Disease In Healthy Children Research Articles

Cytomegalovirus Infections in Children with Primary and Secondary Immune Deficiencies.

Cytomegalovirus (CMV) is a human herpes virus that causes significant morbidity and mortality in immunosuppressed children. CMV primary infection causes a clinically mild disease in healthy children, usually in early childhood; the virus then utilises several mechanisms to establish host latency, which allows for periodic reactivation, particularly when the host is immunocompromised. It is this reactivation that is responsible for the significant morbidity and mortality in immunocompromised children. We review CMV infection in the primary immunodeficient host, including early identification of these infants by newborn screening to allow for CMV infection prevention strategies. Furthermore, clinical CMV is discussed in the context of children treated with secondary immunodeficiency, particularly paediatric cancer patients and children undergoing haematopoietic stem cell transplant (HSCT). Treatments for CMV are highlighted and include CMV immunotherapy.

Comparison of severe pediatric complicated influenza patients with and without neurological involvement.

Although influenza is generally an acute, self-limited, and uncomplicated disease in healthy children, it can result in severe morbidity and mortality. The objectives of this study were to analyze and compare the clinical features and outcome of severe pediatric influenza with and without central nervous system (CNS) involvement.We conducted a retrospective observational study of children admitted to the pediatric intensive care unit (PICU) of China Medical University Children's Hospital in Taiwan with a confirmed diagnosis of influenza. The demographic data, clinical and laboratory presentations, therapeutic strategies, and neurodevelopmental outcomes for these patients were analyzed. Furthermore, comparison of patients with and without CNS involvement was conducted.A total of 32 children with severe influenza were admitted during the study periods. Sixteen children were categorized as the non-CNS (nCNS) group and 16 children were categorized as the CNS group. Nine of them had underlying disease. The most common complication in the nCNS group was acute respiratory distress syndrome, (n = 8/16), followed by pneumonia (n = 7/16, 44%). In the CNS group, the most lethal complication was acute necrotizing encephalopathy (n = 3/16) which led to 3 deaths. The overall mortality rate was higher in the CNS group (n = 6) than in the nCNS group (n = 1) (37.5% vs 6.25%, P = .03).The mortality rate of severe complicated influenza was significantly higher with CNS involvement. Children with primary cardiopulmonary abnormalities were at high risk of developing severe complicated influenza, while previously healthy children exhibited risk for influenza-associated encephalitis/encephalopathy.

Efficacy and Effectiveness of the PCV-10 and PCV-13 Vaccines Against Invasive Pneumococcal Disease.

Pneumococcal conjugate vaccines (PCVs) (pneumococcal 13-valent conjugate vaccine [PCV-13] and pneumococcal 10-valent conjugate vaccine [PCV-10]) are available for prevention of pneumococcal infections in children. To determine the vaccine effectiveness (VE) of PCV-13 and PCV-10 in preventing invasive pneumococcal disease (IPD) and acute otitis media (AOM) in children <5 years. Systematic searches of Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, Web of Science, and Cochrane. Eligible studies examined the direct effectiveness and/or efficacy of PCV-10 and PCV-13 in reducing the incidence of disease in healthy children <5 years. Two reviewers independently conducted data extraction and methodologic quality assessment. Significant effectiveness against vaccine-type IPD in children ≤5 years was reported for ≥1 dose of PCV-13 in the 3 + 1 (86%-96%) and 2 + 1 schedule (67.2%-86%) and for PCV-10 for the 3 + 1 (72.8%-100%) and 2 + 1 schedules (92%-97%). In children <12 months of age, PCV-13 VE against serotype 19A post-primary series was significant for the 3 + 1 but not the 2 + 1 schedule. PCV-10 crossprotection against 19A was significant in children ≤5 years with ≥1 dose (82.2% and 71%). Neither PCVs were found effective against serotype 3. PCV-13 was effective against AOM (86%; 95% confidence interval [CI]: 61 to 94). PCV-10 was effective against clinically defined (26.9%; 95% CI: 5.9 to 43.3) and bacteriologically confirmed AOM (43.3%; 95% CI: 1.7 to 67.3). Because of the large heterogeneity in studies, a meta-analysis for pooled estimates was not done. Both PCVs afford protection against pneumococcal infections, with PCV-10 protecting against 19A IPD, but this VE has not been verified in the youngest age groups.

