Showing papers by "Pejman Rohani published in 2018"

The impact of past vaccination coverage and immunity on pertussis resurgence

Abstract: The resurgence of pertussis over the past decades has resulted in incidence levels not witnessed in the United States since the 1950s. The underlying causes have been the subject of much speculation, with particular attention paid to the shortcomings of the latest generation of vaccines. We formulated transmission models comprising competing hypotheses regarding vaccine failure and challenged them to explain 16 years of highly resolved incidence data from Massachusetts, United States. Our results suggest that the resurgence of pertussis is a predictable consequence of incomplete historical coverage with an imperfect vaccine that confers slowly waning immunity. We found evidence that the vaccine itself is effective at reducing overall transmission, yet that routine vaccination alone would be insufficient for elimination of the disease. Our results indicated that the core transmission group is schoolchildren. Therefore, efforts aimed at curtailing transmission in the population at large, and especially in vulnerable infants, are more likely to succeed if targeted at schoolchildren, rather than adults.

Anticipating epidemic transitions with imperfect data.

Abstract: Epidemic transitions are an important feature of infectious disease systems. As the transmissibility of a pathogen increases, the dynamics of disease spread shifts from limited stuttering chains of transmission to potentially large scale outbreaks. One proposed method to anticipate this transition are early-warning signals (EWS), summary statistics which undergo characteristic changes as the transition is approached. Although theoretically predicted, their mathematical basis does not take into account the nature of epidemiological data, which are typically aggregated into periodic case reports and subject to reporting error. The viability of EWS for epidemic transitions therefore remains uncertain. Here we demonstrate that most EWS can predict emergence even when calculated from imperfect data. We quantify performance using the area under the curve (AUC) statistic, a measure of how well an EWS distinguishes between numerical simulations of an emerging disease and one which is stationary. Values of the AUC statistic are compared across a range of different reporting scenarios. We find that different EWS respond to imperfect data differently. The mean, variance and first differenced variance all perform well unless reporting error is highly overdispersed. The autocorrelation, autocovariance and decay time perform well provided that the aggregation period of the data is larger than the serial interval and reporting error is not highly overdispersed. The coefficient of variation, skewness and kurtosis are found to be unreliable indicators of emergence. Overall, we find that seven of ten EWS considered perform well for most realistic reporting scenarios. We conclude that imperfect epidemiological data is not a barrier to using EWS for many potentially emerging diseases.

Assessing the Prevalence and Treatment of Malnutrition in Hospitalized Children in Mofid Children's Hospital During 2015-2016.

Abstract: Background: Malnutrition in hospitalized patients causes problems in treatment and increases hospitalization duration. The aim of this research was to determine the prevalence of malnutrition in ho ...

Introduction to pertussis transmission and epidemiological dynamics

Abstract: Resolving the long-term, population-level consequences of changes in pertussis epidemiology, arising from bacterial evolution, shifts in vaccine-induced immunity, or changes in surveillance, are key challenges for devising effective control strategies. This chapter reviews some of the key features of pertussis epidemiology, together with the underlying epidemiological principles that set the context for their interpretation. These include the relationship between the age distribution of cases and pertussis transmission potential, the impact of vaccine uptake on incidence, periodicity and age incidence, as well as spatially explicit recurrent pertussis epidemics and associated extinction frequency. This review highlights some of the predictable and consistent aspects of pertussis epidemiology (e.g. the systematic increase in the inter-epidemic period with the introduction of whole-cell vaccines) and a number of important heterogeneities, including variations in contemporary patterns of incidence and geographic spread.

A simulation study on the relative role of age groups under differing pertussis transmission scenarios

Abstract: Pertussis has resurged in many countries where it was once regarded as under control, with the recent outbreaks showing a shift in incidence towards teens and older individuals Here, using an age-stratified transmission model, we tested two potential causes for underlying changes in pertussis transmission dynamics We did so assuming hypothesized mechanisms supporting present-day pertussis epidemiology: (I) improved diagnostics, (II) acellular vaccines leading to asymptomatic transmission (III) both We used the relative risks and odds ratio methods to examine the impact of these differing assumptions on signatures of relative roles of key age groups through time, allowing us to explore those age cohorts that disproportionately account for transmission Our findings show that for epidemics after the vaccine switch, a scenario with increased adult reporting and no asymptomatic transmission reflect a loss of signal, where no age group appears to be key While scenarios with asymptomatic transmission, reflect a population where children (1-10 years old) are still disproportionally at risk These results demonstrate that understanding the underlying transmission mechanisms in a population are paramount for vaccination policies in attaining herd immunity and eventually eradication

Pertussis immunity and the epidemiological impact of adult transmission: Statistical evidence from Sweden and Massachusetts

Abstract: An understanding of the consequences of infection and vaccination on host immunity sets the stage for interpreting pertussis epidemiology. Yet, with no known serological marker of protection, such an understanding is currently not possible. This chapter interrogates longitudinal age-stratified pertussis incidence reports from Sweden and Massachusetts, United States, with the aim of quantifying the impact of infection and immunization on protective immunity. The analysis of data from Sweden during the vaccination hiatus period (1986–1996) indicates that adults contribute little to transmission. This may either be because infection-derived immunity is very long-lasting, or that individuals whose immunity has waned are subsequently less susceptible. The analysis of data from Massachusetts (1990–2005) identifies the primary mechanism of vaccine failure—for both whole-cell and acellular pertussis vaccines—to be waning. However, the average duration of immunity is identified as many decades, though the model predicts substantial individual variability in this trait. Finally, the chapter demonstrates the estimates to be consistent with those obtained from popular measures of vaccine effectiveness, though the interpretation of these findings is quite different.

