A low-energy core-collapse supernova without a hydrogen envelope.

The final fate of massive stars depends on many factors. Theory suggests that some with initial masses greater than 25 to 30 solar masses end up as Wolf-Rayet stars, which are deficient in hydrogen in their outer layers because of mass loss through strong stellar winds. The most massive of these stars have cores which may form a black hole and theory predicts that the resulting explosion of some of them produces ejecta of low kinetic energy, a faint optical luminosity and a small mass fraction of radioactive nickel. An alternative origin for low-energy supernovae is the collapse of the oxygen-neon core of a star of 7-9 solar masses. No weak, hydrogen-deficient, core-collapse supernovae have hitherto been seen. Here we report that SN 2008ha is a faint hydrogen-poor supernova. We propose that other similar events have been observed but have been misclassified as peculiar thermonuclear supernovae (sometimes labelled SN 2002cx-like events). This discovery could link these faint supernovae to some long-duration gamma-ray bursts, because extremely faint, hydrogen-stripped core-collapse supernovae have been proposed to produce such long gamma-ray bursts, the afterglows of which do not show evidence of associated supernovae.

A very faint core-collapse supernova in M85.

An anomalous transient in the early Hubble-type (S0) galaxy Messier 85 (M85) in the Virgo cluster was discovered by Kulkarni et al. on 7 January 2006 that had very low luminosity (peak absolute R-band magnitude M(R) of about -12) that was constant over more than 80 days, red colour and narrow spectral lines, which seem inconsistent with those observed in any known class of transient events. Kulkarni et al. suggest an exotic stellar merger as the possible origin. An alternative explanation is that the transient in M85 was a type II-plateau supernova of extremely low luminosity, exploding in a lenticular galaxy with residual star-forming activity. This intriguing transient might be the faintest supernova that has ever been discovered.

A giant outburst two years before the core-collapse of a massive star.

The death of massive stars produces a variety of supernovae, which are linked to the structure of the exploding stars. The detection of several precursor stars of type II supernovae has been reported (see, for example, ref. 3), but we do not yet have direct information on the progenitors of the hydrogen-deficient type Ib and Ic supernovae. Here we report that the peculiar type Ib supernova SN 2006jc is spatially coincident with a bright optical transient that occurred in 2004. Spectroscopic and photometric monitoring of the supernova leads us to suggest that the progenitor was a carbon-oxygen Wolf-Rayet star embedded within a helium-rich circumstellar medium. There are different possible explanations for this pre-explosion transient. It appears similar to the giant outbursts of luminous blue variable stars (LBVs) of 60-100 solar masses, but the progenitor of SN 2006jc was helium- and hydrogen-deficient (unlike LBVs). An LBV-like outburst of a Wolf-Rayet star could be invoked, but this would be the first observational evidence of such a phenomenon. Alternatively, a massive binary system composed of an LBV that erupted in 2004, and a Wolf-Rayet star exploding as SN 2006jc, could explain the observations.

Castellated tiles as the beam-facing components for the diagnostic calorimeter of the negative ion source SPIDER.

This paper presents the results of numerical simulations and experimental tests carried out to assess the feasibility and suitability of graphite castellated tiles as beam-facing component in the diagnostic calorimeter of the negative ion source SPIDER (Source for Production of Ions of Deuterium Extracted from Radio frequency plasma). The results indicate that this concept could be a reliable, although less performing, alternative for the present design based on carbon fiber composite tiles, as it provides thermal measurements on the required spatial scale.

Risk of hepatitis B virus infection following upper gastrointestinal endoscopy: a prospective study in an endemic area.

