Inmunogenicidad y reactogenicidad de una vacuna de difteria, tétanos, pertussis acelular de contenido antigénico reducido, dTpa, en niños de 10 a 11 años de edad y en adultos / Immunogenicity and reactogenicity of a reduced antigen content diphteria, tetanus, acellular pertussis vaccine, dTpa, in 10 to 11 years old children and in adults

Background: New vaccination strategies are needed to control the increasing problem of pertussis in teenagers and adults. Aim: To determine the immunogenicity and reactogenicity of a diphtheria-tetanus-acellular pertussis (dTpa) vaccine with reduced antigen content. Material and Methods: A single dose of the dTpa vaccine was administered to 60 children 10 to 11 years old and 60 healthy adults. At the moment of vaccination and one month later, antibody levels were measured against 3 B pertussis antigens: anti-pertussis toxin (PT), anti-pertactin (PRN) and anti-filamentous hemagglutinin (FHA), as well as anti-tetanus and anti-diphtheria antibodies. Local and general symptoms were registered during 14 days following vaccine administration. Results: Antibody response for PT, FHA and PRN was 98.3 percent, 100 percent and 100 percent in adults and 98.2 percent, 100 percent and 98.2 percent in children. Seropositivity for all pertussis antigens was 100 percent in adults and in children one month after vaccination. Geometric mean titers (GMT) significantly increased in adults and children. The seroprotection level achieved for tetanus and diphtheria antibodies one month after vaccination was 96.7 percent for adults and 100 percent for children, respectively. No serious adverse events were reported during the study. Among local symptoms pain was the most frequent (88-90 percent), but it was mostly mild or moderate. Solicited general symptoms observed for children and adults, respectively, included headache (37 percent and 53 percent), fatigue (18 percent and 35 percent) gastrointestinal symptoms (18 percent and 25 percent) and fever (8 percent and 3 percent). Only one vaccinee had fever above 39­C. Conclusions: the dTpa vaccine showed an adequate safety profile and induced an intense immunological response to all antigens in adults and children aged 10-11

Prevalencia de anticuerpos anti hantavirus en 10 comunas de la Novena Región de Chile donde se han diagnosticado casos de infección clínica por hantavirus / Seroprevalence of antibodies anti-hantavirus in 10 communities of the IX region of Chile where hantavirus cardiopulmonary syndrome cases were reported

Background: Thirty six cases of clinical Hantavirus Cardiopulmonary Syndrome occurred in the IX Region of Chile. Most of these patients were young males, farm or timber workers, who lived near the Andes Mountain chain. Aim: To conduct an epidemiological and serosurvey study to determine the seroprevalence of IgG antibodies against Hantavirus in the general adult population living in rural and urban areas of 10 endemic communities of the IX region of Chile. Material and methods: A total of 400 subjects were included, 40 of each community, 20 rural residents and 20 urban residents, 20 males and 20 females. Results: Seroprevalence was 7.5 percent in Melipeuco, 5.0 percent in Lonquimay, 2.5 percent in Curacautin, 2.5 percent in Puc-n and 0.0 percent in the remaining communities. Seroprevalence was higher in rural population (2.5 percent) than in the urban areas (1 percent). All seropositive subjects worked in farms or forests and observed rodents near their homes or working places. Females were affected the same as males and no differences were observed between Chilean natives and Hispanics. Conclusions: Prevalence of Hantavirus antibodies correlated with the geographic zone (Andes Mountain chain), overgrowth of wild rodents and exposure to rodent-infested environments

Diagnóstico de diarrea por clostridium difficile: en busca de un enfoque clínico más eficiente / Clinical diagnosis of clostridium difficile diarrhea: searching a more efficient clinical view

