Off-label use of dalbavancin in children: a case series.

INTRODUCTION: Dalbavancin is an antibiotic active against most Gram-positive bacteria approved for acute bacterial skin and skin structure infections (ABSSSI). Owing to its long half-life, it is being increasingly used for other indications. PATIENTS AND METHODS: We present a case series of children and adolescents treated with dalbavancin for osteoarticular, catheter-related and other non-ABSSSI infections. RESULTS: Dalbavancin was prescribed to 15 patients. Six (40%) were female and median age at prescription was 11.9 (IQR 1.3-18.0) years. Most of them (12/15) had significant comorbidities. Patients presented mainly with deep surgical site infections, osteoarticular infections and central-line-associated bloodstream infections. The most common isolate was Staphylococcus aureus followed by Staphylococcus epidermidis. Major reasons to prescribe dalbavancin were to ensure compliance and patients' convenience. Two patients discontinued the drug due to adverse events possibly related to it. The rest of the patients completed the treatment with dalbavancin, with a median duration of 56 days (IQR 17.5, 115.5). All achieved complete resolution and present no relapse after a median follow-up of 9.9 months (IQR 4.8, 16.6). CONCLUSIONS: Dalbavancin was a safe, effective and convenient alternative in selected paediatric patients with complicated non-ABSSSI infections caused by Gram-positive bacteria.

Performance of QuantiFERON-TB Gold Plus assays in children and adolescents at risk of tuberculosis: a cross-sectional multicentre study.

INTRODUCTION: The QuantiFERON-TB Gold Plus (QFT-Plus) assay, which features two antigen-stimulated tubes (TB1 and TB2) instead of a single tube used in previous-generation interferon-gamma release assays (IGRAs), was launched in 2016. Despite this, data regarding the assay's performance in the paediatric setting remain scarce. This study aimed to determine the performance of QFT-Plus in a large cohort of children and adolescents at risk of tuberculosis (TB) in a low-burden setting. METHODS: Cross-sectional, multicentre study at healthcare institutions participating in the Spanish Paediatric TB Research Network, including patients <18 years who had a QFT-Plus performed between September 2016 and June 2020. RESULTS: Of 1726 patients (52.8% male, median age: 8.4 years), 260 (15.1%) underwent testing during contact tracing, 288 (16.7%) on clinical/radiological suspicion of tuberculosis disease (TBD), 649 (37.6%) during new-entrant migrant screening and 529 (30.6%) prior to initiation of immunosuppressive treatment. Overall, the sensitivity of QFT-Plus for TBD (n=189) and for latent tuberculosis infection (LTBI, n=195) was 83.6% and 68.2%, respectively. The agreement between QFT-Plus TB1 and TB2 antigen tubes was excellent (98.9%, κ=0.961). Only five (2.5%) patients with TBD had discordance between TB1 and TB2 results (TB1+/TB2-, n=2; TB1-/TB2+, n=3). Indeterminate assay results (n=54, 3.1%) were associated with young age, lymphopenia and elevated C reactive protein concentrations. CONCLUSIONS: Our non-comparative study indicates that QFT-Plus does not have greater sensitivity than previous-generation IGRAs in children in both TBD and LTBI. In TBD, the addition of the second antigen tube, TB2, does not enhance the assay's performance substantially.

Diagnostic Accuracy of QuantiFERON-TB Gold Plus Assays in Children and Adolescents with Tuberculosis Disease.

In 2016, a new interferon-gamma release assay, QuantiFERON-TB Gold Plus, was introduced. We conducted a cross-sectional multicenter study, involving 158 children and adolescents with tuberculosis disease. The overall sensitivity of the assay was 82.9% (IQR 77.0%-88.8%), indicating that in children this test does not have higher sensitivity than previous generation interferon-gamma release assays.

CENTRAL NERVOUS SYSTEM INFECTION BY GROUP A STREPTOCOCCUS IN CHILDREN IN SPAIN (2019-2023).

Central nervous system infections in children caused by group A Streptococcus are rare. This study, conducted across 52 hospitals in Spain from 2019 to 2023, identified 32 cases of central nervous system infections in children caused by group A Streptococcus, with a significant increase from October 2022 onward (1.1% vs. 5.9%, P = 0.002). Half required pediatric intensive care unit admission, 12.5% exhibited sequelae and the mortality rate was 6.2%. Mastoiditis was the predominant primary infection.

