Francesco Gesualdo

Close Encounters in a Pediatric Ward: Measuring Face-to-Face Proximity and Mixing Patterns with Wearable Sensors

Background Nosocomial infections place a substantial burden on health care systems and represent one of the major issues in current public health, requiring notable efforts for its prevention. Understanding the dynamics of infection transmission in a hospital setting is essential for tailoring interventions and predicting the spread among individuals. Mathematical models need to be informed with accurate data on contacts among individuals. Methods and Findings We used wearable active Radio-Frequency Identification Devices (RFID) to detect face-to-face contacts among individuals with a spatial resolution of about 1.5 meters, and a time resolution of 20 seconds. The study was conducted in a general pediatrics hospital ward, during a one-week period, and included 119 participants, with 51 health care workers, 37 patients, and 31 caregivers. Nearly 16,000 contacts were recorded during the study period, with a median of approximately 20 contacts per participants per day. Overall, 25% of the contacts involved a ward assistant, 23% a nurse, 22% a patient, 22% a caregiver, and 8% a physician. The majority of contacts were of brief duration, but long and frequent contacts especially between patients and caregivers were also found. In the setting under study, caregivers do not represent a significant potential for infection spread to a large number of individuals, as their interactions mainly involve the corresponding patient. Nurses would deserve priority in prevention strategies due to their central role in the potential propagation paths of infections. Conclusions Our study shows the feasibility of accurate and reproducible measures of the pattern of contacts in a hospital setting. The obtained results are particularly useful for the study of the spread of respiratory infections, for monitoring critical patterns, and for setting up tailored prevention strategies. Proximity-sensing technology should be considered as a valuable tool for measuring such patterns and evaluating nosocomial prevention strategies in specific settings.

An infectious disease model on empirical networks of human contact: bridging the gap between dynamic network data and contact matrices

BackgroundThe integration of empirical data in computational frameworks designed to model the spread of infectious diseases poses a number of challenges that are becoming more pressing with the increasing availability of high-resolution information on human mobility and contacts. This deluge of data has the potential to revolutionize the computational efforts aimed at simulating scenarios, designing containment strategies, and evaluating outcomes. However, the integration of highly detailed data sources yields models that are less transparent and general in their applicability. Hence, given a specific disease model, it is crucial to assess which representations of the raw data work best to inform the model, striking a balance between simplicity and detail.MethodsWe consider high-resolution data on the face-to-face interactions of individuals in a pediatric hospital ward, obtained by using wearable proximity sensors. We simulate the spread of a disease in this community by using an SEIR model on top of different mathematical representations of the empirical contact patterns. At the most detailed level, we take into account all contacts between individuals and their exact timing and order. Then, we build a hierarchy of coarse-grained representations of the contact patterns that preserve only partially the temporal and structural information available in the data. We compare the dynamics of the SEIR model across these representations.ResultsWe show that a contact matrix that only contains average contact durations between role classes fails to reproduce the size of the epidemic obtained using the high-resolution contact data and also fails to identify the most at-risk classes. We introduce a contact matrix of probability distributions that takes into account the heterogeneity of contact durations between (and within) classes of individuals, and we show that, in the case study presented, this representation yields a good approximation of the epidemic spreading properties obtained by using the high-resolution data.ConclusionsOur results mark a first step towards the definition of synopses of high-resolution dynamic contact networks, providing a compact representation of contact patterns that can correctly inform computational models designed to discover risk groups and evaluate containment policies. We show in a typical case of a structured population that this novel kind of representation can preserve in simulation quantitative features of the epidemics that are crucial for their study and management.

Switched memory B cells maintain specific memory independently of serum antibodies: the hepatitis B example.

The immunogenicity of a vaccine is conventionally measured through the level of serum Abs early after immunization, but to ensure protection specific Abs should be maintained long after primary vaccination. For hepatitis B, protective levels often decline over time, but breakthrough infections do not seem to occur. The aim of this study was to demonstrate whether, after hepatitis B vaccination, B‐cell memory persists even when serum Abs decline. We compared the frequency of anti‐hepatitis‐specific memory B cells that remain in the blood of 99 children five years after priming with Infanrix®‐hexa (GlaxoSmithKline) (n=34) or with Hexavac® (Sanofi Pasteur MSD) (n=65). These two vaccines differ in their ability to generate protective levels of IgG. Children with serum Abs under the protective level, <10 mIU/mL, received a booster dose of hepatitis B vaccine, and memory B cells and serum Abs were measured 2 wk later. We found that specific memory B cells had a similar frequency in all children independently of primary vaccine. Booster injection resulted in the increase of memory B cell frequencies (from 11.3 in 106 cells to 28.2 in 106 cells, p<0.01) and serum Abs (geometric mean concentration, GMC from 2.9 to 284 mIU/mL), demonstrating that circulating memory B cells effectively respond to Ag challenge even when specific Abs fall under the protective threshold.