Viruses associated with acute respiratory infection in a community-based cohort of healthy New Zealand children.

Acute respiratory infections (ARIs) are a major cause of morbidity among children. Respiratory viruses are commonly detected in both symptomatic and asymptomatic periods. The rates of infection and community epidemiology of respiratory viruses in healthy children needs further definition to assist interpretation of molecular diagnostic assays in this population. Children otherwise healthy aged 1 to 8 years were prospectively enrolled in the study during two consecutive winters, when ARIs peak in New Zealand. Parents completed a daily symptom diary for 8 weeks, during which time they collected a nasal swab from the child for each clinical ARI episode. A further nasal swab was collected by research staff during a clinic visit at the conclusion of the study. All samples were tested for 15 respiratory viruses commonly causing ARI using molecular multiplex polymerase chain reaction assays. There were 575 ARIs identified from 301 children completing the study, at a rate of 1.04 per child‐month. Swabs collected during an ARI were positive for a respiratory virus in 76.8% (307 of 400), compared with 37.3% (79 of 212) of swabs collected during asymptomatic periods. The most common viruses detected were human rhinovirus, coronavirus, parainfluenza viruses, influenzavirus, respiratory syncytial virus, and human metapneumovirus. All of these were significantly more likely to be detected during ARIs than asymptomatic periods. Parent‐administered surveillance is a useful mechanism for understanding infectious disease in healthy children in the community. Interpretation of molecular diagnostic assays for viruses must be informed by understanding of local rates of asymptomatic infection by such viruses.

Epidemiology and burden of influenza in healthy children aged 6 to 35\u2009months: analysis of data from the placebo arm of a phase III efficacy trial

BackgroundDespite World Health Organization recommendations, in many countries young children are not targeted for influenza vaccination. To help inform influenza vaccination policy, we examined the occurrence and burden of influenza in healthy children aged 6 to 35 months using data from a recent phase III placebo-controlled influenza vaccine trial conducted in countries in the Northern and Southern Hemispheres.MethodsThis was an analysis of data from participants included in the placebo arm of a phase III clinical trial in healthy children aged 6 to 35 months (EudraCT no. 2013–001231-51). Included children had never been vaccinated for influenza and were observed for one influenza season. Outcome measures included the occurrence of influenza-like illness (ILI), laboratory-confirmed influenza, virus types/subtypes, severe symptoms and complications of confirmed influenza, and healthcare use associated with confirmed influenza.ResultsData from 2210 participants were analysed. ILI was reported for 811 participants (36.7%). Of these, 255 participants (31.4%) had 263 virologically confirmed episodes of influenza. The overall influenza attack rate was 11.5%. The most common influenza virus detected was A(H3N2) (40.7%), followed by B/Yamagata (23.6%), A(H1N1) (18.6%), and B/Victoria (8.0%). Grade 3 fever was reported in 24.3% of confirmed episodes, acute lower respiratory infection in 8.7%, acute otitis media in 6.1%, and pneumonia in 1.9%. In most influenza episodes (93.2%), antipyretics, analgesics, or non-steroidal anti-inflammatory drugs were taken. Antibiotics were prescribed for 41.4% of influenza episodes. More than half of the influenza episodes (57.0%) resulted in outpatient visits. Influenza resulted in overnight hospitalisation in 1.1% of episodes.ConclusionsInfluenza is associated with a significant burden of disease in healthy children. This analysis also revealed that antibiotics continue to be frequently used for young children with influenza.Trial registrationEudraCT no. 2013–001231-51.