Clinical, microbiological, and molecular characterization of pediatric invasive infections by Streptococcus pyogenes in Spain in a context of global outbreak.

In December 2022, an alert was published in the UK and other European countries reporting an unusual increase in the incidence of Streptococcus pyogenes infections. Our aim was to describe the clinical, microbiological, and molecular characteristics of group A Streptococcus invasive infections (iGAS) in children prospectively recruited in Spain (September 2022-March 2023), and compare invasive strains with strains causing mild infections. One hundred thirty isolates of S. pyogenes causing infection (102 iGAS and 28 mild infections) were included in the microbiological study: emm typing, antimicrobial susceptibility testing, and sequencing for core genome multilocus sequence typing (cgMLST), resistome, and virulome analysis. Clinical data were available from 93 cases and 21 controls. Pneumonia was the most frequent clinical syndrome (41/93; 44.1%), followed by deep tissue abscesses (23/93; 24.7%), and osteoarticular infections (11/93; 11.8%). Forty-six of 93 cases (49.5%) required admission to the pediatric intensive care unit. iGAS isolates mainly belonged to emm1 and emm12; emm12 predominated in 2022 but was surpassed by emm1 in 2023. Spread of M1UK sublineage (28/64 M1 isolates) was communicated for the first time in Spain, but it did not replace the still predominant sublineage M1global (36/64). Furthermore, a difference in emm types compared with the mild cases was observed with predominance of emm1, but also important representativeness of emm12 and emm89 isolates. Pneumonia, the most frequent and severe iGAS diagnosed, was associated with the speA gene, while the ssa superantigen was associated with milder cases. iGAS isolates were mainly susceptible to antimicrobials. cgMLST showed five major clusters: ST28-ST1357/emm1, ST36-ST425/emm12, ST242/emm12.37, ST39/emm4, and ST101-ST1295/emm89 isolates. IMPORTANCE: Group A Streptococcus (GAS) is a common bacterial pathogen in the pediatric population. In the last months of 2022, an unusual increase in GAS infections was detected in various countries. Certain strains were overrepresented, although the cause of this raise is not clear. In Spain, a significant increase in mild and severe cases was also observed; this study evaluates the clinical characteristics and the strains involved in both scenarios. Our study showed that the increase in incidence did not correlate with an increase in resistance or with an emm types shift. However, there seemed to be a rise in severity, partly related to a greater rate of pneumonia cases. These findings suggest a general increase in iGAS that highlights the need for surveillance. The introduction of whole genome sequencing in the diagnosis and surveillance of iGAS may improve the understanding of antibiotic resistance, virulence, and clones, facilitating its control and personalized treatment.

The Value of the Second QuantiFERON-TB Gold-Plus Antigen Tube at Diagnosis and at Treatment Completion in Spanish Children With Tuberculosis.

We studied 295 children (tuberculosis disease, n = 159; latent tuberculosis infection, n = 136) with positive QuantiFERON-TB Gold-Plus assay results. No significant differences between first and second antigen tube interferon-gamma responses were detected, irrespective of patient and disease characteristics at diagnosis. Of patients with a repeat assay after treatment completion (n = 65), only 16.9% converted to negative results.

Host, technical, and environmental factors affecting QuantiFERON-TB Gold In-Tube performance in children below 5 years of age.

Interferon-gamma release assays performance can be impaired by host-related, technical and environmental factors, but data in young children are limited. We performed a cross-sectional study of children < 5 years-of-age at risk of tuberculosis (TB), using QuantiFERON-TB Gold In-Tube (QFT-GIT) assays. The impact of the following was evaluated: (i) host-related [age; hematological parameters; erythrocyte sedimentation rate (ESR); C-reactive protein (CRP); and tobacco smoke exposure (TSE) based on serum cotinine concentrations], (ii) technical (pre-analytical delay) and (iii) environmental factors (annual season; monthly temperatures). Of 204 children, 35 (17.2%) were diagnosed with latent TB infection or TB disease. QFT-GIT results were indeterminate in 14 (6.9%) patients. In multivariate analysis, younger age and higher ESR were associated with lower positive control responses (beta: 0.247, p = 0.002 and - 0.204, p = 0.007, respectively), and increasing age was associated with lower rates of indeterminate QFT-GIT results [OR (95% CI) 0.948 (0.903-0.996) per month, p = 0.035]. In children with positive QFT-GIT results, average monthly temperatures correlated with antigen responses (r = 0.453, p = 0.020); also, antigen responses were lower in winter than in other seasons (p = 0.027). Serum cotinine concentrations determined in a subgroup of patients (n = 41) indicated TSE in 36 (88%), positive control responses being lower in children with TSE (p = 0.034). In children < 5 years-of-age, young age, elevated ESR, temperature, annual season and TSE can affect the performance of QFT-GIT assays.