Influenza-Like Illness Surveillance on Twitter through Automated Learning of Naïve Language

Twitter has the potential to be a timely and cost-effective source of data for syndromic surveillance. When speaking of an illness, Twitter users often report a combination of symptoms, rather than a suspected or final diagnosis, using naïve, everyday language. We developed a minimally trained algorithm that exploits the abundance of health-related web pages to identify all jargon expressions related to a specific technical term. We then translated an influenza case definition into a Boolean query, each symptom being described by a technical term and all related jargon expressions, as identified by the algorithm. Subsequently, we monitored all tweets that reported a combination of symptoms satisfying the case definition query. In order to geolocalize messages, we defined 3 localization strategies based on codes associated with each tweet. We found a high correlation coefficient between the trend of our influenza-positive tweets and ILI trends identified by US traditional surveillance systems.

Preserved antibody levels and loss of memory B cells against pneumococcus and tetanus after splenectomy: Tailoring better vaccination strategies

Splenectomized patients are exposed to an increased risk of septicemia caused by encapsulated bacteria. Defense against infection is ensured by preformed serum antibodies produced by long‐lived plasma cells and by memory B cells that secrete immunoglobulin in response to specific antigenic stimuli. Studying a group of asplenic individuals (57 adults and 21 children) without additional immunologic defects, we found that spleen removal does not alter serum anti‐pneumococcal polysaccharide (PnPS) IgG concentration, but reduces the number of PnPS‐specific memory B cells, of both IgM and IgG isotypes. The number of specific memory B cells was low in splenectomized adults and children that had received the PnPS vaccine either before or after splenectomy. Seven children were given the 13‐valent pneumococcal conjugated vaccine after splenectomy. In this group, the number of PnPS‐specific IgG memory B cells was similar to that of eusplenic children, suggesting that pneumococcal conjugated vaccine administered after splenectomy is able to restore the pool of anti‐PnPS IgG memory B cells. Our data further elucidate the crucial role of the spleen in the immunological response to infections caused by encapsulated bacteria and suggest that glycoconjugated vaccines may be the most suitable choice to generate IgG‐mediated protection in these patients.

Effect of duration of breastfeeding on neuropsychological development at 10 to 12 years of age in a cohort of healthy children

Aim  The aim of this article was to explore the effect of duration of breastfeeding on neurocognitive development.

The effect of physician’s recommendation on seasonal influenza immunization in children with chronic diseases

BackgroundDespite recommendations by Health Authorities, influenza immunization coverage remains low in children with chronic diseases. Different medical providers involved in the management of children with chronic conditions may affect the pattern of influenza vaccine recommendations and coverage. The likelihood of vaccination by type of provider in children with chronic conditions is poorly understood. Therefore, the objectives of this study were to analyze the pattern and the effect of recommendations for seasonal influenza immunization provided by different physician profiles to families of children with chronic diseases and to measure the frequency of immunization in the study population.MethodsWe recruited children with chronic diseases aged 6 months–18 years who subsequently presented to specialty clinics for routine follow-up visits, during spring 2009, in three Italian Regions Families of children with chronic diseases were interviewed during routine visits at reference centers through a face-to-face interview. We analyzed the following immunization predictors: having received a recommendation toward influenza immunization by a health provider; child’s sex and age; mothers and fathers’ age; parental education and employment; underlying child’s disease; number of contacts with health providers in the previous year. Influenza immunization coverage was calculated as the proportion of children who received at least one dose of seasonal influenza vaccine in the previous season. We calculated prevalence ratios and we used a generalized linear model with Poisson family, log link and robust error variance to assess the effect of socio-demographic variables, underlying diseases, and recommendations provided by physicians on influenza immunization.ResultsWe enrolled 275 families of children with chronic diseases. Overall influenza coverage was 57.5%, with a low of 25% in children with neurological diseases and a high of 91.2% in those with cystic fibrosis. While 10.6% of children who did not receive any recommendation toward influenza immunization were immunized, among those who received a recommendation 87.5-94.7% did, depending on the health professional providing the recommendation. Receiving a recommendation by any provider is a strong predictor of immunization (PR = 8.5 95% CI 4.6;15.6) Most children received an immunization recommendation by a specialty (25.8%) or a family pediatrician (23.3%) and were immunized by a family pediatrician (58.7%) or a community vaccinator (55.2%).ConclusionsReceiving a specific recommendation by a physician is a strong determinant of being immunized against seasonal influenza in children with chronic diseases independently of other factors. Heterogeneity exists among children with different chronic diseases regarding influenza recommendation despite international guidelines. Increasing the frequency of appropriate recommendations toward influenza immunization by physicians is a single powerful intervention that may increase coverage in children with chronic conditions.