The Seroprevalence of Varicella Zoster Virus in a Healthy Population from Tehran, Iran

Background: Varicella zoster virus (VZV) is responsible for chickenpox, which is generally a mild self-limited disease in healthy children. However, this disease may progress to a complicated and even life-threatening disease in adolescents, young adults, and immunocompromised patients in particular. The present study was conducted to investigate the seroprevalence of VZV in different age groups, selected among residents of Tehran, Iran. Methods: We performed varicella serological tests (IgG) on the serum specimens of healthy people, collected from 3 main laboratories in Tehran. VZV IgG was measured with the ELISA method. We divided the subjects into 6 subgroups: below 2 years, 2 - 5 years, 5 - 12 years, 12 - 19 years, 19 - 25 years, and above 25 years. We tested almost 95 specimens from each age group. Results: Samples were collected from 570 individuals, including 231 males. The VZV IgG was positive in 393 subjects; cumulatively, 81.3% of the population were immune to VZV. The seroprevalence rate was 43.2% in infants below 2 years, 32.6% in children aged 2 - 5 years, 47.2% in children aged 5 - 12 years, 74.7% in adolescents aged 12 - 19 years, 83.2% in young adults up to 25 years, and 90.5% in adults > 25 years. Conclusions: Although the cumulative seroprevalence was estimated at 81.3% for all age groups, this rate was only 43% in children below 12 years; therefore, adolescents and young adults (high-risk age groups) are prone to chickenpox infection. In order to protect individuals against this infection, we suggest well-designed studies to address the need for routine chickenpox immunization programs in young children.

Varicella Pneumonia: Case Report and Review of a Potentially Lethal Complication of a Common Disease.

Varicella zoster virus causes varicella (chickenpox). It can be reactivated endogenously many years later to cause herpes zoster (shingles). Although varicella is usually a benign disease in healthy children, it resulted in over 11 000 hospitalizations and over 100 deaths every year, in all ages, in the United States. Morbidity was considerably worse in older teenagers and adults. Between 5% and 15% of cases of adult chickenpox will produce some form of pulmonary illness. Progression to pneumonia risk factors include pregnancy, age, smoking, chronic obstructive pulmonary disease, and immunosuppression. Typically, pulmonary symptoms occur 1 to 6 days after varicella zoster infection. They often include cough, fever, and dyspnea. Treatment is a 7-day course of intravenous acyclovir for varicella pneumonia. Early intervention may modify the course of this complication. This review illustrates practical features with a case of a 34-year-old female with severe varicella pneumonia. Despite the lack of significant past medical history and absence of immunosuppression, her pneumonia worsened and by using continuous positive airway pressure mask, intubation was avoided. More important, the radiographic progression of severe varicella pneumonia is shown. This highlights how a common disease of varicella can progress in an adult and manifest with significant organ malfunction.

Negative IgG Varicella Zoster Virus Antibody Status: Immune Responses Pre and Post Re-immunization.

IntroductionVaricella zoster virus (VZV) causes chicken pox and herpes zoster and is a self-limiting disease in healthy children. Vaccination is recommended for children, adolescents, and adults. This study discusses a healthy pediatric patient with negative immunoglobulin (Ig) G VZV antibody (Ab) status after two doses of varicella vaccine and then subsequently re-immunized. Since measurement of serum IgG titers alone may not reflect vaccine protection, we further evaluated cell-mediated and humoral immune responses before and after re-immunization.MethodsBlood lymphocyte distributions (CD3+CD4+, CD3+CD8+, CD19+, CD4+CD60+, CD8+CD60+), total serum IgG and IgE levels, and VZV-IgG, IgM, and IgE Ab levels were measured in a healthy girl (14 year-old) pre- and post-VZV re-immunization (weeks 1–8) [flow microfluorimetry, nephelometry, ELISA, enzyme immunoassay (EIA)].ResultsPre-re-immunization numbers of T cells (CD3+CD4+, CD3+CD8+, CD4+CD60+, CD8+CD60+) and B cells (CD19+) were within normal ranges. After re-immunization, numbers of T cells remained relatively unchanged; however, numbers of CD19+ B cells increased (48%). Total serum IgG was low (757 mg/dl), and total serum IgE was normal (30 IU/ml). Pre-reimmunization, VZV IgG and IgM Ab levels were negative (< 0.90 and < 0.90 antibody index, respectively), and VZV IgE levels were undetectable. After re-immunization, VZV IgG Ab levels were positive (690.70 Ab index), VZV IgM Ab levels were negative (≤ 0.90), and VZV IgE levels remained undetectable.ConclusionVaccination with the VZV vaccine may boost IgG but not IgE-specific viral responses and concurrently increase the numbers of CD19+ B cells.

