Margaret A. Fearon

Acute childhood encephalitis and encephalopathy associated with influenza: a prospective 11-year review.

Background: Influenza virus infection has been associated with a variety of neurologic complications. The objective of this study was to evaluate prospectively the role of influenza viruses in acute childhood encephalitis/encephalopathy (ACE). Methods: All children admitted to the Hospital for Sick Children, Toronto, during an 11-year period with ACE and evidence of acute influenza virus infection were included. Acute influenza virus infection was defined by detection of the organism in the nasopharynx by direct immunofluorescence microscopy or viral culture and/or by a 4-fold or greater rise in complement fixation titer. Results: A total of 311 children with ACE were evaluated; evidence of influenza infection was detected in 7% (22 of 311). Eight were excluded from the main analysis because of evidence implicating other potential pathogens. Eleven of the 14 included subjects were <5 years of age. A respiratory prodrome was documented in 93% of subjects. In 64% neurologic manifestations developed within 5 days of onset of respiratory symptoms. Neuroimaging abnormalities were more common in children <2 years of age. Neurologic sequelae occurred in more than one-half of subjects. Conclusions: In this prospective registry, influenza virus infection was associated with 5% of ACE cases. The majority of children were <5 years of age and the prevalence of neuroimaging abnormalities was higher in children <2 years of age suggesting that younger children are predisposed to the neurologic complications of influenza. An acute rather than a postinfectious process was suggested by the briefness of the respiratory prodrome in most cases.

West Nile Virus Surveillance and Diagnostic: A Canadian Perspective

A surveillance program has been in place since 2000 to detect the presence of West Nile virus (WNV) in Canada. Serological assays are most appropriate when monitoring for human disease and undertaking case investigations. Genomic amplification procedures are more commonly used for testing animal and mosquito specimens collected as part of ongoing surveillance efforts. The incursion of WNV into this country was documented for the first time in 2001 when WNV was demonstrated in 12 Ontario health units during the late summer and fall. In 2002 WNV activity was documented by avian surveillance in Ontario by mid-May with subsequent expansion of the virus throughout Ontario and into Quebec, Manitoba, Saskatchewan and Nova Scotia. Human cases were recorded in both Ontario and Quebec in 2002 with approximately 800 to 1000 probable, confirmed and suspect cases detected. The possible recurrence and further spread of WNV to other parts of Canada in 2003 must be anticipated with potential risk to public health. The continued surveillance and monitoring for WNV-associated human illness is necessary and appropriate disease prevention measures need to be in place in 2003.

Trypanosoma cruzi infection in North America and Spain: evidence in support of transfusion transmission (CME)

BACKGROUND: The United States, Canada, and Spain perform selective testing of blood donors for Trypanosoma cruzi infection (Chagas disease) to prevent transfusion transmission. The donor, product, and patient characteristics associated with transfusion‐transmitted infections are reviewed and the infectivity of components from donors with serologic evidence of infection is estimated.

Hepatitis B virus DNA–positive, hepatitis B surface antigen–negative blood donations intercepted by anti‐hepatitis B core antigen testing: the Canadian Blood Services experience

BACKGROUND: The benefit of introducing anti‐hepatitis B core antigen (HBc) screening for intercepting potentially infectious donations missed by hepatitis B surface antigen (HBsAg) screening in Canada was studied.

Declining hepatitis C rates in first‐time blood donors: insight from surveillance and case‐control risk factor studies

BACKGROUND: Hepatitis C virus (HCV) rates have decreased steadily in first‐time donors in Canada since testing was implemented but reasons are unclear. A description of factors that may have played a role in this decline is reported.

The laboratory diagnosis of HIV infections.

HIV diagnostic testing has come a long way since its inception in the early 1980s. Current enzyme immunoassays are sensitive enough to detect antibody as early as one to two weeks after infection. A variety of other assays are essential to confirm positive antibody screens (Western blot, polymerase chain reaction [PCR]), provide an adjunct to antibody testing (p24 antigen, PCR), or provide additional information for the clinician treating HIV-positive patients (qualitative and quantitative PCR, and genotyping). Most diagnostic laboratories have complex testing algorithms to ensure accuracy of results and optimal use of laboratory resources. The choice of assays is guided by the initial screening results and the clinical information provided by the physician; both are integral to the laboratorys ability to provide an accurate laboratory diagnosis. Laboratories should also provide specific information on specimen collection, storage and transport so that specimen integrity is not compromised, thereby preserving the accuracy of laboratory results. Point of Care tests have become increasingly popular in the United States and some places in Canada over the past several years. These tests provide rapid, on-site HIV results in a format that is relatively easy for clinic staff to perform. However, the performance of these tests requires adherence to good laboratory quality control practices, as well as the backup of a licensed diagnostic laboratory to provide confirmation and resolution of positive or indeterminate results. Laboratory quality assurance programs and the participation in HIV proficiency testing programs are essential to ensure that diagnostic laboratories provide accurate, timely and clinically relevant laboratory results.

Epidemiology of hepatitis B in Canadian blood donors

BACKGROUND: The residual risk of hepatitis B is higher than for other markers such as human immunodeficiency virus and hepatitis C virus in nonendemic countries. Evaluating the potential for further risk reduction requires a better understanding of the relationship between donor selection criteria, immigration from endemic countries, and public health vaccination strategies.

Fatal septic shock associated with transfusion-transmitted Serratia marcescens

Volume 46, April 2006 TRANSFUSION 679 stockpiles. Clearly, in the United States, screening will not be paid for from Medicare, Medicaid, and insurance funds used to support health care. Unless we accept the more general public health case, it does not strike us a responsible use of resources. Louis M. Katz, MD e-mail: katzid@ix.netcom.net Mississippi Valley Regional Blood Center Scott County Health Department Davenport, Iowa Merlyn Sayers, MB, BCh, PhD Carter BloodCare Bedford, Texas University of Texas Southwestern Medical Center Dallas, Texas

Proceedings of a Consensus Conference: Risk-Based Decision Making for Blood Safety

Blood safety decision making has become increasingly complex, and a framework for risk-based decision making is, thus, needed. The purpose of this consensus conference was to bring together international experts in an effort to develop the foundations for such a framework. These proceedings are described with a view to making available to the transfusion medicine community the considerable amount of information and insight that was presented and that emerged through debate by the experts, panel members, and delegates.

Assessment of a travel question to identify donors with risk of Trypanosoma cruzi: operational validity and field testing

BACKGROUND: Because Trypanosoma cruzi (T. cruzi) infection in Canada and the United States is largely contracted in endemic countries, targeted testing of blood donors with risk travel may improve safety. The operational validity of a travel question suitable for donor screening was tested, and it was field‐tested.