Family presence during invasive procedures at the emergency department: what is the opinion of Spanish medical staff?

OBJECTIVES: Family presence (FP) during invasive procedures (IPs) in children remains controversial among pediatric emergency department (PED) staff. The authors aimed to determine health care providers' attitudes toward FP during IPs in Spain, to learn whether parents are given the option of being present during different IPs, and to study which factors influence the providers' opinions. METHODS: Observational study. Physicians and nurses were asked to answer a questionnaire, which was sent to 43 PEDs and was available at the Spanish Pediatric Emergency Society Web site. RESULTS: We obtained 222 questionnaires from 36 Spanish hospitals. A total of 65.8% of the surveys were answered by physicians (66.4% pediatricians) and 34.2% by nurses. The median age of the respondents was 32 years, and 69.2% were women. Parents were given the option of being present during blood sampling (36.4%), intravenous line placement (32.7%), urethral catheterization (32.1%), lumbar puncture (13.5%), and resuscitation (1%). More than 60% of providers approved of FP during blood sampling, sutures, intravenous line placement, and urethral catheterization; however, only 10.8% of providers encourages FP during resuscitation. Against FP, health care staff argue procedural invasiveness (75.6%), parents' anxiety (87.6%), and worsened performance of the procedure (66%). Commonly expressed advantages were reducing patient distress (72.9%) and parent anxiety (62.3%). Physicians, especially the older ones, are more likely to encourage FP than nurses for some IPs. CONCLUSIONS: The PED staff tend to prefer parents not to be present during IPs as the level of invasiveness increases. Family presence is not common in Spanish PEDs. Older physicians are more likely to support FP than nurses.

Prospective validation of two systems of classification for the diagnosis of acute appendicitis.

OBJECTIVES: The objectives of this study were (1) to validate the Alvarado score and pediatric appendicitis score (PAS) in a prospectively identified pediatric cohort and (2) to assess abdominal ultrasonography (AUS) as a tool to increase the diagnostic reliability of both scores. PATIENTS AND METHODS: Prospective study conducted from January 10, 2008, to January 1, 2009. All patients attended at the emergency department with suspected acute appendicitis (AA) who had a blood sample collected were included. Items from both scores were recorded. The performance of an AUS, the decision to admit the patient, and the therapeutics were decided by the physician, disregarding the scores values. Nonadmitted patients were contacted by telephone. RESULTS: Ninety-nine patients were included. Mean age was 11 years, and 62.6% were males. Appendectomy was performed in 44.4% patients. The area under the receiver operating characteristic curve for the Alvarado score was 0.96 and that for PAS was 0.97. Not a single patient with an Alvarado score less than 5 or PAS less than 4 had AA. All patients with an Alvarado score greater than 8 or PAS greater than 7 had AA. For both scores, the optimum cutoff point was 6 (sensibility of 90.4% and specificity of 91.2% for the Alvarado score and sensibility of 88.1% and specificity of 98.2% for PAS). Abdominal ultrasonography was performed on 31 patients (sensibility of 84.6% and specificity of 94.4%). We studied the value of scores and AUS together. Assuming an Alvarado score from 1 to 4 and PAS from 1 to 3 as no AA, an Alvarado score from 9 to 10 and PAS from 8 to 9 as AA, and proceeding according to the AUS for intermediate values, a sensibility of 93.3% and 97.2% and a specificity of 100% and 97.6%, respectively, were obtained. CONCLUSIONS: Both scores are a useful tool in the evaluation of children with possible AA. For extreme values of scores, the results really ensure their use in the emergency department. The AUS can help on decision making for intermediate values.

QuantiFERON-TB Gold Plus Assay Specificity in Children and Adolescents With Suspected Tuberculosis-A Multicenter Cross-sectional Study in Spain.