Immunogenicity and safety of single‐dose, 13‐valent pneumococcal conjugate vaccine in pediatric and adolescent oncology patients

Children receiving immunosuppressive treatment for cancer are at high risk for invasive pneumococcal disease. The 13-valent pneumococcal conjugate vaccine (PCV13) can prevent pneumococcal disease in healthy children; however, there is an absence of literature regarding the benefit of PCV13 in immunocompromised children with cancer. A prospective, open-label cohort study recruited children between ages 1 and 18 years who were receiving active immunosuppressive therapy (AIT) or were within 12 months after completing immunosuppressive therapy (CIT). Blood samples were taken before and 4 weeks after the administration of single-dose PCV13. Serotype-specific immunoglobulin G antibody titers were measured, and titers ≥0.35 μg/mL were considered protective. Solicited side effects were recorded in a 7-day diary after vaccination. Eighty-five children were recruited. At baseline, ≤50% had protective antibody titers against Streptococcus pneumoniae for 10 serotypes in the AIT group and for 8 serotypes in the CIT group. Postvaccination, ≥70% had protective antibody titers for 9 and 11 serotypes in the AIT and CIT groups, respectively. Both groups had comparable responses to PCV7 serotypes, whereas a significantly higher proportion in the CIT group achieved protective antibody titers to PCV13 serotypes. There was a low rate of serious adverse events (3.5%). A single-dose of PCV13 is safe and immunogenic in children diagnosed with cancer. All children who are receiving therapy for cancer should receive a single dose of PCV13 as soon as possible after diagnosis, regardless of prior PCV exposure. The current data support the recommendation for an additional dose of PCV13 after the completion of immunosuppressive therapy to provide additional protection against invasive pneumococcal disease. Cancer 2017;123:4215-4223. © 2017 American Cancer Society.

Chickenpox: An update

Chickenpox, caused by the varicella-zoster virus, is mostly a mild disease in healthy children, but can be debilitating in immunocompromised individuals or susceptible adults. The disease is highly contagious. The lesions start as rose-colored macules, and progress rapidly to become papules, vesicles with the classic “dew drop on a rose petal” appearance, pustules and, finally, crusts. The distribution of the lesions is typically central, with the greatest concentrations on the trunk. Characteristically, lesions are intensely pruritic and appear in crops. The most common complication associated with chickenpox is secondary bacterial infections of the skin followed by post-inflammatory scarring of the lesions. The diagnosis is mainly clinical and treatment symptomatic. Oral acyclovir should be considered in high-risk individuals. Intravenous acyclovir is effective for the treatment of chickenpox in immunocompromised individuals and for serious complications of chickenpox in normal patients. To eradicate chickenpox, universal childhood immunization with varicella vaccine is the way to go. The Advisory Committee for Immunization Practices of the Centers for Disease Control and Prevention and the American Academy of Pediatrics recommend a routine two-dose varicella vaccination program for children, with the first dose administered at 12 to 18 months and the second dose at 4 to 6 years of age. The Advisory Committee on Immunization Practices further recommends two doses of varicella vaccine, 4 to 8 weeks apart, for all susceptible adolescents and adults and a catch-up second dose for everyone who received one dose of varicella vaccine previously.

Follow-up formula consumption in 3- to 4-year-olds and respiratory infections: an RCT.