Background: The clinical parameters for the suspicion of Clostridium difficile infections, namely the use of antimicrobials and diarrhea, have a low predictive value for the diagnosis. Aim: To search other clinical variables and determine a clinical prediction model for (Clostridium difficile diarrhea. Patients and methods: All patients to whom a Clostridium difficile study was requested, were prospectively studied during 5 months. Clinical variables of these patients were registered. The diagnosis of Clostridium difficile was done using the cytotoxicity test in fibroblast cultures. Results: Ninety two patients were analyzed and in 26, the diagnosis of Clostridium difficile was confirmed. A logistic regression model disclosed an age over 60 years old, the presence of mucus in the stools and a temperature over 37.8 ­C in the previous 24 h, as significant predictors of the infection. The correlation of the model, between the predicted probability and the observed condition, was 81.5 per cent. Conclusions: The presence of the clinical variables identified in this study are associated with a high probability of an infection by Clostridium difficile in patients with diarrhea and the recent use of antimicrobials

Prevalencia de anticuerpos IgG de virus de hepatitis A anti IgG VHA en un estrato socioeconómico ABC1 / Prevalence of IgG antibodies of hepatitis A virus in a socioeconomic level ABC1

Los estudios de la hepatitis A en Chile han demostrado un cambio epidemiológico de una alta endemia de hepatitis A a una endemia mixta. Nuestro propósito es investigar la prevalencia de anti IgG VHA en una población infantil, de adolescente y adultos jóvenes de un estrato socioeconómico medio-alto (ABC-1). Se recolectaron 200 muestras de individuos menores de 20 años y de 101 adultos jóvenes con un rango de edad de 20 a 32 años, todos controlados en Clínica las Condes. Los niños y adultos jóvenes investigado revelaron que entre el 82 y el 94 por ciento de ellos están desprovistos de anti IgG VHA, y por lo tanto susceptibles de ser infectados por el VHA

Complicaciones en niños con varicela en cuatro hospitales de Santiago-Chile: espectro clínico y estimación de costos directos / Varicella complications requiring hospitalization in four hospitals in Santiago, Chile: clinical spectrum and estimation of direct costs

Background: The knowledge of varicella complications and their associated cost may help for a better evaluation of varicella immunization benefits. Aim: To determine frequency, type, outcome and affected population of varicella complications in children requiring hospitalization, and to estimate their direct costs. Material and methods: Retrospective analysis of medical records of children admitted to four hospitals in Santiago, Chile, due to varicella complications between January 1997 and February 1999. Calculation of direct costs of hospitalizations in a sample of 30 patients. Results: One hundred fifty four patients were identified, 74 percent were younger than 5 years old, only one was immunocompromised. Complications identified were skin and soft tissue infections in 63 percent, invasive infections in 25,3 percent, neurological in 7.1 percent and miscellaneous in 4,5 percent. Staphylococcus aureus and Group A ß-haemolytic Streptococcus (GABS) were predominantly isolated. S. aureus was the main agent identified in superficial infections and GABS in invasive infections (sterile sites). Two patients died due to invasive infections (streptococcal toxic shock and S. aureus septicaemia) and 11 required surgical procedures. The average cost per hospitalization was US$ 600 in public hospitals and US$ 1,800 in the private hospital. Conclusions: Varicella complications requiring hospitalization are due mainly to bacterial infections and they affect immunocompetent toddlers. These complications can be severe and even fatal

Antivirugrama: ¿ciencia ficción o realidad? / Antivirugram: science fiction or reality?

El panorama creciente de infecciones virales severas, que amenazan la vida de los pacientes, la disponibilidad de técnicas de diagnósticos virológico rápido y los conocimientos patogénicos más acabados con biología molecular, han estimulado el desarrollo explosivo de fármacos antivirales. Como consecuencia nace la necesidad de incorporar a las decisiones clínicas la evaluación in vitro de algunos de estos medicamentos y la aparición de resistencia durante tratamientos prolongados, como ha sido el dramático caso de la infección por VIH/SIDA. Se revisan los antivirales licenciados para el uso médico y el grado de aplicación clínica de los estudios de susceptibilidad in vitro alcanzado en la actualidad

Epidemiología molecular del virus de inmunodeficiencia humana tipo 1 en Santiago, Chile / Molecular epidemiology of the human immunodeficiency virus tipe 1 in Santiago, Chile

