Performance evaluation of selected n95 respirators and surgical masks when challenged with aerosolized endospores and inert particles.

The objective of this study was to assess how the relative efficiency of N95 respirators and surgical masks might vary with different challenge aerosols, utilizing a standardized manikin head form as a surrogate to human participation. A Collision nebulizer aerosolized B. anthracis Sterne strain endospores and polystyrene latex (PSL) particles to evaluate 11 models of N95 respirators and surgical masks. An automated breathing simulator, calibrated to normal tidal volume and active breathing rate, mimicked human respiration. A manikin head form with N95 respirators or surgical masks, and manikin head form without N95 respirators or surgical masks were placed in the bioaerosol chamber. An AGI-30 sampler filled with phosphate buffered water was fitted behind the mouth of each manikin head form to collect endospore bioaerosol samples. PSL aerosols concentrations were quantified by an ARTI Hand Held Particle Counter. Geometric Mean (GM) relative efficiency of N95 respirators and surgical masks challenged with endospore bioaerosol ranged from 34-65%. In PSL aerosol experiments, GM relative efficiency ranged from 35-64% for 1.3 µm particles. GM filtration efficiency of all N95 and surgical N95 respirators filter media evaluated was ≥99% when challenged with particles ≥0.1 µm. GM filtration efficiency of surgical mask filter media ranged from 70-83% with particles ≥0.1 µm and 74-92% with 1.3 µm PSL particles. Relative efficiencies of N95 respirators and surgical masks challenged with aerosolized B. anthracis endospores and PSL were similar. Relative efficiency was similar between N95 respirators and surgical masks on a manikin head form despite clear differences in filtration efficiency. This study further highlights the importance of face seal leakage in the respiratory protection provided by N95 respirators, and demonstrates it on a human surrogate.

Assessment of management policies and practices for occupational exposure to bloodborne pathogens in dialysis facilities.

BACKGROUND: Occupational exposure management is an important element in preventing the transmission of bloodborne pathogens in health care settings. In 2008, the US Centers for Disease Control and Prevention conducted a survey to assess procedures for managing occupational bloodborne pathogen exposures in outpatient dialysis facilities in the United States. STUDY DESIGN: A cross-sectional survey of randomly selected outpatient dialysis facilities. SETTING & PARTICIPANTS: 339 outpatient dialysis facilities drawn from the 2006 US end-stage renal disease database. PREDICTORS: Hospital affiliation (free-standing vs hospital-based facilities), profit status (for-profit vs not-for-profit facilities), and number of health care personnel (≥100 vs <100 health care personnel). OUTCOMES: Exposures to hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV); provision of HBV and HIV postexposure prophylaxis. MEASUREMENTS: We calculated the proportion of facilities reporting occupational bloodborne pathogen exposures and offering occupational exposure management services. We analyzed bloodborne pathogen exposures and provision of postexposure prophylaxis by facility type. RESULTS: Nearly all respondents (99.7%) had written policies and 95% provided occupational exposure management services to health care personnel during the daytime on weekdays, but services were provided infrequently during other periods of the week. Approximately 10%-15% of facilities reported having HIV, HBV, or HCV exposures in health care personnel in the 12 months prior to the survey, but inconsistencies were noted in procedures for managing such exposures. Despite 86% of facilities providing HIV prophylaxis for exposed health care personnel, only 37% designated a primary HIV postexposure prophylaxis regimen. For-profit and free-standing facilities reported fewer exposures, but did not as reliably offer HBV prophylaxis or have a primary HIV postexposure prophylaxis regimen relative to not-for-profit and hospital-based facilities. LIMITATIONS: The survey response rate was low (37%) and familiarity of individuals completing the survey with facility policies or national guidelines could not be ascertained. CONCLUSIONS: Significant improvements are required in the implementation of guidelines for managing occupational exposures to bloodborne pathogens in outpatient dialysis facilities.

Recommendations for postexposure interventions to prevent infection with hepatitis B virus, hepatitis C virus, or human immunodeficiency virus, and tetanus in persons wounded during bombings and other mass-casualty events--United States, 2008: recommendations of the Centers for Disease Control and Prevention (CDC).

