Immunity to Haemophilus influenzae type b on sample population from central Italy.

A study on natural immunity to Haemophilus influenzae type b (Hib) was carried out in the province of Siena on 474 subjects ranging in age from 3 days to 70 years. The titration of antibody to capsular polysaccharide (PRP) was performed by the radioantigen-binding assay (RABA) method. A total of 66.67% of the population studied presented an antibody level considered to be protective (greater than or equal to 0.15 microgram ml-1). Seropositivity was 5.7% in the 5-7 month age group and 29.09% in the 8-17 month age group. This rose progressively in successive age groups reaching 79.54% between 4 and 6 years old and a value greater than 90% after 7 years old. From 3 to 17 months even the geometric mean of antibodies to PRP was below the protective limit. Our data indicate that, even in Italy, the majority of the infant population is not protected against H. influenzae, and therefore that vaccination should also be introduced in this country.

Intrafamilial hepatitis A outbreak: projection on the community in an area of Tuscany.

In 1988, 3 intrafamilial cases of hepatitis A occurred in a little town in the nearby of Siena: shellfishes were probably responsible for the index case, close contacts for the two secondary cases, characterized by a very long incubation period (above 60 days). An inapparent infection was detected in one household contact. No other cases of hepatitis A have been observed in that area since the intrafamilial outbreak until now. A seroepidemiological survey was carried out in a group of persons living in the same area, and attending the same school or class-room of one of the secondary intrafamilial cases. 210 sera belonging to 105 teenagers were available; an IgG anti A test was performed on a double serum sample (before and after the outbreak): no seroconversion was observed. Our report underlines the hypoendemicity of hepatitis A infection in our country.

Development of immunoglobulin M-antibodies after rubella immunization with RA27/3 attenuated live vaccine in teen-agers: remaining problems.

Four-hundred-fourty-two rubella seronegative teen-agers living in Siena and the surroundings were vaccinated with RA 27/3 live attenuated rubella over a two years period (1985-1987). One-hundred-twenty seven vaccinees' sera were randomly selected for the rubella specific antibodies of the IgM class detection with two Elisa Methods; the sera were collected 10 and 30 days after the challenge; in 58 girls a serum sample was also obtained 1 yr later. None of the sera showed reactivity for RF. The comparison between the two Elisa methods gave satisfactory results, the percentage of discrepancies being low (3.9%). Ten days after the immunization the IgM positive sera were only 7.56% (Elisa Abbott) and 5.88% (Elisa Enzygnost Behringwerke). One month later, 86.61% of the specimens showed reactivity for specific IgM antibodies. None of 58 sera gave positive results after 1 yr. Rubella antibodies of the IgG class could be demonstrated in the "screening" sera of 3 IgM negative subjects, when an Elisa method was applied. Nine subjects (7%) repeatedly resulted IgM negative one month after the challenge although a seroconversion was observed using both HAI and EIA. A serum sample was also obtained in 6/9 IgM "non responders" after a rubella epidemic observed in 1988-1989; no subclinical reinfection due to the wild virus was detected in this group, no changes in HAI antibody title nor evidence of IgM class specific response were observed. Although most of the diagnostic aspects related with rubella and rubella vaccination appear to be resolved, it should be underlined that there are several remaining problems especially associated with IgM detection.

Impact of hepatitis A in Siena: a "traveller's disease"?

Over a period of seven years (from 1980 to 1987) 58 acute viral hepatitis A cases were admitted to the Departments for Infectious Diseases. This number represents 10.76% of all viral hepatitis patients. Most of the patients had travelled to foreign countries or to areas in Italy with high hepatitis A virus (HAV) circulation. An assessment of specific immunization against HAV in normal healthy people aged 1-60, performed by ELISA, showed a very low number of sero-positive subjects. The disappearance of HAV in Italy, which is similar to other western European countries, is probably due to the improved socio-economical conditions; the "imported cases" seem to have little impact on public health.

Seroepidemiological research on hepatitis A (HA) in the city of Siena.

The circulation of Hepatitis A Virus in the city of Siena and the tight neighbouring area appears to be fairly rare. In fact, the number of cases suffering from Hepatitis A, admitted into the Clinic of Infectious Diseases of the University of Siena, has been 33 out of 4,905 patients (yrs 1975-1985). Of these, only 6 were patients resident in Siena. Seroepidemiological research, carried out with the ELISA method on 275 people of an age between 1 and 20 years, has confirmed a specifically low immunization as regards to Hepatitis Virus A (in fact the total antibodies were present only in 1.54% of the cases tested). This report is a long way off the one indicated in other Italian cities in the south as well as the central north of Italy; it can be put in relation to the peculiar demographical situation of the city or to the general fall of Hepatitis A Virus infection also indicated in other areas of the world.