Creatinine Phosphokinase (CPK) Elevation in the Coexistence of Wilson's Disease and Autoimmune Hepatitis with Atypical Presentation: A Diagnostic Dilemma

Abstract: Background: Wilson's disease (WD) is a genetic disorder with various clinical presentations due to excessive accumulation of copper in the liver and other organs. It can present as acute/chronic hepatitis, liver failure, extrahepatic and neuromuscular manifestations. Autoimmune hepatitis (AIH) is a necroinflammatory disease of the liver, which affects a lot of people particularly the children population. AIH has a broad clinical presentation that is similar to WD. Coexistence of WD with elevated creatinine phosphokinase (CPK) and AIH, may be a diagnostic dilemma. Case Report: We presented a 6 years old boy with dysarthria, aggressive behavior, weak attention, concentration and weight loss with abnormal physical examination. Laboratory, histochemical, genomic studies, muscle/liver biopsy and atomic absorption test confirmed the diagnosis of both WD and AIH in the boy. Conclusion Although CPK and liver enzyme elevation is a rare presentation of chronic hepatitis with dominant feature of WD and AIH; however, simultaneous therapy with immunosuppressive drugs and Penicillamine may have superior benefit with a significant response.

Diagnostic Challenges in the Early Onset of Inflammatory Bowel Disease: A Case Report.

Abstract: Inflammatory bowel disease (IBD) with very early onset manifestations (younger than six years of age) is an essential pediatric gastrointestinal disease that encompasses a group of diverse and rare genetic defects. It may be associated with chronicity, premalignant nature, and high morbidity and mortality during childhood. Because of overlapping phenotypes, the definitive diagnosis based on conventional strategies is frequently a challenge. However, many patients with different molecular pathologies are treated with the same therapeutic strategy. In this context, it is essential to define a more reliable method to provide an opportunity for a rapid and accurate diagnosis. Here we report a novel homozygous exonic variant in a patient with an IBD-like lesion in the colon during the infancy period. A 7 months old boy who was born of a consanguineous marriage developed gastrointestinal disorders early in life. After complete diagnostic workups, this case underwent conventional therapy of IBD for five months; but clinical remission was not achieved. We identified a novel homozygous mutation (c.684C>T p(=)) in exon 7 of IL-12RB1 gene that in silico studies indicated its significance in the splicing process. At the 14th month of age, this case died. Our finding reveals the importance of genetic screening as an early diagnostic tool in the identification of the underlying causes of IBD with very early onset manifestations, particularly infantile (< 2 years of age) IBD. This strategy makes an opportunity in prompt diagnosis and targeted therapy.

Feeding the disparities: the geography and trends of breastfeeding in the United States

Abstract: There is scientific consensus on the importance of breastfeeding for the present and future health of newborns, in high- and low-income settings alike. In the United States, improving breast milk access is a public health priority but analysis of secular trends are largely lacking. Here, we used data from the National Immunization Survey of the CDC, collected between 2003 and 2016, to illustrate the temporal trends and the spatial heterogeneity in breastfeeding. We also considered the effect sizes of two key determinants of breastfeeding rates. We show that, while access to breast milk both at birth and at 6 months old has steadily increased over the past decade, large spatial disparities still remain at the state level. We also find that, since 2009, the proportion of households below the poverty level has become the strongest predictor of breastfeeding rates. We argue that, because variations in breastfeeding rates are associated with socio-economic factors, public health policies advocating for breastfeeding are still needed in particular in underserved communities. This is key to reducing longer term health disparities in the U.S., and more generally in high-income countries.

Response to Comment on “The impact of past vaccination coverage and immunity on pertussis resurgence”

Abstract: We present new evidence that the immunity conferred against pertussis by the DTaP acellular vaccine wanes more slowly than widely believed.

Does Ketamine is Safe and Effective for Procedural Sedation in Percutaneous Liver Biopsy in Children? A Cohort Study in Iran

Abstract: Background: Effective and safe procedural sedation is necessary for percutaneous liver biopsy in children. There are a number of different protocols for this purpose. The current study investigated ketamine and DPT cocktail (meperidine (Demerol®) + promethazine (Phenergan®) + chlorpromazine (Thorazine®)). Methods: The current cohort of 80 Iranian children aimed at investigating percutaneous liver biopsy. Each of the 2 study groups (ketamine and DPT) included 40 patients. Both groups were matched by age (number of participants under and above 7 years old). The current study evaluated the efficacy of 2 protocols by CHEOPS (children’s hospital of Eastern Ontario pain scale) and visual analogue scale (VAS) pain scoring system and sedation scoring A,B,C, and D. Results: Ketamine group was sedated and recovered much more rapidly than the DPT receiving patients. Also, they had significantly less pain during the biopsy. The most common side effect of ketamine was vomiting (27%); in the other group, transient hypotension and tachycardia were more common. Conclusions: Ketamine is a safe and effective choice for procedural sedation in percutaneous liver biopsy in children.

