The episodic resurgence of highly pathogenic avian influenza H5 virus

Highly pathogenic avian influenza (HPAI) H5N1 activity has intensified globally since 2021, increasingly causing mass mortality in wild birds and poultry and incidental infections in mammals1-3. However, the ecological and virological properties that underscore future mitigation strategies still remain unclear. Using epidemiological, spatial and genomic approaches, we demonstrate changes in the origins of resurgent HPAI H5 and reveal significant shifts in virus ecology and evolution. Outbreak data show key resurgent events in 2016-2017 and 2020-2021, contributing to the emergence and panzootic spread of H5N1 in 2021-2022. Genomic analysis reveals that the 2016-2017 epizootics originated in Asia, where HPAI H5 reservoirs are endemic. In 2020-2021, 2.3.4.4b H5N8 viruses emerged in African poultry, featuring mutations altering HA structure and receptor binding. In 2021-2022, a new H5N1 virus evolved through reassortment in wild birds in Europe, undergoing further reassortment with low-pathogenic avian influenza in wild and domestic birds during global dissemination. These results highlight a shift in the HPAI H5 epicentre beyond Asia and indicate that increasing persistence of HPAI H5 in wild birds is facilitating geographic and host range expansion, accelerating dispersion velocity and increasing reassortment potential. As earlier outbreaks of H5N1 and H5N8 were caused by more stable genomic constellations, these recent changes reflect adaptation across the domestic-bird-wild-bird interface. Elimination strategies in domestic birds therefore remain a high priority to limit future epizootics.

Long-Term Epidemiology and Evolution of Swine Influenza Viruses, Vietnam

Influenza A viruses are a One Health threat because they can spill over between host populations, including among humans, swine, and birds. Surveillance of swine influenza virus in Hanoi, Vietnam, during 2013-2019 revealed gene pool enrichment from imported swine from Asia and North America and showed long-term maintenance, persistence, and reassortment of virus lineages. Genome sequencing showed continuous enrichment of H1 and H3 diversity through repeat introduction of human virus variants and swine influenza viruses endemic in other countries. In particular, the North American H1-δ1a strain, which has a triple-reassortant backbone that potentially results in increased human adaptation, emerged as a virus that could pose a zoonotic threat. Co-circulation of H1-δ1a viruses with other swine influenza virus genotypes raises concerns for both human and animal health.

Resurgence of Omicron BA.2 in SARS-CoV-2 infection-naive Hong Kong

Hong Kong experienced a surge of Omicron BA.2 infections in early 2022, resulting in one of the highest per-capita death rates of COVID-19. The outbreak occurred in a dense population with low immunity towards natural SARS-CoV-2 infection, high vaccine hesitancy in vulnerable populations, comprehensive disease surveillance and the capacity for stringent public health and social measures (PHSMs). By analyzing genome sequences and epidemiological data, we reconstructed the epidemic trajectory of BA.2 wave and found that the initial BA.2 community transmission emerged from cross-infection within hotel quarantine. The rapid implementation of PHSMs suppressed early epidemic growth but the effective reproduction number (Re) increased again during the Spring festival in early February and remained around 1 until early April. Independent estimates of point prevalence and incidence using phylodynamics also showed extensive superspreading at this time, which likely contributed to the rapid expansion of the epidemic. Discordant inferences based on genomic and epidemiological data underscore the need for research to improve near real-time epidemic growth estimates by combining multiple disparate data sources to better inform outbreak response policy.

Detection of Clade 2.3.4.4b Avian Influenza A(H5N8) Virus in Cambodia, 2021

In late 2021, highly pathogenic avian influenza A(H5N8) clade 2.3.4.4b viruses were detected in domestic ducks in poultry markets in Cambodia. Surveillance, biosafety, and biosecurity efforts should be bolstered along the poultry value chain to limit spread and infection risk at the animal-human interface.

Diagnostic stewardship for Clostridioides difficile testing in an acute care hospital: A quality improvement intervention

Objective:

To evaluate the impact of a diagnostic stewardship intervention on Clostridioides difficile healthcare-associated infections (HAI).

Design:

Quality improvement study.

Setting:

Two urban acute care hospitals.

Interventions:

All inpatient stool testing for C. difficile required review and approval prior to specimen processing in the laboratory. An infection preventionist reviewed all orders daily through chart review and conversations with nursing; orders meeting clinical criteria for testing were approved, orders not meeting clinical criteria were discussed with the ordering provider. The proportion of completed tests meeting clinical criteria for testing and the primary outcome of C. difficile HAI were compared before and after the intervention.

Results:

The frequency of completed C. difficile orders not meeting criteria was lower [146 (7.5%) of 1,958] in the intervention period (January 10, 2022–October 14, 2022) than in the sampled 3-month preintervention period [26 (21.0%) of 124; P < .001]. C. difficile HAI rates were 8.80 per 10,000 patient days prior to the intervention (March 1, 2021–January 9, 2022) and 7.69 per 10,000 patient days during the intervention period (incidence rate ratio, 0.87; 95% confidence interval, 0.73–1.05; P = .13).

Conclusions:

A stringent order-approval process reduced clinically nonindicated testing for C. difficile but did not significantly decrease HAIs.

Genomic Epidemiology of Seasonal Influenza Circulation in China During Prolonged Border Closure from 2020 to 2021

China experienced a resurgence of seasonal influenza activity throughout 2021 despite intermittent control measures and prolonged international border closure. We show genomic evidence for multiple A(H3N2), A(H1N1), and B/Victoria transmission lineages circulating over 3 years, with the 2021 resurgence mainly driven by two B/Victoria clades. Phylodynamic analysis revealed unsampled ancestry prior to widespread outbreaks in December 2020, showing that influenza lineages can circulate cryptically under non-pharmaceutical interventions enacted against COVID-19. Novel haemagglutinin gene mutations and altered age profiles of infected individuals were observed, and Jiangxi province was identified as a major source for nationwide outbreaks. Following major holiday periods, fluctuations in the effective reproduction number were observed, underscoring the importance of influenza vaccination prior to holiday periods or travel. Extensive heterogeneity in seasonal influenza circulation patterns in China determined by historical strain circulation indicates that a better understanding of demographic patterns is needed for improving effective controls.

Letter to the Editor on: "The Effects of Physical Exercise on Tumor Vasculature: Systematic Review and Meta-Analysis."