A prospective survey, comprising 623 consecutive upper gastrointestinal endoscopies (in 588 patients) was carried out simultaneously at two endoscopy centres of a Mediterranean country, without altering the routine procedures. Each patient was tested for HBsAg, and sera found to be HBsAg-positive were tested for HBeAg/antiHBe: 40/588 (7.1%) subjects were found to be HBsAg-positive and 6 of them were HBeAg-positive. Sera of the first 5 HBsAg-negative patients in whom the same endoscope and/or biopsy forceps were used after a HBsAg-positive subject, were tested for antiHBc to ascertain antecedent HBV immunity: 77/136 (56.6%) were found to be antiHBc-positive. Forty-eight out of the 59 individuals "at risk" lacking evidence of previous HBV infection were contacted 6 months after endoscopy: none reported symptoms of hepatitis; 40 of them had blood tests for HBsAg and antiHBc: none showed serum markers of HBV infection. It is therefore concluded that, in spite of the high number of HBsAg carriers among endoscopy candidates, the risk of HBV spread during upper G.I. endoscopy is very low, even in high prevalence areas.

Hepatitis B virus infection in prisons. A seroepidemiological survey in prisoners and attending staff.

Prisoners and attending staff from six houses of detention were screened for serum HBsAg, anti HBs, antiHBc and transaminases. Both prisoners and warders showed an increased prevalence of HBV serum markers with respect to age- and sex-matched general population control groups. The HBsAg carrier rate was 6.7% in prisoners and 6.6% in staff. Sixty-five per cent of the HBsAg-positive subjects were antiHBe-positive. When the blood samples were taken, all the HBsAg-positive subjects were asymptomatic; transaminases were normal in 80% and only slightly elevated in 20%. Illicit drug abuse was found to be a relevant risk factor for HBV infection among prisoners under 35 yearts of age, but not in the older group, whereas no correlation emerged between presence of HBV serum markers and tattoos or admitted homosexuality. A high prevalance of HBV serum markers as also found among young warders who had been in service for a short time: most of them, however, come from areas of Italy with a particularly elevated HBV circulation. Although the results suggest that many of the HBV infections are not recently acquired within the institution, this survey confirms that prisons should be regarded as high risk areas for HBV infection, both for prisoners and warders.

Hepatitis A and hepatitis B virus infection in children and adolescents in north-east Italy.

The sera of 722 children and adolescents without overt liver disease were tested for hepatitis B surface antigen (HBsAg), antiHBs and anti-hepatitis B core anti-HBc; 658 of the sera were also tested for anti-hepatitis A virus anti-HAV. Except for the "passive" antibody peak observed in babies, the anti-HAV age-specific prevalence was negligible until the age of 3; it then increased, reaching 35% by the age of 15. Serological evidence of HBV was present in 16% of the subjects: this prevalence was almost constant at all ages. The HBsAg carrier rate was highest in children under 5 years of age (7.6%) and decreased with age. However, only one HBsAg carrier was under 1 year of age. Anti-HBs age-specific prevalence increased progressively from 2.7% to 11.4%. Anti-HBc alone was present in 4.1% of the subjects. No significant sex differences were found in the prevalence of HBV serum markers or in the HBsAg carrier rate. Neither HAV nor HBV infection was significantly influenced by place of residence or socioeconomic status. It is concluded that in this area both HAV and HBV are endemic, but while HAV is mainly acquired at school, most of the HBV infections occur within the household. The results suggest that not only perinatal transmission, but also intrafamilial horizontal infection, plays a role in HBV spread among infants.

The risk of hepatitis A virus infection for hospital staff.

The prevalence of antiHA was assessed in 594 hospital employees and in control groups comprising 932 "healthy" adults not working in the hospital, selected from different socioeconomic classes. Age specific antiHA prevalence which was lower in doctors than in nurses and ancillary staff, was also found to be lower in each group than in the respective controls, matched according to socioeconomic criteria. It is concluded that in our population (i.e. high risk area) the hospital environment does not involve an increased risk of HAV infection for personnel. However, precautions should be taken when working in high risk department, as this study demonstrated that a considerable proportion of health care workers (above all doctors) are still susceptible to Hepatitis A virus infection.

Prevalence of anti-HCV and risk factors for hepatitis C virus infection in healthy pregnant women.

