Incidence of West Nile virus infection in the Dallas-Fort Worth metropolitan area during the 2012 epidemic.

The 2012 West Nile virus (WNV) epidemic was the largest since 2003 and the North Texas region was the most heavily impacted. We conducted a serosurvey of blood donors from four counties in the Dallas-Fort Worth area to characterize the epidemic. Blood donor specimens collected in November 2012 were tested for WNV-specific antibodies. Donors positive for WNV-specific IgG, IgM, and neutralizing antibodies were considered to have been infected in 2012. This number was adjusted using a multi-step process that accounted for timing of IgM seroreversion determined from previous longitudinal studies of WNV-infected donors. Of 4971 donations screened, 139 (2·8%) were confirmed WNV IgG positive, and 69 (1·4%) had IgM indicating infection in 2012. After adjusting for timing of sampling and potential seroreversion, we estimated that 1·8% [95% confidence interval (CI) 1·5-2·2] of the adult population in the Dallas-Fort Worth area were infected during 2012. The resulting overall estimate for the ratio of infections to reported WNV neuroinvasive disease (WNND) cases was 238:1 (95% CI 192-290), with significantly increased risk of WNND in older age groups. These findings were very similar to previous estimates of infections per WNND case, indicating no change in virulence as WNV evolved into an endemic infection in the United States.

Enhanced Humoral Responses Induced by Targeting of Antigen to Murine Dendritic Cells.

Dendritic cells (DCs) are superior in their ability to induce and control adaptive immune responses. These qualities have motivated the hypothesis that targeted delivery of antigen to DCs in vivo may be an effective way of enhancing immunization. Recent results show that antigen targeted to certain DC surface molecules may indeed induce robust immune responses. Targeting of antigen to DCs can be accomplished by the means of monoclonal antibodies. This study compared the humoral responses induced in mice by in vivo targeting of DCs using monoclonal antibodies specific for CD11c, CD36, CD205, Clec6A, Clec7A, Clec9A, Siglec-H and PDC-TREM. The results demonstrate that antigen delivery to different targets on DCs in vivo gives rise to humoral responses that differ in strength. Targeting of antigen to CD11c, CD36, CD205, Clec6A, Clec7A and PDC-TREM induced significantly stronger antibody responses compared to non-targeted isotype-matched controls. Targeting of Clec9A and Siglec-H did not lead to efficient antibody responses, which may be due to unfavourable properties of the targeting antibody, in which case, other antibodies with the same specificity might elicit a different outcome. Anti-CD11c was additionally used for elucidating the impact of the route of vaccination, and the results showed only minor differences between the antibody responses induced after immunization either s.c., i.v. or i.p. Altogether, these data show that targeting of different surface molecules on DCs result in very different antibody responses and that, even in the absence of adjuvants, strong humoral responses was induced.

Estimated cumulative incidence of West Nile virus infection in US adults, 1999-2010.

West Nile virus (WNV) was first recognized in the USA in 1999. We estimated the cumulative incidence of WNV infection in the USA from 1999 to 2010 using recently derived age- and sex-stratified ratios of infections to WNV neuroinvasive disease (WNND) and the number of WNND cases reported to national surveillance. We estimate that over 3 million persons have been infected with WNV in the USA, with the highest incidence rates in the central plains states. These 3 million infections would have resulted in about 780 000 illnesses. A substantial number of WNV infections and illnesses have occurred during the virus' first decade in the USA.

Amendment of arsenic and chromium polluted soil from wood preservation by iron residues from water treatment.

An iron-rich water treatment residue (WTR) consisting mainly of ferrihydrite was used for immobilization of arsenic and chromium in a soil contaminated by wood preservatives. A leaching batch experiment was conducted using two soils, a highly contaminated soil (1033 mg kg(-1) As and 371 mg kg(-1) Cr) and slightly contaminated soil (22 5mg kg(-1) As and 27 mg kg(-1) Cr). Compared to an untreated reference soil, amendment with 5% WTR reduced leaching in the highly contaminated soil by 91% for Cr and 98% for As. No aging effect was observed after 103 d. In a small field experiment, soil was mixed with 2.5% WTR in situ. Pore water was extracted during 3 years from the amended soil and a control site. Pore water arsenic concentrations in the amended soil were more than two orders of magnitude lower than in the control for the upper samplers. An increased release of arsenic was observed during winter in both fields, mostly in the deepest samplers. This is likely due to the formation of a pseudo-gley because of precipitation surplus. Stabilization of arsenic and chromium contaminated soil using WTR is a promising method but the transformation of ferrihydrite in soil proves a concern in case of waterlogged soils. Still the amendment minimized the leaching of arsenic, even in cases of seasonal releases.

