Experimental production of infectious bovine keratoconjunctivitis: comparison of serological and immunological responses using pili fractions of Moraxella bovis.
The effect of vaccinating cattle and mice on the development of keratoconjunctivitis was studied. Cattle were vaccinated with whole cells, disrupted cells and pili fractions of three strains of Moraxella bovis. Mice were vaccinated with pili fractions of three strains. The resistance of all vaccinated animals was challenged with virulent cultures of M. bovis. In an attempt to correlate the response seen after vaccination and challenge with a pili fraction of M. bovis, vaccinated cattle and mice were grouped on the basis of signs of disease manifested and compared on the basis of serological responses. Serum samples were tested for antibodies by a gel diffusion precipitin test. A greater number of the sera of resistant cattle had antibodies to the homologous pili antigen than those of vaccinated nonresistant cattle. Cattle vaccinated with disrupted cells were not resistant to infectious bovine kerato-conjuctivitis and their sera lacked antibodies against the pili antigens. Vaccinated mice were more resistant to infectious bovine kerato-conjuctivitis and their sera lacked antibodies against the pili antigens. Vaccinated mice were more resistant to challenge exposure by homologous than heterologous cultures. A greater number of the sera of resistant mice had antibodies to pili antigens than nonresistant mice. (+info)
Cluster survey evaluation of coverage and risk factors for failure to be immunized during the 1995 National Immunization Days in Egypt.
BACKGROUND: In 1995, Egypt continued to experience endemic wild poliovirus transmission despite achieving high routine immunization coverage with at least three doses of oral poliovirus vaccine (OPV3) and implementing National Immunization Days (NIDs) annually for several years. METHODS: Parents of 4188 children in 3216 households throughout Egypt were surveyed after the second round of the 1995 NIDs. RESULTS: Nationwide, 74% of children are estimated to have received both NID doses, 17% one NID dose, and 9% neither NID dose. Previously unimmunized (47%) or partially immunized (64%) children were less likely to receive two NID doses of OPV than were fully immunized children (76%) (P < 0.001). Other risk factors nationwide for failure to receive NID OPV included distance from residence to nearest NID site >10 minute walk (P < 0.001), not being informed about the NID at least one day in advance (P < 0.001), and residing in a household which does not watch television (P < 0.001). Based on these findings, subsequent NIDs in Egypt were modified to improve coverage, which has resulted in a marked decrease in the incidence of paralytic poliomyelitis in Egypt. CONCLUSIONS: In selected situations, surveys can provide important information that is useful for planning future NIDs. (+info)
Paediatric, invasive pneumococcal disease in Switzerland, 1985-1994. Swiss Pneumococcal Study Group.
BACKGROUND: Cost effective use of new vaccines against pneumococcal disease in children requires detailed information about the local epidemiology of pneumococcal infections. METHODS: Data on 393 culture-confirmed cases of invasive pneumococcal infection in children (<17 years) hospitalized in Swiss paediatric clinics were collected retrospectively for the years 1985-1994. RESULTS: Meningitis (42%) was most frequent, followed by pneumonia (28%) and bacteraemia (26%). The overall annual incidence was 2.7 cases per 100000 children <17 years old and 11 cases per 100000 children <2 years old. Annual incidence rates were stable over the study period. Lethality was high for meningitis (8.6%) and bacteraemia (8.9%). A history of basal skull fracture was reported in 3.3% of children with pneumococcal meningitis. Residence in a rural region was associated with an increased risk of pneumococcal infection (relative risk = 1.45, 95% confidence interval: 1.01-2.00). CONCLUSIONS: Paediatric, invasive pneumococcal disease seems to be less frequent in Switzerland than in other European and non-European countries. This may be due to differences in diagnostic strategies and lower frequency of risk factors such as the use of day care. Children with a history of basal skull fracture are at increased risk for pneumococcal meningitis. Further investigation of the association of invasive pneumococcal infection with rural residence and the use of antibiotics for upper respiratory tract infections might give new insight into the dynamics of Streptococcus pneumoniae infection and the development of antibiotic resistance. (+info)
Safety and immunogenicity of a Pseudomonas aeruginosa hybrid outer membrane protein F-I vaccine in human volunteers.