In this cross-sectional study of 284 children and adolescents with clinically or radiologically suspected tuberculosis in a low-endemic country, the QuantiFERON-TB Gold Plus assay specificity, sensitivity, positive predictive value and negative predictive value were 91.5%, 87.3%, 86.4%, and 91.2%, respectively. The specificity was higher than that observed in tuberculin skin tests performed simultaneously, but similar to previous-generation interferon-gamma release assays.

Prevention of Mother-to-Child Transmission of HIV ­ an Update from Rural Africa. / Prävention der Übertragung von HIV von Mutter auf Kind - Update aus dem ländlichen Afrika

Sub-Saharan Africa is home of 85 % of pregnant women living with HIV and 90 % of HIV-infected children. WHO issued the first prevention of mother-to-child transmission of HIV (PMTCT) recommendations in 2000. These guidelines have been revised to incorporate new evidence and align with the goal of universal treatment access and zero infections among children. Currently, 82 % of HIV-infected pregnant women receive antiretroviral treatment, and infections among children have halved since 2010. However, in 2018, 160,000 children became infected. Reasons hindering the success of PMTCT are: a) non-universal HIV testing during pregnancy; b) low retention through the PMTCT cascade; and c) missed opportunities to diagnose women who acquire HIV while pregnant or breastfeeding. To address these gaps innovative strategies are needed.

Brief Report: No HIV Transmission From Virally Suppressed Mothers During Breastfeeding in Rural Tanzania.

BACKGROUND: To what extent antiretroviral therapy (ART) reduces mother-to-child HIV transmission (MTCT) during breastfeeding remains unclear. We assessed the MTCT risk from mothers on ART to their infants during breastfeeding. SETTING: Ifakara, rural Tanzania. METHODS: We included infants born between January 2013 and May 2016 to mothers who initiated ART before delivery, had a negative HIV DNA polymerase chain reaction at 4-12 weeks and exclusively breastfed for ≥6 months. Mothers' plasma HIV-RNA viral loads (VLs) were measured up to 11 months postdelivery. Infants were tested for HIV following national guidelines. RESULTS: Among 214 women with 218 pregnancies and 228 infants (10 twins), the median age at delivery was 33 years (interquartile range 28-36 years), and the mean time on ART was 23 months (interquartile range, 4-52 months). VL was measured twice in 53% (113/218) of pregnancies. During breastfeeding, 91% of mothers (199/218) had VL of <1000 copies per milliliter, and 75% (164/218) had <100 copies per milliliter. To November 2017, 8% (19/228) of infants were lost to follow-up (LTFU), 2% (5/228) transferred, and 8% (18/228) died before the determination of final HIV serostatus. Among the remaining 186 infants, 2 (1%; 95% confidence interval: 0.3% to 4%) were HIV positive: 1 born from a mother with high VL 1-month postdelivery and 1 from a mother who interrupted ART. Assuming a 15% MTCT risk through breastfeeding among the 42 infants LTFU, transferred, or dead, the overall MTCT risk would be 4%. CONCLUSIONS: We found no MTCT from mothers who were retained in care and had suppressed VL. Breastfeeding signifies a very low risk when mothers adhere to ART. Adherence counseling, VL monitoring, and strategies to trace back those LTFU should be a priority.

Prevention of mother-to-child transmission of HIV Option B+ cascade in rural Tanzania: The One Stop Clinic model.

