Tao Kwan-Gett

The mechanism of low-frequency sound production in muscle

Frog gastrocnemius muscles stimulated isometrically in a saline bath at 20 degrees C were found to produce a single ringing sound event beginning just before the tension record began to rise. The sound event was substantially over by the time the isometric tension began to fall. Results from studies correlating the spatial pattern of the sound, the amplitude and frequency of the sound as a function of the muscle length, and the response of both the passive and active muscle to a transverse pluck were found to be consistent with the conclusion that the sounds in these muscles are caused primarily by transverse resonant vibrations. As the muscle develops force, its lack of cylindrical symmetry gives rise to lateral motions, which are most likely the initiators of the bending vibrations detected as sound.

Toxic Shock Associated With Clostridium sordellii and Clostridium perfringens After Medical and Spontaneous Abortion

OBJECTIVE: To better understand the risk of fatal toxic shock caused by Clostridium sordellii in women who had a recent medical abortion with mifepristone and misoprostol. METHODS: We performed active and passive surveillance for cases of toxic shock associated with medical or spontaneous abortion. To identify the cause of toxic shock, immunohistochemical assays for multiple bacteria were performed on formalin-fixed surgical and autopsy tissues. We extracted DNA from tissues, performed Clostridium species–specific polymerase chain reaction assays, and sequenced amplified products for confirmation of Clostridium species. RESULTS: We report four patients with toxic shock associated with Clostridium species infection after medical or spontaneous abortion. Two women had fatal Clostridium perfringens infections after medically induced abortions: one with laminaria and misoprostol and one with the regimen of mifepristone and misoprostol. One woman had a nonfatal Clostridium sordellii infection after spontaneous abortion. Another woman had a fatal C sordellii infection after abortion with mifepristone and misoprostol. All four patients had a rapidly progressive illness with necrotizing endomyometritis. CONCLUSION: Toxic shock after abortion can be caused by C perfringens as well as C sordellii, can be nonfatal, and can occur after spontaneous abortion and abortion induced by medical regimens other than mifepristone and misoprostol. LEVEL OF EVIDENCE: III

Effectiveness of a parental educational intervention in reducing antibiotic use in children: a randomized controlled trial.

Objective: To determine whether an educational intervention aimed at parents leads to fewer antibiotic prescriptions for their children. Design: Placebo-controlled, randomized controlled trial. Setting: Offices of primary care pediatricians who are members of a regional practice-based research network. Participants: Healthy children younger than 24 months old enrolled at the time of an office visit. Interventions: Parents of study children were randomized to receive either a pamphlet and videotape (featuring one of their childs pediatricians) promoting the judicious use of antibiotics (intervention group) or brochures about injury prevention (control group). A total of 499 eligible children were enrolled, and data on outpatient visits during a 12-month observation period were collected. Main Outcome Measures: We compared the number of visits for upper respiratory tract infections (URIs), number of diagnoses and antibiotic prescriptions for otitis media and/or sinusitis and total number of antibiotics per patient among children in the intervention and control groups using Poisson regression analysis, adjusted for clustering into different practices. Results: Data on 4924 visits were reviewed; 28.8% of these visits were because of URI symptoms. The mean number of visits per study patient for URI symptoms was 2.8. Including all visits, the mean number of diagnoses of otitis media in study children was 2.1, mean number of diagnoses of otitis media and/or sinusitis was 2.3 and mean number of antibiotic prescriptions was 2.4; there were no significant differences between children in the intervention and control groups for any of these outcomes. Overall physicians prescribed 1 or more antibiotics during 45.9% of visits for a chief complaint of URI symptoms; 92% of antibiotic usage in children presenting with URI symptoms was for a diagnosis of otitis media and/or sinusitis. Conclusions: An educational intervention aimed at parents did not result in a decrease in the number of antibiotic prescriptions in their children. The use of antibiotics among children with URI symptoms was common; other interventions promoting the judicious use of these medications are needed.

Spring 2009 H1N1 influenza outbreak in King County, Washington.

