Trace-forward investigation of mice in response to lymphocytic choriomeningitis virus outbreak

Isolation and genomic characterization of lymphocytic choriomeningitis virus in ticks from northeastern China

Lymphocytic choriomeningitis virus (LCMV) is a rodent-borne arenavirus that is considered a neglected cause of neurologic diseases in humans. In this study, we described genomic characterization of newly isolated LCMVs in Haemaphysalis longicornis, Dermacentor nuttalli, Dermacentor silvarum and Ixodes persulcatus in Jilin Province, northeastern China. The complete sequences of the small (S) and large (L) segments of LCMVs in ticks contained 3,375 and 7,235-7,241 nucleotides, respectively. Sequence comparison showed 82.1%-86.0% identity of S segment with other lineage I strains at the nucleotide level and 91.2%-97.5% at the deduced amino acid level, while a lower identity was observed in the L segment at both nucleotide (75.4%-82.2%) and amino acid (82.4%-93.4%) levels. Phylogenetic analysis grouped the tick LCMVs together with the lineage I strains, but in an isolated cluster with a high bootstrap value. Bayesian analysis indicated that the molecular evolutionary rate was estimated to be 3.3 × 10^-4 substitutions/site/year for the S segment and 6.3 × 10^-4 substitutions/site/year for the L segment, and the time to most recent common ancestor was 1980 and 1970 years ago, respectively, showing that tick LCMVs were predicted to originate between 1970s and 1980s. A long evolutionary history and high prevalence of LCMV in H. longicornis were found compared to other tick species. This study represented the first report on isolation of LCMV in China, showing that LCMV is circulating among ticks in Jilin Province, but the role of ticks in the epidemiology of LCMV remains to be explored.

Challenges in laboratory diagnosis of acute viral central nervous system infections in the era of emerging infectious diseases: the syndromic approach

INTRODUCTION

Many acute viral infections of the central nervous system (CNS) remain without etiological diagnosis. Specific treatment is available for only few of them; however, accurate diagnosis is essential for patient's life and public health.

AREAS COVERED

In the current article, the main parameters playing a role for a successful etiological diagnosis of acute CNS infections are analysed and the syndromic approach based on clinical and demographic data combined with surrogated indicators is discussed. For the development of a relevant test panel, knowledge on the microbes causing CNS infections in a particular geographic region is essential. The modern screening strategies covering a large panel of potential causative agents are described. Examples of the successful application of next generation sequencing in the identification of etiological agents, including novel and emerging viruses, are given. Expert commentary: Knowledge on epidemiology of the viruses, expertise on syndromic grouping of the etiological agents and advances in technology enable the laboratory diagnosis of acute CNS infections, and the rapid identification, containment and mitigation of probable outbreaks.

Public Health Implications of Changing Rodent Importation Patterns - United States, 1999-2013

The United States imports a large volume of live wild and domestic animal species; these animals pose a demonstrated risk for introduction of zoonotic diseases. Rodents are imported for multiple purposes, including scientific research, zoo exhibits and the pet trade. Current U.S. public health regulatory restrictions specific to rodent importation pertain only to those of African origin. To understand the impacts of these regulations and the potential public health risks of international rodent trade to the United States, we evaluated live rodent import records during 1999-2013 by shipment volume and geographic origin, source (e.g. wild-caught versus captive- or commercially bred), intended purpose and rodent taxonomy. Live rodent imports increased from 2737 animals during 1999 to 173 761 animals during 2013. Increases in both the number and size of shipments contributed to this trend. The proportion of wild-captured imports declined from 75% during 1999 to <1% during 2013. Nearly all shipments during these years were imported for commercial purposes. Imports from Europe and other countries in North America experienced notable increases in volume. Gerbils and hamsters arriving from Europe and chinchillas, guinea pigs and hamsters arriving from other countries in North America were predominant taxa underlying this trend. After 2003, African-origin imports became sporadic events under the federal permit process. These patterns suggest development of large-scale captive rodent breeding markets abroad for commercial sale in the United States. While the shift from wild-captured imports alleviates many conservation concerns and risks for novel disease emergence, such consolidated sourcing might elevate exposure risks for zoonotic diseases associated with high-density rodent breeding (e.g. lymphocytic choriomeningitis or salmonellosis). A responsive border health system must periodically re-evaluate importation regulations in conjunction with key stakeholders to ensure a balance between the economic benefits of rodent trade against the potential public health risks.

Lymphocytic choriomeningitis virus in employees and mice at multipremises feeder-rodent operation, United States, 2012

Outbreaks can be prevented with strict biosecurity and microbiological monitoring.

We investigated the extent of lymphocytic choriomeningitis virus (LCMV) infection in employees and rodents at 3 commercial breeding facilities. Of 97 employees tested, 31 (32%) had IgM and/or IgG to LCMV, and aseptic meningitis was diagnosed in 4 employees. Of 1,820 rodents tested in 1 facility, 382 (21%) mice (Mus musculus) had detectable IgG, and 13 (0.7%) were positive by reverse transcription PCR; LCMV was isolated from 8. Rats (Rattus norvegicus) were not found to be infected. S-segment RNA sequence was similar to strains previously isolated in North America. Contact by wild mice with colony mice was the likely source for LCMV, and shipments of infected mice among facilities spread the infection. The breeding colonies were depopulated to prevent further human infections. Future outbreaks can be prevented with monitoring and management, and employees should be made aware of LCMV risks and prevention.