This report outlines recommendations for postexposure interventions to prevent infection with hepatitis B virus, hepatitis C virus, or human immunodeficiency virus, and tetanus in persons wounded during bombings or other events resulting in mass casualties. Persons wounded during such events or in conjunction with the resulting emergency response might be exposed to blood, body fluids, or tissue from other injured persons and thus be at risk for bloodborne infections. This report adapts existing general recommendations on the use of immunization and postexposure prophylaxis for tetanus and for occupational and nonoccupational exposures to bloodborne pathogens to the specific situation of a mass-casualty event. Decisions regarding the implementation of prophylaxis are complex, and drawing parallels from existing guidelines is difficult. For any prophylactic intervention to be implemented effectively, guidance must be simple, straightforward, and logistically undemanding. Critical review during development of this guidance was provided by representatives of the National Association of County and City Health Officials, the Council of State and Territorial Epidemiologists, and representatives of the acute injury care, trauma and emergency response medical communities participating in CDC's Terrorism Injuries: Information, Dissemination and Exchange (TIIDE) project. The recommendations contained in this report represent the consensus of U.S. federal public health officials and reflect the experience and input of public health officials at all levels of government and the acute injury response community.

Widespread outbreak of norovirus gastroenteritis among evacuees of Hurricane Katrina residing in a large "megashelter" in Houston, Texas: lessons learned for prevention.

BACKGROUND: After Hurricane Katrina, an estimated 200,000 persons were evacuated to the Houston metropolitan area, >27,000 of whom were housed in 1 large "megashelter," the Reliant Park Complex. We investigated an outbreak of gastroenteritis reported among the evacuees who resided in the Reliant Park Complex to assess the spread of the infectious agent, norovirus, and to implement and evaluate the effectiveness of interventions used for control. METHODS: Public health authorities conducted surveillance of gastroenteritis among evacuees treated at the Reliant Park Medical Clinic during 2-12 September 2005. Basic demographic and clinical data were recorded. Specimens of stool and vomitus were collected and tested for bacteria, parasites, and viruses. Shelter census data were used to estimate the daily incidence of disease. RESULTS: During a period of 11 days, >1000 patients were treated at the clinic for gastroenteritis, which accounted for 17% of all clinic visits. Norovirus was the sole enteric pathogen identified, but multiple different strains were involved. Among the evacuees residing in the Reliant Park Complex, the incidence of gastroenteritis was estimated to be 4.6 visits per 1000 persons per day, and among the evacuees who resided there for 9 days, 1 (4%) of 24 persons would have been ill. Intensive public health measures were promptly instituted but did not definitively slow the progression of the outbreak of norovirus gastroenteritis. CONCLUSIONS: Our investigation underscores the difficulties in managing such outbreaks in crowded settings and the need for rapid, sensitive laboratory assays to detect norovirus. Additional research is needed to establish more effective measures to control and prevent this highly contagious gastrointestinal illness.

Costs of management of occupational exposures to blood and body fluids.

OBJECTIVE: To determine the cost of management of occupational exposures to blood and body fluids. DESIGN: A convenience sample of 4 healthcare facilities provided information on the cost of management of occupational exposures that varied in type, severity, and exposure source infection status. Detailed information was collected on time spent reporting, managing, and following up the exposures; salaries (including benefits) for representative staff who sustained and who managed exposures; and costs (not charges) for laboratory testing of exposure sources and exposed healthcare personnel, as well as any postexposure prophylaxis taken by the exposed personnel. Resources used were stratified by the phase of exposure management: exposure reporting, initial management, and follow-up. Data for 31 exposure scenarios were analyzed. Costs were given in 2003 US dollars. SETTING: The 4 facilities providing data were a 600-bed public hospital, a 244-bed Veterans Affairs medical center, a 437-bed rural tertiary care hospital, and a 3,500-bed healthcare system. RESULTS: The overall range of costs to manage reported exposures was $71-$4,838. Mean total costs varied greatly by the infection status of the source patient. The overall mean cost for exposures to human immunodeficiency virus (HIV)-infected source patients (n=19, including those coinfected with hepatitis B or C virus) was $2,456 (range, $907-$4,838), whereas the overall mean cost for exposures to source patients with unknown or negative infection status (n=8) was $376 (range, $71-$860). Lastly, the overall mean cost of management of reported exposures for source patients infected with hepatitis C virus (n=4) was $650 (range, $186-$856). CONCLUSIONS: Management of occupational exposures to blood and body fluids is costly; the best way to avoid these costs is by prevention of exposures.

Preventing percutaneous injuries among dental health care personnel.

