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Volume 12, Number 3—March 2006

Volume 12, Number 3—March 2006   PDF Version [PDF - 6.02 MB - 179 pages]

Perspective

  • Possibilities for Relapsing Fever Reemergence PDF Version [PDF - 199 KB - 6 pages]
    S. J. Cutler
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    Increasing globalization may pave the way for reemergence of relapsing fever.

       View Abstract

    Relapsing fever Borrelia infections have attracted little attention in recent years; however, where endemic, these infections still result in considerable illness and death. Despite the marked antimicrobial drug susceptibility of these organisms, therapy is often delayed through lack of clinical suspicion. With increasing travel, infections may be imported, through exotic relapsing fever infection or through resurgence of infected disease vectors. Although louseborne relapsing fever is now geographically limited, it was once of global importance. The possibility for reemergence was recently highlighted by the probable reemergence of louseborne relapsing fever in homeless persons from France. Host limitations enforced through louseborne transmission are less applicable for the tickborne forms of relapsing fever. Although the latter have reduced potential for epidemic spread, they have the ability to infect diverse hosts, thus establishing reservoirs of infection and presenting greater challenges for their control.

  • Cost-effectiveness of West Nile Virus Vaccination PDF Version [PDF - 101 KB - 6 pages]
    A. Zohrabian et al.
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    Vaccination is unlikely to result in societal monetary savings.

       View Abstract

    West Nile virus (WNV) was first detected in the Western Hemisphere in 1999 in New York City. From 1999 through 2004, >16,600 cases of WNV-related illnesses were reported in the United States, of which >7,000 were neuroinvasive disease and >600 were fatal. Several approaches are under way to develop a human vaccine. Through simulations and sensitivity analysis that incorporated uncertainties regarding future transmission patterns of WNV and costs of health outcomes, we estimated that the range of values for the cost per case of WNV illness prevented by vaccination was US $20,000–$59,000 (mean $36,000). Cost-effectiveness was most sensitive to changes in the risk for infection, probability of symptomatic illness, and vaccination cost. Analysis indicated that universal vaccination against WNV disease would be unlikely to result in societal monetary savings unless disease incidence increases substantially over what has been seen in the past 6 years.

Synopses

  • Web-based Surveillance and Global Salmonella Distribution, 2000–2002 PDF Version [PDF - 296 KB - 8 pages]
    E. Galanis et al.
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    Surveillance improves control of Salmonella infections.

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    Salmonellae are a common cause of foodborne disease worldwide. The World Health Organization (WHO) supports international foodborne disease surveillance through WHO Global Salm-Surv and other activities. WHO Global Salm-Surv members annually report the 15 most frequently isolated Salmonella serotypes to a Web-based country databank. We describe the global distribution of reported Salmonella serotypes from human and nonhuman sources from 2000 to 2002. Among human isolates, S. Enteritidis was the most common serotype, accounting for 65% of all isolates. Among nonhuman isolates, although no serotype predominated, Salmonella enterica serovar Typhimurium was reported most frequently. Several serotypes were reported from only 1 region of the world. The WHO Global Salm-Surv country databank is a valuable public health resource; it is a publicly accessible, Web-based tool that can be used by health professionals to explore hypotheses related to the sources and distribution of salmonellae worldwide.

  • Bartonella Spp. in Pets and Effect on Human Health PDF Version [PDF - 98 KB - 5 pages]
    B. B. Chomel et al.
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    Pets represent a large reservoir for human infection.

       View Abstract

    Among the many mammals infected with Bartonella spp., pets represent a large reservoir for human infection because most Bartonella spp. infecting them are zoonotic. Cats are the main reservoir for Bartonella henselae, B. clarridgeiae, and B. koehlerae. Dogs can be infected with B. vinsonii subsp. berkhoffii, B. henselae, B. clarridgeiae, B. washoensis, B. elizabethae, and B. quintana. The role of dogs as an important reservoir of Bartonella spp. is less clear than for cats because domestic dogs are more likely to be accidental hosts, at least in nontropical regions. Nevertheless, dogs are excellent sentinels for human infections because a similar disease spectrum develops in dogs. Transmission of B. henselae by cat fleas is better understood, although new potential vectors (ticks and biting flies) have been identified. We review current knowledge on the etiologic agents, clinical features, and epidemiologic characteristics of these emerging zoonoses.

Research

  • West Nile Virus Infections Projected from Blood Donor Screening Data, United States, 2003 PDF Version [PDF - 200 KB - 8 pages]
    M. P. Busch et al.
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    Routine donor nucleic acid amplification testing is a valuable surveillance screening tool.