Dear Editor,We read with interest the recent article "The Effects of Physical Exercise on Tumor Vasculature: Systematic Review and Meta-analysis" 1 and after careful appraisal and consideration we feel that some aspects of the data and analysis warrant further review. The study reported some promising results, namely that both chronic and acute exercise appear to improve intratumoral vascularisation in animal models. This is an important finding given increased vascularisation through tumor modulation may have the potential to improve chemotherapy delivery and efficacy 2. However, after conducting further investigations, we query several details in the data extraction and analysis decision-making that we believe impact the conclusions of this article.

Air travel-related outbreak of multiple SARS-CoV-2 variants

BACKGROUND

A large cluster of 59 cases were linked to a single flight with 146 passengers from New Delhi to Hong Kong in April 2021. This outbreak coincided with early reports of exponential pandemic growth in New Delhi, which reached a peak of > 400 000 newly confirmed cases on 7 May 2021.

METHODS

Epidemiological information including date of symptom onset, date of positive-sample detection and travel and contact history for individual cases from this flight were collected. Whole genome sequencing was performed, and sequences were classified based on the dynamic Pango nomenclature system. Maximum-likelihood phylogenetic analysis compared sequences from this flight alongside other cases imported from India to Hong Kong on 26 flights between June 2020 and April 2021, as well as sequences from India or associated with India-related travel from February to April 2021 and 1217 reference sequences.

RESULTS

Sequence analysis identified six lineages of SARS-CoV-2 belonging to two variants of concern (Alpha and Delta) and one variant of public health interest (Kappa) involved in this outbreak. Phylogenetic analysis confirmed at least three independent sub-lineages of Alpha with limited onward transmission, a superspreading event comprising 37 cases of Kappa and transmission of Delta to only one passenger. Additional analysis of another 26 flights from India to Hong Kong confirmed widespread circulation of all three variants in India since early March 2021.

CONCLUSIONS

The broad spectrum of disease severity and long incubation period of SARS-CoV-2 pose a challenge for surveillance and control. As illustrated by this particular outbreak, opportunistic infections of SARS-CoV-2 can occur irrespective of variant lineage, and requiring a nucleic acid test within 72 hours of departure may be insufficient to prevent importation or in-flight transmission.

SARS-CoV-2 under an elimination strategy in Hong Kong

Hong Kong utilized an elimination strategy with intermittent use of public health and social measures and increasingly stringent travel regulations to control SARS-CoV-2 transmission. By analyzing >1700 genome sequences representing 17% of confirmed cases from 23-January-2020 to 26-January-2021, we reveal the effects of fluctuating control measures on the evolution and epidemiology of SARS-CoV-2 lineages in Hong Kong. Despite numerous importations, only three introductions were responsible for 90% of locally-acquired cases, two of which circulated cryptically for weeks while less stringent measures were in place. We found that SARS-CoV-2 within-host diversity was most similar among transmission pairs and epidemiological clusters due to a strong transmission bottleneck through which similar genetic background generates similar within-host diversity.

ONE SENTENCE SUMMARY

Out of the 170 detected introductions of SARS-CoV-2 in Hong Kong during 2020, three introductions caused 90% of community cases.

The effect of exercise on vaccine-related pain, anxiety and fear during HPV vaccinations in adolescents

INTRODUCTION

With increased school-based vaccinations for improved coverage rates and practicality, the World Health Organization (WHO) recently endorsed research to identify possible interventions to reduce vaccine-related pain in mass clinical and school-based settings. In particular, the lack of research in adolescents indicate a particular need in this population. Acute exercise has analgesic effects and has been used as a behavioural adjuvant to vaccination. Here, we examine the effect of exercise on vaccine-related pain, anxiety and fear in adolescents, during a school-based program for HPV vaccinations.

METHODS

116 students (Female: 61, Male: 55) aged 11-13 years were randomly allocated to either an Exercise (n = 60) or Control (n = 56) group. All participants completed demographic and Trait-anxiety questionnaires prior to receiving the vaccine according to usual care. The Exercise group also performed upper body exercise for 15 min prior to receiving the vaccine. Immediately after the vaccine administration, all participants reported on pain, anxiety and fear at the time of receiving the vaccine.

RESULTS

Female adolescents in the Exercise group reported significantly less pain (3.64; 95% CI, 2.98-4.30) than Controls (4.58; 95% CI, 3.96-5.19; p = 0.04). Further, females reported greater pain and anxiety than males in the Control group but not the Exercise group.

CONCLUSION

This study supports the use of exercise prior to vaccine administration, especially in female adolescents who are particularly vulnerable to negative experiences during vaccination procedures. Furthermore, the ease of application, as well as the benefit of exercise, provides support for the use of simple exercise prior to vaccination in mass vaccination settings. Clinical trial registry: ANZCTR, ACTRN12614001185651.

Conveying campus sexual misconduct policy information to college and university students: Results from a 7-campus study

OBJECTIVE

To examine the efficacy of different methods (ie, in-class policy reading; in-class policy reading and discussion; no reading or discussion) to deliver campus sexual misconduct policy information to students on 7 campuses.

PARTICIPANTS

A total of 1,195 participants at 7 colleges and universities participated in the study from August to October 2014. Participants were randomly assigned at the class level and completed pretest and posttest surveys assessing knowledge of campus policy and resources and confidence to seek help for sexual assault.

RESULTS

Students exposed to a larger dosage of material (in-class policy reading plus discussion) showed greater positive changes in attitudes and knowledge than students who did not receive information or were only read the policy. However, on some indices, students who were only read the policy showed positive outcomes compared with students receiving no intervention.

CONCLUSION

Colleges and universities must use engaging methods to disseminate campus sexual misconduct policies to students.

Effects on blood pressure and autonomic nervous system function of a 12-week exercise or exercise plus DASH-diet intervention in individuals with elevated blood pressure

AIM

Hypertension is related to abnormalities in autonomic nervous system (ANS) function, with increased sympathetic output and decreased parasympathetic tone. Lifestyle interventions are the first line of treatment in hypertension, and decreased blood pressure (BP) effects may be related to changes in ANS function. Using heart rate recovery (HRR) from exercise as an index of parasympathetic tone and plasma noradrenaline as an index of sympathetic tone, we investigated the effects of lifestyle interventions on ANS function in patients with elevated BP.