BACKGROUND: The Occupational Safety and Health Administration and the Centers for Disease Control and Prevention (CDC) recommend that health care personnel (HCP) adopt safer work practices and consider using medical devices with safety features. This article describes the circumstances of percutaneous injuries among a sample of hospital-based dental HCP and estimates the preventability of a subset of these injuries: needlesticks. METHODS: The authors analyzed percutaneous injuries reported by dental HCP in the CDC's National Surveillance System for Health Care Workers (NaSH) from December 1995 through August 2004 to describe the circumstances. RESULTS: Of 360 percutaneous injuries, 36 percent were reported by dentists, 34 percent by oral surgeons, 22 percent by dental assistants, and 4 percent each by hygienists and students. Almost 25 percent involved anesthetic syringe needles. Of 87 needlestick injuries, 53 percent occurred after needle use and during activities in which a safety feature could have been activated (such as during passing and handling) or a safer work practice used. CONCLUSIONS: NaSH data show that needlestick injuries still occur and that a majority occur at a point in the workflow at which safety syringes--in addition to safe work practices and recapping systems--could contribute to injury prevention. CLINICAL IMPLICATIONS: All dental practices should have a comprehensive written program for preventing needlestick injuries that describes procedures for identifying, screening and, when appropriate, adopting safety devices; mechanisms for reporting and providing medical follow-up for percutaneous injuries; and a system for training staff members in safe work practices and the proper use of safety devices.

Updated U.S. Public Health Service guidelines for the management of occupational exposures to HIV and recommendations for postexposure prophylaxis.

This report updates U.S. Public Health Service recommendations for the management of health-care personnel (HCP) who have occupational exposure to blood and other body fluids that might contain human immunodeficiency virus (HIV). Although the principles of exposure management remain unchanged, recommended HIV postexposure prophylaxis (PEP) regimens have been changed. This report emphasizes adherence to HIV PEP when it is indicated for an exposure, expert consultation in management of exposures, follow-up of exposed workers to improve adherence to PEP, and monitoring for adverse events, including seroconversion. To ensure timely postexposure management and administration of HIV PEP, clinicians should consider occupational exposures as urgent medical concerns.

Tuberculin skin testing surveillance of health care personnel.

To estimate the incidence of and assess risk factors for occupational Mycobacterium tuberculosis transmission to health care personnel (HCP) in 5 New York City and Boston health care facilities, performance of prospective tuberculin skin tests (TSTs) was conducted from April 1994 through October 1995. Two-step testing was used at the enrollment of 2198 HCP with negative TST results. Follow-up visits were scheduled for every 6 months. Thirty (1.5%) of 1960 HCP with >/=1 follow-up evaluation had TST conversion (that is, an increase in TST induration of >/=10 mm). Independent risk factors for TST conversion were entering the United States after 1991 and inclusion in a tuberculosis-contact investigation in the workplace. These findings suggest that occupational transmission of M. tuberculosis occurred, as well as possible nonoccupational transmission or late boosting among foreign-born HCP who recently entered the United States. These results demonstrate the difficulty in interpreting TST results and estimating conversion rates among HCP, especially when large proportions of foreign-born HCP are included in surveillance.

Estimate of the annual number of percutaneous injuries among hospital-based healthcare workers in the United States, 1997-1998.

OBJECTIVE: To construct a single estimate of the number of percutaneous injuries sustained annually by healthcare workers (HCWs) in the United States. DESIGN: Statistical analysis. METHODS: We combined data collected in 1997 and 1998 at 15 National Surveillance System for Health Care Workers (NaSH) hospitals and 45 Exposure Prevention Information Network (EPINet) hospitals. The combined data, taken as a sample of all U.S. hospitals, were adjusted for underreporting. The estimate of the number of percutaneous injuries nationwide was obtained by weighting the number of percutaneous injuries at each hospital by the number of admissions in all U.S. hospitals relative to the number of admissions at that hospital. RESULTS: The estimated number of percutaneous injuries sustained annually by hospital-based HCWs was 384,325 (95% confidence interval, 311,091 to 463,922). The number of percutaneous injuries sustained by HCWs outside of the hospital setting was not estimated. CONCLUSIONS: Although our estimate is smaller than some previously published estimates of percutaneous injuries among HCWs, its magnitude remains a concern and emphasizes the urgent need to implement prevention strategies. In addition, improved surveillance could be used to monitor injury trends in all healthcare settings and evaluate the impact of prevention interventions.

Factors influencing health care workers' adherence to work site tuberculosis screening and treatment policies.