BACKGROUND: Strategies to improve the uptake of Prevention of Mother-To-Child Transmission of HIV (PMTCT) are needed. We integrated HIV and maternal, newborn and child health services in a One Stop Clinic to improve the PMTCT cascade in a rural Tanzanian setting. METHODS: The One Stop Clinic of Ifakara offers integral care to HIV-infected pregnant women and their families at one single place and time. All pregnant women and HIV-exposed infants attended during the first year of Option B+ implementation (04/2014-03/2015) were included. PMTCT was assessed at the antenatal clinic (ANC), HIV care and labour ward, and compared with the pre-B+ period. We also characterised HIV-infected pregnant women and evaluated the MTCT rate. RESULTS: 1,579 women attended the ANC. Seven (0.4%) were known to be HIV-infected. Of the remainder, 98.5% (1,548/1,572) were offered an HIV test, 94% (1,456/1,548) accepted and 38 (2.6%) tested HIV-positive. 51 were re-screened for HIV during late pregnancy and one had seroconverted. The HIV prevalence at the ANC was 3.1% (46/1,463). Of the 39 newly diagnosed women, 35 (90%) were linked to care. HIV test was offered to >98% of ANC clients during both the pre- and post-B+ periods. During the post-B+ period, test acceptance (94% versus 90.5%, p<0.0001) and linkage to care (90% versus 26%, p<0.0001) increased. Ten additional women diagnosed outside the ANC were linked to care. 82% (37/45) of these newly-enrolled women started antiretroviral treatment (ART). After a median time of 17 months, 27% (12/45) were lost to follow-up. 79 women under HIV care became pregnant and all received ART. After a median follow-up time of 19 months, 6% (5/79) had been lost. 5,727 women delivered at the hospital, 20% (1,155/5,727) had unknown HIV serostatus. Of these, 30% (345/1,155) were tested for HIV, and 18/345 (5.2%) were HIV-positive. Compared to the pre-B+ period more women were tested during labour (30% versus 2.4%, p<0.0001). During the study, the MTCT rate was 2.2%. CONCLUSIONS: The implementation of Option B+ through an integrated service delivery model resulted in universal HIV testing in the ANC, high rates of linkage to care, and MTCT below the elimination threshold. However, HIV testing in late pregnancy and labour, and retention during early ART need to be improved.

Development of HIV drug resistance and therapeutic failure in children and adolescents in rural Tanzania: an emerging public health concern.

OBJECTIVE: To investigate the prevalence and determinants of virologic failure and acquired drug resistance-associated mutations (DRMs) in HIV-infected children and adolescents in rural Tanzania. DESIGN: Prospective cohort study with cross-sectional analysis. METHODS: All children 18 years or less attending the paediatric HIV Clinic of Ifakara and on antiretroviral therapy (ART) for at least 12 months were enrolled. Participants with virologic failure were tested for HIV-DRM. Pre-ART samples were used to discriminate acquired and transmitted resistances. Multivariate logistic regression analysis identified factors associated with virologic failure and the acquisition of HIV-DRM. RESULTS: Among 213 children on ART for a median of 4.3 years, 25.4% failed virologically. ART-associated DRM were identified in 90%, with multiclass resistances in 79%. Pre-ART data suggested that more than 85% had acquired key mutations during treatment. Suboptimal adherence [odds ratio (OR) = 3.90; 95% confidence interval (CI) 1.11-13.68], female sex (aOR = 2.57; 95% CI 1.03-6.45), and current nonnucleoside reverse transcriptase inhibitor-based ART (aOR = 7.32; 95% CI 1.51-35.46 compared with protease inhibitor-based) independently increased the odds of virologic failure. CD4 T-cell percentage (aOR = 0.20; 0.10-0.40 per additional 10%) and older age at ART initiation (aOR = 0.84 per additional year of age; 95% CI 0.73-0.97) were protective (also in predicting acquired HIV-DRM). At the time of virologic failure, less than 5% of the children fulfilled the WHO criteria for immunologic failure. CONCLUSION: Virologic failure rates in children and adolescents were high, with the majority of ART-failing children harbouring HIV-DRM. The WHO criteria for immunologic treatment failure yielded an unacceptably low sensitivity. Viral load monitoring is urgently needed to maintain future treatment options for the millions of African children living with HIV.

A decade of HIV care in rural Tanzania: Trends in clinical outcomes and impact of clinic optimisation in an open, prospective cohort.