METHODS

Sedentary participants with elevated BP were randomly assigned to either an exercise only (N = 25), exercise plus dietary approaches to stop hypertension (DASH) diet (N = 12), or waitlist control (N = 15) 12-week intervention. Plasma noradrenaline was measured at rest and participants performed a peak exercise test before and after the intervention. HRR was calculated as peak heart rate (HR) minus HR at 1 min post-exercise.

RESULTS

Heart rate recovery showed a significant group by time interaction; both intervention groups showed increases in HRR from pre- to post-intervention, while waitlist showed no change. Similarly, both exercise plus diet and exercise groups, but not waitlist, showed significant reductions in BP from pre- to post-intervention. Linear regression revealed that BP post-intervention was significantly predicted by change in HRR when controlling for pre-BP, age, gender and BMI.

CONCLUSIONS

Lifestyle interventions induced training-reduced BP and altered autonomic tone, indexed by HRR. This study indicates the importance of behavioural modification in hypertension and that increased parasympathetic function is associated with success in reduction of BP.

Influenza vaccination in the organ transplant recipient: review and summary recommendations

Influenza virus causes a spectrum of illness in transplant recipients with a high rate of lower respiratory disease. Seasonal influenza vaccination is an important public health measure recommended for transplant recipients and their close contacts. Vaccine has been shown to be safe and generally well tolerated in both adult and pediatric transplant recipients. However, responses to vaccine are variable and are dependent on various factors including time from transplantation and specific immunosuppressive medication. Seasonal influenza vaccine has demonstrated safety and no conclusive evidence exists for a link between vaccination and allograft dysfunction. Annually updated trivalent inactivated influenza vaccines have been available and routinely used for several decades, although newer influenza vaccination formulations including high-dose vaccine, adjuvanted vaccine, quadrivalent inactivated vaccine and vaccine by intradermal delivery system are now available or will be available in the near future. Safety and immunogenicity data of these new formulations in transplant recipients requires investigation. In this document, we review the current state of knowledge on influenza vaccines in transplant recipients and make recommendations on the use of vaccine in both adult and pediatric organ transplant recipients.

Leukocyte membrane bleb and pseudopod formation in hypertension

Leukocyte activation, including adhesion molecule expression, oxygen radical generation and, in animal studies, pseudopod formation, is a hallmark of hypertension. This study examined pseudopod and bleb formation and demonstrates that leukocytes from hypertensive individuals are more susceptible to produce membrane blebs than leukocytes from normotensive individuals. Bleb formation is likely indicative of apoptosis, thus this observation adds to previous observations of increased apoptosis in various tissues in hypertension.

International Bordetella pertussis assay standardization and harmonization meeting report. Centers for Disease Control and Prevention, Atlanta, Georgia, United States, 19-20 July 2007

An international meeting on Bordetella pertussis assay standardization and harmonization was held at the Centers for Disease Control and Prevention (CDC), Atlanta, GA, 19–20 July 2007. The goal of the meeting was to harmonize the immunoassays used for pertussis diagnostics and vaccine evaluation, as agreed upon by academic and government researchers, regulatory authorities, vaccine manufacturers, and the World Health Organization (WHO).

The primary objectives were (1) to provide epidemiologic, laboratory, and statistical background for support of global harmonization; (2) to overview the current status of global epidemiology, pathogenesis and immunology of pertussis; (3) to develop a consensus opinion on existing gaps in understanding standardization of pertussis assays used for serodiagnosis and vaccine evaluation; and (4) to search for a multicenter process for addressing these priority gaps. Presentations and discussions by content experts addressed these objectives. A prioritized list of action items to improve standardization and harmonization of pertussis assays was identified during a group discussion at the end of the meeting. The major items included: (1) to identify a group that will organize, prepare, maintain, and distribute proficiency panels and key reagents such as reference and control sera; (2) to encourage the development and identification of one or more reference laboratories that can serve as an anchor and resource for other laboratories; (3) to define a performance-based assay method that can serve as a reference point for evaluating laboratory differences; (4) to develop guidance on quality of other reagents, e.g., pertussis toxin and other antigens, and methods to demonstrate their suitability; (5) to establish an international working group to harmonize the criteria to evaluate the results obtained on reference and proficiency panel sera; (6) to create an inventory to determine the amount of appropriate and well-characterized sera that are available globally to be used as bridging reagents for vaccine licensure; and (7) to seek specific guidance from regulatory authorities regarding the expectations and requirements for the licensure of new multicomponent pertussis vaccines.

Iron-cofactored superoxide dismutase inhibits host responses to Mycobacterium tuberculosis

Superoxide dismutase (SOD) is a ubiquitous metalloenzyme in aerobic organisms that catalyzes the conversion of superoxide anion to hydrogen peroxide. Mycobacterium tuberculosis is unusual in that it secretes large quantities of iron-cofactored SOD. To determine the role of SOD in pathogenesis, we constructed mutants of M. tuberculosis H37Rv with reduced SOD production. Compared with controls, SOD-diminished isolates were more susceptible to killing by hydrogen peroxide. The isolates were markedly attenuated, exhibiting nearly 100,000-fold fewer bacilli than virulent control strains in the lungs and spleens of C57BL/6 mice 4 wk after intravenous inoculation. In the lung, SOD-attenuated M. tuberculosis induced robust interstitial mononuclear cell infiltration within 24 h and many cells were apoptotic by TUNEL staining, whereas virulent H37Rv exhibited minimal early inflammatory response and only rare interstitial mononuclear cell apoptosis. During prolonged infections, C57BL/6 mice tolerated SOD-attenuated M. tuberculosis better than BCG, exhibiting 68% greater weight gain, quicker eradication of bacilli from the spleen, and less alveolar lung infiltration. These results establish the importance of SOD in the pathogenesis of tuberculosis. Its effect appears to be mediated in part by inhibiting innate host immune responses, including early mononuclear cell infiltration of infected tissues and apoptosis.

Development, acceptance, and use of immunologic correlates of protection in monitoring the effectiveness of combination vaccines

The establishment of immunologic correlates of protection for all vaccine antigens is a worthwhile goal. It allows new vaccines to be licensed on the basis of attainment of defined immunologic benchmarks, without the need for large-scale efficacy trials for each new product. This is particularly important for the evaluation of new combination products. Efficacy trials of each new mixture would be unethical because routinely recommended vaccines would be denied children in the control group. The establishment of immunologic correlates of protection should be a defined goal of every efficacy trial. Additional ways to evaluate the immune responses-such as cell-mediated immunity, mucosal immunity, memory responses, and antibody avidity-should also be studied. Finally, ongoing surveillance efforts are also needed, to monitor the impact of new and combined vaccines on disease rates.

