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Biomedical subjects

S Riedemann

Publications and source records attributed to S Riedemann.

At least 19 recordsLinked to original sources
PubMed2004

Immunogenicity and safety of a virosomal hepatitis A vaccine (Epaxal) in healthy toddlers and children in Chile.

UNLABELLED: In this open study, 20 toddlers and 80 schoolchildren received an intramuscular dose of Epaxal and a booster dose 12 mo later to assess the efficacy and safety of this aluminium-free, virosomal hepatitis A vaccine. Four weeks after primary vaccination, 94% of toddlers and 99% of schoolchildren had seroconverted, and all toddlers and 94% of schoolchildren remained seroprotected for 12 mo. CONCLUSION: After vaccination with Epaxal and booster, all subjects were seroprotected. Epaxal was very well tolerated by both age groups.

Adolescent↗
PubMed2002

Immunogenicity and reactogenicity of a combined hepatitis A and B vaccine in healthy Chilean subjects.

OBJECTIVES: A combination vaccine against hepatitis A and B provides the opportunity for simultaneous protection against both diseases with a single vaccine. This clinical study investigated the reactogenicity and immunogenicity of a combined hepatitis A and B vaccine (Twinrix, GlaxoSmithKline Biologicals, Rixensart, Belgium) in healthy Chilean adults between 18 and 40 years of age. METHODS: In total, 345 healthy, seronegative health care workers were enrolled and randomized to three groups who received one of three lots of Twinrix on a 0-, 1- and 6-month schedules. Blood samples were screened 1 month after each dose for anti-HAV and anti-HBs antibodies. Reactogenicity after each dose was assessed using diary cards. RESULTS: The nature and incidence of symptoms were similar to those reported for other Twinrix studies. Very few symptoms were scored as severe. Upon completion of the vaccination, all subjects had anti-HAV antibodies with titers $6000 mIU/mL, and all but one were protected against hepatitis B, with titers $4000 mIU/mL. CONCLUSIONS: We have demonstrated the high immunogenicity and tolerance of the combined hepatitis A and B vaccine. Combined vaccination has the advantage of offering dual protection with a reduction in the number of injections needed, lower associated costs, and a positive impact on compliance.

Adolescent↗
PubMed2001

[Acute hepatitis caused by virus A, E and non A-E in Chilean adults].

BACKGROUND: Sanitary and socioeconomic changes and the identification of new causative virus, have changed the epidemiology of hepatitis in Chile. AIM: To study the natural history of acute hepatitis caused by virus A, E and non A-E in Chilean adults. PATIENTS AND METHODS: A special study protocol was followed for patients with a clinical picture of acute hepatitis. Anti HAV IgM, anti HBc IgM, anti HEV IgG and IgM and Anti HCV antibodies were determined by ELISA. RESULTS: Fifty nine patients (30 male), aged 15 to 58 years old were studied. Eighty nine percent had jaundice and 50 to 70% had malaise and abdominal pain. Virus A was positive in 80%, virus E in 7%. In 14% of patients, all viral markers were negative. The evolution was typical in 78%, biphasic in 14% and cholestatic in 5%. One patient had a prolonged and one a fulminant course. Mean ALT was 1148 U/l and mean total bilirubin was 5.5 mg/dl. Seventy three percent of cases occurred during early winter and spring and 27% during summer and early autumn. CONCLUSIONS: The main etiology of acute viral hepatitis in Chile is virus A and most cases occur during the rainy season. Clinical features of hepatitis non A-E are similar to enteral transmission forms.

Acute Disease↗
PubMed2000

Use of linear and multiple antigenic peptides in the immunodiagnosis of acute hepatitis A virus infection.

The reactivities of two panels of anti-HAV human sera from geographically distinct areas (Chile and Spain) to synthetic peptides from the VP1, VP2 and VP3 hepatitis A virus capsid proteins were examined by an enzyme-linked immunosorbent assay (ELISA) procedure. Two and four branched multiple antigenic peptides (MAPs) and palmitoylated peptides were compared with free synthetic sequences for the detection of IgM anti-HAV antibodies in the two panels of human sera. Our results showed that acute hepatitis A patient sera recognized preferentially homogeneous two branched MAPs and palmitic acid conjugated peptides. The palmitoyl-derived VP3(110-121) peptide and the corresponding dimeric MAP were the most sensitive and appropriate for serological studies of HAV-infected patients by ELISA, sensitivity and specificity being higher than 90% and 95%, respectively. These peptide-based tests open up new avenues in the development of peptide-based immunosorbent assays for the detection of acute HAV disease.

Acute Disease↗
PubMed1999

[Current status of immunity to hepatitis A virus in various adult groups].

