False-positive transcription-mediated amplification assay detection of West Nile virus in blood from a patient with viremia caused by an Usutu virus infection.

Detection of West Nile virus (WNV) by nucleic acid amplification technology (NAAT) is used widely to screen blood and organ donations in areas where WNV is endemic. We report a false-positive result of a WNV transcription-mediated amplification assay (TMA) in a patient with viremia that was caused by Usutu virus, a mosquito-borne flavivirus.

Toscana virus infections in northern Italy: laboratory and clinical evaluation.

Toscana virus (TOSv) is a neurotropic arthropod-borne virus that causes meningitis in the Mediterranean basin during the summer months. A total of 120 patients suffering from acute aseptic meningitis between July 1 and October 31, 2010 in northern Italy were evaluated. Eighteen of them (15%) were in the acute stage of TOSv disease.

A rapid and specific real-time RT-PCR assay to identify Usutu virus in human plasma, serum, and cerebrospinal fluid.

BACKGROUND: Usutu virus (USUV), a flavivirus that belongs to the Japanese encephalitis virus (JEV) family, has recently emerged as a human pathogen, necessitating new diagnostic tools. OBJECTIVE: The development and assessment of a real-time RT-PCR assay to detect USUV in human samples. STUDY DESIGN: Based on USUV genomic sequences from GenBank, USUV-specific primers and probes that target the NS5 gene were designed. The sensitivity was evaluated in a 10-fold dilution series of plasmid that contained the amplicon and in a dilution series of a quantified human USUV isolate. The specificity was determined by testing various concentrations of related ArBo viruses, including flaviviruses and phleboviruses. Human RNAse P was also amplified in the assay. One hundred four human specimens from patients who suffered from viral meningoencephalitis were evaluated. RESULTS: The real-time RT-PCR assay had a sensitivity of 50 genomic copies per reaction (corresponding to 2200 copies/ml) and 1 PFU/ml of USUV isolate. USUV isolates from Austria were identified with identical efficiency, and no ArBo viruses, other than USUV, were detected. USUV was also identified in 3 cerebrospinal fluid samples. All human samples were positive for RNAse P. CONCLUSIONS: This PCR assay is recommended for all cases in which a rapid and clinically accurate diagnosis of human USUV infection is required.

Chikungunya virus in North-Eastern Italy: a seroprevalence survey.

After an outbreak of Chikungunya infection in Emilia-Romagna Region (North-eastern Italy), a survey was performed to estimate the seroprevalence of antibody to Chikungunya virus and the proportion of asymptomatic infections, to identify factors associated with infection, and evaluate the performance of the surveillance system. The method used was a survey on a random sample of residents of the village with the largest number of reported cases. The prevalence was 10.2% (33 of 325), being higher in older people and males, and lower when window screens and insect repellents were used. Only 18% of infected persons were fully asymptomatic, 85% of the 27 symptomatic confirmed cases satisfied the surveillance case definition, and 63% of the persons meeting the criteria for suspect case were identified by the active surveillance system. This study provides basic parameters for modeling the transmission potential of outbreaks and planning control measures for Chikungunya infection in temperate settings.

Chikungunya: an emerging and spreading arthropod-borne viral disease.

The virus causing Chikungunya disease was identified over 50 years ago; however, because the disease appeared only in developing countries, little research on it has been done. Research interest in the disease increased after an important epidemiological outbreak occurred in 2005 on the French metropolitan island of La Reunion located in the south-eastern part of the Indian Ocean. In 2007, a smaller outbreak of Chikungunya developed in the north-eastern part of Italy made possible by immigration of a viremic patient from the Indian Ocean area and the enormous population of Aedes albopictus in Italy. Currently, Chikungunya is spreading in Southeast Asian aspects, clinical pictures, diagnosis and treatment of the disease caused by Chikungunya virus.

Blood culture systems: rapid detection--how and why?

Bloodstream infections are associated with high morbidity and mortality. Blood culture is considered to be the most important tool in their diagnosis. In this study we compared standard blood culture with two different molecular techniques (Prove-it Sepsis and LightCycler SeptiFast M) to detect bacterial species and fungi in the blood of septic patients. Both methods showed significant agreement with the results obtained by blood culture. The results of these studies suggest that both the LightCycler SeptiFast and Prove-it Sepsis tests can be used for the rapid and specific diagnosis of bacteraemia and bloodstream infections. It is important, however, to emphasize that molecular methods cannot replace blood cultures, as the latter allow the evaluation of the antimicrobial susceptibility of isolated microbes.