Transfusion-transmitted arboviruses.

There exists considerable risk for transfusion transmission of arboviruses due to short periods of asymptomatic viraemia in populations with variable and sometimes extremely high incidence of arboviral infections. Aside from West Nile virus, few arbovirus transfusion transmissions have been proven, mostly due to difficulties in ruling out vector-borne transmission in recipients with arbovirus disease. Nevertheless, arbovirus transfusion risk models and assessments of viraemia prevalence in blood donations indicate substantial transfusion transmission of dengue and Chikungunya viruses in epidemic areas. Many other arboviruses, several of which are importation risks in the Americas, Europe and Asia, also cause large outbreaks and threaten transfusion safety. Prevention largely depends on excluding donors from outbreak areas or implementation of highly sensitive nucleic acid amplification tests. Because of the increasing emergence of arboviral disease globally, it is prudent to prepare for both endemic and exotic arboviruses capable of producing large epidemics and subsequent transfusion transmission risk.

West Nile virus infection and serologic response among persons previously vaccinated against yellow fever and Japanese encephalitis viruses.

It is hypothesized that previous heterologous flaviviral exposure may modulate clinical illness among persons infected with West Nile virus (WNV). Little is known about the serological response in such persons. In summer 2003, a WNV outbreak occurred in Colorado, the location of the Centers for Disease Control and Prevention, Division of Vector-Borne Infectious Diseases (DVBID). DVBID employees, most previously vaccinated with yellow fever virus (YFV) or Japanese encephalitis virus (JEV) vaccines, were studied to determine whether previous vaccination affected symptom development among those subsequently infected with WNV during the outbreak, as well as their serological response. Serum samples collected in December 2003 and previously banked samples were tested using the plaque reduction neutralization test (PRNT) against WNV, Saint Louis encephalitis virus, dengue- 4 virus, JEV, and YFV. Specimens shown to have WNV antibody by PRNT were tested by IgM and IgG enzymelinked immunosorbent assays (ELISAs). Ten (9%) of 113 serosurvey participants had WNV neutralizing antibody titers in December 2003. PRNT titers from previous specimens showed that one of the ten had seroconverted to WNV before 2003. Of the remaining nine participants, seven reported illness in the summer of 2003, two of which were unvaccinated and five previously vaccinated. In the December 2003 specimens, five persons previously unvaccinated or vaccinated only against YFV had a fourfold or greater neutralizing titer with WNV than with other flaviviruses, whereas no persons previously vaccinated against JEV or JEV and YFV showed a similar difference in neutralizing titers. Eight of nine persons infected in 2003 had negative or indeterminate WNV MAC-ELISA results in the December 2003 sample; the ninth person was vaccinated against YFV one month previously, and was also YFV positive by MAC-ELISA. We conclude that previous flaviviral vaccination does not markedly affect the development of WNV fever and that the IgM antibody response in patients without neuroinvasive WNV disease is transient.

The seasonal distribution of campylobacter infection in nine European countries and New Zealand.

In all temperate countries campylobacter infection in humans follows a striking seasonal pattern, but little attention has been given to exploring the epidemiological explanations. In order to better characterize the seasonal patterns, data from nine European countries and New Zealand have been examined. Several European countries with weekly data available showed remarkably consistent seasonal patterns from year to year, with peaks in week 22 in Wales, week 26 in Scotland, week 32 in Denmark, week 30 in Finland and week 33 in Sweden. In Europe, the seasonal peak was most prominent in Finland and least prominent in Scotland and Austria. In New Zealand the seasonality was less consistent since the peak was more prolonged. Possible explanations for the seasonal peaks are discussed. Research into the causes of campylobacter seasonality should help considerably in elucidating the sources of human infection.

Widespread West Nile virus activity, eastern United States, 2000.