OBJECTIVES: Our objectives were to describe trends in enrolment and clinical outcomes in the open, prospective Kilombero and Ulanga Antiretroviral Cohort (KIULARCO) in the Morogoro region of southern Tanzania, and identify strengths and areas for improvement in the care of HIV-positive individuals in rural Tanzania. METHODS: We included adults (≥15 years) and children (<15 years) enrolled in the cohort in 2005-2014. The cohort underwent significant changes from autumn 2012 to optimise care. We evaluated mortality and loss to follow-up (LTFU) using competing risks methods, ART usage, opportunistic infections (OI), co-infections and laboratory abnormalities. RESULTS: Overall, 7010 adults and 680 children were enrolled; enrolment peaked in 2008 but has increased steadily since 2011. Among adults (65% female; median age 37 [interquartile range 31-45] years), the proportion referred from hospital wards quadrupled in 2013-14 versus earlier years. 653 (9%) adults died and 2648 (38%) were LTFU; the five-year cumulative probabilities of death and LTFU were 10.3% and 44.0%, respectively. Among children, 69 (10%) died and 225 (33%) were LTFU. The corresponding five-year probabilities were 12.1% and 39.6%. Adult ART use (regardless of eligibility) increased from 5% in 2005 to 89% in 2014 (similarly among children), with 9% on second-line therapy in 2014 (17% of children). OI diagnoses increased over time; tuberculosis prevalence at enrolment quadrupled from 6% in 2011 to 26% in 2014. The proportion of newly-enrolled participants assessed for laboratory abnormalities peaked at nearly 100% in 2014 (from a minimum of 24%), yet abnormality prevalences remained fairly constant. CONCLUSIONS: In this cohort, ART usage improved dramatically and is approaching targets of 90%. Improved screening led to increases in detection of OIs and laboratory abnormalities, suggesting that a large number of these co-morbidities previously went undetected and untreated. Further work will address the high LTFU rates and implications for mortality estimates, and the management and outcomes of co-morbidities.

Cohort profile: The Kilombero and Ulanga Antiretroviral Cohort (KIULARCO) - A prospective HIV cohort in rural Tanzania.

BACKGROUND: The Kilombero and Ulanga Antiretroviral Cohort (KIULARCO) is a single-site, open and ongoing prospective cohort of people living with human immunodeficiency virus (PLWHIV) established in 2005 at the Chronic Diseases Clinic of Ifakara (CDCI), within the Saint Francis Referral Hospital (SFRH) in Ifakara, Tanzania. The objectives of KIULARCO are to (i) provide patient and cohort-level information on the outcomes of HIV treatment; (ii) provide cohort-level information on opportunistic infections and comorbidities; (iii) evaluate aspects of human immunodeficiency virus (HIV) care and treatment that have national or international policy relevance; (iv) provide a platform for studies on improving HIV care and treatment in sub-Saharan Africa; and (v) contribute to generating local capacity to deal with the challenges posed by the HIV/AIDS pandemic in this region. Moreover, KIULARCO may serve as a model for other healthcare settings in rural sub-Saharan Africa. METHODS: Since 2005, all patients diagnosed with HIV at the Saint Francis Referral Hospital are invited to participate in the cohort, including non-pregnant adults, pregnant women, adolescents, children and infants. The information collected includes demographics, baseline and follow-up clinical data, laboratory data, medication history, drug toxicities, diagnoses and outcomes. Real-time data are captured during the patient encounter through an electronic medical record system that allowed transition to a paperless clinic in 2013. In addition, KIULARCO is associated with a biobank of cryopreserved plasma samples and cell pellets collected from all participants before and at different time-points during antiretroviral treatment. RESULTS: Up to the end of 2016, 12 185 PLWHIV have been seen at the CDCI; 9218 (76%) of whom have been enrolled into KIULARCO and 6965 (76%) of these have received ART from the clinic. Patients on ART attend at least every 3 months, with laboratory monitoring every 6 months. KIULARCO data have been used to generate relevant information regarding ART outcomes, opportunistic infections, non-AIDS comorbidities, prevention of mother-to-child transmission of HIV, paediatric HIV, and mortality and retention in care. Requests for collaborations on analyses can be submitted to the KIULARCO scientific committee. CONCLUSIONS: KIULARCO provides a framework for improving the quality of care of people living with HIV in sub-Saharan Africa, to generate relevant information to evaluate ART programmes and to build local capacity to deal with HIV/AIDS. The comprehensiveness of the data collected, together with the biobank spanning over ten years has created a unique research platform in rural sub-Saharan Africa.

A Case Series of Acquired Drug Resistance-Associated Mutations in Human Immunodeficiency Virus-Infected Children: An Emerging Public Health Concern in Rural Africa.

The acquisition of drug-resistance mutations among African children living with in human immunodeficiency virus on antiretroviral treatment has been scarcely reported. This threatens the overall success of antiretroviral programs and the clinical outcomes of children in care. We present a well characterized series of children from rural Tanzania with acquired drug-resistance mutations to contribute to the better understanding of this emerging public health concern.