Children are vulnerable to diet inadequacies, which may affect immune function. Our objective was to determine if a follow-up formula (FUF) containing DHA, the prebiotics PDX and GOS, and yeast β-glucan affects incidence of respiratory infections and diarrheal disease in healthy children. In a double-blind, randomized, controlled, prospective trial, 3-4 year old children were fed 3 servings per day of either a FUF with 25 mg DHA, 1.2 g PDX/GOS, and 8.7 mg yeast β-glucan per serving or an unfortified, cow's milk-based beverage (control) for 28 weeks. Fecal and blood samples were collected to assess immune markers and iron/zinc status. Incidence of acute respiratory infections (ARI), diarrheal disease, and antibiotic treatment were obtained from medical records. The FUF group had fewer episodes and shorter duration of ARI (mean days [SE]; control = 4.3 [0.2]; FUF = 3.5 [0.2]; P = .007), less antibiotic use (n [%]; control = 21 [14%]; FUF = 8 [5%]; P = .01), and fewer missed days of day care due to illness. No diarrheal disease was diagnosed in either group. The FUF group had higher interleukin-10 and white blood cell count at the end of the study. There were no differences in hemoglobin, serum ferritin and zinc, or fecal secretory immunoglobulin A. Daily consumption of a FUF was associated with fewer episodes and shorter duration of ARI, as well as less antibiotic use. The children who consumed the FUF had increased interleukin-10 and white blood cells, suggesting an antiinflammatory mechanism and/or an increase of effector immune cells.

Necrotizing fasciitis and streptococcal toxic shock syndrome secondary to varicella in a healthy child.

Varicella is usually considered to be a benign disease in healthy children; however, serious complications can occur such as necrotizing fasciitis and toxic shock syndrome. We describe a 38-month-old girl with necrotizing fasciitis and streptococcal toxic shock syndrome following varicella. She was previously healthy and vaccinated against varicella at 12 months of age. She had been diagnosed with varicella three days prior to presenting at our facility; she developed fever, vomiting, and painful swelling on her left flank. Her skin lesions worsened, she became lethargic, and had episodes of hypotension and coagulopathy. Necrotizing fasciitis on the left abdominal wall, buttocks, and left thigh was diagnosed by magnetic resonance imaging, and group A Streptococcus was isolated from a tissue culture. She was diagnosed as necrotizing fasciitis and streptococcal toxic shock syndrome, and successfully treated with repeated surgical debridement and fasciotomy, in addition to intensive antibiotics. Our experience suggests that necrotizing fasciitis in patients with varicella should be considered to be a rare complication even with widespread vaccine use. Early diagnosis and intensive treatment are required to prevent a fatal outcome.

Disseminated Staphylococcal Disease in Healthy Children—Experience from Two Tertiary Care Hospitals of West Bengal

To assess the etiology, precipitating factors, treatment and outcome of disseminated staphylococcal disease (DSD) in healthy immunocompetent children. This hospital based observational prospective study was conducted in two tertiary care hospitals of West Bengal, India during the period of March, 2011 through February, 2012. Inclusion criteria were 1) children between 1 and 12 y and 2) clinical features DSD characterized by i) involvement of at least two distant organs with presence of gram positive cocci in clusters and/or growth of Staphylococcus aureus from at least one normally sterile body fluid, ii) fever, persistent bacteremia despite antibiotics and focal involvement of two or more separate tissue sites (skin, bone, joint, kidney, lung, liver, heart). Thirty six cases fulfilled the criteria of DSD with mean age in years 6.03 ± 3.04 (range 1-12). The age group of 5-12 y was found to be more vulnerable (p < 0.001). Septic arthritis following accidental blunt closed trauma, was the significant precipitating factor for DSD in this age group (p = 0.031). Methicillin resistant Staphylococcus aureus (MRSA) was the causative agent in all the cases. Vancomycin resistant Staphylococcus aureus (VRSA) was detected in 88.9% of cases. All cases were sensitive to linezolid. No significant side effects were observed with 28 d of linezolid therapy. DSD is more common in 5-12 y age group. Trauma is a significant precipitating factor for DSD in this age group. Linezolid may be considered as the first line drug in DSD with MRSA.

