Loredana Nicoletti

Infection with chikungunya virus in Italy: an outbreak in a temperate region

BACKGROUND Chikungunya virus (CHIKV), which is transmitted by Aedes spp mosquitoes, has recently caused several outbreaks on islands in the Indian Ocean and on the Indian subcontinent. We report on an outbreak in Italy. METHODS After reports of a large number of cases of febrile illness of unknown origin in two contiguous villages in northeastern Italy, an outbreak investigation was done to identify the primary source of infection and modes of transmission. An active surveillance system was also implemented. The clinical case definition was presentation with fever and joint pain. Blood samples were gathered and analysed by PCR and serological assays to identify the causal agent. Locally captured mosquitoes were also tested by PCR. Phylogenetic analysis of the CHIKV E1 region was done. FINDINGS Analysis of samples from human beings and from mosquitoes showed that the outbreak was caused by CHIKV. We identified 205 cases of infection with CHIKV between July 4 and Sept 27, 2007. The presumed index case was a man from India who developed symptoms while visiting relatives in one of the villages. Phylogenetic analysis showed a high similarity between the strains found in Italy and those identified during an earlier outbreak on islands in the Indian Ocean. The disease was fairly mild in nearly all cases, with only one reported death. INTERPRETATION This outbreak of CHIKV disease in a non-tropical area was to some extent unexpected and emphasises the need for preparedness and response to emerging infectious threats in the era of globalisation.

Emergence of Toscana virus in Europe.

In southern Europe, Toscana virus is one of the three leading causes of aseptic meningitis.

Circulation of West Nile virus lineage 1 and 2 during an outbreak in Italy.

In 2011, from 26 September to 16 October, a small outbreak of West Nile virus (WNV) disease occurred on the island of Sardinia (Italy). According to the national case definition, six cases with acute neurological disease were confirmed in hospitalized patients, and four of them died; one of these was only 34 years old. In two case, WNV RNA was detected in urine, suggesting renal involvement. Sequence analysis showed lineage 1 and 2 circulation.

Description of two measles outbreaks in the Lazio Region, Italy (2006-2007). Importance of pockets of low vaccine coverage in sustaining the infection

BackgroundDespite the launch of the national plan for measles elimination, in Italy, immunization coverage remains suboptimal and outbreaks continue to occur. Two measles outbreaks, occurred in Lazio region during 2006-2007, were investigated to identify sources of infection, transmission routes, and assess operational implications for elimination of the disease.MethodsData were obtained from several sources, the routine infectious diseases surveillance system, field epidemiological investigations, and molecular genotyping of virus by the national reference laboratory.ResultsOverall 449 cases were reported, sustained by two different stereotypes overlapping for few months. Serotype D4 was likely imported from Romania by a Roma/Sinti family and subsequently spread to the rest of the population. Serotype B3 was responsible for the second outbreak which started in a secondary school. Pockets of low vaccine coverage individuals (Roma/Sinti communities, high school students) facilitated the reintroduction of serotypes not endemic in Italy and facilitated the measles infection to spread.ConclusionsCommunities with low vaccine coverage represent a more serious public health threat than do sporadic susceptible individuals. The successful elimination of measles will require additional efforts to immunize low vaccine coverage population groups, including hard-to-reach individuals, adolescents, and young adults. An enhanced surveillance systems, which includes viral genotyping to document chains of transmission, is an essential tool for evaluating strategy to control and eliminate measles

Sandfly fever viruses in Italy

Two serologically distinct agents, the sandfly fever Sicilian and the sandfly fever Naples viruses, were isolated by Sabin from blood samples taken during an Italian epidemic of febrile illness. Since then, several different viruses have been isolated from sandflies and/or humans in both the Old and New World. Toscana virus, a new virus closely antigenically related to sandfly fever Naples virus, was isolated in 1971 from the sandfly Phlebotomus perniciosus in Italy. Extensive studies on the importance of Toscana virus as a human pathogen demonstrated its association with acute neurologic diseases. A serosurvey for the presence of antibodies to sandfly fever Sicilian, sandfly fever Naples and Toscana viruses indicated that, as in other Mediterranean areas, both sandfly fever Sicilian and sandfly fever Naples viral infections decreased or disappeared after the 1940s in countries performing insecticide-spraying malaria eradication campaigns. In contrast, clinical cases of aseptic meningitis or meningoencephalitis caused by Toscana virus are observed annually in Central Italy during the summer. Toscana virus may be present in other Mediterranean countries where sandflies of the genus Phlebotomus are present.