MRSA nasal colonization in children: prevalence meta-analysis, review of risk factors and molecular genetics.

Background: We report a meta-analysis of methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization prevalence in children and a review of the risk factors as well as molecular genetic characterization. Methods: All relevant studies reporting prevalence data on MRSA nasal colonization in children published between January 2000 and August 2010 were retrieved from the MEDLINE database and analyzed. Results: After screening 544 studies, 50 studies were included. We obtained an estimate of MRSA prevalence of 2.7% (95% confidence interval [CI]: 2.2–3.1); of 5.2% (95% CI: 3.1–7.3) in children with underlying conditions and of 2.3% (95% CI: 1.8–2.7) in healthy children; 5.4% (95% CI: 3.1–7.7) in children recruited in hospitals and 3% (95% CI: 2.4–3.6) in children recruited in the community. Staphylococcal cassette chromosome mec type IV is the most diffused cassette globally. Conclusion: The hospital remains the environment where the microorganism circulates most. Children with underlying conditions could act as vectors of microorganisms between the hospital and the community. MRSA prevention strategies should be tailored to each specific institution, taking into account the nosocomial prevalence of MRSA nasal colonization and infections, and the prevalence of nasal colonization in the community that refers to the specific health care center.

An unusual case of left aberrant innominate artery with right aortic arch: evaluation with high-resolution CT

A left aberrant innominate (brachiocephalic) artery is an angiographically well-known entity that may cause tracheal compression. We report a male newborn who was admitted for further investigation of a prenatally suspected major vessel anomaly. High-resolution CT was used to completely assess the abnormal anatomy and the relationship with the airway, as well as to guide the surgical approach for its correction.

Women participating in a web-based preconception study have a high prevalence of risk factors for adverse pregnancy outcomes

BackgroundAdverse pregnancy outcomes (APOs) can be increased by preconception risk factors and lifestyles.We measured the prevalence of preconception risk factors for APOs in a population of Italian women of childbearing age enrolled in a web-based study.MethodsParticipants were enrolled through a web platform (http://www.mammainforma.it). After enrollment, participants filled in a questionnaire regarding socio-demographic characteristics, clinical data and preconception risk factors for adverse pregnancy outcomes. Through logistic regression, we explored how the prevalence of risk factors was affected by age, education level, employment, parity, physician’s recommendation and knowledge of the specific risk factor.ResultsWe enrolled a total of 728 women. Sixty-two percent had a University degree, 84% were employed and 77% were planning their first pregnancy.Nearly 70% drank alcohol in any quantity; 16% were smokers; 6% was underweight; 21.4% was overweight; 51.6% did not assume folic acid; 22% was susceptible to rubella, 44.5% to hepatitis b and 13.2% to varicella.According to the multivariate analysis, compared to women who already had at least one pregnancy, nulliparous women had a higher BMI [OR 1.60 (CI 1.02;2.48)] and were less likely to be susceptible to rubella [OR 0.33 (CI 0.20;0.58)] and to be consuming alcohol [OR 0.47 (CI 0.31;0.70)] or cigarettes [OR 0.48 (CI 0.26;0.90)].Appropriate knowledge was associated with a correct behavior regarding smoking, drinking alcohol and folic acid supplementation.ConclusionsThis study shows that the prevalence of risk factors for APOs in our population is high.Interventions aimed at reducing risk factors for APOs are needed and, to this purpose, a web intervention may represent a feasible tool to integrate tailored information and to inform preconception counseling targeting a specific group of women planning a pregnancy who are engaged on the web.