Last data update: Apr 22, 2024. (Total: 46599 publications since 2009)
Records 1-30 (of 32 Records) |
Query Trace: McKay S [original query] |
---|
Reply to Gonzales-Luna et al
Gargis AS , Karlsson M , Kamile Rasheed J , Kent AG , McKay SL , Paulick AL , Anderson KF , Adamczyk M , Campbell D , Korhonen LC , McAllister G , Vlachos N , Halpin AL , Lutgring JD , Guh AY , Clifford McDonald L , Elkins CA . Clin Infect Dis 2023 76 (11) 2039-2041 We thank Gonzales-Luna and colleagues [1] for their comments. We agree that laboratories must have access to accurate and standardized methods for antimicrobial susceptibility testing (AST) results to be clinically meaningful. The reference method for performing Clostridioides difficile AST is agar dilution according to Clinical and Laboratory Standards Institute (CLSI) guidelines [2]. The CLSI method for performing AST for anaerobic bacteria recommends that 5 μg/mL of hemin be incorporated into agar dilution plates and that the hemin stock solution should be protected from light and stored at 4°C–8°C for no longer than 1 month [2]. The susceptibility testing done by Gargis et al [3] was performed according to these guidelines, and the hemin stock solution was protected from light. | | Nevertheless, we read with interest the research in recent years [4–6] related to heme-dependent metronidazole resistance, including the reported association between isolates characterized as heme dependent and metronidazole resistant and the presence of a T to G mutation (PnimBG) in the −10 promoter region of the nitroimidazole reductase gene, nimB [5]. While Olaitan et al [5] found that not all heme-dependent metronidazole-resistant isolates contained the PnimBG mutation, Olaitan et al [5] indicate that most do; therefore, the presence of PnimBG may be predictive of resistance. We determined that the nimB mutation was present in 20% of our study isolates (116 of 593), of which 99% (115 of 116) belonged to RT027 (Table 1). The remaining isolate was RT014, the only RT014 isolate containing the PnimBG mutation among the 65 evaluated. |
How real-time case-based malaria surveillance helps Zanzibar get a step closer to malaria elimination: Description of operational platform and resources
Mkali HR , Lalji SM , Al-Mafazy AW , Joseph JJ , Mwaipape OS , Ali AS , Abbas FB , Ali MH , Hassan WS , Reaves EJ , Kitojo C , Serbantez N , Kabula BI , Nyinondi SS , McKay M , Cressman G , Ngondi JM , Reithinger R . Glob Health Sci Pract 2023 11 (5) Testing and treating asymptomatic populations have the potential to reduce the population's parasite reservoir and reduce malaria transmission. Zanzibar's malaria case notification (MCN) platform collects detailed sociodemographic and epidemiological data from all confirmed malaria cases to inform programmatic decision-making. We describe the design and operationalization process of the platform and other malaria surveillance resources that are enabling Zanzibar's progress toward malaria elimination.The MCN platform consists of an interactive short message service (SMS) system for case notification, a software application for Android mobile devices, a visual question set and workflow manager, a back-end database server, and a web browser-based application for data analytics, configuration, and management. Malaria case data were collected from August 2012 to December 2021 and reported via SMS from all public and private health facilities to a central database and then to district malaria surveillance officers' mobile devices. Data included patient names, shehia (administrative area), and date of diagnosis, enabling officers to track patients, ideally within 24 hours of reporting. Patients' household members were tested for malaria using conventional rapid diagnostic tests (RDTs). Treatment using artemisinin-based combination therapy was provided for persons testing positive.Between 2012 and 2021, a total of 48,899 index malaria cases were confirmed at health facilities, 22,152 (45.3%) within 24 hours of reporting; 41,886 (85.7%) cases were fully investigated and followed up to the household level. A total of 111,811 additional household members were tested with RDTs, of whom 10,602 (9.5%) were malaria positive.The MCN platform reports malaria case data in near real time, enabling prompt follow-up of index cases and prompt testing and treatment of members in index case households. Along with routine testing and treatment and other preventive interventions, the MCN platform is foundational to the programmatic efforts in further reducing malaria and ultimately eliminating autochthonous malaria transmission in Zanzibar. |
How enhanced surveillance is helping Zanzibar get one step closer to malaria elimination: description of the operational platforms and resources for real-time case-based malaria surveillance (preprint)
Mkali HR , Lalji SM , Al-Mafazy AW , Joseph JJ , Mwaipape OS , Ali AS , Abbas FB , Ali MH , Hassan WS , Reaves EJ , Kitojo C , Serbantez N , Kabula BI , Nyinondi SS , McKay M , Cressman G , Ngondi JM , Reithinger R . medRxiv 2023 24 Testing and treating asymptomatic populations has the potential to reduce the population's parasite reservoir and reduce malaria transmission. Zanzibar's electronic malaria case notification (MCN) platform collects detailed socio-demographic and epidemiological data from all confirmed malaria cases to inform programmatic decision-making. This Field Action Report describes the design and operationalization process of the platform, as well as other malaria surveillance resources that are enabling Zanzibar to progress toward malaria elimination. The MCN platform consists of an interactive short message service (SMS) system for case notification, a software application for Android mobile devices, a visual question set and workflow manager, a back-end database server, and a web browser-based application for data analytics, configuration, and management. Malaria case data were collected from August 2012 to December 2021 and reported via SMS from all public and private health facilities to a central database, and then to District Malaria Surveillance Officers' mobile devices. Data included patient names, shehia and date of diagnosis, which enabled the officers to track patients, ideally within 24 hours of reporting. Patients' household members were tested for malaria using conventional rapid diagnostic tests (RDTs). Treatment using artemisinin-based combination therapy was provided for persons testing positive. Between 2012 and 2021, a total of 48,899 index malaria cases were confirmed at health facilities, 22,152 (45.3%) of whom within 24 hours of reporting; 41,886 (85.7%) cases were fully investigated and followed up to household level. A total of 111,811 additional household members were tested with RDTs, of whom 10,602 (9.5%) were malaria positive. The MCN platform reports malaria case data in near real-time, enabling prompt testing and treatment of members in index case households. Along with routine testing and treatment and other preventive interventions, combined with comprehensive reactive-case detection efforts, the continued use of the MCN platform is likely to reduce malaria transmission and malaria morbidity even further, thereby enhancing malaria elimination in Zanzibar. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC 4.0 International license. |