In 1999, the U.S. West Nile (WN) virus epidemic was preceded by widespread reports of avian deaths. In 2000, ArboNET, a cooperative WN virus surveillance system, was implemented to monitor the sentinel epizootic that precedes human infection. This report summarizes 2000 surveillance data, documents widespread virus activity in 2000, and demonstrates the utility of monitoring virus activity in animals to identify human risk for infection.

The Field Epidemiology Training Program (FETP) in Germany.

The German Field Epidemiology Training Programme (FETP), which started in January 1996, is part of a national effort to improve research capacity for the epidemiology of infectious diseases in Germany. The aim of the two year programme is to develop a cadre of epidemiologists capable of performing outbreak investigations, epidemiological research, and surveillance at an international standard measured in articles published in international peer-reviewed journals. These epidemiologists will also be instructed to train future epidemiologists and public health personnel. The programme is similar to the Epidemic Intelligence Service (EIS) at the Centers for Disease Control and Prevention (CDC) in the United States and the European Programme for Intervention Epidemiology Training (EPIET). The German Federal Ministry for Education and Research funded the costs of a senior epidemiologist who was seconded from the CDC to help initiate this programme.

An outbreak of primary pneumonic tularemia on Martha's Vineyard.

BACKGROUND: In the summer of 2000, an outbreak of primary pneumonic tularemia occurred on Martha's Vineyard, Massachusetts. The only previously reported outbreak of pneumonic tularemia in the United States also occurred on the island in 1978. METHODS: We conducted a case-control study of adults with pneumonic tularemia and investigated the environment to identify risk factors for primary pneumonic tularemia. Patients with confirmed cases were residents of or visitors to Martha's Vineyard who had symptoms suggestive of primary pneumonic tularemia, were ill between May 15 and October 31, 2000, and had a positive laboratory test for tularemia. Controls were adults who had spent at least 15 days on Martha's Vineyard between May 15 and September 28, 2000. RESULTS: We identified 15 patients with tularemia; 11 of these cases were primary pneumonic tularemia. Francisella tularensis type A was isolated from blood and lung tissue of the one man who died. Patients were more likely than controls to have used a lawn mower or brush cutter in the two weeks before the illness or before an interview, for controls (odds ratio, 9.2; 95 percent confidence interval, 1.6 to 68.0) and during the summer (odds ratio, undefined; 95 percent confidence interval, 1.8 to infinity). Lawn mowing and brush cutting remained significant risk factors after adjustment for other potentially confounding variables. Only one patient reported being exposed to a rabbit while cutting brush. Of 40 trapped animals, 1 striped skunk (Mephitis mephitis) and 1 Norway rat (Rattus norvegicus) were seropositive for antibodies against F. tularensis. CONCLUSIONS: Study of this outbreak of primary pneumonic tularemia implicates lawn mowing and brush cutting as risk factors for this infection.

West Nile virus serosurvey and assessment of personal prevention efforts in an area with intense epizootic activity: Connecticut, 2000.

West Nile virus (WNV) can cause large outbreaks of febrile illness and severe neurologic disease. This study estimates the seroprevalence of WNV infection and assesses risk perception and practices regarding potential exposures to mosquitoes of persons in an area with intense epizootics in 1999 and 2000. A serosurvey of persons aged > or = 12 years was conducted in southwestern Connecticut during October 10-15, 2000, using household-based stratified cluster sampling. Participants completed a questionnaire regarding concern for and personal measures taken with respect to WNV and provided a blood sample for WNV testing. Seven hundred thirty persons from 645 households participated. No person tested positive for WNV (95% CI: 0-0.5%). Overall, 44% of persons used mosquito repellent, 56% practiced > or = two personal precautions to avoid mosquitoes, and 61% of households did > or = two mosquito-source reduction activities. In multivariate analyses, using mosquito repellent was associated with age < 50 years, using English as the primary language in the home, being worried about WNV, being a little worried about pesticides, and finding mosquitoes frequently in the home (P<0.05). Females (OR = 2.0; CI = 1.2-2.9) and persons very worried about WNV (OR = 3.8; CI = 2.2-6.5) were more likely to practice > or = two personal precautions. Taking > or = two mosquito source reductions was associated with persons with English as the primary language (OR = 2.0; CI = 1.1-3.5) and finding a dead bird on the property (OR = 1.8; CI = 1.1-2.8). An intense epizootic can occur in an area without having a high risk for infection to humans. A better understanding of why certain people do not take personal protective measures, especially among those aged > or = 50 years and those whose primary language is not English, might be needed if educational campaigns are to prevent future WNV outbreaks.