In vitro activity of ABT-773, telithromycin and eight other antimicrobials against erythromycin-resistant Streptococcus pneumoniae respiratory isolates of children

The activity of the ketolide ABT-773 against 180 erythromycin-resistant Streptococcus pneumoniae obtained from children was compared with telithromycin, azithromycin, clarithromyin, roxithromycin, clindamycin, penicillin, levofloxacin and gatifloxacin. Ketolide MICs were all < or =1 mg/l, with ABT-773 being the most potent of all drugs tested. MIC(90)s for macrolides and azithromycin in mefE+ isolates were 16-32 compared with >128 mg/l for ermB+ isolates. ABT-773 and telithromycin MIC(90)s for mefE+ isolates were 0.125 and 0.5, compared with 0.032 and 0.016 mg/l for ermB+ isolates and 0.5 and 1 mg/l, respectively, for isolates containing both genes. Clindamycin was active against mefE+ but not ermB+ isolates. 155 isolates were resistant to penicillin. All fluoroquinolone MICs were < 1 mg/l. Further studies of ketolides for treatment of paediatric S. pneumoniae infections are warranted.

Predictors of influenza virus vaccination status in hospitalized children

OBJECTIVE

To determine predictors of influenza virus vaccination status in children who are hospitalized during the influenza season.

METHODS

A cross-sectional study was conducted among children who were hospitalized with fever between 6 months and 3 years of age or with respiratory symptoms between 6 months and 18 years of age. The 1999 to 2000 influenza vaccination status of hospitalized children and potential factors that influence decisions to vaccinate were obtained from a questionnaire administered to parents/guardians.

RESULTS

Influenza vaccination rates for hospitalized children with and without high-risk medical conditions were 31% and 14%, respectively. For both groups of children, the vaccination status was strongly influenced by recommendations from physicians. More than 70% of children were vaccinated if a physician had recommended the influenza vaccine, whereas only 3% were vaccinated if a physician had not. Lack of awareness that children can receive the influenza vaccine was a commonly cited reason for nonvaccination.

CONCLUSIONS

A minority of hospitalized children with high-risk conditions had received the influenza vaccine. However, parents' recalling that a clinician had recommended the vaccine had a positive impact on the vaccination status of children.

Varicella in a pediatric heart transplant population on nonsteroid maintenance immunosuppression

OBJECTIVE

Varicella-zoster virus has been reported to produce serious, often life-threatening, disease in immunosuppressed patients with a variety of diagnoses. The impact of this virus on the young child after heart transplantation has not been reported.

METHODS

We reviewed the charts of 28 children who were <10 years of age at heart transplantation and had at least 1 year of follow-up. The median follow-up period was 7 years (1.4-13.0 years). All were seronegative for varicella-zoster virus before transplantation. Fourteen (50%) developed varicella at a median time posttransplantation of 3.3 years. The first 7 were admitted for intravenous acyclovir for 3 days followed by oral acyclovir for 7 days. The last 7 were treated as outpatients with oral valacyclovir for 7 days (n = 6) or with oral acyclovir for 10 days (n = 1).

RESULTS

Intravenous and oral regimens both were well tolerated and were without complications. No patient was receiving steroids at the time that they developed their initial episode of varicella. One patient was receiving steroids for therapy of posttransplantation lymphoproliferative disease when she developed recurrent varicella or generalized zoster. No episodes of rejection were attributed to the varicella-zoster virus infection. There were no episodes of localized zoster. All patients experienced seroconversion from undetectable to detectable antibody titers early after varicella, and 12 of the 14 patients continued to have persistent detectable titers in late follow-up. Two of the 14 who received chemotherapy or enhanced immunosuppression after retransplantation transiently lost detectable varicella-zoster virus antibodies but currently have detectable titers.

CONCLUSIONS

Primary varicella-zoster infection was well tolerated in our young pediatric heart transplant recipients, with no serious complications. We now reserve inpatient/intravenous therapy for those who are unable to tolerate oral medications or those who are receiving enhanced immunosuppression.

Efficacy of inactivated and cold-adapted vaccines against influenza A infection, 1985 to 1990: the pediatric experience

BACKGROUND

Influenza is a common and potentially serious infection in children. Although there is interest in broadening the use of influenza vaccine in healthy children, there are few large, randomized, controlled trials that evaluate the safety and efficacy of inactivated vaccine in the pediatric population.

METHODS

From 1985 through 1990 a randomized, controlled trial of cold-adapted and inactivated vaccines for the prevention of influenza A disease was conducted at Vanderbilt University, and the cumulative results from this trial in patients of all ages have been previously published. We reanalyzed the data from this trial in the subset of patients who were younger than 16 years at the time of their participation. We determined vaccine safety, immunogenicity and efficacy, based on culture-positive illness and seroconversion, in this subset of patients.

RESULTS

During the 5 years of the study, 791 children younger than 16 years received 1809 doses of either inactivated or cold-adapted vaccine or placebo. The vaccines were well-tolerated, and there were no serious reactions. Inactivated trivalent influenza vaccines were 91.4 and 77.3% efficacious in preventing symptomatic, culture-positive influenza A H1N1 and H3N2 illness, respectively. The efficacy of the inactivated vaccine based on hemagglutination inhibition assay seroconversion was 67.1 and 65.5%, respectively, for H1N1 and H3N2 serotypes.

CONCLUSIONS

Inactivated trivalent influenza A vaccines are well-tolerated and efficacious in the prevention of influenza A disease in children 1 to 16 years old.

Clones of Streptococcus pneumoniae isolated from nasopharyngeal carriage and invasive disease in young children in central Tennessee

To determine whether nasopharyngeal carriage isolates of Streptococcus pneumoniae are of the same genetic background as isolates that caused invasive disease in one community, IS1167 and boxA genotypes were obtained for 182 pneumococcal isolates from children living in central Tennessee. The isolates represented 70 combined IS1167-boxA genotypes. The genotypic diversity of the invasive isolates was significantly less than that of the total population (P=.003). Most of the carriage isolates belonged to genotypes unique to carriage, whereas most of the invasive isolates belonged to genotypes common to carriage and disease (P=.02). Monte Carlo simulations showed a greater number of genotypes unique to carriage than can be explained by chance (P<.05 in all cases). Two genotypes were identified by multilocus sequence typing as members of globally disseminated clones, and one such genotype that was strictly carriage in this sample caused disease in other studies. Thus, clones can have different propensities for carriage and invasion.