BACKGROUND: Despite the known risk of tuberculosis (TB) to health care workers (HCWs), research suggests that many are not fully adherent with local TB infection control policies. The objective of this exploratory study was to identify factors influencing HCWs' adherence to policies for routine tuberculin skin tests (TSTs) and treatment of latent TB infection (LTBI). METHODS: Sixteen focus groups were conducted with clinical and nonclinical staff at 2 hospitals and 2 health departments. Participants were segmented by adherence to TST or LTBI treatment policies. In-depth, qualitative analysis was conducted to identify facilitators and barriers to adherence. RESULTS: Among all focus groups, common themes included the perception that the TST was mandatory, the belief that conducting TSTs at the work site facilitated adherence, and a general misunderstanding about TB epidemiology and pathogenesis. Adherent groups more commonly mentioned facilitators, such as the perception that periodic tuberculin skin testing was protective and the employee health (EH) provision of support services. Barriers, such as the logistic difficulty in obtaining the TST, the perception that LTBI treatment was harmful, and a distrust of EH, emerged consistently in nonadherent groups. CONCLUSIONS: This information may be used to develop more effective interventions for promoting HCW adherence to TB prevention policies. Informed efforts can be implemented in coordination with reevaluations of infection control and EH programs that may be prompted by the publication of the revised TB infection control guidelines issued by the Centers for Disease Control and Prevention in 2005.

Updated US Public Health Service guidelines for the management of occupational exposures to human immunodeficiency virus and recommendations for postexposure prophylaxis.

This report updates US Public Health Service recommendations for the management of healthcare personnel (HCP) who experience occupational exposure to blood and/or other body fluids that might contain human immunodeficiency virus (HIV). Although the principles of exposure management remain unchanged, recommended HIV postexposure prophylaxis (PEP) regimens and the duration of HIV follow-up testing for exposed personnel have been updated. This report emphasizes the importance of primary prevention strategies, the prompt reporting and management of occupational exposures, adherence to recommended HIV PEP regimens when indicated for an exposure, expert consultation in management of exposures, follow-up of exposed HCP to improve adherence to PEP, and careful monitoring for adverse events related to treatment, as well as for virologic, immunologic, and serologic signs of infection. To ensure timely postexposure management and administration of HIV PEP, clinicians should consider occupational exposures as urgent medical concerns, and institutions should take steps to ensure that staff are aware of both the importance of and the institutional mechanisms available for reporting and seeking care for such exposures. The following is a summary of recommendations: (1) PEP is recommended when occupational exposures to HIV occur; (2) the HIV status of the exposure source patient should be determined, if possible, to guide need for HIV PEP; (3) PEP medication regimens should be started as soon as possible after occupational exposure to HIV, and they should be continued for a 4-week duration; (4) new recommendation-PEP medication regimens should contain 3 (or more) antiretroviral drugs (listed in Appendix A ) for all occupational exposures to HIV; (5) expert consultation is recommended for any occupational exposures to HIV and at a minimum for situations described in Box 1 ; (6) close follow-up for exposed personnel ( Box 2 ) should be provided that includes counseling, baseline and follow-up HIV testing, and monitoring for drug toxicity; follow-up appointments should begin within 72 hours of an HIV exposure; and (7) new recommendation-if a newer fourth-generation combination HIV p24 antigen-HIV antibody test is utilized for follow-up HIV testing of exposed HCP, HIV testing may be concluded 4 months after exposure ( Box 2 ); if a newer testing platform is not available, follow-up HIV testing is typically concluded 6 months after an HIV exposure.

Effectiveness of selected surgical masks in arresting vegetative cells and endospores when worn by simulated contagious patients.

OBJECTIVE: The objective of this study was to quantify the effectiveness of selected surgical masks in arresting vegetative cells and endospores in an experimental model that simulated contagious patients. SETTING: Laboratory. METHODS: Five commercially available surgical masks were tested for their ability to arrest infectious agents. Surgical masks were placed over the nose and mouth of mannequin head forms (Simulaids adult model Brad CPR torso). The mannequins were retrofitted with a nebulizer attached to an automated breathing simulator calibrated to a tidal volume of 500 mL/breath and a breathing rate of 20 breaths/min, for a minute respiratory volume of 10 L/min. Aerosols of endospores or vegetative cells were generated with a modified microbiological research establishment-type 6-jet collision nebulizer, while air samples were taken with all-glass impinger (AGI-30) samplers downstream of the point source. All experiments were conducted in a horizontal bioaerosol chamber. RESULTS: Mean arrestance of bioaerosols by the surgical masks ranged from 48% to 68% when the masks were challenged with endospores and from 66% to 76% when they were challenged with vegetative cells. When the arrestance of endospores was evaluated, statistical differences were observed between some pairs, though not all, of the models evaluated. There were no statistically significant differences in arrestance observed between models of surgical masks challenged with vegetative cells. CONCLUSIONS: The arrestance of airborne vegetative cells and endospores by surgical masks worn by simulated contagious patients supports surgical mask use as one of the recommended cough etiquette interventions to limit the transmission of airborne infectious agents.