A hybrid protein [Met-Ala-(His)6OprF190-342-OprI21-83] consisting of the mature outer membrane protein I (OprI) and amino acids 190 to 342 of OprF of Pseudomonas aeruginosa was expressed in Escherichia coli and purified by Ni2+ chelate-affinity chromatography. After safety and pyrogenicity evaluations in animals, four groups of eight adult human volunteers were vaccinated intramuscularly three times at 4-week intervals and revaccinated 6 months later with either 500, 100, 50, or 20 microg of OprF-OprI adsorbed onto A1(OH)3. All vaccinations were well tolerated. After the first vaccination, a significant rise of antibody titers against P. aeruginosa OprF and OprI was measured in volunteers receiving the 100- or the 500-microg dose. After the second vaccination, significant antibody titers were measured for all groups. Elevated antibody titers against OprF and OprI could still be measured 6 months after the third vaccination. The capacity of the elicited antibodies to promote complement binding and opsonization could be demonstrated by a C1q-binding assay and by the in vitro opsonophagocytic uptake of P. aeruginosa bacteria. These data support the continued development of an OprF-OprI vaccine for use in humans. (+info)
Protective efficacy of recombinant Yersinia outer proteins against bubonic plague caused by encapsulated and nonencapsulated Yersinia pestis.
To evaluate the role of Yersinia outer proteins (Yops) in conferring protective immunity against plague, six yop loci from Yersinia pestis were individually amplified by PCR, cloned, and expressed in Escherichia coli. The recombinant proteins were purified and injected into mice. Most Yop-vaccinated animals succumbed to infection with either wild-type encapsulated Y. pestis or a virulent, nonencapsulated isogenic variant. Vaccination with YpkA significantly prolonged mean survival time but did not increase overall survival of mice infected with the nonencapsulated strain. The only significant protection against death was observed in YopD-vaccinated mice challenged with the nonencapsulated strain. (+info)
Sustained reduction in the carriage of Neisseria meningitidis as a result of a community meningococcal disease control programme.
The effect of a community intervention programme of antibiotics and meningitis vaccine on pharyngeal carriage of Neisseria meningitidis was investigated. Carriage rates were determined in pupils at both secondary schools (ages 11-18 years) included in the community intervention programme and compared with two schools outside the area matched for socio-economic status. A total of 1869 pupils were studied 6 months after the programmes, and 2457 pupils after 11 months. Six months after the programme was completed there was a 72% reduction in pharyngeal carriage of Neisseria meningitidis in pupils attending the schools in the intervention area compared with pupils in the control schools. After 11 months this difference persisted in the 11-14 age group but not in the 15-18 age group. No resistance to the antibiotics used in the programme was found. A community intervention programme of antibiotics and vaccine for the control of meningococcal disease led to a long-term reduction in Neisseria meningitidis carriage in some age groups. (+info)
Seroepidemiological evaluation of 1989-91 mass vaccination campaigns against measles, in Italy.
In 1989-91 anti-measles vaccination campaigns were conducted in several Italian regions to vaccinate all children aged between 13 months and 10-12 years without a history of measles or measles vaccination. This study was conducted to evaluate serological status after the mass vaccination campaigns. In 1994, capillary blood samples were collected from randomly selected children, aged 2-14 years, living in 13 local health units. Antibody titres were determined by ELISA. Blood spot samples were analysed for 4114 (75.6%) of 5440 selected children. Among the 835 that reported measles before 1990, 806 (96.5%) were immune and of the 2798 vaccinated, 2665 (95.2%) were immune. The Edmoston-Zagreb (E-Z) strain vaccine was associated with a lower level of immunity than the Schwarz (SW) strain. A history of measles identified almost all immune children. Vaccination with the SW strain conferred persistent immunity (at least 5 years) in 98% of vaccinees. The strategy was able to unite natural and induced immunity. (+info)
A model-based evaluation of the national immunization programme against rubella infection and congenital rubella syndrome in The Netherlands.
In order to improve the prevention of cases of congenital rubella syndrome in The Netherlands, in 1987 the selective vaccination strategy against rubella infection in girls was replaced by mass vaccination. This decision was supported by mathematical model analyses carried out by Van Druten and De Boo. In order to compare the predicted impact of the rubella vaccination programme with the current available data in more detail, a similar model was built. Although the model predicts elimination of the rubella virus, data show that virus circulation is still present at a higher level than expected by the model. Simulation studies indicate that import of infection and a lower vaccine effectiveness, related to possible asymptomatic reinfection of vaccinated people, could be sources contributing to the present virus circulation. Even though the number of infections is much higher than the number of reported cases of disease, limited serosurveillance data and case notification data show that females of childbearing age are well protected by immunization. (+info)