Linezolid for the treatment of community-acquired pneumonia in hospitalized children. Linezolid Pediatric Pneumonia Study Group

OBJECTIVE

To determine the safety, tolerance, pharmacokinetics and efficacy of linezolid, a new oxazolidinone antibiotic in the treatment of community-acquired pneumonia in hospitalized children.

DESIGN

A Phase II, open label multicenter study of intravenous linezolid followed by oral linezolid suspension, both at a dose of 10 mg/kg every 12 h. Efficacy was assessed at 7 to 14 days after the last dose of linezolid.

PATIENTS

Children 12 months to 17 years old with community-acquired pneumonia admitted to the hospital of 14 participating centers.

RESULTS

From July 21, 1998, through May 14, 1999, 79 children were enrolled and 78 received linezolid. Sixty-six children completed treatment and follow-up and were evaluable for clinical outcome. The median age of the evaluable patients was 3 years (range, 1 to 12 years); 47 were 2 to 6 years old. Pathogens were isolated from blood or pleural fluid cultures in 8 children: Streptococcus pneumoniae, 6 (2 penicillin-resistant); Group A Streptococcus, 1; methicillin-resistant Staphylococcus aureus, 1. Chest tubes were placed in 9 patients. The mean total duration of intravenous and oral administration was 12.2 +/- 6.2 days (range, 6 to 41 days). The mean peak and trough plasma concentrations of linezolid were 9.5 +/- 4.8 and 0.8 +/- 1.2 microg/ml, respectively. At the follow-up visit 7 to 14 days after the last dose of linezolid, 61 patients (92.4%) were considered cured including all the patients with proven pneumococcal pneumonia, one failed (methicillin-resistant Staphylococcus aureus) and 4 were considered indeterminate. The most common adverse effects in the intent to treat group were diarrhea (10.3%), neutropenia (6.4%) and elevation in alanine aminotransferase (6.4%).

CONCLUSIONS

Linezolid was well-tolerated and could be considered an alternative to vancomycin for treating serious infections caused by antibiotic-resistant Gram-positive cocci in children pending results of additional studies.

Fifth vaccination with dipthteria, tetanus and acellular pertussis is beneficial in four- to six-year-olds

OBJECTIVE

Diphtheria, tetanus and pertussis serum antibody titers were assessed before a fifth dose of diphtheria-tetanus-acellular pertussis (DTaP) or diphtheria-tetanus-whole cell pertussis (DTwP) vaccination at age 4 to 6 years.

METHODS

Healthy children who had participated in a series of National Institutes of Health-sponsored trials assessing DTwP and DTaP vaccines provided prevaccination sera before a fifth dose of DTwP or DTaP. The trial design was prospective, randomized and double blind. Diphtheria, tetanus and pertussis antibody titers were measured by enzyme-linked immunosorbent assay. Pertussis results are expressed in enzyme-linked immunosorbent assay units/ml based on US Food and Drug Administration reference sera. Tetanus and diphtheria toxin concentrations are expressed in IU/ml with a WHO international reference sera as a standard.

RESULTS

For diphtheria 100% of the children had antibody titers above the minimum protective level of 0.01 IU/ml and 86 to 100% (depending on prior vaccine product) had titers >0.1 IU/ml. However, only 0 to 40% of the children had antibody titers > or =1.0 IU/ml, a titer associated with more certain durable protection. For tetanus none of the children had an antibody titer below 0.01 IU/ml, and 93 to 100% had titers > or =0.1 IU/ml, a titer associated with more certain, durable protection. For pertussis the geometric mean concentrations of antibody before booster were uniformly very low, and the percentage of children exceeding the minimum detectable titer of antibody by 4-fold was also low.

CONCLUSION

Before a 4- to 6-year-old booster, a large proportion of children have titers of antibody to diphtheria below the certain, durable protective level. Because serologic correlates and minimum protective titers of antibody to pertussis antigens have not been established, the relevance of the low titers determined in the current study is unknown but a potential concern.

Combination vaccines

The past decade has shown a marked increase in the number of vaccines currently licensed and recommended for use in infants and children. Although most agree that it is desirable to combine as many of these vaccines as possible into a single injection, safety and efficacy must not be sacrificed. Clearly, a resurgence in Hib meningitis or measles (for example) would not be an acceptable price for the convenience of a single injection; but it is not clear how large a reduction in immunogenicity can be incurred without paying such a price. This conundrum has slowed the licensure of useful combination vaccines, despite a consensus that parents and practitioners have reached a limit to the number of injections they will deliver to young children. We anticipate US licensure for infant use of (at least) one DTaP-IPV-Hib vaccine and one DTaP-IPV-HB vaccine within the next few years, given the apparent lack of material reduction in immunogenicity of these specific combination products. Licensure in the United States of some of the other combinations now used in Europe is also possible, given supporting national surveillance data or improvements in our understanding of the correlates of immunity. Enhanced vaccination tracking systems and postmarketing efficacy surveillance should provide confidence that material reductions in efficacy could be detected following licensure, and thereby ease the approval of combinations that result in moderate, but perhaps immaterial, declines in immunogenicity.

Safety and immunogenicity of four doses of Neisseria meningitidis group C vaccine conjugated to CRM197 in United States infants

BACKGROUND

Following widespread use of conjugate pneumococcal vaccine, Neisseria meningitidis likely will become the leading cause of bacterial sepsis and meningitis in US children. This report describes the safety and immunogenicity in US children of four consecutive doses of a meningococcal group C vaccine conjugated to CRM197 via reductive amination (MnCC).

METHODS

One hundred six healthy 2-month-old infants received MnCC at 2, 4 and 6 months of age in a randomized, controlled double blind study; children in the other treatment arm were given a 7-valent conjugate pneumococcal vaccine. Parents reenrolled 64 of these children at 12 to 15 months to receive a fourth dose of MnCC. Routine childhood vaccines, including DTP, were coadministered. Temperatures and symptoms were recorded for 3 days after each immunization. Serum enzyme-linked immunosorbent assay IgG and bactericidal antibodies were measured prevaccination and before and 1 month after Doses 3 and 4.