Characteristics of chickenpox in children and adults at a tertiary health center in Sarajevo, Bosnia-Herzegovina

Introduction: Chickenpox is very contagious childhood disease, which occurs due to varicella-zoster virus (VZV) primary infection. Disease in healthy children resolves usually without complications, but risk of complication is much higher in adults and immunocompromised hosts. The goal of this study was to determine different clinical and epidemiological characteristics, laboratory features, clinical course, and outcome of chickenpox in children and adults. Material and methods: The descriptive study was conducted at the Department of Infectious Diseases, Clinical Center in Sarajevo, Bosnia-Herzegovina. The study included 120 patients chosen randomly. We compared their clinical and epidemiological characteristics, laboratory investigations, complications and the outcome of the disease. Results: Age of patients was in range from one to 48 years. Male patients prevailed in both groups (65% in adults, 52% in children). Hospitalization rate was 10.7/100,000 inhabitants. Positive contact with chickenpox was confirmed in 80% adults and 82% children. Dominating symptoms were fever, rash and muscle aches. Levels of C-reactive protein, erythrocyte sedimentation rates (ESR) and fibrinogen levels were elevated in both groups, while thrombocytopenia was presented in 33% of adults and 3% of children. Adults had complications in 83.3% and their hospitalization rate was longer compared to children (11.5 days vs. 9.5 days, p<0.001). Conclusions: Chickenpox is a potentially severe illness in adult patients. Introduction of active immunization in BosniaHerzegovina should be considered to prevent severe forms of chickenpox. J Microbiol Infect Dis 2012; 2(2): 64-67

Concomitant Use of Acyclovir and Intravenous Immunoglobulin Rescues an Immunocompromised Child With Disseminated Varicella Caused Multiple Organ Failure

Varicella is a common and mild disease in healthy children. However, when patients are in immunocompromised conditions, such as receiving chemotherapy for cancer treatment, they are highly vulnerable and it can even prove lethal. Herein, we report a 14-year-old boy with acute lymphoblastic leukemia who was receiving chemotherapy for induction with vincristine, idarubicin, L-asparaginase, and prednisolone, presented with typical varicella skin lesions and varicella-zoster virus was detected in his serum by real-time polymerase chain reaction (PCR). His condition was advanced to multiple organs failure, including fulminant hepatitis, disseminated intravascular coagulation, and myocarditis despite acyclovir administration. After a combined therapy with intravenous acyclovir and high-dose intravenous immunoglobulin, his condition was dramatically improved. We suggest that IVIG may be used immediately with acyclovir when immunocompromised patients with varicella advanced to dissemination are identified.

Seroconversion Status After Single Dose and Double Doses of Varicella Vaccination in Children With Leukemia

Although varicella is a benign self-limiting disease in healthy children, it can be fatal when it occurs in immunocompromised hosts. Despite that immunosuppressed children are suggested to require 2 doses of vaccine to achieve seroconversion, conflicting results are reported in the literature. The aim of this study was to investigate the seroconversion status and mean antibody titers at first year after single dose and double doses of varicella vaccination in acute lymphoblastic leukemia patients. Patients with leukemia in remission for at least 1 year who were seronegative for varicella-zoster virus immunoglobulin G (IgG) were vaccinated. Titers above the cutoff level (0.65) were accepted as seroconversion. Seventeen patients were vaccinated with single dose whereas 24 patients were vaccinated with double doses. Mean prevaccination antibody titers were 0.56 ± 0.05 in patients with single dose and 0.51 ± 0.08 in patients with double doses (P > .05, Student t test). The mean antibody titers at first year were 0.61 ± 0.05 in patients with single-dose vaccination (P > .05, Wilcoxon signed-rank test) and 1.48 ± 0.04 in patients with double doses (P < .001, Wilcoxon signed-rank test). Seroconversion after single-dose vaccination was achieved in 29% of patients (n = 5/17) and in 75% of patients with double doses (n = 18/24) at first year (P = .004, chi-square test). These results suggest that seroconversion after single-dose vaccination might not persist at first year in malignancy patients. Double doses should be applied in order to provide long-term seroconversion.