Hepatitis B and C among Berlin dental personnel: incidence, risk factors, and effectiveness of barrier prevention measures.

A study of 215 Berlin dentists and 108 dental assistants recruited at the 1997 Berlin Dental Society meeting assessed their occupational risk of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. HBV vaccine coverage, and barrier prevention methods used. Among dentists, 7% (95% CI 4-11) and 0.5% (95% CI 0-3) had serological evidence of previous HBV and HCV infection, respectively. Similar figures for dental assistants were 1% (95% CI 0-5) and 0% (95% CI 0-4). Only 74% of dentists and 63% of dental assistants reported HBV vaccination. Approximately half always used gloves, eye glasses, or face masks. HBV unvaccinated dentists whose patients had HBV risk factors had a greater risk of HBV infection; those who always wore face masks were at lower risk (OR 0.2, 95% CI 0.02-0.98). These data indicate that among Berlin dentists, the HCV risk was lower than that of HBV and that face masks may have lowered the risk of HBV. The use of eye glasses or gloves did not appear to lower the risk of HBV acquisition in this population.

Developing national epidemiologic capacity to meet the challenges of emerging infections in Germany.

In January 1996, the Robert Koch Institute, Germany's national public health institute, began strengthening its epidemiologic capacity to respond to emerging and other infectious diseases. Six integrated strategies were initiated: developing employee training, outbreak investigation, and epidemiologic research programs; strengthening surveillance systems; improving communications to program partners and constituents; and building international collaborations. By December 1999, five employees had completed a 2-year applied epidemiology training program, 186 health department personnel had completed a 2-week training course, 27 outbreak investigations had been completed, eight short-term research projects had been initiated, major surveillance and epidemiologic research efforts for foodborne and nosocomial infections had begun, and 16 scientific manuscripts had been published or were in press. The German experience indicates that, with a concerted effort, considerable progress in building a national applied infectious disease program can be achieved in a short time frame.

An outbreak of pyodermas among neonates caused by ultrasound gel contaminated with methicillin-susceptible Staphylococcus aureus.

OBJECTIVE: To investigate an outbreak of methicillin-susceptible Staphylococcus aureus (MSSA) infections in a neonatal clinic. DESIGN: Prospective chart review, environmental sampling, and genotyping by two independent methods: pulsed-field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). A case-control study was performed with 31 controls from the same clinic. SETTING: A German 1,350-bed tertiary-care teaching university hospital. RESULTS: There was a significant increase in the incidence of pyodermas with MSSA; 10 neonates in good physical condition with no infection immediately after birth developed pyodermas. A shared spatula and ultrasound gel were the only identified infection sources. The gel contained MSSA and was used for hip joint sonographies in all neonates. PFGE and RAPD-PCR patterns from 6 neonates and from the gel were indistinguishable and thus genetically related clones. The case-control study revealed no significant risk factor with the exception of cesarean section (P=.006). The attack rate by days of hip-joint sonography between April 15 and April 27, 1994, was 11.8% to 40%. CONCLUSIONS: Inappropriate hygienic measures in connection with lubricants during routine ultrasound scanning may lead to nosocomial S. aureus infections of the skin. To our knowledge this source of S. aureus infections has not previously been described.

An echovirus 30 outbreak with a high meningitis attack rate among children and household members at four day-care centers.

Echovirus 30 (E 30) outbreaks in defined cohorts have rarely been reported. In June 1996, an outbreak of E 30 occurred in four day-care centers (DCCs) in neighboring villages in Germany. A retrospective cohort study of DCC children, employees and household members was done to determine the extent of the outbreak and risk factors for illness. Forty-two percent (39/92) of DCC children, 13% (30/228) of their household members, 5% (1/19) of employees and 2% (1/49) of household members of employees were ill. Onsets occurred over 31 days. Thirteen percent (12/92) of DCC children had meningitis. In only one of 16 households with multiple family members ill, illness in a family member preceeded that of the DCC child. Household members of ill DCC children were 15 times more likely to report illness than those of non-ill DCC children. We conclude that this outbreak was associated with a very high incidence of meningitis, the outbreak began in the DCCs and then spread to household members, and that household members of ill children compared to those of non-ill children were much more likely to report illness.