Longitudinal serologic and viral testing post-SARS-CoV-2 infection and post-receipt of mRNA COVID-19 vaccine in a nursing home cohort-Georgia, October 2020-April 2021 (preprint)
Tobolowsky FA , Waltenburg MA , Moritz ED , Haile M , DaSilva JC , Schuh AJ , Thornburg NJ , Westbrook A , McKay SL , LaVoie SP , Folster JM , Harcourt JL , Tamin A , Stumpf MM , Mills L , Freeman B , Lester S , Beshearse E , Lecy KD , Brown LG , Fajardo G , Negley J , McDonald LC , Kutty PK , Brown AC , Bhatnagar A , Bryant-Genevier J , Currie DW , Campbell D , Gilbert SE , Hatfield KM , Jackson DA , Jernigan JA , Dawson JL , Hudson MJ , Joseph K , Reddy SC , Wilson MM . medRxiv 2022 01 (10) e0275718 Importance: There are limited data describing SARS-CoV-2-specific immune responses and their durability following infection and vaccination in nursing home residents. Objective(s): To evaluate the quantitative titers and durability of binding antibodies detected after SARSCoV-2 infection and subsequent COVID-19 vaccination. Design(s): A prospective longitudinal evaluation included nine visits over 150 days; visits included questionnaire administration, blood collection for serology, and paired anterior nasal specimen collection for testing by BinaxNOWTM COVID-19 Ag Card (BinaxNOW), reverse transcription polymerase chain reaction (RT-PCR), and viral culture. Setting(s): A nursing home during and after a SARS-CoV-2 outbreak. Participant(s): 11 consenting SARS-CoV-2-positive nursing home residents. Main Outcomes and Measures: SARS-CoV-2 testing (BinaxNOWTM, RT-PCR, viral culture); quantitative titers of binding SARS-CoV-2 antibodies post-infection and post-vaccination (beginning after the first dose of the primary series). Result(s): Of 10 participants with post-infection serology results, 9 (90%) had detectable Pan-Ig, IgG, and IgA antibodies and 8 (80%) had detectable IgM antibodies. At first antibody detection post-infection, two-thirds (6/9, 67%) of participants were RT-PCR-positive but none were culture positive. Ten participants received vaccination; all had detectable Pan-Ig, IgG, and IgA antibodies through their final observation <=90 days post-first dose. Post-vaccination geometric means of IgG titers were 10-200-fold higher than post-infection. Conclusions and Relevance: Nursing home residents in this cohort mounted robust immune responses to SARS-CoV-2 post-infection and post-vaccination. The augmented antibody responses post-vaccination are potential indicators of enhanced protection that vaccination may confer on previously infected nursing home residents. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available for use under a CC0 license. |
Multiple MIS-C readmissions and giant coronary aneurysm after COVID-19 illness and vaccination: A case report
Haq K , Anyalechi EG , Schlaudecker EP , McKay R , Kamidani S , Manos CK , Oster ME . Pediatr Infect Dis J 2022 42 (3) e64-e69 BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) rarely involves delayed giant coronary aneurysms, multiple readmissions or occurrence after COVID-19 vaccination. METHODS: We describe a child with all 3 of these unusual features. We discuss his clinical presentation, medical management, review of the current literature and CDC guidance recommendations regarding further vaccinations. RESULTS: A 5-year-old boy had onset of MIS-C symptoms 55 days after COVID-19 illness and 15 days after receiving his first BNT162b2 COVID-19 vaccination. He was admitted 3 times for MIS-C, and twice after his steroid dose was tapered. On his initial admission, he was given intravenous immunoglobulin and steroids. During his second admission, new, moderate coronary dilation was noted, and he was treated with intravenous immunoglobulin and steroids. At his last admission, worsening coronary dilation was noted, and he was treated with infliximab and steroids. During follow-up, he had improvement in his coronary artery dilatation. However, his inflammatory markers increased after steroid wean, and his steroid taper was further extended, after which time his inflammatory markers improved. This is the only such reported case of a patient who was admitted 3 times for MIS-C complications after COVID-19 vaccination. CONCLUSION: MIS-C rarely involves delayed giant coronary aneurysms, multiple readmissions, or occurrence after COVID-19 vaccination. Whether our patient's COVID-19 vaccine 6 weeks after COVID-19 illness contributed to his MIS-C is unknown. After consultation with the CDC-funded Clinical Immunization Safety Assessment Project, the patient's care team decided against further COVID-19 vaccination until at least 3 months post normalization of inflammatory markers. |
Longitudinal serologic and viral testing post-SARS-CoV-2 infection and post-receipt of mRNA COVID-19 vaccine in a nursing home cohort-Georgia, October 2020‒April 2021.
Tobolowsky FA , Waltenburg MA , Moritz ED , Haile M , DaSilva JC , Schuh AJ , Thornburg NJ , Westbrook A , McKay SL , LaVoie SP , Folster JM , Harcourt JL , Tamin A , Stumpf MM , Mills L , Freeman B , Lester S , Beshearse E , Lecy KD , Brown LG , Fajardo G , Negley J , McDonald LC , Kutty PK , Brown AC , Bhatnagar A , Bryant-Genevier J , Currie DW , Campbell D , Gilbert SE , Hatfield KM , Jackson DA , Jernigan JA , Dawson JL , Hudson MJ , Joseph K , Reddy SC , Wilson MM . PLoS One 2022 17 (10) e0275718 There are limited data describing SARS-CoV-2-specific immune responses and their durability following infection and vaccination in nursing home residents. We conducted a prospective longitudinal evaluation of 11 consenting SARS-CoV-2-positive nursing home residents to evaluate the quantitative titers and durability of binding antibodies detected after SARS-CoV-2 infection and subsequent COVID-19 vaccination. The evaluation included nine visits over 150 days from October 25, 2020, through April 1, 2021. Visits included questionnaire administration, blood collection for serology, and paired anterior nasal specimen collection for testing by BinaxNOW™ COVID-19 Ag Card (BinaxNOW), reverse transcription polymerase chain reaction (RT-PCR), and viral culture. We evaluated quantitative titers of binding SARS-CoV-2 antibodies post-infection and post-vaccination (beginning after the first dose of the primary series). The median age among participants was 74 years; one participant was immunocompromised. Of 10 participants with post-infection serology results, 9 (90%) had detectable Pan-Ig, IgG, and IgA antibodies, and 8 (80%) had detectable IgM antibodies. At first antibody detection post-infection, two-thirds (6/9, 67%) of participants were RT-PCR-positive, but none were culture- positive. Ten participants received vaccination; all had detectable Pan-Ig, IgG, and IgA antibodies through their final observation ≤90 days post-first dose. Post-vaccination geometric means of IgG titers were 10-200-fold higher than post-infection. Nursing home residents in this cohort mounted robust immune responses to SARS-CoV-2 post-infection and post-vaccination. The augmented antibody responses post-vaccination are potential indicators of enhanced protection that vaccination may confer on previously infected nursing home residents. |
Reference Susceptibility Testing and Genomic Surveillance of Clostridioides difficile, United States, 2012-17.