Influenza vaccination coverage among Spanish children, 2006

Traditionally, influenza is not considered to be a serious disease in healthy children. However, for vulnerable populations, such as young children and those with chronic medical conditions, influenza can lead to serious complications and even death. This study aimed to assess vaccination coverage among Spanish children under 16 years of age in 2006, and to describe the factors associated with vaccination. Cross-sectional survey. In total, 8851 records of children included in the Spanish National Health Survey for 2006 were analysed. The reply ('yes' or 'no') to the question: 'Did you have a flu shot in the latest campaign?' was used as a dependent variable. Influenza vaccine coverage was calculated as the percentage of individuals aged 6 months to 16 years whose parents reported that they had been vaccinated against influenza in the most recent campaign. The influence of sociodemographic variables on vaccination and the presence of associated chronic diseases (asthma and/or diabetes) were also analysed. Vaccination coverage among Spanish children in 2006 was 6.82%: 19.43% in children with associated conditions (asthma and/or diabetes), and 5.81% in healthy children. The only factor significantly associated with influenza vaccination in children with associated conditions was household income; children with a lower household monthly income were more likely to have been vaccinated against influenza than children with a higher household monthly income (odds ratio 1.96). In children for whom vaccination is not indicated, the probability of being vaccinated against influenza was greater in those whose parents were not university graduates. Influenza vaccination coverage in Spanish children is low. Socio-economic inequalities continue to be a factor at the time of vaccination.

A Near‐Fatal Infection with Oseltamivir‐Resistant Seasonal Influenza A in a Previously Healthy Child: Case Report

A case of near-fatal oseltamivir-resistant seasonal influenza A infection in a previously healthy four-year-old boy is reported. This case highlights three important points for physicians: oseltamivir-resistant influenza A (H1N1) has recently emerged in North America; contrary to previously held beliefs, such strains are capable of causing severe disease in healthy children; and given this change in epidemiology, clinicians caring for children with severe seasonal influenza A infection should consider empiric dual therapy with oseltamivir and amantadine.

Portación faríngea de Mycoplasma pneumoniae en niños chilenos

PCR has become a sensitive option for the rapid detection of Mycoplasma pneumoniae in respiratory specimens, but little is known of the frequency of its asymptomatic carriage or persistence in the throat after Mycoplasma disease in healthy children. To investigate the frequency of asymptomatic carriage of M. pneumoniae in children, we studied by PCR throat specimens from 185 respiratory asymptomatic children aged 1-14 years, enrolled at two pediatric ambulatory health services of Santiago, Chile from September 2002 through August 2003. M. pneumoniae DNA was detected in 4 (2.16%) children. Positive specimens could represent either asymptomatic carriage or persistence of the organism from a previous disease.

Characterization of genetic and phenotypic diversity of invasive nontypeable Haemophilus influenzae.

The ability of unencapsulated (nontypeable) Haemophilus influenzae (NTHi) to cause systemic disease in healthy children has been recognized only in the past decade. To determine the extent of similarity among invasive nontypeable isolates, we compared strain R2866 with 16 additional NTHi isolates from blood and spinal fluid, 17 nasopharyngeal or throat isolates from healthy children, and 19 isolates from middle ear aspirates. The strains were evaluated for the presence of several genetic loci that affect bacterial surface structures and for biochemical reactions that are known to differ among H. influenzae strains. Eight strains, including four blood isolates, shared several properties with R2866: they were biotype V (indole and ornithine decarboxylase positive, urease negative), contained sequence from the adhesin gene hia, and lacked a genetic island flanked by the infA and ksgA genes. Multilocus sequence typing showed that most biotype V isolates belonged to the same phylogenetic cluster as strain R2866. When present, the infA-ksgA island contains lipopolysaccharide biosynthetic genes, either lic2B and lic2C or homologs of the losA and losB genes described for Haemophilus ducreyi. The island was found in most nasopharyngeal and otitis isolates but was absent from 40% of invasive isolates. Overall, the 33 hmw-negative isolates were much more likely than hmw-containing isolates to have tryptophanase, ornithine decarboxylase, or lysine decarboxylase activity or to contain the hif genes. We conclude (i) that invasive isolates are genetically and phenotypically diverse and (ii) that certain genetic loci of NTHi are frequently found in association among NTHi strains.