Background: most of the studies of HIV-1 infection in South America have been limited to Brazil and little is known about the viral variants that are causing disease else where in the continent. Aim: to determine the characteristics of the viral variants present in Chile as well as patterns of viral transmission. Material and methods: viral sequences were obtained from 21 HIV-1 infected people from Santiago, Chile who were infected either via sexual contact or intravenous drug use. Cloned sequences obtained from both the third variable and conserved regions of the envelope as well as the viral protease were evaluated. Results: we found only clade B subtype viruses in Santiago. An evaluation of the envelope gene revealed no evidence that the sequences were monophyletic by risk group. A number of the protease sequences were predicted to encode amino acid substitutions commonly found during selection for protease inhibitor resistance. Conclusions: the HIV-1 strains studied in Chile, belong to the subtype B. There is no molecular evidence of separate introductions of the virus into the different risk groups. A number of substitutions in the protease gene that may confer resistance to protease inhibitors were found in patients with no previous exposure to this class of drugs

Detección de virus Norwalk y México, dos calicivirus humanos en deposiciones de niños chilenos / Detection of Norwalk and Mexico virus, 2 human calciviruses in feces of chilean children

Background: Human calciviruses (HuCVs) cause diarrhea outbreaks associated with consumption of contaminated food and water. Seroepidemiological studies in developing countries, suggest that HuCVs can cause acute gastroenteritis in children. Aim: To study the presence of Norwalk (NV) and Mexico (MX) virus, two HuCVs, in stools of Chilean children from different settings. Subjects and methods: ELISA tests for NV and MX were performed in 677 stool samples for children aged 0 to 132 years old, with acute diarrhea occurring in day care centers or consulting in outpatient clinics or emergency rooms. We also studied eight samples from children involved in a diarrhea outbreak that occurred in a rural community in 1992. A subset of samples was tested with polymerase chain reactions using different primers. Results: Only one sample from a child with acute diarrhea occurring in a day care center was positive for HuCV by polymerase chain reaction. Three samples from the outbreak were positive by the latter method and by ELISA. The HuCV obtained from the day care center was genetically different from other known HuCV. Conclusions: Despite the high seroprevalence, NV and MX viruses were detected in a very low proportion of Chilean children stools

Etiología del síndrome coqueluchoídeo y rendimiento de las técnicas para el diagnóstico de bordetella pertussis en pacientes hospitalizados / Etiology of pertussis syndrome and yield of diagnostic methods for bordetella pertussis in hospitalized patients

El síndrome coqueluchoídeo es frecuente en el lactante menor siendo causa importante de morbilidad. Con el objeto de estudiar la importancia de bordetella pertussis como causa de este síndrome, las características clínicas de coqueluche y la sensibilidad y especificidad de las distintas técnicas para el diagnóstico de B. pertussis, se realizó un estudio con 66 niños hospitalizados con el diagnóstico de síndrome coqueluchoídeo. B. pertussis fue el principal agente causal (56 por ciento) seguido de varios virus respiratorios (14 por ciento) como adenovirus, virus respiratorio sincicial y parainfluenza. Las características clínicas que permitieron diferenciar a la coqueluche de las otras causas del síndrome coqueluchoídeo fueron la asociación de tos paroxística, emetizante y estridor inspiratorio. La linfocitosis absoluta sobre 10.000/mm elevado a 3, especialmente si se asoció a tos característica, tuvo buena especificidad con fines diagnósticos. La sensibilidad del cultivo, IFD y RPC para el diagnóstico de coqueluche fue de 32, 36 y 93 por ciento respectivamente. La especificidad de la IFD y la RPC fue de 87 y 98 por ciento respectivamente. El uso previo de antibióticos o la obtención de la muestra en estapas avanzadas de la enfermedad no modificó la sensibilidad de la técnica de RPC, no sucedió así con el cultivo e IFD. Por todo esto la RPC sería el método de elección para el diagnóstico de coqueluche

Resistencia del virus de inmunodeficiencia humano (VIH) a zidovudina (AZT): análisis genotípico en cepas aisladas de pacientes chilenos / Resistance of human immunodeficiency virus (VIH) to zidovudine: genotypic analysis in strains isolated from chilean patients