Large human outbreak of West Nile virus infection in north-eastern Italy in 2012.

Human cases of West Nile virus (WNV) disease have been reported in Italy since 2008. So far, most cases have been identified in north-eastern Italy, where, in 2012, the largest outbreak of WNV infection ever recorded in Italy occurred. Most cases of the 2012 outbreak were identified in the Veneto region, where a special surveillance plan for West Nile fever was in place. In this outbreak, 25 cases of West Nile neuroinvasive disease and 17 cases of fever were confirmed. In addition, 14 WNV RNA-positive blood donors were identified by screening of blood and organ donations and two cases of asymptomatic infection were diagnosed by active surveillance of subjects at risk of WNV exposure. Two cases of death due to WNND were reported. Molecular testing demonstrated the presence of WNV lineage 1 in all WNV RNA-positive patients and, in 15 cases, infection by the novel Livenza strain was ascertained. Surveillance in other Italian regions notified one case of neuroinvasive disease in the south of Italy and two cases in Sardinia. Integrated surveillance for WNV infection remains a public health priority in Italy and vector control activities have been strengthened in areas of WNV circulation.

Probable Dengue Virus Infection Among Italian Troops, East Timor, 1999–2000

To investigate the attack rate and risk factors for probable dengue fever, a cross-sectional study was conducted of an Italian military unit after its deployment to East Timor. Probable dengue was contracted by 16 (6.6%) of 241 army troops and caused half of all medical evacuations (12/24); no cases were detected among navy and air force personnel.

A fatal case of encephalitis associated with Chikungunya virus infection

An outbreak of Chikungunya fever occurred in north-east Italy in the summer of 2007. Only 1 fatal case was observed, in an 83-y-old male hospitalized with encephalitis. Viral genome was detected at high level (1.5×108 copies/ml) in the cerebrospinal fluid 7 d after symptoms onset.

Establishment and maintenance of persistent infection by the Phlebovirus Toscana in Vero cells

Persistent infections were established by serial undiluted passages of the Toscana virus of the genus Phlebovirus in Vero cells. Persistence was maintained through more than 70 passages over a period of 2 years. The persistently infected cells were morphologically similar to the parental Vero cells and released variable amounts of infectious virus. A small percentage of the persistently infected cells produced infectious virus while a larger percentage was shown to possess viral antigens by fluorescent antibody staining. Temperature sensitivity and host cell interferon production were not involved in establishment or maintenance of persistence. The persistently infected cultures were resistant to superinfection with homologous Toscana virus, but they were susceptible to superinfection with heterologous viruses of different genera or families. Toscana virus persistently infected cells showed a selective graded resistance to the replication of other Phleboviruses. Additionally, the virus from persistently infected cells interfered with the replication of standard Toscana virus when they co-infected normal cells. The characteristics of the persistently infected cultures are compatible with some of the characteristics described for the persistence mediated by defective-interfering particles of other viruses.

Immunological characterization of Toscana virus proteins

Summary. The genome of Toscana virus (Bunyaviridae family, Phlebovirus genus) consists of three single stranded RNA segments (L, M, S), with negative polarity. The L and M segments contain a single ORF in viral complementary sense and the S segment contains two ORFs in “ambisense” orientation. The M segment codes for three proteins in 3′–5′ genomic orientation: a 30 kDa non structural protein and two 65 kDa glycoproteins, GN, and GC. In this paper we report the expression in E. coli of the S segment ORFs and of three regions of the L ORF. The expressed proteins were used to produce monospecific polyclonal antibodies in mice. By using these antibodies the N and the NSs proteins were unequivocally assigned to the S viral-complementary and viral-sense ORFs, respectively, and the L protein to the L ORF. We have found that like N and L proteins, NSs protein is associated with the viral nucleocapsids in mature virions, suggesting its possible involvement in early events of viral replication. NSs protein was also found associated with cellular polysomes. In virus-infected cells the anti-L antibodies recognized proteins shorter than the full-length L protein, possibly products of L subgenomic segments. Interestingly these defective products were not found in mature virions, suggesting specific mechanisms in virion assembly.