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    National blood donor screening for West Nile virus (WNV) RNA using minipool nucleic acid amplification testing (MP-NAT) was implemented in the United States in July 2003. We compiled national NAT yield data and performed WNV immunoglobulin M (IgM) testing in 1 WNV-epidemic region (North Dakota). State-specific MP-NAT yield, antibody seroprevalence, and the average time RNA is detectable by MP-NAT were used to estimate incident infections in 2003. WNV donor screening yielded 944 confirmed viremic donors. MP-NAT yield peaked in August with >0.5% of donations positive for WNV RNA in 4 states. Peak IgM seroprevalence for North Dakota was 5.2% in late September. The average time viremia is detectable by MP-NAT was 6.9 days (95% confidence interval [CI] 3.0–10.7). An estimated 735,000 (95% CI 322,000–1,147,000) infections occurred in 2003, with 256 (95% CI 112–401) infections per neuroinvasive case. In addition to preventing transfusion-transmitted WNV infection, donor screening can serve as a tool to monitor seasonal incidence in the general population.

  • Aspergillus ustus Infections among Transplant Recipients PDF Version [PDF - 166 KB - 6 pages]
    A. A. Panackal et al.
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    This is the first report of clustered Aspergillus ustus causing systemic disease in transplant patients.

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    Aspergillus ustus is a mold that rarely infects humans; only 15 systemic cases have been reported. We report the first outbreak of invasive infection caused by A. ustus among hematopoietic stem cell transplant (HSCT) recipients. Six patients with infections were identified; 3 infections each occurred in both 2001 and 2003. Molecular typing by using randomly amplified polymorphic DNA (RAPD) and antifungal drug susceptibility testing were performed on clinical and environmental isolates recovered from our hospital from 1999 to 2003. The highest overall attack rate in HSCT patients was 1.6%. The overall death rate was 50%, and death occurred within 8 days after diagnostic culture collection. Clinical isolates exhibited decreased susceptibility to antifungal drugs, especially azoles. RAPD and phylogenetic analysis showed genetic similarity between isolates from different patients. Based on the clustering of cases in space and time and molecular data, common-source acquisition of this unusual drug-resistant species is possible.

  • Clostridium difficile Infection in Patients Discharged from US Short-stay Hospitals, 1996–2003 PDF Version [PDF - 153 KB - 7 pages]
    L. McDonald et al.
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    Clinicians should be aware of the increasing risk of C. difficile–associated disease and make efforts to control its transmission.

       View Abstract

    US hospital discharges for which Clostridium difficile–associated disease (CDAD) was listed as any diagnosis doubled from 82,000 (95% confidence interval [CI] 71,000–94,000) or 31/100,000 population in 1996 to 178,000 (95% CI 151,000–205,000) or 61/100,000 in 2003; this increase was significant between 2000 and 2003 (slope of linear trend 9.48; 95% CI 6.16–12.80, p = 0.01). The overall rate during this period was severalfold higher in persons >65 years of age (228/100,000) than in the age group with the next highest rate, 45–64 years (40/100,000; p<0.001). CDAD appears to be increasing rapidly in the United States and is disproportionately affecting older persons. Clinicians should be aware of the increasing risk for CDAD and make efforts to control transmission of C. difficile and prevent disease.

  • Medication Sales and Syndromic Surveillance, France PDF Version [PDF - 175 KB - 6 pages]
    E. Vergu et al.
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    Real-time over-the-counter drug sales provide an additional tool for disease surveillance.

       View Abstract

    Although syndromic surveillance systems using nonclinical data have been implemented in the United States, the approach has yet to be tested in France. We present the results of the first model based on drug sales that detects the onset of influenza season and forecasts its trend. Using weekly lagged sales of a selected set of medications, we forecast influenzalike illness (ILI) incidence at the national and regional level for 3 epidemic seasons (2000-01, 2001-02, and 2002-03) and validate the model with real-time updating on the fourth (2003-04). For national forecasts 1–3 weeks ahead, the correlation between observed ILI incidence and forecast was 0.85–0.96, an improvement over the current surveillance method in France. Our findings indicate that drug sales are a useful additional tool to syndromic surveillance, a complementary and independent source of information, and a potential improvement for early warning systems for both epidemic and pandemic planning.

  • Personal Hygiene and Methicillin-resistant Staphylococcus aureus Infection PDF Version [PDF - 127 KB - 6 pages]
    G. Turabelidze et al.
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    Improving personal hygienic practices may prevent and control MRSA outbreaks.

       View Abstract

    Methicillin-resistant Staphylococcus aureus (MRSA) infections outside the healthcare setting are an increasing concern. We conducted a case-control study to investigate an MRSA outbreak during 2002–2003 in a Missouri prison and focused on hygiene factors. Information on sociodemographic characteristics, medical history, and hygiene practices of study participants was collected by interview and medical record review. Logistic regression was used to evaluate MRSA infection in relation to hygiene factors individually and as a composite hygiene score; potential confounding factors were controlled. Selected MRSA isolates were analyzed by pulsed-field gel electrophoresis (PFGE). MRSA infection was significantly associated with a low composite hygiene score. Transmission among prison inmates appeared to be responsible for this outbreak. PFGE analysis showed that isolates were indistinguishable and associated with community-onset MRSA infections in other US prisons. Improving hygiene practices and environmental conditions may help prevent and interrupt future MRSA outbreaks in prison settings.