BACKGROUND In April 2009, King County, Washington, experienced a sustained outbreak of 2009 H1N1 influenza A. This report describes the epidemiology of that outbreak in King County, home to a diverse population of 1.9 million people. METHODS The 2 primary sources of data are case investigations of reported laboratory-confirmed 2009 H1N1 influenza A and a population-based syndromic surveillance system that captures data from emergency departments (EDs). A syndromic category for influenza-like illness was defined based on chief complaint and diagnosis. RESULTS ED visits for influenza-like illness peaked quickly in the first week of the outbreak and remained high for approximately 6 weeks, with school-age children accounting for the greater number of ED visits, followed by young adults. Children ages 0 to 4 years had the highest rate of hospitalization. Among reported cases, blacks, Asians, and Hispanics were more likely to be hospitalized. Predisposing factors associated with admission were immune compromise, chronic lung disease, chronic heart disease, pregnancy, diabetes, and asthma. Of people receiving antiviral treatment, 34% started their medication more than 2 calendar days after the onset of illness. Mean days between illness onset and antiviral treatment were greater for blacks, Hispanics, and foreign language speakers. CONCLUSIONS The spring 2009 influenza A H1N1 outbreak disproportionately affected children, young adults, and racial and ethnic minorities. Opportunities exist to improve the timeliness of antiviral treatment. Potential barriers to care for racial and ethnic minorities should be proactively addressed to ensure prompt evaluation and treatment.

Association between school closure and subsequent absenteeism during a seasonal influenza epidemic.

Background: Mathematical models suggest that social distancing measures, such as school closures, may mitigate community transmission during an influenza pandemic. Because closures are disruptive to schools and families, they are rarely employed during seasonal influenza outbreaks. A rare circumstance enabled us to examine the association between school closure and absenteeism during a seasonal influenza outbreak when half of King County, Washington public schools closed for a winter recess 19–23 February 2007, while half remained open for all or part of the week. Methods: Using absenteeism as a proxy for influenza activity, we tested the hypothesis that schools on break would experience lower rates of post-break absenteeism than schools remaining open. We conducted daily retrospective and prospective surveillance from 5 February–9 March 2007 in schools on break (n = 256) and in session (n = 205). We use generalized estimating equations with Poisson distribution to evaluate whether mean absenteeism after the break differed between schools on break and those in session, adjusting for baseline absenteeism and repeated measurements by schools over time. Results: Results indicate no difference in post-break absenteeism in schools on break compared with schools that remained in session (relative risk = 1.07 [95% confidence interval = 0.96–1.20]). This result held in elementary schools (1.00 [0.91–1.10]), where absenteeism patterns are thought to be most representative of community influenza activity. Conclusion: We did not find that school closure during a seasonal influenza outbreak reduced subsequent absenteeism. However, limitations in this “natural experiment” hampered our ability to detect a benefit if one truly was present.

Risk factors for infections in international travelers: an analysis of travel-related notifiable communicable diseases.

BACKGROUND We sought to describe travel-related illness among our residents and gain insight into targeting pre-travel health advice to prevent travel-related illness. METHODS A supplemental travel questionnaire was developed and administered for cases with a legally notifiable communicable disease reported in 2011-2012, who spent at least part of their exposure period outside the United States. RESULTS Among 451 cases meeting the eligibility criteria, 259 were interviewed. Forty four percent reported receiving pre-travel advice. Two-thirds adhered fully with risk behavior recommendations; 94% followed immunization recommendations partially or fully; and 84% adhered fully with malaria prophylaxis recommendations. The primary reasons for not obtaining pre-travel advice were being unaware of the need (47.5%), or believing they already knew what to do (34.5%). Adults (OR = 2.8, 95% CI = 1.4-5.5), males (OR = 1.8, 95% CI = 1.1-3.0), those born outside the United States (OR = 2.0, 95% CI = 1.1-3.7), and those with planning time under two weeks (OR = 4.8, 95% CI = 1.5-15.9) or travel duration less than 7 days (OR = 7.9, 95% CI = 3.0-20.9) were more likely to travel without seeking pre-travel advice. CONCLUSIONS The majority of cases reported not receiving pre-travel advice. Understanding the predictors of failure to receive pre-travel advice may help target public health prevention efforts.

Local Health Department Food Safety and Sanitation Expenditures and Reductions in Enteric Disease, 2000–2010

OBJECTIVES In collaboration with Public Health Practice-Based Research Networks, we investigated relationships between local health department (LHD) food safety and sanitation expenditures and reported enteric disease rates. METHODS We combined annual infection rates for the common notifiable enteric diseases with uniquely detailed, LHD-level food safety and sanitation annual expenditure data obtained from Washington and New York state health departments. We used a multivariate panel time-series design to examine ecologic relationships between 2000-2010 local food safety and sanitation expenditures and enteric diseases. Our study population consisted of 72 LHDs (mostly serving county-level jurisdictions) in Washington and New York. RESULTS While controlling for other factors, we found significant associations between higher LHD food and sanitation spending and a lower incidence of salmonellosis in Washington and a lower incidence of cryptosporidiosis in New York. CONCLUSIONS Local public health expenditures on food and sanitation services are important because of their association with certain health indicators. Our study supports the need for program-specific LHD service-related data to measure the cost, performance, and outcomes of prevention efforts to inform practice and policymaking.

