The emergence of human Powassan virus infection in North America

Powassan virus (POWV) is a tickborne flavivirus discovered in Ontario, Canada in 1958 that causes long-term neurological sequelae in about half the reported cases and death in a little more than 10 % of cases. The incidence of POWV disease is rising in the United States but there is limited understanding of the scope and causes of recent changes in POWV epidemiology. We focus on quantifying the increase in human POWV disease incidence and infection prevalence in the United States. We also examine differences in the frequency of symptomatic cases and asymptomatic or mildly symptomatic cases, as well as limitations in national and state surveillance for POWV infection. We searched SCOPUS for all articles containing original POWV prevalence research, case studies, or literature reviews published in English. Case studies were supplemented by Morbidity and Mortality Weekly Report POWV data from the Centers for Disease Control and Prevention (CDC) and surveillance information from state health department websites. An increase in the number of POWV cases has been reported in the United States over the past 50 yr, and the geographic range of human POWV cases has expanded. The age distribution of symptomatic POWV cases has shifted, with significantly more individuals over 40 yr old being diagnosed after 1998. The emergence of POWV is due in large part to: (i) a change in transmission of POWV from a vector that rarely bites people (Ixodes cookei) to a new vector that often bites people (Ixodes scapularis) and has expanded its geographic range, (ii) enhanced surveillance efforts for arboviruses, and (iii) a greater awareness of POWV infection.     

基于大自然时间轴的测量时序分类法

因果推断中，时序（或方向性）的概念尚未完全明确。本文从因果思维出发，以真实因和真实果的发生时间将大自然时间轴划分为3个时域和2个时点，从而锚定了因果推断只能实现于第3时域。测量时序可分为5种类型：跨第1和3时域纵向时序（实验性时序）、跨第2和3时域纵向时序、同时域纵向时序、同时域逆纵向时序和同时域横向时序（观察性时序）。这种分类法适用于首次或多次测量、及时和延后测量等所有测量策略。除了实验中真实因的测量（或干预措施）在其发生之前（第1时域）或观察和实验中真实因的测量在真实果发生之前（第2时域）的情形外，所有其他测量策略类似于历史重建或"考古"，测量时序的重要性次于测量的准确性。从研究设计应整合偏倚设计的观点来看，本文提出基于大自然时间轴的测量时序五分类法，概念清楚并将有助于判断研究过程中可能出现的偏倚，为正确进行因果推断研究奠定基础。     

Enhanced surveillance of tetanus toxoid,reduced diphtheria toxoid,and acellular pertussis (Tdap) vaccines in pregnancy in the Vaccine Adverse Event Reporting System (VAERS), 2011–2015

BackgroundIn October 2011, the Advisory Committee on Immunization Practices (ACIP) issued updated recommendations that all pregnant women routinely receive a dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine.ObjectivesWe characterized reports to the Vaccine Adverse Event Reporting System (VAERS) in pregnant women who received Tdap after this updated recommendation (2011–2015) and compared the pattern of adverse events (AEs) with the period before the updated recommendation (2005–2010).MethodsWe searched the VAERS database for reports of AEs in pregnant women who received Tdap vaccine after the routine recommendation (11/01/2011–6/30/2015) and compared it to published data before the routine Tdap recommendation (01/01/2005–06/30/2010). We conducted clinical review of reports and available medical records. The clinical pattern of reports in the post-recommendation period was compared with the pattern before the routine Tdap recommendation.ResultsWe found 392 reports of Tdap vaccination after the routine recommendation. One neonatal death but no maternal deaths were reported. No maternal or neonatal deaths were reported before the recommendation. We observed an increase in proportion of reports for stillbirths (1.5–2.8%) and injection site reactions/arm pain (4.5–11.9%) after the recommendation compared to the period before the routine recommendation for Tdap during pregnancy. We noted a decrease in reports of spontaneous abortion (16.7–1%). After the 2011 Tdap recommendation, in most reports, vaccination (79%) occurred during the third trimester compared to 4% before the 2011 Tdap recommendation. Twenty-six reports of repeat Tdap were received in VAERS; 13 did not report an AE. One medical facility accounted for 27% of all submitted reports.ConclusionsNo new or unexpected vaccine AEs were noted among pregnant women who received Tdap after routine recommendations for maternal Tdap vaccination. Changes in reporting patterns would be expected, given the broader use of Tdap in pregnant women in the third trimester.     

Diabetic nephropathy in Africa:A systematic review

AIM:To determine the prevalence and incidence of diabetic nephropathy in Africa.METHODS:We performed a systematic narrative review of published literature following the MOOSE Guidelines for Meta-Analysis and Systematic Reviewsof Observational Studies.We searched Pub MedMEDLINE for all articles published in English and French languages between January 1994 and July 2014 using a predefined strategy based on the combination of relevant terms and the names of each of the 54 African countries and African sub-regions to capture the largest number of studies,and hand-searched the reference lists of retrieved articles.Included studies reported on the prevalence,incidence or determinants of chronic kidney disease(CKD) in people with diabetes within African countries.RESULTS:Overall,we included 32 studies from 16 countries;two being population-based studies and the remaining being clinic-based surveys.Most of the studies(90.6%) were conducted in urban settings.Methods for assessing and classifying CKD varied widely.Measurement of urine protein was the most common method of assessing kidney damage(62.5% of studies).The overall prevalence of CKD varied from 11% to 83.7%.Incident event rates were 94.9% for proteinuria at 10 years of follow-up,34.7% for endstage renal disease at 5 years of follow-up and 18.4% for mortality from nephropathy at 20 years of followup.Duration of diabetes,blood pressure,advancing age,obesity and glucose control were the common determinants of kidney disease.CONCLUSION:The burden of CKD is important among people with diabetes in Africa.High quality data from large population-based studies with validated measures of kidney function are still needed to better capture the magnitude and characteristics of diabetic nephropathy in Africa.     

Varicella in Europe—A review of the epidemiology and experience with vaccination

There is no consensus as regards the European varicella immunisation policy; some countries have introduced varicella vaccination in their routine childhood immunisation programs whereas others have decided against or are debating. With the aim of providing an overview of the epidemiology of varicella in Europe and addressing the different strategies and the experiences so far, we performed a review of epidemiological studies done in Europe from 2004 to 2014. Varicella is mainly a disease of childhood, but sero-epidemiological studies show regional differences in the proportion of susceptible adults. Hospitalisation due to varicella is not common, but complications and hospitalisation mainly affect previously healthy children, which underlines the importance of not dismissing varicella as a disease of little importance. The experience with universal vaccination in Europe shows that vaccination leads to a rapid reduction of disease incidence. Vaccine effectiveness is high and a protective herd effect is obtained. Experience with vaccination in Europe has not been long enough, though, to draw conclusions on benefits and drawbacks with vaccination as well as the capacity for national programs in Europe to maintain a sufficiently high coverage to prevent a change in age group distribution to older children and young adults or on the impact that varicella immunisation may have on the epidemiology of shingles.