Feasibility of selected prophylactic barriers in arrestance of airborne bacterial vegetative cells and endospores.

BACKGROUND: Transmission of infection by airborne agents is a risk for health care personnel, patients, and visitors. This risk is heightened in regions without access to environmental controls and personal protective equipment. The ability of 2 prophylactic barriers (ie, semitransparent netting for insect control) to arrest bioaerosols was assessed for potential use within the malarial zones. METHODS: Barriers (pore sizes of 0.8 mm and 0.25 mm) were challenged with bioaerosols of vegetative cells and endospores of Bacillus anthracis strain Sterne 34F2 using a bioaerosol chamber. Barriers were also challenged with airborne inert polystyrene latex particles of known diameters (0.1, 0.43, 0.6, 1.3, 3.2, and 8.0 µm), and the arrestance provided by barrier with the 0.25 mm pore size was expressed as a function of aerodynamic diameter of challenge aerosols. RESULTS: Barrier with the 0.8 mm pore size provided no significant arrestance of aerosols, whereas the barrier with the 0.25 mm pore size provided an 8% arrestance of vegetative cells and a 13% arrestance of endospores. No arrestance at or below the 0.6 µm particle size was observed. CONCLUSION: The level of arrestance provided by these prophylactic barriers does not justify their use as a sole method of preventing transmission.

Tuberculosis epidemiology, diagnosis and infection control recommendations for dental settings: an update on the Centers for Disease Control and Prevention guidelines.

BACKGROUND: Although rates of tuberculosis (TB) in the United States have decreased in recent years, disparities in TB incidence still exist between U.S.-born and foreign-born people (people living in the United States but born outside it) and between white people and nonwhite people. In addition, the number of TB outbreaks among health care personnel and patients has decreased since the implementation of the 1994 Centers for Disease Control and Prevention (CDC) guidelines to prevent transmission of Mycobacterium tuberculosis. In this article, the authors provide updates on the epidemiology of TB, advances in TB diagnostic methods and TB infection control guidelines for dental settings. RESULTS: In 2008, 83 percent of all reported TB cases in the United States occurred in nonwhite people and 17 percent occurred in white people. Foreign-born people had a TB rate about 10 times higher than that of U.S.-born people. New blood assays for M. tuberculosis have been developed to diagnose TB infection and disease. Changes from the 1994 CDC guidelines incorporated into CDC's "Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005" include revised risk classifications, new TB diagnostic methods, decreased frequencies of tuberculin skin testing in various settings and changes in terminology. CLINICAL IMPLICATIONS: Although the principles of TB infection control have remained the same, the changing epidemiology of TB and the advent of new diagnostic methods for TB led to the development of the 2005 update to the 1994 guidelines. Dental health care personnel should be aware of the modifications that are pertinent to dental settings and incorporate them into their overall infection control programs.

Postexposure interventions to prevent infection with HBV, HCV, or HIV, and tetanus in people wounded during bombings and other mass casualty events--United States, 2008: recommendations of the Centers for Disease Control and Prevention and Disaster Medicine and Public Health Preparedness.

People wounded during bombings or other events resulting in mass casualties or in conjunction with the resulting emergency response may be exposed to blood, body fluids, or tissue from other injured people and thus be at risk for bloodborne infections such as hepatitis B virus, hepatitis C virus, human immunodeficiency virus, or tetanus. This report adapts existing general recommendations on the use of immunization and postexposure prophylaxis for tetanus and for occupational and nonoccupational exposures to bloodborne pathogens to the specific situation of a mass casualty event. Decisions regarding the implementation of prophylaxis are complex, and drawing parallels from existing guidelines is difficult. For any prophylactic intervention to be implemented effectively, guidance must be simple, straightforward, and logistically undemanding. Critical review during development of this guidance was provided by representatives of the National Association of County and City Health Officials, the Council of State and Territorial Epidemiologists, and representatives of the acute injury care, trauma, and emergency response medical communities participating in the Centers for Disease Control and Prevention's Terrorism Injuries: Information, Dissemination and Exchange project. There recommendations contained in this report represent the consensus of US federal public health officials and reflect the experience and input of public health officials at all levels of government and the acute injury response community.