The prevalence of anti-HCV antibodies and the risk factors for HCV infection were assessed in 5,672 pregnant women living in North Italy. All reactive sera were confirmed by RIBA-2 test. Anti-HCV positive pregnant women together with an anti-HCV negative control group, were interviewed by standardised questionnaire to identify "known" or "potential" risk factors for HCV infection. The anti-HCV prevalence was 0.7% (40/5,672), higher than that observed among blood donors in the same geographical area (0.2%). The RIBA-2 assay was positive in 60% (24/40) of cases, indeterminate in 10% (4/40) and negative in 30% (12/40). As for "known" risk factors, considering RIBA-2 positivity, intravenous drug use was by far the main risk factor for HCV infection, resulting in a significantly higher risk than in the control group (50% versus 5.9% [O. R. 15.8, CI 5.4-45.5]). The ten RIBA-2 positive women without histories of transfusion or IV drug use had a significantly higher frequency of "sexual contacts with IV drug users" compared to controls (50% vs 4.9% [O. R. 19.0, CI 3.6-94.0]). In conclusion, our study provides evidence that in our geographical area the anti-HCV antibody prevalence is higher in pregnant women than in blood donors and that IV drug use and sexual contacts with IV drug users represent the most important risk factors for HCV infection among young women in North Italy.

[Viral hepatitis B. Seroepidemiological study in Veneto]. / Epatite virale B. Indagine sieroepidemiologica nel Veneto.

Sera from 3160 subjects without overt liver disease were tested for the presence of HBsAg, anti-HBs, anti-HBc. This group corresponds to a 4%, sample of the population resident in Padova and the surrounding district, selected according to sex and age distribution (in 5 to 5 year classes). The overall prevalence of HBV infection was 23%. The prevalence of HBsAg+ subjects was 3.2% higher in males than in females (3.8% v.s. 2.7%). Children under 5 years of age showed the maximum HBsAg carrier rate (7.3%), which was found to decrease with advancing age. Prevalence of anti-HBs is similar in both sexes (M 15.8% v.s. F 14.2%) and increases with age. Anti-HBc without HBsAg or anti-HBs was found in 4.6%, higher in males than in females (5.8% v.s. 3.6%). These result stress the importance of anti-HBc detection in HBV seroepidemiological surveys and suggest that HBV transmission within the household (both vertical and horizontal) plays a relevant role in HBV spread in our population.

Investigation of a Q-fever outbreak in northern Italy.

OBJECTIVES: A study was conducted to evaluate the extent of a Q-fever epidemic through active case finding in the area of Vicenza (north-eastern Italy), and to identify risk factors for Q-fever in this outbreak. METHODS: 1) Descriptive epidemiology; 2) Seroepidemiological survey; 3) Case-control study. 1) Epidemic curve and maps with the location of cases. Identification of the road followed by the flocks of sheep. 2) Cross-sectional study on humans and flocks of sheep tested for anti-Coxiella burnetii antibodies. 3) Cases were defined by the presence of fever > 38 degrees C plus serological confirmation. Controls were 94 apparently healthy individuals attending outpatient facilities for control visits or certification, group-matched by geographical area, age and gender. A standardized questionnaire was administered by trained interviewers. Odds ratio and 95% confidence intervals (CI) were used to evaluate risk factors for Q-fever. RESULTS: A total 58 cases were identified in a 5-month period. Male to female ratio was 2.8:1; mean age was 42 years (range: 20-65 years). Twenty-eight patients (48%) were hospitalized. Fever was accompanied by asthenia (81%), headache (76%), chills (72%), and myalgia and arthralgia (53%); cough was present in 47% of patients. Rx abnormalities were found in 81% of the patients undergoing chest X-ray. Among 111 apparently healthy family members who underwent serological testing, four (3.6%) had antibodies to Coxiella burnetii. Three flocks which passed through the outbreak area between late May and early June were shown to be infected, with prevalence of antibodies ranging between 45 and 53%. The case-control study showed a significant association with exposure to flocks of sheep (Odds ratio = 6.1; 95% CI 2.5, 16.3). Other potential risk factors were not more commonly reported by cases with respect to controls. CONCLUSIONS: Indirect exposure to flocks of sheep was a determinant of this outbreak of Q-fever. This finding suggests that transmission occurred through inhalation of contaminated airborne particles. The importance of control measures should be stressed in areas traversed by flocks of sheep.