Gargis AS , Karlsson M , Paulick AL , Anderson KF , Adamczyk M , Vlachos N , Kent AG , McAllister GA , McKay SL , Halpin AL , Albrecht V , Campbell D , Korhonen L , Elkins CA , Rasheed JK , Guh AY , McDonald LC , Lutgring JD . Clin Infect Dis 2022 76 (5) 890-896 BACKGROUND: Antimicrobial susceptibility testing (AST) is not routinely performed for Clostridioides difficile and data evaluating minimum inhibitory concentrations (MICs) are limited. We performed AST and whole genome sequencing (WGS) for 593 C. difficile isolates collected between 2012-2017 through the Centers for Disease Control and Prevention's Emerging Infections Program. METHODS: MICs to six antimicrobial agents (ceftriaxone, clindamycin, meropenem, metronidazole, moxifloxacin, and vancomycin) were determined using the reference agar dilution method according to Clinical and Laboratory Standards Institute guidelines. WGS was performed on all isolates to detect the presence of genes or mutations previously associated with resistance. RESULTS: Among all isolates, 98.5% displayed a vancomycin MIC ≤ 2 μg/mL and 97.3% displayed a metronidazole MIC ≤ 2 μg/mL. Ribotype 027 (RT027) isolates displayed higher vancomycin MICs (MIC50: 2 μg/mL; MIC90: 2 μg/mL) than non-RT027 isolates (MIC50: 0.5 μg/mL; MIC90: 1 μg/mL) (P < 0.01). No vanA/B genes were detected. RT027 isolates also showed higher MICs to clindamycin and moxifloxacin and were more likely to harbor associated resistance genes or mutations. CONCLUSIONS: Elevated MICs to antibiotics used for treatment of C. difficile infection were rare and there was no increase in MICs over time. The lack of vanA/B genes or mutations consistently associated with elevated vancomycin MICs suggests there are multifactorial mechanisms of resistance. Ongoing surveillance of C. difficile using reference AST and WGS to monitor MIC trends and the presence of antibiotic resistance mechanisms is essential. |
Provider perspectives: Identification and follow-up of infants who are deaf or hard of hearing
Cree RA , Bitsko R , Grimm C , Nash A , Cahill E , Dunham E , Logan N , McKay SL , Martinez DR , Gaffney M . Am J Perinatol 2022 OBJECTIVE: Without timely screening, diagnosis, and intervention, hearing loss can cause significant delays in a child's speech, language, social, and emotional development. In 2019, Texas had nearly twice the average rate of loss to follow-up (LFU) or loss to documentation (LTD; i.e., missing documentation of services received) among infants who did not pass their newborn hearing screening compared to the United States overall (51.1% vs. 27.5%). We aimed to identify factors contributing to LFU/LTD among infants who do not pass their newborn hearing screening in Texas. STUDY DESIGN: Data were collected through semi-structured qualitative interviews with 56 providers along the hearing care continuum, including hospital newborn hearing screening program staff, audiologists, primary care physicians, and early intervention (EI) program staff located in three rural and urban public health regions in Texas. Following recording and transcription of the interviews, we used qualitative data analysis software to analyze themes using a conventional content analysis approach. RESULTS: Frequently cited barriers included problems with family access to care, difficulty contacting patients, problems with communication between providers and referrals, lack of knowledge among providers and parents, and problems using the online reporting system. Providers in rural areas more often mentioned problems with family access to care and contacting families compared to providers in urban areas. CONCLUSION: These findings provide insight into strategies that public health professionals and health care providers can use to work together to help further increase the number of children identified early who may benefit from EI services. |
Public health response to a case of paralytic poliomyelitis in an unvaccinated person and detection of poliovirus in wastewater - New York, June-August 2022
Link-Gelles R , Lutterloh E , Schnabel Ruppert P , Backenson PB , St George K , Rosenberg ES , Anderson BJ , Fuschino M , Popowich M , Punjabi C , Souto M , McKay K , Rulli S , Insaf T , Hill D , Kumar J , Gelman I , Jorba J , Ng TFF , Gerloff N , Masters NB , Lopez A , Dooling K , Stokley S , Kidd S , Oberste MS , Routh J . MMWR Morb Mortal Wkly Rep 2022 71 (33) 1065-1068 On July 18, 2022, the New York State Department of Health (NYSDOH) notified CDC of detection of poliovirus type 2 in stool specimens from an unvaccinated immunocompetent young adult from Rockland County, New York, who was experiencing acute flaccid weakness. The patient initially experienced fever, neck stiffness, gastrointestinal symptoms, and limb weakness. The patient was hospitalized with possible acute flaccid myelitis (AFM). Vaccine-derived poliovirus type 2 (VDPV2) was detected in stool specimens obtained on days 11 and 12 after initial symptom onset. To date, related Sabin-like type 2 polioviruses have been detected in wastewater* in the patient's county of residence and in neighboring Orange County up to 25 days before (from samples originally collected for SARS-CoV-2 wastewater monitoring) and 41 days after the patient's symptom onset. The last U.S. case of polio caused by wild poliovirus occurred in 1979, and the World Health Organization Region of the Americas was declared polio-free in 1994. This report describes the second identification of community transmission of poliovirus in the United States since 1979; the previous instance, in 2005, was a type 1 VDPV (1). The occurrence of this case, combined with the identification of poliovirus in wastewater in neighboring Orange County, underscores the importance of maintaining high vaccination coverage to prevent paralytic polio in persons of all ages. |
Are vancomycin non-susceptible clostridioides difficile strains emerging
Lutgring JD , McKay SL , Gargis AS , Halpin AL , McDonald LC . Clin Infect Dis 2022 75 (9) 1677-1678 TO THE EDITORWe read with concern the report by Darkoh and colleagues describing vancomycin resistance in Clostridioides difficile isolates recovered from patients in Houston, Texas, and Nairobi, Kenya [1]. The authors suggested that vancomycin resistance, which they found to be common, may lead to therapeutic failure for patients infected with C. difficile and that routine antimicrobial susceptibility testing (AST) should be expanded. The authors report that 26% of C. difficile toxin gene-positive patients in Houston and 67% of sequential hospitalized patients in Nairobi with acute diarrhea had growth on primary screening media containing 4g/mL vancomycin. This alarmingly high proportion of a vancomycin resistant phenotype exceeds initial treatment failure rates reported in the literature [2], calling into question the reliability of these findings. |
Molecular Epidemiology of Carbapenem-Resistant Acinetobacter baumannii in the United States, 2013-2017.