New-Onset Bacterial Sinusitis in Pediatric Liver Transplant Recipients; Case Series and Review of Literature

Abstract: Introduction: As a standard measure in some chronic liver disorder, liver transplantation (LT) has performed for about 3 decades in pediatric populations. Post operatively some patients suffering from infectious complications by viral, bacterial and fungal etiologies. Here in we presented 10 children diagnosed as bacterial sinusitis presenting with prolonged fever and upper respiratory tract symptoms post LT and review the literature.Case presentation: Ten pediatric LT recipients including 7 boys and 3 girls, aged 1.5 to 8 years (4.7±2.34) with mean weight of 15.6 Kg (range; 11.4–27.5 Kg) were diagnosed as bacterial sinusitis during December 2013 to March 2017. Patients were suffering from respiratory symptoms and prolonged fever. After ruling out other diagnosis and by performing through investigation, we confirmed bacterial sinusitis by sputum culture and result of antibiogram and paranasal Computed Tomography (CT) scan. All patients dramatically responded to intravenous broad-spectrum antibiotic.Conclusion: In post LT patients who are, suffering from fever or prolonged fever with upper respiratory signs and symptoms, acute sinusitis should kept in mind. Therefore, timely diagnoses coupled with taking therapeutic measures using broad-spectrum antibiotics could prevent disease progression and complications.

Rethinking the efficacy of acellular pertussis vaccines for primary immunization

Abstract: Background The US has experienced a nationwide resurgence of pertussis since the mid-1970s, despite high vaccine coverage. Short-lived immunity induced by Diphtheria-Tetanus-acellular Pertussis (DTaP) vaccines in young children is widely believed to be responsible for this growing burden. However, the duration of protection conferred by DTaP vaccines remains incompletely quantified. Methods and Findings We employed a rigorously validated, age-structured model of pertussis transmission to explore a range of hypotheses regarding the degree of waning DTaP-derived immunity. For every hypothesis, we calculated the vaccine effectiveness and the relative increase in the odds of acquiring pertussis (or odds ratio) in children aged 5 to 9 years. We then assessed the simulated DTaP vaccine traits that best reproduced the empirical values of odds ratios from recent US epidemiological studies. We found a marked association between the degree of waning immunity, the vaccine effectiveness, and the odds ratio. Unexpectedly, the odds ratio was positively associated with the vaccine effectiveness, as a consequence of non-linear, age-assortative dynamics. Based on the empirical odds ratios, we estimated that vaccine effectiveness exceeded 75% and that more than 65% of children remained immune to pertussis 5 years after the last DTaP dose. Conclusions Our results show that temporal trends in the odds of acquiring pertussis are a seriously flawed measure of the durability of vaccine-induced protection. They further demonstrate that DTaP vaccines confer imperfect, but long-lived protection. We argue that control strategies should be based upon the best available estimates of vaccine properties and the age-structure of the transmission network.

Validation of Aspartate Aminotransferase to Platelet Ratio for Diagnosis of Hepatic Fibrosis and Prognostic Prediction of Infants with Biliary Atresia after Portoenterostomy

Abstract: Objectives: We aimed to evaluate the role of aspartate aminotransferase to platelet ratio in the diagnosis of liver fibrosis and its prognosis after surgery in infants with biliary atresia. Methods: This retrospective study was conducted using the medical records of patients diagnosed with biliary atresia who underwent surgery and liver biopsy in Mofid Children’s Hospital from 2008 to 2016. The sampling method was complete enumeration and all patients admitted to the hospital in these 8 years were selected as the sample. In this study, an author - made checklist was used. According to data available in the archives of Mofid Children’s Hospital, a total of 100 patients with preoperative diagnosis of biliary atresia entered the study. The obtained data were analyzed using descriptive statistics and inferential statistics. The significance level in this study was considered to be 0.05. Results: A total of 100 patients were enrolled in this study, with 64 male patients and 36 female. The patients gave birth at a minimum of 29 weeks and a maximum of 40 weeks. The gestational age was significantly related to the final diagnosis of the disease among children (p = 0.011). With a cut off value of aspartate aminotransferase to platelet ratio of 0.95, 25 patients (50%) with biliary atresia were in the group of significant fibrosis (F4, cirrhosis) and the others were in the non - significant fibrosis group (p value = 0.021). Conclusions: In our study, aspartate aminotransferase to platelet ratio was calculated and showed significant relationship to the final diagnosis based on liver biopsy categorizations among infants with Biliary Atresia after Portoenterostomy.