BACKGROUND: As sanitary and economic conditions improve, the prevalence of antibodies to hepatitis A is now significantly lower. AIM: To evaluate the prevalence of hepatitis A virus antibodies in healthy Chilean adults. MATERIAL AND METHODS: Antibodies to hepatitis A virus were measured, using a commercial ELISA assay, in 215 voluntary blood donors (163 male, aged 19 to 30 years old) and 295 medical students and health personnel (156 male, aged 19 to 39 years old), residing in Valdivia, Chile. RESULTS: Antibodies against hepatitis A virus were found in 68.2% of the total sample (351/510). Ninety percent of flood donors and 54% of health personnel and students were positive (p < 0.01). Age specific prevalence in blood donors 19 to 22, 23 to 29 and 27 to 30 years old was 81.0%, 95.2% and 95.6% respectively. Among the same age groups in medical students, the prevalence was 47.9%, 53.2% and 61.9% respectively (p < 0.01). CONCLUSIONS: This study indicates a reduction in the prevalence of hepatitis A virus antibodies among adults in Valdivia (Chile). Differences detected between individuals are probably related to different socioeconomic levels. Medical students have an increased risk for hepatitis A infections than the general population.

Adult↗
PubMed1998

[Prevalence of antibodies against hepatitis A in school children].

BACKGROUND: As sanitary conditions of a population improve, hepatitis A virus infection occurs at higher ages, thus decreasing the prevalence of antibodies against the virus. In the eighties, the prevalence of antibodies among children was 97% and depended on the socioeconomic level. AIM: To assess the prevalence of antibodies against hepatitis A virus in school age children living in Valdivia. SUBJECTS AND METHODS: Two thousand three hundred thirty three school age children were studied. Total antibodies against hepatitis A virus were detected using an ELISA kit from Abbott. Children were stratified in age groups and school were classified as private, subsidized, municipal or foster homes. RESULTS: Antibodies were positive in 65% of children (59% in children aged 6 to 8 years old, 66% in children aged 9 to 11 years and 69% in children aged 12 to 15 years. In private schools, the prevalence was 26%, in subsidized schools the figure was 54%, in municipal schools 73% and in foster homes 91%. CONCLUSIONS: The general prevalence of antibodies against hepatitis A virus is higher in low socioeconomic level children. There is a global decrease in the prevalence of these antibodies in the last years.

Adolescent↗
PubMed1997

[Prevalence of hepatitis E virus antibodies in blood donors and other population groups in southern Chile].

Little is known about hepatitis E virus (HEV) prevalence in South American countries. Anti-HEV was studied in 1,773 subjects from 1,360 blood donors of 3 cities in Chile, 72 in health care workers, 241 inmates in state jails, and in 100 Araucanian indians. Anti-HEV was detected in 109 out of 1,360 (8.0%) total donors (6.3%, 6.1%, and 18.8% from the cities of Valdivia, Osorno and Puerto Montt respectively); 9 out of 72 (12.5%) health care workers; 18 out of 241 (7.5%) inmates, and 17 out of 100 (17%) Araucanian indians. Prevalence of anti-HEV was not related to age and sex. Hepatitis E is an endemic infection in some population groups of Southern Chile, associated to environmental pollution, crowding and low socioeconomic level.

Adolescent↗
PubMed1995

[Hepatitis C virus: results of detection in several high risk groups in the X region of Chile].

The aim of this study was to determine the prevalence of hepatitis C virus antibodies in high risk patients coming from Valdivia, Osorno and Puerto Montt. Fifty-six patients in hemodialysis, 51 renal graft recipients, 42 cirrhotics and 14 patients with acute non A non B hepatitis were studied. Antibodies were detected with a second generation ELISA technique and positive cases were confirmed with RIBA. All hemodialysis patients and renal graft recipients were negative for hepatitis C virus antibodies. In one non alcoholic patient with cirrhosis, a positive ELISA was confirmed with RIBA. Six patients with acute hepatitis had positive ELISA tests but none was confirmed with RIBA. It is concluded that the prevalence of hepatitis C virus antibodies in this region of Chile is very low.

Acute Disease↗
PubMed1994

[Acute sporadic hepatitis caused by the E virus in Chile. Clinical case].

A 53 year old female nurse presenting with malaise, jaundice and pruritus is reported. Physical examination only disclosed jaundice and laboratory values showed an ALT of 445 U/l, ASAT of 179 U/l, alkaline phosphatases of 455 U/l and a total bilirubin of 7.7 mg/dl. Serological markers for hepatitis virus E were positive and negative for hepatitis virus A, B and C, cytomegalovirus and Epstein Barr virus. The patient recovered fully in 10 weeks and is asymptomatic after 5 years of follow up. Health care workers probably have a higher risk for hepatitis E than the general population and this is the first acute sporadic case described in Chile.