McKay SL , Vlachos N , Daniels JB , Albrecht VS , Stevens VA , Rasheed JK , Johnson JK , Lutgring JD , Sjölund-Karlsson M , Halpin AL . Microb Drug Resist 2022 28 (6) 645-653 Healthcare-associated carbapenem-resistant Acinetobacter baumannii (CRAB) infections are a serious threat associated with global epidemic clones and a variety of carbapenemase gene classes. In this study, we describe the molecular epidemiology, including whole-genome sequencing analysis and antimicrobial susceptibility profiles of 92 selected, nonredundant CRAB collected through public health efforts in the United States from 2013 to 2017. Among the 92 isolates, the Oxford (OX) multilocus sequence typing scheme identified 30 sequence types (STs); the majority of isolates (n = 59, 64%) represented STs belonging to the international clonal complex 92 (CC92(OX)). Among these, ST208(OX) (n = 21) and ST281(OX) (n = 20) were the most common. All isolates carried an OXA-type carbapenemase gene, comprising 20 alleles. Ninety isolates (98%) encoded an intrinsic OXA-51-like enzyme; 67 (73%) harbored an additional acquired bla(OXA) gene, most commonly bla(OXA-23) (n = 45; 49%). Compared with isolates harboring only intrinsic oxacillinase genes, acquired bla(OXA) gene presence was associated with higher prevalence of resistance and a higher median minimum inhibitory concentration to the carbapenem imipenem (64 μg/mL vs. 8 μg/mL), and antibiotics from other drug classes, including penicillin, aminoglycosides, cephalosporins, and polymyxins. These data illustrate the wide distribution of CC92(OX) and high prevalence of acquired bla(OXA) carbapenemase genes among CRAB in the United States. |
Comparative pulmonary toxicities of lunar dusts and terrestrial dusts (TiO(2) & SiO(2)) in rats and an assessment of the impact of particle-generated oxidants on the dusts' toxicities
Lam CW , Castranova V , Zeidler-Erdely PC , Renne R , Hunter R , McCluskey R , Scully RR , Wallace WT , Zhang Y , Ryder VE , Cooper B , McKay D , McClellan RO , Driscoll KE , Gardner DE , Barger M , Meighan T , James JT . Inhal Toxicol 2022 34 51-67 Humans will set foot on the Moon again soon. The lunar dust (LD) is potentially reactive and could pose an inhalation hazard to lunar explorers. We elucidated LD toxicity and investigated the toxicological impact of particle surface reactivity (SR) using three LDs, quartz, and TiO(2). We first isolated the respirable-size-fraction of an Apollo-14 regolith and ground two coarser samples to produce fine LDs with increased SR. SR measurements of these five respirable-sized dusts, determined by their in-vitro ability to generate hydroxyl radicals (OH), showed that ground LDs>unground LDTiO(2) quartz. Rats were each intratracheally instilled with 0, 1, 2.5, or 7.5mg of a test dust. Toxicity biomarkers and histopathology were assessed up to 13weeks after the bolus instillation. All dusts caused dose-dependent-increases in pulmonary lesions and toxicity biomarkers. The three LDs, which possessed mineral compositions/properties similar to Arizona volcanic ash, were moderately toxic. Despite a 14-fold OH difference among these three LDs, their toxicities were indistinguishable. Quartz produced the lowest OH amount but showed the greatest toxicity. Our results showed no correlation between the toxicity of mineral dusts and their ability to generate free radicals. We also showed that the amounts of oxidants per neutrophil increased with doses, time and the cytotoxicity of the dusts in the lung, which supports our postulation that dust-elicited neutrophilia is the major persistent source of oxidative stress. These results and the discussion of the crucial roles of the short-lived, continuously replenished neutrophils in dust-induced pathogenesis are presented. |
Molecular Characterization of Carbapenem-Resistant Enterobacterales Collected in the United States.
Karlsson M , Lutgring JD , Ansari U , Lawsin A , Albrecht V , McAllister G , Daniels J , Lonsway D , McKay S , Beldavs Z , Bower C , Dumyati G , Gross A , Jacob J , Janelle S , Kainer MA , Lynfield R , Phipps EC , Schutz K , Wilson L , Witwer ML , Bulens SN , Walters MS , Duffy N , Kallen AJ , Elkins CA , Rasheed JK . Microb Drug Resist 2022 28 (4) 389-397 Carbapenem-resistant Enterobacterales (CRE) are a growing public health concern due to resistance to multiple antibiotics and potential to cause health care-associated infections with high mortality. Carbapenemase-producing CRE are of particular concern given that carbapenemase-encoding genes often are located on mobile genetic elements that may spread between different organisms and species. In this study, we performed phenotypic and genotypic characterization of CRE collected at eight U.S. sites participating in active population- and laboratory-based surveillance of carbapenem-resistant organisms. Among 421 CRE tested, the majority were isolated from urine (n = 349, 83%). Klebsiella pneumoniae was the most common organism (n = 265, 63%), followed by Enterobacter cloacae complex (n = 77, 18%) and Escherichia coli (n = 50, 12%). Of 419 isolates analyzed by whole genome sequencing, 307 (73%) harbored a carbapenemase gene; variants of bla(KPC) predominated (n = 299, 97%). The occurrence of carbapenemase-producing K. pneumoniae, E. cloacae complex, and E. coli varied by region; the predominant sequence type within each genus was ST258, ST171, and ST131, respectively. None of the carbapenemase-producing CRE isolates displayed resistance to all antimicrobials tested; susceptibility to amikacin and tigecycline was generally retained. |
Risk factors associated with malaria infection identified through reactive case detection in Zanzibar, 2012-2019
Mkali HR , Reaves EJ , Lalji SM , Al-Mafazy AW , Joseph JJ , Ali AS , Abbas FB , Ali MH , Hassan WS , Kitojo C , Serbantez N , Kabula BI , Nyinondi SS , Bisanzio D , McKay M , Eckert E , Reithinger R , Ngondi JM . Malar J 2021 20 (1) 485 BACKGROUND: Over the past two decades, Zanzibar substantially reduced malaria burden. As malaria decreases, sustainable improvements in control interventions may increasingly depend on accurate knowledge of malaria risk factors to further target interventions. This study aimed to investigate the risk factors associated with malaria infection in Zanzibar. METHODS: Surveillance data from Zanzibar's Malaria Case Notification system from August 2012 and December 2019 were analyzed. This system collects data on malaria cases passively detected and reported by all health facilities (index cases), and household-based reactive case detection (RCD) activities linked to those primary cases. All members of households of the index cases were screened for malaria using a malaria rapid diagnostic test (RDT). Individuals with a positive RDT were treated with artemisinin-based combination therapy. Univariate and multivariate logistic regression analyses were done to investigate the association between RDT positivity among the household members and explanatory factors with adjustment for seasonality and clustering at Shehia level. RESULTS: A total of 30,647 cases were reported of whom household RCD was completed for 21,443 (63%) index case households and 85,318 household members tested for malaria. The findings show that younger age (p-value for trend [Ptrend] < 0.001), history of fever in the last 2 weeks (odds ratio [OR] = 35.7; 95% CI 32.3-39.5), travel outside Zanzibar in the last 30 days (OR = 2.5; 95% CI 2.3-2.8) and living in Unguja (OR = 1.2; 95% CI 1.0-1.5) were independently associated with increased odds of RDT positivity. In contrast, male gender (OR=0.8; 95% CI 0.7-0.9), sleeping under an LLIN the previous night (OR = 0.9; 95% CI 0.7-0.9), having higher household net access (Ptrend < 0.001), and living in a household that received IRS in the last 12 months (OR = 0.8; 95% CI 0.7-0.9) were independently associated with reduced odds of RDT positivity. A significant effect modification of combining IRS and LLIN was also noted (OR = 0.7; 95% CI 0.6-0.8). CONCLUSIONS: The findings suggest that vector control remains an important malaria prevention intervention: they underscore the need to maintain universal access to LLINs, the persistent promotion of LLIN use, and application of IRS. Additionally, enhanced behavioural change and preventive strategies targeting children aged 5-14 years and travellers are needed. |
Repeated Antigen Testing Among SARS-CoV-2-Positive Nursing Home Residents.