  • Rickettsia prowazekii and Real-time Polymerase Chain Reaction PDF Version [PDF - 150 KB - 5 pages]
    S. Svraka et al.
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    This highly standardized and adaptable assay could improve epidemic typhus surveillance.

       View Abstract

    Rickettsia prowazekii is the causative agent of epidemic typhus and a potential bioterrorism agent. Sensitive and specific rapid assays are needed to complement existing methods of detecting this organism. We developed a real-time quantitative polymerase chain reaction assay by using a species-specific probe targeting the gltA gene. This assay, which was rapid, specific for R. prowazekii only, and sensitive (cutoff detection of 1 to 5 copies per sample), detected and directly identified R. prowazekii in blood of 12 experimentally infected mice sampled at day 3 and 6 postinfection or in naturally or experimentally infected lice. Because our assay is highly standardized and easily adaptable, it could improve epidemic typhus surveillance in public health programs, especially for countries with underdiagnosed or unrecognized human cases.

  • Serosurvey on Household Contacts of Marburg Hemorrhagic Fever Patients PDF Version [PDF - 147 KB - 7 pages]
    M. Borchert et al.
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    Asymptomatic secondary infections are rare.

       View Abstract

    The first major outbreak of Marburg hemorrhagic fever (MHF) outside a laboratory environment occurred in the subdistrict of Watsa, Democratic Republic of Congo, from October 1998 to August 2000. We performed a serosurvey of household contacts of MHF patients to identify undetected cases, ascertain the frequency of asymptomatic Marburg infection, and estimate secondary attack risk and postintervention reproduction number. Contacts were interviewed about their exposure and symptoms consistent with MHF. Blood samples were tested for anti–Marburg immunoglobulin G (IgG). One hundred twenty-one (51%) of 237 identified contacts participated; 72 (60%) were not known to the health authorities. Two participating contacts were seropositive and reported becoming ill after the contact; no serologic evidence for asymptomatic or mild Marburg infection was found. The secondary attack risk was 21%; the postintervention reproduction number was 0.9, consistent with an outbreak sustained by repeated primary transmission, rather than large-scale secondary transmission.

  • Canine Visceral Leishmaniasis, United States and Canada, 2000–2003 PDF Version [PDF - 142 KB - 7 pages]
    Z. H. Duprey et al.
    View Summary

    Foxhounds infected with Leishmania spp. were found in 18 states and 2 Canadian provinces.

       View Abstract

    Visceral leishmaniasis, caused by protozoa of the genus Leishmania donovani complex, is a vectorborne zoonotic infection that infects humans, dogs, and other mammals. In 2000, this infection was implicated as causing high rates of illness and death among foxhounds in a kennel in New York. A serosurvey of >12,000 foxhounds and other canids and 185 persons in 35 states and 4 Canadian provinces was performed to determine geographic extent, prevalence, host range, and modes of transmission within foxhounds, other dogs, and wild canids and to assess possible infections in humans. Foxhounds infected with Leishmania spp. were found in 18 states and 2 Canadian provinces. No evidence of infection was found in humans. The infection in North America appears to be widespread in foxhounds and limited to dog-to-dog mechanisms of transmission; however, if the organism becomes adapted for vector transmission by indigenous phlebotomines, the probability of human exposure will be greatly increased.

  • Chemoprophylaxis and Malaria Death Rates PDF Version [PDF - 137 KB - 5 pages]
    G. Krause et al.
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    Malaria chemoprophylaxis increases the survival of nonimmune travelers.

       View Abstract

    To determine the effect of chemoprophylaxis on the case-fatality rate of malaria, we analyzed all cases of Plasmodium falciparum malaria in nonimmune persons reported from 1993 to 2004 in Germany. In univariate and multivariate logistic regression analysis, we determined the effect of age, sex, chemoprophylaxis, chemoprophylactic regimen, compliance for chemoprophylactic regimen, exposure prophylaxis, country of infection, and year of reporting on the outcome. Of 3,935 case-patients, 116 (3%) died of malaria. Univariate analysis showed significant associations with death for chemoprophylaxis with chloroquine plus proguanil compared to no chemoprophylaxis. The multivariate model showed that patients who had taken chemoprophylaxis were less likely to die compared to those who had not taken chemoprophylaxis, adjusted for patient age and reporting year. The study demonstrated that chemoprophylaxis significantly reduced fatality rates among nonimmune malaria patients and supports the importance of existing guidelines for malaria prevention.