Acute Disease↗
PubMed1992

Accumulation and persistence of hepatitis A virus in mussels.

Accumulation and persistence of hepatitis A virus (HAV) in the mussel Mytilus chilensis was evaluated. Under optimal filtration activity of mussels (temperature 12 degrees C, salinity 3%, feeding twice a day with Dunaliella marina), HAV was concentrated 100-fold from the surrounding water. Similar concentrations of HAV were reached in the filtration apparatus and in the digestive system (hepatopancreas). HAV persisted for about 7 days in mussels. Elimination of HAV from mussels was slower than elimination of poliovirus. Without feeding of mussels (causing low filtration activity), there was no measurable uptake of HAV into mussels, and depuration of HAV from mussels was slower. The ability of mussels to concentrate HAV was used successfully to monitor fecally contaminated river water for the presence of HAV.

Animals↗
PubMed1992

Placebo-controlled efficacy study of hepatitis A vaccine in Valdivia, Chile.

A placebo-controlled, double-blind study on the efficacy of a hepatitis A vaccine (SmithKline Beecham Biologicals) was started in a region of Chile in September 1990, using hepatitis B vaccine as control. A total of 260 healthy children, 6-15 years of age, negative for antibody to hepatitis A virus (anti-HAV), antibody to HAV immunoglobulin M (IgM), hepatitis B surface antigen, and antibody to hepatitis B surface and core antigens by ELISA tests within 7 days before vaccination, were randomly assigned to two study groups: 128 children received the vaccine with a yellow label (group 1), and 132 children the vaccine with an orange label (group 2) at months 0, 1 and 6. Blood for serology and transaminase determination was drawn at months 1, 2, 6, 7 and 12. Both vaccines were tolerated equally well and no serious side effects were seen. In group 1 (presumed hepatitis A vaccine group), anti-HAV was detected (20% inhibition was used as the cut-off level) in 122 of 128 children (95.5%) tested at month 1, in 126 of 127 (99.2%) at month 2, in 126 of 127 (99.2%) at month 6 and in 126 of 126 (100%) at month 7. One anti-HAV seroconversion seen at month 1 was associated with presence of anti-HAV IgM and therefore probably represents HAV infection. Geometric mean anti-HAV concentration of the other children was 128, 342, 214 and 2301 mIU/ml at months 1, 2, 6 and 7, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Serological survey of human leptospirosis in a high risk population in Chile].

Two hundred and sixty five subjects with high risk works for leptospirosis were submitted to microscopic agglutination test for leptospira. 122 worked at animal farms, 71 in rice growing fields and 72 in slaughter houses. 30 control subjects were also tested. A total of 66 samples (22%) were positive, most of them with low titers. Percentage of positive reactions were higher for persons working in rice fields, followed by those working in slaughter houses and animal farms. The 21-40 year age group was most affected in all working sites. Serovars found most commonly were ichterohemorrhagic in rice field workers, hardjo and ballum in slaughter houses and pomona and hardjo in animal farms.

Adolescent↗
PubMed1990

[Post-transfusion hepatitis iin Chile: the reference parameters].

Most cases of post-transfusion hepatitis correspond to infection by non-A non-B virus. Indirect test (ALT elevation, anti-HBc titers) have been used to detect the presence of this virus. We screened 692 blood donors and health personnel, measuring anti-HBc (n = 572), HBs antigen (340), and ALT serum levels (190). Positive results were obtained for anti-HBc in 1.7% and HBs in 0%. ALT levels were 25 +/- 12 u/l in males and 18 +/- 14 in females (p < 0.01). ALT levels above 45 u/l were found in 6% of subjects. ALT levels were not related to anti-HBc positiveness nor to alcohol intake. The possible risk of posttransfusion hepatitis related to increased ALT levels remains to be clarified by specific markers.

Adolescent↗
PubMed1989

Coronavirus as agent of neonatal calf diarrhea in southern Chile.

Neonatal calf diarrhea is one of the most serious problems of cattle industry all over the world. Although the aetiology is complex, it is possible to assess that viruses play a very important role. During an investigation to study the importance of Rotavirus in enteric problems in calves and piglets, it was possible to demonstrate the presence, for the first time in southern Chile, of Coronavirus-like particles in a faecal sample of a 15 day old calf by means of electron microscopy. The importance of this diagnosis and some clinical characteristics of the disease are briefly discussed. Finally, the need for more research on this complex subject is recognized.

Animals↗