Moritz ED , McKay SL , Tobolowsky FA , LaVoie SP , Waltenburg MA , Lecy KD , Thornburg NJ , Harcourt JL , Tamin A , Folster JM , Negley J , Brown AC , McDonald LC , Kutty PK . Infect Control Hosp Epidemiol 2021 43 (12) 1-10 Repeated antigen testing of 12 SARS-CoV-2-positive nursing home residents using Abbott BinaxNOW™ identified 9/9 (100%) culture-positive specimens up to 6 days after initial positive test. Antigen positivity lasted 2-24 days. Antigen positivity might last beyond the infectious period, but was reliable in residents with evidence of early infection. |
Performance Evaluation of Serial SARS-CoV-2 Rapid Antigen Testing During a Nursing Home Outbreak.
McKay SL , Tobolowsky FA , Moritz ED , Hatfield KM , Bhatnagar A , LaVoie SP , Jackson DA , Lecy KD , Bryant-Genevier J , Campbell D , Freeman B , Gilbert SE , Folster JM , Medrzycki M , Shewmaker PL , Bankamp B , Radford KW , Anderson R , Bowen MD , Negley J , Reddy SC , Jernigan JA , Brown AC , McDonald LC , Kutty PK . Ann Intern Med 2021 174 (7) 945-951 BACKGROUND: To address high COVID-19 burden in U.S. nursing homes, rapid SARS-CoV-2 antigen tests have been widely distributed in those facilities. However, performance data are lacking, especially in asymptomatic people. OBJECTIVE: To evaluate the performance of SARS-CoV-2 antigen testing when used for facility-wide testing during a nursing home outbreak. DESIGN: A prospective evaluation involving 3 facility-wide rounds of testing where paired respiratory specimens were collected to evaluate the performance of the BinaxNOW antigen test compared with virus culture and real-time reverse transcription polymerase chain reaction (RT-PCR). Early and late infection were defined using changes in RT-PCR cycle threshold values and prior test results. SETTING: A nursing home with an ongoing SARS-CoV-2 outbreak. PARTICIPANTS: 532 paired specimens collected from 234 available residents and staff. MEASUREMENTS: Percentage of positive agreement (PPA) and percentage of negative agreement (PNA) for BinaxNOW compared with RT-PCR and virus culture. RESULTS: BinaxNOW PPA with virus culture, used for detection of replication-competent virus, was 95%. However, the overall PPA of antigen testing with RT-PCR was 69%, and PNA was 98%. When only the first positive test result was analyzed for each participant, PPA of antigen testing with RT-PCR was 82% among 45 symptomatic people and 52% among 343 asymptomatic people. Compared with RT-PCR and virus culture, the BinaxNOW test performed well in early infection (86% and 95%, respectively) and poorly in late infection (51% and no recovered virus, respectively). LIMITATION: Accurate symptom ascertainment was challenging in nursing home residents; test performance may not be representative of testing done by nonlaboratory staff. CONCLUSION: Despite lower positive agreement compared with RT-PCR, antigen test positivity had higher agreement with shedding of replication-competent virus. These results suggest that antigen testing could be a useful tool to rapidly identify contagious people at risk for transmitting SARS-CoV-2 during nascent outbreaks and help reduce COVID-19 burden in nursing homes. PRIMARY FUNDING SOURCE: None. |
Effects of Access to Legal Same-Sex Marriage on Marriage and Health
Carpenter CS , Eppink ST , Gonzales G , McKay T . J Policy Anal Manage 2021 40 (2) 376-411 We provide the first comprehensive evidence on the effects of access to legal same-sex marriage (SSM) on marriage and adult health using the full rollout of marriage equality across the United States. Using data from the CDC BRFSS from 2000 to 2017, we relate changes in outcomes for individuals in same-sex households (SSH) coincident with adoption of legal SSM in two-way fixed effects models. A substantial share of these households includes gay and lesbian couples. For men in SSH, we find robust evidence that access to legal SSM significantly increased marriage take-up, health insurance coverage, access to care, and healthcare utilization. Results for women in SSH are inconclusive apart from a clear increase in marriage take-up. Our results provide the first evidence that legal access to SSM significantly improved health for adult gay men. |
How adequate is measles surveillance in the United States Investigations of measles-like illness, 2010-2017
McKay SL , Leung J , Gastañaduy PA , Routh JA , Harpaz R . Hum Vaccin Immunother 2020 17 (3) 1-7 Given the availability of an effective and safe vaccine, the World Health Organization (WHO) declared that global measles eradication is achievable, and measles elimination goals have since been established as interim steps toward eradication. As part of a strategy to maintain elimination, the Pan American Health Organization (PAHO) and WHO stipulate a minimum annual reporting rate of discarded non-measles cases of ≥2 per 100,000 population, in order to ensure sensitive surveillance and adequate investigative effort. With its effective vaccination program, the United States in 2000 was among the first countries to verify elimination, although subsequently, it has not routinely reported discarded rates. We estimated MLI investigation rates among insured individuals during 2010-2017, using data from the MarketScan® databases. We defined "MLI investigations" as measles serologic testing within 5 days following diagnostic codes for measles-compatible symptoms and conditions. We provide a rationale for pre-specifying three subgroups for analysis: children aged ≤15 years; males aged 16-22 years excluding data from summer months; and males aged ≥23 years. MLI investigation rates ranged from 6.6─26.4 per 100,000, remaining stable over time except during the 2015 measles outbreaks when rates increased, particularly among young children. In addition to high vaccine uptake, measles elimination requires ongoing vigilance by clinicians and high-quality, case-based surveillance. Estimated rates of MLI investigations in this U.S. population suggesting that the quality of measles surveillance is sufficiently sensitive to detect endemic measles circulation if it were to be occurring. |
Evidence-based interventions for high blood pressure and glycemic control among Illinois health systems