  • Self-medication with Antimicrobial Drugs in Europe PDF Version [PDF - 270 KB - 8 pages]
    L. Grigoryan et al.
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    Antimicrobial drug self-medication occurs most often in eastern and southern Europe and least often in northern and western Europe.

       View Abstract

    We surveyed the populations of 19 European countries to compare the prevalence of antimicrobial drug self-medication in the previous 12 months and intended self-medication and storage and to identify the associated demographic characteristics. By using a multistage sampling design, 1,000–3,000 adults in each country were randomly selected. The prevalence of actual self-medication varied from 1 to 210 per 1,000 and intended self-medication from 73 to 449 per 1,000; both rates were high in eastern and southern Europe and low in northern and western Europe. The most common reasons for self-medication were throat symptoms (e.g., dry, inflamed, red, or sore throat, inflamed tonsils, tonsil pain). The main medication sources were pharmacies and medication leftover from previous prescriptions. Younger age, higher education, and presence of a chronic disease were associated with higher rates of self-medication. Attempts to reduce inappropriate self-medication should target prescribers, pharmacists, and the general public.

  • Pneumonic Plague Cluster, Uganda, 2004 PDF Version [PDF - 271 KB - 8 pages]
    E. M. Begier et al.
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    In a case cluster, pneumonic plague transmission was compatible with respiratory droplet rather than aerosol transmission.

       View Abstract

    The public and clinicians have long-held beliefs that pneumonic plague is highly contagious; inappropriate alarm and panic have occurred during outbreaks. We investigated communicability in a naturally occurring pneumonic plague cluster. We defined a probable pneumonic plague case as an acute-onset respiratory illness with bloody sputum during December 2004 in Kango Subcounty, Uganda. A definite case was a probable case with laboratory evidence of Yersinia pestis infection. The cluster (1 definite and 3 probable cases) consisted of 2 concurrent index patient–caregiver pairs. Direct fluorescent antibody microscopy and polymerase chain reaction testing on the only surviving patient's sputum verified plague infection. Both index patients transmitted pneumonic plague to only 1 caregiver each, despite 23 additional untreated close contacts (attack rate 8%). Person-to-person transmission was compatible with transmission by respiratory droplets, rather than aerosols, and only a few close contacts, all within droplet range, became ill.

  • Host Feeding Patterns of Culex Mosquitoes and West Nile Virus Transmission, Northeastern United States PDF Version [PDF - 192 KB - 7 pages]
    G. Molaei et al.
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    Culex salinarius is a bridge vector to humans, while Cx. pipiens and Cx. restuans are more efficient enzootic vectors.

       View Abstract

    To evaluate the role of Culex mosquitoes as enzootic and epidemic vectors for WNV, we identified the source of vertebrate blood by polymerase chain reaction amplification and sequencing portions of the cytochrome b gene of mitochondrial DNA. All Cx. restuans and 93% of Cx. pipiens acquired blood from avian hosts; Cx. salinarius fed frequently on both mammals (53%) and birds (36%). Mixed-blood meals were detected in 11% and 4% of Cx. salinarius and Cx. pipiens, respectively. American robin was the most common source of vertebrate blood for Cx. pipiens (38%) and Cx. restuans (37%). American crow represented <1% of the blood meals in Cx. pipiens and none in Cx. restuans. Human-derived blood meals were identified from 2 Cx. salinarius and 1 Cx. pipiens. Results suggest that Cx. salinarius is an important bridge vector to humans, while Cx. pipiens and Cx. restuans are more efficient enzootic vectors in the northeastern United States.

  • Identifying and Quantifying Genotypes in Polyclonal Infections due to Single Species PDF Version [PDF - 321 KB - 8 pages]
    J. M. Colborn et al.
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    The combination of real-time PCR and capillary electrophoresis permits the rapid identification and quantification of pathogen genotypes.

       View Abstract

    Simultaneous infection with multiple pathogens of the same species occurs with HIV, hepatitis C, Epstein-Barr virus, dengue, tuberculosis, and malaria. However, available methods do not distinguish among or quantify pathogen genotypes in individual patients; they also cannot test for novel insertions and deletions in genetically modified organisms. The strategy reported here accomplishes these goals with real-time polymerase chain reaction (PCR) and capillary electrophoresis. Real-time PCR with allotype-specific primers defines the allotypes (strains) present and the intensity of infection (copy number). Capillary electrophoresis defines the number of genotypes within each allotype and the intensity of infection by genotype. This strategy can be used to study the epidemiology of emerging infectious diseases with simultaneous infection by multiple genotypes, as demonstrated here with malaria. It also permits testing for insertions or deletions in genetically modified organisms that may be used for bioterrorism.

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