Background: Resistance of HIV to AZT is the result of mutations in the pol gene that codifies the enzyme reverse transcriptase. Aim: To asses the resistance to antiretroviral drugs in Chhilean patients infected with HIV. Material and methods: The presence of mutations was searched in 22 patients infected with HIV. The emergence or persistence of these mutations was studiend in sequential samples of 19 patients. The presence of the mutation that confers resistance to didanosine (ddi) was studied in those subjects exposed to the drug. Polymerase chain reaction techniques were used to analyze mutations in codons 41, 70 and 215 of the pol gene (resistance to AZT) and the mutation in codon 71 (resistance to DDI). Results: On admission, none of the patients without previous exposure to AZT had drug resistance mutations. Seven of 12 patients (58.3 percent) that had received AZT had mutations in codon 215. In two, they were associated to a mutation in codon 41 and in two, to a mutation in codon 70. After a mean follow up of 14 months, 13 of 15 patients (86 percent) that received AZT had viral strains genotypically resistant to the drug. In nine of these, the resistance was associated with disease progression. None of the 10 patients that received DDI had the mutation in codon 74 that confers resistance to the drug. However, in one of these patients, that never receided AZT, virus with a mutation in codon 215 was detected. Conclusions: A high percentage of patients that have received monotheraphy with AZT have genotypic resistance to the drug. This resistance is associated with clinical and immunological derangement in 70 percent of these subjects

Seroprevalencia de citomegalovirus y toxoplasma gondii en población sana menor de 30 años, en Santiago de Chile / Seroprevalence of cytomegalovirus y toxoplasma gondii in health population under 30 years old at Santiago, Chile

Subjects and methods: The prevalence of IgG antibodies against Cytomegalovirus and Toxoplasma gondii were studied in 560 subjetcs under 30 years old, using and ELISA technique. Age, socioeconomic level, breast feeding, assistance to nurseries and number of family members were considered as risk factors for these infections. Results: Infection by Cytomegalovirus and Toxoplasma gondii were studied in 560 subjetcs under 30 years old, using an ELISA technique. Age, socioeconomic level, breast feeding, assistance to nurseries and number of family members were considered as risk factors for these infections. Results: Infection by Cytomegalovirus had a global prevalence of 60 percent. It showed an epidemiological pattern of late adquisition in high socioeconomic levels and a pattern of early infection in medium and low socioeconomic levels. Eighty to 90 percent of sera were positive for the infection in adult subjetcs of the three socioeconomic levels. There was a positive correlation between the duration of breast feeding and the frequency of Cytomegalovirus infection. Infection by Toxoplasma gondii had a global prevalence of 24.6 percent. The rates of susceptible individuals were 80 and 50 percent in high and medium-low socioeconomic levels respectively. Conclusions: The knowledge about the frequency of these infections in high risk populations such as women during their reproductive years and immunodepressed individuals, will allow the implementation of preventive measures

Infección por bartonella henselae en pacientes inmunocompetentes: enfermedad por arañazo de gato / Infection by bartonella henselae in immunocompetent patients: cat scratch disease

Ten children (7 males), aged between 6 and 13 years old, with histologically or serologically confirmed cat scratch disease are reported. Lympadenopathy location was pre auricular in four cases, axillary in two, inguinal in 2 and epitrochlear in 2. Three children had fever over 39ºC and 2 had a Parinaud syndrome. Nine children had a history of cat scratch and one of a cat byte. Six had an arythrocyte sedimentation rate over 40. Lymph node ultrasound examination was a useful diagnostic tool. Two patients had splenic granulomas. Lymph node biopsies were obtained in 4 cases, showing a suppurative granulomatous lymphadenitis in all and positive Warthin-Starry stain in 2. Serology, done in patients without histological confirmation was positive with titles ranging from 1:64 to 1:8192. All patients had a satisfactory outcome with regression of lymphadenopathy. Infection by bartonella henselae occur in the Chilean population and must be considered in the differential diagnosis of regional lymph node enlargement

Efecto de dos formas de suplementación de vitamina D en el crecimiento y metabolismo óseo del lactante / Effects of 2 ways of vitamin D supplementation on infant growth and bone metabolism