Price JD , Jayaprakash M , McKay CM , Amerson NL , Jimenez PL , Barbour KE , Cunningham TJ . Prev Chronic Dis 2020 17 E08 INTRODUCTION: Evidence-based interventions (referral, team-based care, self-management, and self-monitoring) for chronic disease management are well documented and widely used by Federally Qualified Health Centers (FQHCs). However, how these interventions are implemented varies substantially. METHODS: The Illinois Health Information Systems Survey was deployed to 49 FQHCs. Responses were grouped into 4 distinct policies, systems, and processes (P/S/P) categories: internal policies/workflows, huddles (brief meetings), electronic health record alerts/tracking tools, and case manager/coordinator interaction. Responses were then direct-matched to the 2016 Health Resources and Services and Administration Uniform Data System clinical quality indicator (QI) percent scores. Descriptive statistics were generated and level of significance (P < .05) was tested for hypertension and type 2 diabetes mellitus. RESULTS: The total number of P/S/Ps in place for hypertension ranged from 0 to 13 (mean, 6.9) and 0 to 8 for diabetes (mean, 5.1). Meeting or exceeding the national mean QI percent score for controlled blood pressure (62.4%) was significant among FQHCs with 9 or more P/S/Ps compared with those with 8 or fewer P/S/Ps. A positive association in clinical QI percent score was found among organizations that had 3 or more P/S/Ps (for all 4 intervention areas), although none were significant. CONCLUSION: An assessment of the types of P/S/Ps used to implement evidence-based interventions for hypertension and diabetes management is a first in Illinois. Initial results support some relationship between the number of P/S/Ps implemented and clinical QI percent score for both hypertension and diabetes. |
Herpes zoster risk in immunocompromised adults in the United States: A systematic review
McKay SL , Guo A , Pergam SA , Dooling K . Clin Infect Dis 2019 71 (7) e125-e134 BACKGROUND: The primary reported risk factors for herpes zoster (HZ) are increasing age and immunodeficiency yet estimates of HZ risk by immunocompromising condition have not been well characterized. We undertook a systematic review of the literature to estimate HZ risk in five categories of immunocompromised patients. METHODS: We systematically reviewed studies examining risk of HZ and its complications in adult patients with hematopoietic cell transplants (HCT), cancer (hematologic and solid tumor), HIV, and solid organ transplant (SOT; kidney and other). We identified studies in Pubmed, Embase, Cochrane, Scopus, and clinicaltrials.gov that presented original data from studies in the United States published after 1992 (1996 for HIV). We assessed risk of bias with Cochrane or GRADE methods. RESULTS: We identified and screened 3,765 records and synthesized 34 studies with low or moderate risk of bias. The majority of studies included (32/34) reported at least one estimate of HZ cumulative incidence (range=0%-41%). Twelve studies reported HZ incidence, which varied widely within and between immunocompromised populations. Incidence estimates ranged between 9 and 92 HZ cases/1,000 patient-years and were highest in HCT, followed by hematologic malignancies, SOT, solid tumor malignancies, and lowest in HIV patients. Among 17 studies of HCT patients, absent or <1 year of post-transplant antiviral prophylaxis were associated with higher HZ cumulative incidence. CONCLUSIONS: HZ is common among all immunocompromised populations studied-exceeding expected HZ incidence among immunocompetent adults >/=60 years. Better evidence of incidence of HZ complications and severity in immunocompromised populations are needed to inform economic and HZ vaccine policy analyses. |
Notes from the field: Measles outbreaks from imported cases in orthodox Jewish communities - New York and New Jersey, 2018-2019
McDonald R , Ruppert PS , Souto M , Johns DE , McKay K , Bessette N , McNulty LX , Crawford JE , Bryant P , Mosquera MC , Frontin S , Deluna-Evans T , Regenye DE , Zaremski EF , Landis VJ , Sullivan B , Rumpf BE , Doherty J , Sen K , Adler E , DiFedele L , Ostrowski S , Compton C , Rausch-Phung E , Gelman I , Montana B , Blog D , Hutton BJ , Zucker HA . MMWR Morb Mortal Wkly Rep 2019 68 (19) 444-445 On October 1, 2018, the Rockland County (New York) Department of Health (RCDOH) alerted the New York State Department of Health (NYSDOH) of an unvaccinated teenaged traveler with diagnosed measles. During the next 17 days, RCDOH learned of an additional six unvaccinated travelers with measles. On October 24, 2018, the Ocean County (New Jersey) Health Department alerted the New Jersey Department of Health (NJDOH) of a case of measles in an international traveler, with rash onset October 17. The unvaccinated travelers reported recent travel in Israel, where an outbreak of approximately 3,150 cases of measles is ongoing (1). Investigations during October 1, 2018–April 30, 2019, identified 242 laboratory-confirmed and epidemiologically linked measles cases in New York, excluding New York City, and during October 17, 2018–November 30, 2018, identified 33 in New Jersey (Figure). The cases of measles were primarily in members of orthodox Jewish communities. |
Notes From The Field: Mumps outbreak in a recently vaccinated population - Kosrae, Federated States of Micronesia, August-December, 2017
McKay SL , Kambui A , Taulung LA , Tippins A , Eckert M , Wharton AK , McNall RJ , Hickman C , Hancock WT , Apaisam C , Judicpa P , Patel M , Routh J . MMWR Morb Mortal Wkly Rep 2019 68 (4) 95-96 On August 6, 2017, the Kosrae Department of Health Services (KDHS) in the Federated States of Micronesia identified a confirmed case of mumps in a Kosrae resident who had 2 documented doses of measles-mumps-rubella (MMR) vaccine. The patient aged 18 years had recently traveled to Seattle, Washington, which was experiencing a mumps outbreak among members of its Pacific Islander population. Other Pacific Islands were concurrently experiencing large mumps outbreaks (1,2), in some places exceeding 500 cases, raising concern about the possibility of a similar outbreak in Kosrae. By October 6, KDHS had identified 17 cases (nine laboratory confirmed and eight suspected [clinically diagnosed as parotitis]) on the island (population 6,600) (Figure), with an attack rate of 14 cases per 1,000 residents in the primary affected municipality. At the request of KDHS, CDC deployed a team on October 17 to assist KDHS in investigation and control activities. The KDHS-CDC team conducted active surveillance to assess outbreak magnitude, interviewed mumps patients, collected specimens for laboratory testing, and reviewed patients’ vaccination records. KDHS conducted islandwide awareness campaigns about the outbreak and mumps prevention measures, and highlighted the importance of vaccination. |
Increase in acute flaccid myelitis - United States, 2018
McKay SL , Lee AD , Lopez AS , Nix WA , Dooling KL , Keaton AA , Spence-Davizon E , Herlihy R , Clark TA , Hopkins SE , Pastula DM , Sejvar J , Oberste MS , Pallansch MA , Patel M , Routh JA . MMWR Morb Mortal Wkly Rep 2018 67 (45) 1273-1275 In August 2018, CDC noted an increased number of reports of patients having symptoms clinically compatible with acute flaccid myelitis (AFM), a rare condition characterized by rapid onset of flaccid weakness in one or more limbs and spinal cord gray matter lesions, compared with August 2017. Since 2014, CDC has conducted surveillance for AFM using a standardized case definition (1,2). An Epi-X* notice was issued on August 23, 2018, to increase clinician awareness and provide guidance for case reporting. |