A large outbreak of hemolytic uremic syndrome caused by an unusual sorbitol-fermenting strain of Escherichia coli O157:H-.

Escherichia coli O157:H7 does not ferment sorbitol, a factor used to differentiate it from other E. coli. From December 1995 to March 1996, 28 children with hemolytic uremic syndrome in Bavaria, Germany, were identified; many had a sorbitol-fermenting (sf) E. coli O157:H- cultured. A case-control study showed a dose-response relationship between sausage consumption and illness. A second case-control study showed a relationship between mortadella and teewurst consumption and illness, particularly during December (mortadella odds ratio [OR], 10.5, P=.004; teewurst OR, 6.2, P=.02). Twelve sf O157:H- were characterized to determine clonality and virulence traits. The strains possessed the Stx2, eae, and EHEC-hlyA genes but were nonhemolytic on blood agar plates. The O157:H- isolates belonged to phage type 88 and had identical pulsed-field gel electrophoresis patterns. This outbreak was caused by sf E. coli O157:H-, which is not detectable by culture on sorbitol MacConkey's agar. Consumption of two sausages, including a raw beef-containing sausage, was statistically related to illness.

Influenza A outbreak among adolescents in a ski hostel.

An outbreak of influenza A H3N2 with a high attack rate (49%) and abrupt onset (69% became ill within 2 days) occurred among 81 ski school participants who stayed in a crowded hostel in Austria in early 1997. Two students were hospitalized with pneumonia; one of them died. Cultures of blood and/or respiratory secretions from the hospitalized students yielded toxin-producing Staphylococcus aureus. Influenza A H3N2 was confirmed serologically in four participants, including one surviving hospitalized student, and by polymerase chain reaction of lung tissue from the deceased student. This investigation demonstrates that influenza can cause an explosive outbreak among skiers in a crowded hostel, leading to severe complications among previously healthy adolescents.

Value and cost-effectiveness of screening blood donors for antibody to hepatitis B core antigen as a way of detecting window-phase human immunodeficiency virus type 1 infections. The HIV Blood Donor Study Group.

BACKGROUND: The value of screening donors for antibody to hepatitis B core antigen (anti-HBc) for the prevention of posttransfusion hepatitis has declined markedly. However, anti-HBc screening may still be useful as a surrogate marker for the window period (WP) of human immunodeficiency virus type 1 (HIV-1) infection. STUDY DESIGN AND METHODS: First, the relationship between anti-HBc reactivity and HIV-1 WP infections was examined among 225 donors who had seroconverted to anti-HIV-1 positivity between 1987 and 1990. In addition, data from 1654 HIV-1 seropositive donors were analyzed to characterize the relationship among anti-HBc reactivity, donor demographics, and HIV-1-related risk factors. The yield and cost-effectiveness of anti-HBc for HIV-1 prevention were then projected on the basis of a published decision analysis model. RESULTS: Forty (18%) of 225 HIV-1-seroconverting donors tested anti-HBc-reactive on the donation preceding anti-HIV-1 seroconversion; in contrast, 341 (34%) of 1014 HIV-1-seropositive donors interviewed tested anti-HBc-reactive (chi-square test; p < 0.001). Anti-HBc reactivity was more common among HIV-1-seropositive donors reporting male-to-male sexual contact (169/360, 47%) and injection drug use (44/83, 53%) than among those with heterosexual contacts known to be HIV-1-positive (31/190, 16%) or transfusion exposure (3/21, 14%) or among females with no identified risk factors (21/124, 17%). The estimates of 18 to 34 percent sensitivity for anti-HBc in detecting HIV-1 WP donations and a current rate of 1 in 676,000 HIV-1 WP donations (after p24 antigen screening) suggest that continued use of anti-HBc screening could result in the transfusion of 5 to 12 fewer HIV-1-infected units per year in the United States, which would add 19 to 48 quality-adjusted years of life for the 3.5 million annual transfusion recipients at a cost of $992,020 to $2,345,000 per quality-adjusted life-year saved. CONCLUSION: The low yield and very poor cost-effectiveness of anti-HBc screening indicate that this test is not an effective screening test for HIV-1 WP donations.