RESULTS

Moderate to severe local reactions, defined as erythema or induration > or =2.4 cm or pain that interfered with limb movement was reported after 0 to 3.2% of MnCC injections, depending on the reaction and dose. Fever occurred in 23 to 37% of children, but the contribution of MnCC to the febrile reactions is unknown. Geometric mean concentrations of IgG antibody to group C meningococcal polysaccharide were 3.72 microg/ml after Dose 3 and 8.03 microg/ml after the booster. Geometric mean functional serum bactericidal antibody titers after Doses 3 and 4 were 1:463 and 1:2341, respectively. One hundred percent of children had a serum bactericidal antibody titer of > or =1:64 after three doses and > or = 1:128 after the booster.

CONCLUSIONS

The MnCC vaccine had an acceptable safety profile and generated high titers of bactericidal antibody in immunized US infants and toddlers. It appears to be an attractive candidate vaccine for the prevention of serogroup C meningococcal disease in young children.

Prevention, diagnosis, and treatment of influenza: current and future options

Because influenza significantly affects the health of children, this review describes the current and future options for preventing, diagnosing, and treating influenza infections. Currently, the inactivated influenza vaccine is recommended for prevention of influenza; however, the live, attenuated, intranasal influenza vaccine is a potential future option. For diagnosis, viral culture is the gold standard, although four rapid diagnostic tests are available for more immediate results. The impetus for rapid results is the availability of effective antiviral agents indicated for early influenza infection. The four currently approved antiviral agents are amantadine, rimantadine, zanamivir [Relenza, Glaxo Wellcome, Inc., Research Triangle Park, NC] and oseltamivir [Tamiflu, Roche Pharmaceuticals, Nutley, NJ]. The indications, benefits, side effects and ages for which each drug is approved are reviewed.

Characterization of bactericidal immune responses following vaccination with acellular pertussis vaccines in adults

Sera from six adults, collected before and after acellular pertussis vaccination, and from a placebo control were examined for the ability to elicit two bactericidal immune defenses, (i) antibody-dependent complement-mediated bacterial lysis and (ii) opsonization and phagocytosis by human neutrophils. The samples were chosen based on low preimmunization titers and strong postimmunization responses to various combinations of vaccine antigens. All but two prevaccination samples demonstrated activity indicative of complement-mediated lysis. Preimmunization activity could have been due to prior infection or childhood immunization. Immunization did not result in improved bactericidal activity for any of the individuals, and in two cases immunization caused a statistically significant decrease in complement-mediated lysis. Similarly, opsonization with the postimmunization sera failed to enhance attachment or phagocytosis of bacteria by neutrophils, and one postimmunization sample with a strong response to filamentous hemagglutinin caused an inhibition of phagocytosis that was statistically significant compared to that observed for the no-serum control. In summary, booster immunization of adults with acellular pertussis vaccines was not found to increase bactericidal activity over preimmunization levels. Identifying ways to promote bactericidal immune responses might improve the efficacy of acellular pertussis vaccines.

Human immune response to streptococcal inhibitor of complement, a serotype M1 group A Streptococcus extracellular protein involved in epidemics

Streptococcal inhibitor of complement (Sic) is a highly polymorphic extracellular protein made by serotype M1 group A Streptococcus strains that contributes to bacterial persistence in the mammalian upper respiratory tract. New variants of the Sic protein arise very rapidly by positive selection in human populations during M1 epidemics. The human antibody response to Sic was analyzed. Of 636 persons living in diverse localities, 43% had anti-Sic serum antibodies, but only 16.4% had anti-M1 protein serum antibody. Anti-Sic antibody was also present in nasal wash specimens in high frequency. Linear B cell epitope mapping showed that serum antibodies recognized epitopes located in structurally variable regions of Sic and the amino terminal hypervariable region of the M1 protein. Phage display analyses confirmed that the polymorphic regions of Sic are primary targets of host antibodies. These results support the hypothesis that selection of Sic variants occurs on mucosal surfaces by a mechanism that involves acquired host antibody.

Effect of vitamin A therapy on serologic responses and viral load changes after influenza vaccination in children infected with the human immunodeficiency virus

Vitamin A administered to children infected with the human immunodeficiency virus before influenza vaccination in a double-blind randomized study did not enhance vaccine serologic responses but did dampen the increase in the human immunodeficiency virus viral load 14 days after immunization (vitamin A, decrease of 0.13 +/- 0.09 log(10) copies/mL; placebo, increase of 0.14 +/- 0.08, P =.02).

Acellular pertussis vaccines

Although whole-cell pertussis vaccines have been highly effective in preventing whooping cough, their common and burdensome adverse reactions have spurred the development of safer alternatives. Seven acellular vaccines are licensed in one or more countries; four have been licensed thus far in the United States, and more may follow. Although the licensed acellular pertussis vaccines differ in their immunogenicity, adverse reactions, and efficacy, all are effective and, compared with whole-cell vaccine, are associated with markedly fewer and milder adverse reactions.

Enhanced production of recombinant Mycobacterium tuberculosis antigens in Escherichia coli by replacement of low-usage codons

A major obstacle to development of subunit vaccines and diagnostic reagents for tuberculosis is the inability to produce large quantities of these proteins. To test the hypothesis that poor expression of some mycobacterial genes in Escherichia coli is due, in part, to the presence of low-usage E. coli codons, we used site-directed mutagenesis to convert low-usage codons to high-usage codons for the same amino acid in the Mycobacterium tuberculosis genes for antigens 85A and 85B and superoxide dismutase. Replacement of five codons in the wild-type gene for antigen 85B increased recombinant protein production in E. coli 54-fold. The recombinant antigen elicited proliferation and gamma interferon production by lymphocytes from healthy tuberculin reactors and was recognized by monoclonal antibodies to native antigen 85, indicating that the recombinant antigen contained T-cell and B-cell epitopes. Northern blotting demonstrated only a 1.7- to 2.5-fold increase in antigen 85B mRNA, suggesting that the enhanced protein production was due primarily to enhanced efficiency of translation. Codon replacement in the genes encoding antigen 85A and superoxide dismutase yielded four- to sixfold increases in recombinant protein production, suggesting that this strategy may be generally applicable to overexpression of mycobacterial genes in E. coli.