The effect of costs on Kenyan households' demand for medical care: why time and distance matter
Kukla M , McKay N , Rheingans R , Harman J , Schumacher J , Kotloff KL , Levine MM , Breiman R , Farag T , Walker D , Nasrin D , Omore R , O'Reilly C , Mintz E . Health Policy Plan 2017 32 (10) 1397-1406 In an environment of constrained resources, policymakers must identify solutions for financing and delivering health services that are efficient and sustainable. However, such solutions require that policymakers understand the complex interaction between household utilization patterns, factors influencing household medical decisions, and provider performance. This study examined whether and under what conditions out-of-pocket, transportation, and time costs influenced Kenyan households' choice of medical provider for childhood diarrhoeal illnesses. It compared these decisions with the actual cost and quality of those providers to assess strategies for increasing the utilization of high quality, low-cost primary care. This study analyzed nationally-representative survey data through several multinomial nested logit models. On average, time costs accounted for the greatest share of total costs. Households spent the most time and transportation costs utilizing public care, yet were more likely to incur catastrophic time and out-of-pocket costs seeking private care for their child's diarrhoeal illness. Out-of-pocket, transportation, and time costs influenced households' choice of provider, though demand was cost inelastic and households were most responsive to transportation costs. Poorer households were the most responsive to changes in all cost types and most likely to self-treat or utilize informal care. Many households utilized informal care that, relative to formal care, cost the same but was of worse quality-suggesting that such households were making poor medical decisions for their children. To achieve public policy objectives, such as financial risk protection for childhood illnesses and equitable access to primary care, policymakers could focus on three areas: (1) refine financing strategies for further reducing household out-of-pocket costs; (2) reduce or subsidize time and transportation costs for households seeking public and private care; and (3) increase transparency of costs and quality to improve household decisions. |
El Nino and the shifting geography of cholera in Africa
Moore SM , Azman AS , Zaitchik BF , Mintz ED , Brunkard J , Legros D , Hill A , McKay H , Luquero FJ , Olson D , Lessler J . Proc Natl Acad Sci U S A 2017 114 (17) 4436-4441 The El Nino Southern Oscillation (ENSO) and other climate patterns can have profound impacts on the occurrence of infectious diseases ranging from dengue to cholera. In Africa, El Nino conditions are associated with increased rainfall in East Africa and decreased rainfall in southern Africa, West Africa, and parts of the Sahel. Because of the key role of water supplies in cholera transmission, a relationship between El Nino events and cholera incidence is highly plausible, and previous research has shown a link between ENSO patterns and cholera in Bangladesh. However, there is little systematic evidence for this link in Africa. Using high-resolution mapping techniques, we find that the annual geographic distribution of cholera in Africa from 2000 to 2014 changes dramatically, with the burden shifting to continental East Africa-and away from Madagascar and portions of southern, Central, and West Africa-where almost 50,000 additional cases occur during El Nino years. Cholera incidence during El Nino years was higher in regions of East Africa with increased rainfall, but incidence was also higher in some areas with decreased rainfall, suggesting a complex relationship between rainfall and cholera incidence. Here, we show clear evidence for a shift in the distribution of cholera incidence throughout Africa in El Nino years, likely mediated by El Nino's impact on local climatic factors. Knowledge of this relationship between cholera and climate patterns coupled with ENSO forecasting could be used to notify countries in Africa when they are likely to see a major shift in their cholera risk. |
Respiratory Protection for Oxygen Deficient Atmospheres
Spelce D , McKay RT , Johnson JS , Rehak TR , Metzler RW . J Int Soc Respir Prot 2016 33 (2) This article describes several aspects of oxygen (O(2)) deficiency with an emphasis on respirator programs and respirator selection. The Occupational Safety and Health Administration's (OSHA) 29 CFR 1910.134 and ANSI/ASSE Z88.2-2015 (Z88.2) have much in common. However, their exposure criteria and terminology used for describing levels of O(2)-deficiency and the approaches to assessing O(2)-deficiency differ. These differences can have a significant impact on an employer's respirator program and respirator selections for workplaces at altitudes above sea level. Under certain circumstances, Z88.2 leads to a more conservative respirator selection than OSHA because its O(2)-deficiency criteria and hazard assessment approach relies directly on partial pressure of oxygen (PO(2)) at all altitudes. Z88.2 defines an O(2)-deficient atmosphere as either immediately dangerous to life or health (IDLH), or non-IDLH based on the atmosphere's PO(2) and defines respirator selection for these two O(2)-deficient atmospheres. Unlike Z88.2, OSHA does not directly access the biologically significant aspect of an atmosphere's PO(2) in its hazard assessment. OSHA defines an O(2)-deficient atmosphere based upon a percentage of oxygen. OSHA does not use the term "O(2)-deficient IDLH"; however, OSHA considers any atmosphere with less than 19.5% O(2) as IDLH and defines respirator selection for IDLH atmospheres. Although OSHA does not use the term "PO(2)" in their respirator standard, OSHA's exceptions to O(2)-deficient IDLH respirator selection policy are based on PO(2) altitude-adjusted, O(2) percentage criteria. This article provides descriptions of OSHA and Z88.2 requirements to evaluate workplace oxygen deficiency, their approaches to O(2)-deficiency hazard assessment, and describes their significance on respirator programs and selections. Alternative solutions to wearing respirators for protection against O(2)-deficiency resulting solely from high altitudes are also discussed. Selection and implementation of alternative solutions by the employer and their Physician or other Licensed Health Care Professional (PLHCP) are not covered by either respirator standard. Appendix A provides information about the physiological effect of wearing respirators and the mechanics of respiration, which is an important consideration in lower O(2) atmospheres. |
1970s and 'Patient 0' HIV-1 genomes illuminate early HIV/AIDS history in North America.
