-animal personnel (p<0.001) in the United States (n = 10), United Kingdom (n = 2), and Denmark (n = 1). MRSA colonization may be an occupational risk for veterinary professionals.

  • Methicillin-resistant Staphylococcus aureus in Veterinary Doctors and Students, the Netherlands PDF Version [PDF - 62 KB - 3 pages]
    M. Wulf et al.
    View Summary

    Livestock may serve as an important source of community-acquired MRSA in a low-prevalence situation.

       View Abstract

    The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the Netherlands, at 1.0%, is among the lowest in Europe. In 2004, a relationship between pig farming and a high risk for MRSA carriage was found. To investigate if those in professional contact with livestock are at higher risk for MRSA carriage, we screened 80 veterinary students and 99 veterinarians and questioned them about animal contacts and known MRSA risk factors. Of these, 27 students who did not have livestock contact were excluded from further analysis. We found 7 carriers of MRSA, a prevalence of 4.6%, which is similar to that found in patients who had previously been treated at foreign hospitals. A correlation of MRSA carriage with a specific animal group could not be established. To preserve the low prevalence of MRSA in the Netherlands, persons involved in the care of livestock should be isolated and screened on admission to the hospital.

  • Evaluating Detection of an Inhalational Anthrax Outbreak PDF Version [PDF - 306 KB - 8 pages]
    D. L. Buckeridge et al.
    View Summary

    When syndromic surveillance detected a substantial proportion of outbreaks before clinical case finding, false-positive results occurred.

       View Abstract

    Timely detection of an inhalational anthrax outbreak is critical for clinical and public health management. Syndromic surveillance has received considerable investment, but little is known about how it will perform relative to routine clinical case finding for detection of an inhalational anthrax outbreak. We conducted a simulation study to compare clinical case finding with syndromic surveillance for detection of an outbreak of inhalational anthrax. After simulated release of 1 kg of anthrax spores, the proportion of outbreaks detected first by syndromic surveillance was 0.59 at a specificity of 0.9 and 0.28 at a specificity of 0.975. The mean detection benefit of syndromic surveillance was 1.0 day at a specificity of 0.9 and 0.32 days at a specificity of 0.975. When syndromic surveillance was sufficiently sensitive to detect a substantial proportion of outbreaks before clinical case finding, it generated frequent false alarms.

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