Screening of organ and tissue donors for West Nile virus by nucleic acid amplification--a three year experience in Alberta

Screening of living organ donors for endemic infections: Understanding the challenges and benefits of enhanced screening

Living organ donor candidates are screened for medical and psychosocial contraindications to donation. One important goal of this process is to prevent donor-derived infectious diseases transmissions. These transmissions are exceptionally rare, but have the potential to cause significant morbidity and mortality. The Organ Procurement and Transplantation Network now requires each recovery hospital to develop a protocol for evaluating living donors for tuberculosis and other geographically-defined endemic pathogens, including Trypanosoma cruzi (the causative pathogen of Chagas' disease), Strongyloides stercoralis, and West Nile Virus (WNV), in addition to universal screening for blood-borne pathogens. Enhanced screening requirements were developed in response to the changing epidemiology and endemicity of these diseases, as well as recent case reports of donor-derived disease transmission. Living organ donor disease screening presents a number of unique challenges to clinicians and policy-makers, including deciding which donors to test, which testing modality to use, when to test, and appropriate interpretation of results. This review will analyze the epidemiology of T. cruzi, S. stercoralis, and WNV, the assays available for screening for these diseases, and the subsequent impact on the living organ donor process . This article is protected by copyright. All rights reserved.

West Nile Virus Infection in the Central Nervous System

West Nile virus (WNV), a neurotropic single-stranded flavivirus has been the leading cause of arboviral encephalitis worldwide.  Up to 50% of WNV convalescent patients in the United States were reported to have long-term neurological sequelae.  Neither antiviral drugs nor vaccines are available for humans.  Animal models have been used to investigate WNV pathogenesis and host immune response in humans.  In this review, we will discuss recent findings from studies in animal models of WNV infection, and provide new insights on WNV pathogenesis and WNV-induced host immunity in the central nervous system.

Major emerging vector-borne zoonotic diseases of public health importance in Canada

In Canada, the emergence of vector-borne diseases may occur via international movement and subsequent establishment of vectors and pathogens, or via northward spread from endemic areas in the USA. Re-emergence of endemic vector-borne diseases may occur due to climate-driven changes to their geographic range and ecology. Lyme disease, West Nile virus (WNV), and other vector-borne diseases were identified as priority emerging non-enteric zoonoses in Canada in a prioritization exercise conducted by public health stakeholders in 2013. We review and present the state of knowledge on the public health importance of these high priority emerging vector-borne diseases in Canada. Lyme disease is emerging in Canada due to range expansion of the tick vector, which also signals concern for the emergence of human granulocytic anaplasmosis, babesiosis, and Powassan virus. WNV has been established in Canada since 2001, with epidemics of varying intensity in following years linked to climatic drivers. Eastern equine encephalitis virus, Jamestown Canyon virus, snowshoe hare virus, and Cache Valley virus are other mosquito-borne viruses endemic to Canada with the potential for human health impact. Increased surveillance for emerging pathogens and vectors and coordinated efforts among sectors and jurisdictions will aid in early detection and timely public health response.

Diagnosis of west nile virus human infections: overview and proposal of diagnostic protocols considering the results of external quality assessment studies

West Nile virus, genus Flavivirus, is transmitted between birds and occasionally other animals by ornithophilic mosquitoes. This virus also infects humans causing asymptomatic infections in about 85% of cases and <1% of clinical cases progress to severe neuroinvasive disease. The virus also presents a threat since most infections remain unapparent. However, the virus contained in blood and organs from asymptomatically infected donors can be transmitted to recipients of these infectious tissues. This paper reviews the presently available methods to achieve the laboratory diagnosis of West Nile virus infections in humans, discussing the most prominent advantages and disadvantages of each in light of the results obtained during four different External Quality Assessment studies carried out by the European Network for ‘Imported’ Viral Diseases (ENIVD).

West Nile virus transmission through organ transplantation in north-eastern Italy: a case report and implications for pre-procurement screening

PURPOSE

West Nile virus (WNV) transmission through organ transplantation occurs rarely and screening of organ donors for WNV infection remains controversial. This report describes the case of WNV encephalitis in a kidney recipient and the case of asymptomatic WNV infection in the organ donor, both observed at Treviso Hospital, northeastern Italy. After briefly reviewing the literature, we discuss the implications for WNV screening.

METHODS

We reviewed medical, laboratory and epidemiological records at our hospital, and the literature concerning cases of organ-transmitted WNV infections and WNV screening of organ donors in Italy and worldwide.

RESULTS

The kidney recipient was the first confirmed case of WNV infection notified in northeastern Italy in 2011, and the first case of WNV infection in a cluster of four transplant recipients who acquired the infection from a common organ donor. The organ donor, whose WNV infection was only retrospectively diagnosed by IgM detection, represents the index case of a WNV outbreak in the Treviso Province. Screening of her blood prior to organ recovery did not show detectable levels of WNV nucleic acid with the use of quantitative real-time polymerase chain reaction.

CONCLUSIONS

This report emphasizes that transplant-acquired WNV neuroinvasive disease can be particularly severe. We suggest that pre-procurement screening of organ donors by testing blood with both WNV IgM capture ELISA and a sensitive nucleic acid testing should be adopted during the transmission season in the present Italian epidemiological setting.

Detection of West Nile virus genome and specific antibodies in Iranian encephalitis patients

West Nile virus (WNV) is a mosquito-borne flavivirus which circulates in birds, horses and humans. An estimated 80% of WNV infections are asymptomatic. Fewer than 1% of infected persons develop neuroinvasive disease, which typically presents as encephalitis, meningitis, or acute flaccid paralysis. This study was conducted from January 2008 to June 2009 in Isfahan, Iran. Patients attending the emergency department with fever and loss of consciousness were consecutively included. Cerebrospinal fluids (CSF) were initially analysed through bacteriology and biochemistry examinations, resulting in those with evidence of meningitis being excluded. Patients' CSF and serum were diagnosed by serological and molecular assays. A total of 632 patients with fever and loss of consciousness were tested by CSF analyses. Samples of the remaining patients (39·4%) were referred for WNV investigation. Three (1·2%) of the patients were positive for both serum and CSF by RT–PCR, and six (2·4%) were positive only for IgG antibodies. History of insect bite, and blood transfusion and transplantation were risk factors for being positive by RT–PCR (P=0·048) and being IgG positive (P=0·024), respectively. The results of this study showed that the prevalence of West Nile fever is low in patients with encephalitis.