Worobey M , Watts TD , McKay RA , Suchard MA , Granade T , Teuwen DE , Koblin BA , Heneine W , Lemey P , Jaffe HW . Nature 2016 539 (7627) 98-101 The emergence of HIV-1 group M subtype B in North American men who have sex with men was a key turning point in the HIV/AIDS pandemic. Phylogenetic studies have suggested cryptic subtype B circulation in the United States (US) throughout the 1970s and an even older presence in the Caribbean. However, these temporal and geographical inferences, based upon partial HIV-1 genomes that postdate the recognition of AIDS in 1981, remain contentious and the earliest movements of the virus within the US are unknown. We serologically screened >2,000 1970s serum samples and developed a highly sensitive approach for recovering viral RNA from degraded archival samples. Here, we report eight coding-complete genomes from US serum samples from 1978-1979-eight of the nine oldest HIV-1 group M genomes to date. This early, full-genome 'snapshot' reveals that the US HIV-1 epidemic exhibited extensive genetic diversity in the 1970s but also provides strong evidence for its emergence from a pre-existing Caribbean epidemic. Bayesian phylogenetic analyses estimate the jump to the US at around 1970 and place the ancestral US virus in New York City with 0.99 posterior probability support, strongly suggesting this was the crucial hub of early US HIV/AIDS diversification. Logistic growth coalescent models reveal epidemic doubling times of 0.86 and 1.12 years for the US and Caribbean, respectively, suggesting rapid early expansion in each location. Comparisons with more recent data reveal many of these insights to be unattainable without archival, full-genome sequences. We also recovered the HIV-1 genome from the individual known as 'Patient 0' (ref. 5) and found neither biological nor historical evidence that he was the primary case in the US or for subtype B as a whole. We discuss the genesis and persistence of this belief in the light of these evolutionary insights. |
Domestic exposure to fungal allergenic particles determined by halogen immunoassay using subject's serum versus particles carrying three non-fungal allergens determined by allergen-specific HIA
Sercombe JK , Liu-Brennan D , McKay KO , Green BJ , Tovey ER . Indoor Air 2014 24 (4) 438-45 Studies that estimate indoor aeroallergen exposure typically measure a pre-selected limited range of allergens. In this study, inhalable aeroallergen particles were quantified using the halogen immunoassay (HIA) to determine the contribution of fungal and non-fungal aeroallergens to total allergen exposure. Bioaerosols from 39 homes of fungal-allergic subjects were sampled using inhalable fraction samplers and immunostained by HIA using resident subject's immunoglobulin E (IgE) to detect allergen-laden particles. Fungal aerosols as well as particles carrying mite, cat, and cockroach allergens were identified and enumerated by HIA. Reservoir dust-mite (Der p 1), cat (Fel d 1), and cockroach (Bla g 1) allergen concentrations were quantified by ELISA. Fungal particles that bound subject's IgE in the HIA were 1.7 (bedroom)- and 1.4 (living room)-fold more concentrated than Der p 1, Fel d 1, and Bla g 1 allergen particles combined. Predominant fungal conidia that bound IgE were derived from common environmental genera including Cladosporium and other fungi that produce amerospores. Airborne mite, cat, and cockroach allergen particle counts were not associated with reservoir concentrations determined by ELISA. This study demonstrates that inhalable fungal aerosols are the predominant aeroallergen sources in Sydney homes and should be considered in future exposure assessments. |
Effects of breathing frequency and flow rate on the total inward leakage of an elastomeric half-mask donned on an advanced manikin headform
He X , Grinshpun SA , Reponen T , McKay R , Bergman MS , Zhuang Z . Ann Occup Hyg 2014 58 (2) 182-94 OBJECTIVES: The objective of this study was to investigate the effects of breathing frequency and flow rate on the total inward leakage (TIL) of an elastomeric half-mask donned on an advanced manikin headform and challenged with combustion aerosols. METHODS: An elastomeric half-mask respirator equipped with P100 filters was donned on an advanced manikin headform covered with life-like soft skin and challenged with aerosols originated by burning three materials: wood, paper, and plastic (polyethylene). TIL was determined as the ratio of aerosol concentrations inside (C in) and outside (C out) of the respirator (C in/C out) measured with a nanoparticle spectrometer operating in the particle size range of 20-200nm. The testing was performed under three cyclic breathing flows [mean inspiratory flow (MIF) of 30, 55, and 85 l/min] and five breathing frequencies (10, 15, 20, 25, and 30 breaths/min). A completely randomized factorial study design was chosen with four replicates for each combination of breathing flow rate and frequency. RESULTS: Particle size, MIF, and combustion material had significant (P < 0.001) effects on TIL regardless of breathing frequency. Increasing breathing flow decreased TIL. Testing with plastic aerosol produced higher mean TIL values than wood and paper aerosols. The effect of the breathing frequency was complex. When analyzed using all combustion aerosols and MIFs (pooled data), breathing frequency did not significantly (P = 0.08) affect TIL. However, once the data were stratified according to combustion aerosol and MIF, the effect of breathing frequency became significant (P < 0.05) for all MIFs challenged with wood and paper combustion aerosols, and for MIF = 30 l/min only when challenged with plastic combustion aerosol. CONCLUSIONS: The effect of breathing frequency on TIL is less significant than the effects of combustion aerosol and breathing flow rate for the tested elastomeric half-mask respirator. The greatest TIL occurred when challenged with plastic aerosol at 30 l/min and at a breathing frequency of 30 breaths/min. |
Toxicity of lunar dust assessed in inhalation-exposed rats
Lam CW , Scully RR , Zhang Y , Renne RA , Hunter RL , McCluskey RA , Chen BT , Castranova V , Driscoll KE , Gardner DE , McClellan RO , Cooper BL , McKay DS , Marshall L , James JT . Inhal Toxicol 2013 25 (12) 661-78 Humans will again set foot on the moon. The moon is covered by a layer of fine dust, which can pose a respiratory hazard. We investigated the pulmonary toxicity of lunar dust in rats exposed to 0, 2.1, 6.8, 20.8 and 60.6 mg/m(3) of respirable-size lunar dust for 4 weeks (6 h/day, 5 days/week); the aerosols in the nose-only exposure chambers were generated from a jet-mill ground preparation of a lunar soil collected during the Apollo 14 mission. After 4 weeks of exposure to air or lunar dust, groups of five rats were euthanized 1 day, 1 week, 4 weeks or 13 weeks after the last exposure for assessment of pulmonary toxicity. Biomarkers of toxicity assessed in bronchoalveolar fluids showed concentration-dependent changes; biomarkers that showed treatment effects were total cell and neutrophil counts, total protein concentrations and cellular enzymes (lactate dehydrogenase, glutamyl transferase and aspartate transaminase). No statistically significant differences in these biomarkers were detected between rats exposed to air and those exposed to the two low concentrations of lunar dust. Dose-dependent histopathology, including inflammation, septal thickening, fibrosis and granulomas, in the lung was observed at the two higher exposure concentrations. No lesions were detected in rats exposed to ≤6.8 mg/m(3). This 4-week exposure study in rats showed that 6.8 mg/m(3) was the highest no-observable-adverse-effect level (NOAEL). These results will be useful for assessing the health risk to humans of exposure to lunar dust, establishing human exposure limits and guiding the design of dust mitigation systems in lunar landers or habitats. |
- Page last reviewed:Feb 1, 2024
- Page last updated:Apr 22, 2024
- Content source:
- Powered by CDC PHGKB Infrastructure