Safety and immunogenicity of six acellular pertussis vaccines and one whole-cell pertussis vaccine given as a fifth dose in four- to six-year-old children

OBJECTIVE

To evaluate the safety and immunogenicity of 6 different acellular pertussis vaccines combined with diphtheria and tetanus toxoids (DTaP) and with 1 licensed whole-cell pertussis vaccine (DTwP) as a fifth dose in children who had previously received the same DTaP, a different DTaP, or DTwP as primary and fourth-dose vaccinations.

METHODS

Healthy 4- to 6-year-old children were enrolled at 5 National Institute of Allergy and Infectious Diseases Vaccine Treatment and Evaluation Units to receive a fifth dose of a DTaP or DTwP vaccine. All had been randomly assigned to receive 3 primary doses of DTaP or DTwP at 2, 4, and 6 months and a fourth-dose booster at 15 to 20 months of age as part of earlier National Institutes of Health multicenter acellular pertussis vaccine trials. Parents recorded the occurrence and magnitude of fever, irritability, and injection site redness, swelling, and pain for 3 days after vaccination. Sera obtained before and 1 month after the booster vaccination were analyzed by enzyme-linked immunosorbent assay for antibody to pertussis toxin, filamentous hemagglutinin, fimbriae, pertactin, and diphtheria and tetanus toxoid. Safety and/or immunogenicity data are reported for 317 children who received DTaP and 10 children who received DTwP.

RESULTS

Fever and moderate or severe irritability were uncommon following the fifth dose of DTaP vaccine and were generally less frequent than following the fourth dose. However, for the DTaP vaccine groups, redness, swelling, and pain increased in prevalence compared with the fourth dose. The time course and frequency of reactions following DTaP vaccination were generally similar in children who received the same DTaP, a different DTaP, or DTwP for previous doses in the 5- dose series. No significant differences among the DTaP vaccines were detected in the occurrence of reactions, but the statistical power to detect differences was limited by sample size. Significant increases in antibodies directed against the included antigens were observed for all DTaP vaccines in paired pre- and post-fifth dose sera. Post-fifth dose antibody concentrations differed significantly among the DTaP vaccines. Some children in the study showed an antibody response to an antigen not reported to be in the DTaP vaccine.

CONCLUSION

All the studied DTaP vaccines performed similarly with regard to reactions, whether given as a fifth sequential dose of the same vaccine, a mix of different DTaP vaccines in the 5-dose sequence, or after 3 DTwP and 1 DTaP vaccinations. Large injection site reactions occurred more frequently after the fifth dose of DTaP than after the previous 4 doses. A fifth dose of all DTaP vaccines induced an antibody response to those antigens contained in the vaccine. No DTaP was consistently most or least reactogenic or immunogenic.

Extensive swelling after booster doses of acellular pertussis-tetanus-diphtheria vaccines

BACKGROUND

Diphtheria and tetanus toxoid combined with acellular pertussis (DTaP) vaccines are less reactogenic than diphtheria and tetanus toxoid combined with whole cell pertussis (DTwP) vaccines. However, local reactions increase in rate and severity with each successive DTaP dose, and swelling of the entire injected limb has been reported after booster doses.

METHODS

We reviewed reports of swelling of the entire thigh or upper arm after the fourth and fifth dose, respectively, of DTaP vaccines administered in the National Institutes of Health multicenter comparative DTaP studies. Relationships were explored among reports of severe swelling, rates of other reactions, quantity of vaccine contents, and prevaccination and postvaccination antibody levels to pertussis toxin, tetanus toxin, and diphtheria toxin.

RESULTS

Entire thigh swelling was an unsolicited reaction reported in 20 (2%) of the 1015 children who received 4 consecutive doses of the same DTaP vaccine. The reaction was associated with 9 of the 12 DTaP vaccines evaluated. Although there were no reports of swelling of the entire upper arm in 121 children given a fifth dose of the same DTaP, 4 (2.7%) of 146 recipients of 5 doses of a mixed schedule of DTaP vaccines experienced such swelling. Rates of other reactions were higher in children with entire thigh swelling than in those without. Of the children with entire thigh swelling, 60% had local pain, and 60% had erythema. All swelling subsided spontaneously without sequelae. There was a significant linear association between the rates of entire thigh swelling after dose 4 and diphtheria toxoid content in the DTaP products. Lesser degrees of swelling (>50 mm but less than entire limb) correlated with pertussis toxoid content after dose 4 and aluminum content after dose 5. No relationship was established between levels of serum antibody to diphtheria, tetanus, or pertussis toxin and rates of swelling of the whole thigh.

CONCLUSIONS

Booster doses of DTaP vaccines can cause entire limb swelling, which is usually associated with redness and pain. Our data suggest that this extensive swelling reaction may be more common with vaccines containing high diphtheria toxoid content.

Immunity to cross-reactive serotypes induced by pneumococcal conjugate vaccines in infants

Infants were immunized with 1 of the 3 experimental pneumococcal conjugate vaccines that contain 6B and 19F but not 6A or 19A serotypes. Their sera were studied for the capacity to opsonize Streptococcus pneumoniae 6A, 6B, 19A, and 19F serotypes and the level of IgG antibody to the 4 serotypes. Significant increases were observed in the number of infants with detectable opsonophagocytic titers with 3 conjugate vaccines for 6B (vaccine) serotype but with only 2 vaccines for 6A (cross-reactive) serotype. Significant increases were observed with 2 conjugate vaccines for 19F serotype but with only 1 vaccine for 19A serotype. Thus, some conjugate vaccines may elicit cross-protection better than others. In addition, correlations between opsonophagocytic titers and IgG antibody levels by ELISA were high for 6B and 19F serotypes but low for 6A and 19A serotypes. Thus, ELISA may be an inadequate surrogate assay of vaccine response for cross-reactive serotypes.

Productive working relationships in the midst of change in health care

Traditional lines of authority that once provided identity and meaning in health care are blurring as delivery organizations adapt to the challenges of controlling cost and providing quality service. Teams and committees tackle work that was once the realm of individual managers. Men and women at different levels of authority in the organization now work together to make decisions. Previous lines of authority in the health administration education setting are also blurring as colleges and universities, under pressure, respond to customer needs. Academia is increasingly drawing upon adjunct and non-tenure-eligible professionals to streamline departments and save money. Within the structure of a department, workers in these temporary positions have less authority than tenured and tenure-track faculty. They have less authority in the classroom as well. In both the health care industry and academia, women endure these changes more than their male counterparts, since women often assume the variety of flexible roles required by these strategies. Changes in traditional academic authority produce anxiety and stress for everyone involved. However, faculty can teach students a flexible paradigm to navigate and find meaning in these situations to ensure successful and productive working relationships between men and women in the changing workplace. This paper identifies the pertinent components of this paradigm and its application in the health administration classroom.