Infant pertussis epidemiology and implications for tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccination: King County, Washington, 2002 through 2007.

OBJECTIVES To describe the epidemiology of infant pertussis in King County, Washington, and to better understand the implications for tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccination among older children, adolescents, and adults. DESIGN Retrospective analysis of reported pertussis cases among infants younger than 1 year, January 1, 2002, through December 31, 2007. SETTING King County, Washington. PARTICIPANTS Reported pertussis cases among infants younger than 1 year between 2002 and 2007. MAIN OUTCOME MEASURES Bordetella pertussis from a household member or close contact was the primary exposure. The main outcome measures were age and vaccination status, incidence by race/ethnicity, suspected exposure, and Tdap eligibility of household members and close contacts. RESULTS Among 176 confirmed cases of infants with pertussis, the median age was 3 months (age range, 0-11 months); 80.1% were younger than 6 months. Seventy-seven percent were age-appropriately vaccinated. Between 2002 and 2007, the overall mean annual incidence was 136 cases per 100,000 infant population. Compared with a mean annual incidence of 73 cases per 100,000 infant population among whites, the incidence was 246 cases per 100,000 infant population among blacks (rate ratio [RR], 3.37; 95% confidence interval [CI], 2.59-4.44) and 194 cases per 100,000 infant population among Hispanics (RR, 2.66; 95% CI, 2.02-3.53). Households were the suspected exposure location for 70.0% of cases. Case households had a median of 3 (range, 1-15) Tdap-eligible persons. CONCLUSIONS The burden of infant pertussis in King County, Washington, was high between 2002 and 2007, especially among racial/ethnic minorities. Tdap vaccination of eligible household members and close contacts should be promoted as an additional means of protecting infants from pertussis.

Shedding of pandemic (H1N1) 2009 virus among health care personnel, Seattle, Washington, USA.

The Centers for Disease Control and Prevention (CDC) recommends that health care personnel (HCP) infected with pandemic influenza (H1N1) 2009 virus not work until 24 hours after fever subsides without the use of antipyretics. During an influenza outbreak, we examined the association between viral shedding and fever among infected HCP. Participants recorded temperatures daily and provided nasal wash specimens for 2 weeks after symptom onset. Specimens were tested by using PCR and culture. When they met CDC criteria for returning to work, 12 of 16 HCP (75%) (95% confidence interval 48%–93%) had virus detected by PCR, and 9 (56%) (95% confidence interval 30%–80%) had virus detected by culture. Fever was not associated with shedding duration (p = 0.65). HCP might shed virus even when meeting CDC exclusion guidelines. Further research is needed to clarify the association between viral shedding, symptoms, and infectiousness.

Is household antibiotic use a risk factor for antibiotic-resistant pneumococcal infection?

We used microbiology and pharmacy data from health-maintenance organizations to determine whether antibiotic use by a household member increases the risk of penicillin-non-susceptible pneumococcal disease. Though it has been well established that an individuals antibiotic use increases ones risk of antibiotic-resistant infection, it is unclear whether the risk is increased if a member of ones household is exposed to antibiotics. We therefore conducted a case-control study of patients enrolled in health maintenance organizations in Western Washington and Northern California. Cases were defined as individuals with penicillin-non-susceptible pneumococcal infection; controls were individuals with penicillin-susceptible pneumococcal infection. Socioeconomic variables were obtained by linking addresses with 1997 census block group data. One-hundred and thirty-four cases were compared with 798 controls. Individual antibiotic use prior to diagnosis increased the odds of penicillin non-susceptibility, with the strongest effect seen for beta-lactam use within 2 months (OR 1.8, 95% CI 1.2, 2.8). When household antibiotic use by persons other than the patient were considered, at 4 months prior to diagnosis there was a trend towards an association between penicillin non-susceptibility and beta-lactam antibiotic use, and a possible association in a small subgroup of patients with eye and ear isolates. However, no significant overall pattern of association was seen. We conclude that though antibiotic use of any kind within 2 months prior to diagnosis is associated with an increased risk of penicillin-non-susceptible pneumococcal disease, there is no significant overall pattern of association between household antibiotic use and penicillin-non-susceptible pneumococcal infection.