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C Ferreccio

Publications and source records attributed to C Ferreccio.

45 records · Page 3Linked to original sources
PubMed1986

Molecular techniques in the study of Salmonella typhi in epidemiologic studies in endemic areas: comparison with Vi phage typing.

We examined 141 Salmonella typhi strains of known phage type isolated during ongoing epidemiologic studies in Santiago, Chile, and Lima, Peru. Plasmids were present in 12 (17%) of 70 S. typhi isolates from Santiago and 5 (7%) of 71 isolates from Lima; these plasmids were not associated with antimicrobial resistance. Identical 21 kilobase (kb) plasmids (as defined by restriction endonuclease digest pattern) were present in 13 of the 17 plasmid-containing isolates. Virtually identical digest patterns were identified when chromosomal DNA of selected strains from Santiago, Lima, and the United States was extracted and then digested with restriction endonucleases. The similarities among plasmids and chromosomal digest patterns emphasize the homogeneity and possible clonal origin of S. typhi isolates; these data also suggest that there is only a limited role for plasmid and chromosomal analysis as a substitute for phage typing in epidemiologic studies.

Bacteriophage Typing↗
PubMed1984

The use of Moore swabs for isolation of Salmonella typhi from irrigation water in Santiago, Chile.

In Chile, a country with an exceedingly high incidence of typhoid, untreated sewage is applied directly to fields where salad vegetables are cultivated. Water used for irrigation was examined for the presence of Salmonella typhi, by making use of the sewer-swab technique. S typhi was isolated in 8 (11%) of 76 irrigation samples examined from nonindustrial, polluted water. This supports the hypothesis that crops grown with water contaminated with feces are important vehicles in the transmission of S typhi in this endemic area. Since sewage treatment plants will not be available in Santiago in the near future, emphasis is being placed on devising alternative methods of irrigation and on growing vegetables that are cooked before being eaten.

Bacteriological Techniques↗
PubMed1984

Typhoid fever in Santiago, Chile: a study of household contacts of pediatric patients.

We obtained clinical, epidemiological, and laboratory data (including three stool cultures) from 155 (96%) of 161 household contacts of 24 patients less than 16 years old with culture-confirmed typhoid fever; these 24 patients represented approximately 40% of such patients seen in three hospitals in Santiago during a 12-week period. A chronic typhoid carrier was identified in only one household, with concurrent or secondary cases seen in two other households. When index cases were matched with household members nearest in age, no specific risk factors for illness could be identified. There was evidence of generalized exposure to enteric pathogens within these households, with nine persons from seven different households culture-positive for non-typhoidal Salmonella, and nine, from eight different households, culture-positive for Shigella; transmission of these pathogens within households did not appear to be common since no household had more than one family member with the same serotype or species of either pathogen.

Adolescent↗
PubMedDate not supplied

Clinical and field trials with attenuated Salmonella typhi as live oral vaccines and as "carrier" vaccines.

In recent years there has been a resurgence of research to develop new and improved attenuated strains of Salmonella typhi to function as live oral vaccines against typhoid fever and to serve as "carrier" vaccines to express foreign antigens of other pathogens and deliver them to the immune system. Strain Ty21a has served as a prototype in clinical and field trials to identify the optimal formulations and dosage schedules for live vaccines and to quantitate the duration of protection that can be achieved. Clinical trials with three new attenuated S. typhi candidate vaccines, a Vi+ variant of Ty21a, an aroC,aroD double mutant recombinant strain and a cya,crp double mutant, are underway or will be initiated shortly.

Administration, Oral↗
PubMedDate not supplied

Worldwide distribution of human papillomavirus types in cytologically normal women in the International Agency for Research on Cancer HPV prevalence surveys: a pooled analysis.

BACKGROUND: The proportion of women infected with human papillomavirus (HPV) varies greatly across populations, as might the distribution of HPV types. We aimed to compare HPV-type distribution in representative samples of women from different world regions. METHODS: Women were randomly selected from the general population of 13 areas from 11 countries (Nigeria, India, Vietnam, Thailand, Korea, Colombia, Argentina, Chile, the Netherlands, Italy, and Spain). A standardised protocol was used for cervical specimen collection. All HPV testing was by GP5+/6+ PCR-based EIA. The proportion of HPV-positive women infected with different HPV types was compared by study area and between pooled regions with age-adjusted odds ratios (ORs) with corresponding 95% floating CIs. FINDINGS: 15 613 women aged 15-74 years without cytological abnormalities were included in a pooled analysis. Age-standardised HPV prevalence varied nearly 20 times between populations, from 1.4% (95% CI 0.5-2.2) in Spain to 25.6% (22.4-28.8) in Nigeria. Although both overall HPV prevalence and HPV16 prevalence were highest in sub-Saharan Africa, HPV-positive women in Europe were significantly more likely to be infected with HPV16 than were those in sub-Saharan Africa (OR 2.64, p=0.0002), and were significantly less likely to be infected with high-risk HPV types other than HPV16 (OR 0.57, p=0.004) and/or low-risk HPV types (OR 0.44. p=0.0002). Women from South America had HPV-type distribution in between those from sub-Saharan Africa and Europe. Heterogeneity between areas of Asia was significant. INTERPRETATION: Heterogeneity in HPV type distribution among women from different populations should be taken into account when developing screening tests for the virus and predicting the effect of vaccines on the incidence of infection.

Adolescent↗
PubMedDate not supplied

Progress in vaccines against typhoid fever.

The widely available heat-phenol-inactivated whole cell typhoid vaccine, which provides approximately 65% protection, has limited usefulness because of the adverse reactions it evokes. In contrast, several new typhoid vaccines promise protection without reactogenicity. Attenuated oral vaccine Ty21a has been evaluated in three field trials of efficacy in Santiago, Chile, involving 530,000 schoolchildren. Three doses of Ty21a in an enteric-coated formulation given within one week provided 69% efficacy for at least four years. Fewer doses conferred less protection, while adding a fourth dose significantly enhanced protection; increasing the interval between doses did not improve protection. Large-scale vaccination with Ty21a appeared to cause a herd-immunity effect. Ty21a has reached the stage of being a practical tool for public health. With respect to other vaccines, the safety and immunogenicity of an auxotrophic (Aro-,Pur-) Salmonella typhi mutant (strain 541Ty) has recently been evaluated. Lastly, parenteral purified Vi polysaccharide of S. typhi was safe and immunogenic and provided 64%-72% protection (for at least 17-21 months) in controlled field trials in Nepal and South Africa.

Chile↗