The human cytotoxic T cell granule serine protease granzyme H has chymotrypsin-like (chymase) activity and is taken up into cytoplasmic vesicles reminiscent of granzyme B-containing endosomes

Serine proteases (granzymes) contained within the cytoplasmic granules of cytotoxic T cells and natural killer cells play a variety of roles including the induction of target cell apoptosis, breakdown of extracellular matrix proteins and induction of cytokine secretion by bystander leukocytes. Different granzymes display proteolytic specificities that mimic the activities of trypsin or chymotrypsin, or may cleave substrates at acidic ("Asp-ase") or at long unbranched amino acids such as Met ("Met-ase"). Here, we report that recombinant granzyme H has chymotrypsin-like (chymase) activity, the first report of a human granzyme with this proteolytic specificity. Recombinant 32-kDa granzyme H expressed in the baculovirus vector pBacPAK8 was secreted from Sf21 cells and recovered by Ni-affinity chromatography, using a poly-His tag encoded at the predicted carboxyl terminus of full-length granzyme H cDNA. The granzyme H efficiently cleaved Suc-Phe-Leu-Phe-SBzl (v = 185 nM/s at [S] = 0.217 mM) and also hydrolyzed Boc-Ala-Ala-X-SBzl (X = Phe, Tyr, Met, Nle, or Nva) with slower rates but had little tryptase or Asp-ase activity. Enzymatic activity was inhibited completely by 0.1 mM 3,4-dichloroisocoumarin and 84% by 1.0 mM phenylmethylsulfonyl fluoride. Fluoresceinated granzyme H was internalized in a temperature-dependent manner by Jurkat cells into endosome-like vesicles, suggesting that it can bind to cell surface receptors similar to those that bind granzyme B. This suggests a hitherto unsuspected intracellular function for granzyme H.

Early childhood mortality from community-acquired infections

In this study, the authors identified maternal and child characteristics that were independent predictors of death from infectious diseases acquired in the community and determined if these factors could be used to identify groups of children with excess risk of mortality from infection. A historical cohort study was conducted of children less than 5 years of age between 1985 and 1994 (the study period), who were born in Tennessee, and had complete information on their birth certificates. The primary outcome was death from infection identified from death certificates and confirmed through medical record review. Among the 1,014,976 children less than 5 years of age, who contributed 3,351,568 child-years of follow-up, there were 247 deaths from infections (7.4 deaths from infections per 100,000 child-years). Respiratory infections accounted for approximately one half of the deaths. Children having three or more older siblings or birth weight of less than 1,500 g had a 3-fold and 10-fold increased risk of death from infection, respectively, while children with both characteristics had a nearly 20-fold increased risk that persisted beyond the first year of life. Interventions should be focused on prevention of these infections in vulnerable children. At-risk children should be targeted for careful follow-up and early hospitalization when signs of infection develop.

A randomized clinical trial of acellular pertussis vaccines in healthy adults: dose-response comparisons of 5 vaccines and implications for booster immunization

The safety and immunogenicity of 5 acellular pertussis vaccines (ACVs) were compared in a multicenter, randomized, double-blind trial. A total of 481 healthy adults were given a single intramuscular booster dose of ACV or placebo. Three different dose levels were tested for 4 ACVs: full strength (the dose level proposed for infant immunization), one-third strength, and one-tenth strength. For 1 multicomponent vaccine, only the pertussis toxoid dose level varied. Minor injection site reactions were common and similar in frequency among vaccinated groups. Late-onset injection site reactions were seen in all ACV groups. Dose-related increases in mean antibody titers against vaccine antigens were seen after immunization with all ACVs. Antibody responses against antigens not known to be present in the vaccines were detected after immunization with 4/5 ACVs. Antibody levels fell significantly during the year after immunization. These data support evaluation of ACVs for broader use among adolescents and adults.

Periodic fever syndrome in children

OBJECTIVES

To describe the presentation, clinical course, therapeutic response, and long-term follow-up of patients with a syndrome of periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA).

STUDY DESIGN

Patients with PFAPA (n = 94) referred over a 10-year period completed a registry form and provided medical records. Follow-up telephone calls were made in late 1997 to determine the persistence of episodes and sequelae.

RESULTS

PFAPA episodes lasted 4.8 days (95% confidence interval 4.5 to 5.1) and recurred every 28 days (confidence interval 26 to 30), with a maximal temperature of 40.5 degrees C (confidence interval 40. 4 degrees to 40.6 degrees ). Of the 83 children available for follow-up, 34 no longer had episodes. In the remainder the episodes did not differ in character but recurred less frequently over time. The affected children had no long-term sequelae. Glucocorticoids were highly effective in controlling symptoms. Tonsillectomy and cimetidine treatment were associated with remission in a small number of patients.

CONCLUSIONS

PFAPA is a not uncommon cause of periodic fever in children. In some children the syndrome resolves, whereas symptoms in others persist. Long-term sequelae do not develop. The syndrome is easily diagnosed when regularly recurring episodes of fever are associated with aphthous stomatitis, pharyngitis, or cervical adenitis.

Acellular pertussis vaccines in adults

The pathogenesis of pertussis, and the epidemiology and clinical manifestations of pertussis after childhood are reviewed as a background for a discussion of recent clinical trials of acellular pertussis vaccines in adults, and the vaccines' potential for routine use in adolescents and adults.

Anti-viral strategies of cytotoxic T lymphocytes are manifested through a variety of granule-bound pathways of apoptosis induction

Cytotoxic T cells and natural killer cells together constitute a major defence against virus infection, through their ability to induce apoptotic death in infected cells. These cytolytic lymphocytes kill their targets through two principal mechanisms, and one of these, granule exocytosis, is essential for an effective in vivo immune response against many viruses. In recent years, the authors and other investigators have identified several distinct mechanisms that can induce death in a targeted cell. In the present article, it is postulated that the reason for this redundancy of lethal mechanisms is to deal with the array of anti-apoptotic molecules elaborated by viruses to extend the life of infected cells. The fate of such a cell therefore reflects the balance of pro-apoptotic (immune) and anti-apoptotic (viral) strategies that have developed over eons of evolutionary time.