Se evaluó el efecto sobre el metabolismo óseo y crecimiento del lactante menor de suplementos de vitamina D de 600.000 UI en el primero y sexto mes (norma ministerial) ante una dosis diaria de 400 UI hasta el sexto mes, en dos grupos de lactantes normales. En controles mensuales se midieron peso, talla, circunferencia craneana, presión arterial, calcemia, fosfemia, fosfatasas alcalinas, hormona paratiroidea y 1.25 (OH)2 vit D. Se encontraron diferencias estadísticamente significativas en favor de los niños que recibían 400 UI diariamente, a contar del tercer mes en la talla, del sexto mes en el peso y del octavo mes en la circunsferencia craneana. La presión arterial fue más alta en los pacientes que recibieron megadosis semestrales de la vitamina, especialmente 30, 60, 90 y 120 días, después de la primera de ellas. La concentración plasmática media de 1,25 (OH)2 vit D fue más alta en los casos tratados con megadosis (110 y 96 pg/ml en el primero y el sexto mes respectivamente), que en los que recibía dosis diarias (55 pg/ml en el primero y sexto mes). No se encontraron diferencias en las restantes variables sanguíneas analizadas. La administración de 400 UI diarias es más fisiológica, promueve mayor crecimiento, evita riesgos de intoxicación a corto plazo y potencial a largo plazo por la hipertensión inducida a esta edad. La norma ministerial debiera ser revisada

Neuroborreliosis en Chile: caso pediátrico de probable adquisición por mascotas importadas / Neuroborreliosis in Chile: pediatric case probably due to imported pets

Lyme disease, caused by spirochete Borrelia burgdorferi, has several clinical manifestations and is transmitted to man by tick bites. In Chile and Latin America, several cases have been reported, but none with inmunoblot confirmation or isolation of the infecting organism. We report a 9 year old boy consulting with bilateral facila palsy, polyradiculoneuritis with tetraparesis and meningeal irritation. Cerebrospinal fluis analysis showed increased protein concentration without pleocytosis and negative viral or bacterial cultures. IgM antibodies against Borrelia burgdorferi, were positive by ELISA and were confirmed by immunoblot at the Reference Laboratory of the University of Connecticut. The child had a recent contact with hamsters brought from Germany. The substantiation of Lyme disease existence in Chile should prompt the search and isolation of the causal agent

Historia natural de la infección por virus de inmunodeficiencia humano en una cohorte de pacientes chilenos / Natural history of human immunodeficiency virus infection in a cohort of chilean patients

We characterized clinical manifestations and the risk to develop AIDS in a cohort of 32 patients infected with human immunodeficiency virus without AIDS. A multivariate analysis was performed to determine association between the progression of infection and control variables (socioeconomic level, age, sex and sexual preferences) and causal variables (psychosocial changes, significant clinical events, stress scoring and sexual activity). The cumulative AIDS incidence, defined as CD4 lymphocyte count below 200 cells/cmü was 50 percent at 6.5 years and 82 percent at 8 years. Using clinical criteria to define AIDS, 50 percent developed tha disease at 8 years of follow up. Among studied factors, only age (faster progression at higher age) and time of evolution were associated with progression. In stages before AIDS, the most frequent diseases were acute diarrhea, sexual transmission diseases, oral candidiasis, sinusitis and varicella zoster infections. The reduction of CD4 lymphocytes below 200 cells/cmü always preceded the symptoms of the disease. Two patients have remained more than eight years without clinical or immunological deterioration

Estudio microscópico de fenómenos biológicos asociados a infecciones por cateteres venosos centrales / Microscopic study of biological phenomenae associated to infections related to central venous catheters

Las complicaciones infecciosas son la principal limitación del uso de cateteres venosos centrales. Se presenta aquí un estudio descriptivo, mediante microscopía de barrido, de la formación de una matriz biológica en el interior y exterior del catéter como condicionante de la adherencia y crecimiento de bacterias, comprobándose que es un fenómeno que se presenta con alta frecuencia al permanecer estos dispositivos de poliuretano en el medio intravascular y subcutáneo. En este estudio preliminar se observa una adecuada correlación ente la observación de colonización del catéter por microscopía y el resultado de cultivo semicuantitativo de la punta de éste. La colonización del catéter, si bien representa uno de los eventos iniciales asociados a infección, no siempre se acompaña de signos clínicos o de bacteremia