Pablo Vial C

Prevalencia de anticuerpos anti-hantavirus en 10 comunas de la Novena Región de Chile donde se han diagnosticado casos de infección clínica por hantavirus

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% in Melipeuco, 5.0% in Lonquimay, 2.5% in Curacautin, 2.5% in Pucon and 0.0% in the remaining communities. Seroprevalence was higher in rural population (2.5%) than in the urban areas (1%). 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 (Rev Med Chile 2002; 130: 251-3)

Complicaciones en niños con varicela en cuatro hospitales de Santiago- Chile: Espectro clínico y estimación de costos directos

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% were younger than 5 years old, only one was immunocompromised. Complications identified were skin and soft tissue infections in 63%, invasive infections in 25,3%, neurological in 7.1% and miscellaneous in 4,5%. Staphylococcus aureus and Group A s-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

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

600 in public hospitals and US

Etiología de la neumonía en pacientes chilenos infectados por el virus de la inmunodeficiencia humana

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. (Rev Med, Chile 2001; 129, 397-404)

Diagnóstico de diarrea por Clostridium difficile: en busca de un enfoque clínico más eficiente

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%, 100% and 100% in adults and 98.2%, 100% and 98.2% in children. Seropositivity for all pertussis antigens was 100% 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% for adults and 100% for children, respectively. No serious adverse events were reported during the study. Among local symptoms pain was the most frequent (88-90%), but it was mostly mild or moderate. Solicited general symptoms observed for children and adults, respectively, included headache (37% and 53%), fatigue (18% and 35%) gastrointestinal symptoms (18% and 25%) and fever (8% and 3%). Only one vaccinee had fever above 39°C. 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 (Rev Med Chile 2002; 130: 502-10)

Epidemiología molecular del virus de inmunodeficiencia humana tipo 1 en Santiago, Chile

Objetivos: Establecer la etiologia de la neumonia y comparar el rendimiento de diferentes tecnicas para el diagnostico de las infecciones por Pneumocystis jiroveci y Mycobacterium tuberculosis en pacientes con infeccion por virus de inmunodeficiencia humana (VIH). Material y Metodos: De cada paciente se obtuvo esputo inducido y se efectuo LBA. A las muestras obtenidas se les realizo tinciones de Gram, Ziehl-Neelsen, plata e inmunofluores-cencia (IF) para P. jiroveci y M. tuberculosis; reaccion de polimerasa en cadena (RPC) para ambos microorganismos; cultivos aerobicos, fungicos, para micobacterias, virus respiratorios y citomegalovirus. Tambien se realizo determinacion de IgM de Mycoplasma pneumoniae y Chlamydophyla pneumoniae y antigeno urinario de Legionella pneumophila. Resultados: Se incluyeron 60 pacientes, lograndose diagnostico etiologico en 97% de los casos. Pneumocystis jiroveci fue la etiologia mas frecuente (58%), seguida por Streptococcus pneumoniae (12%) y Mycobacterium avium complex (MAC) (12%). Mycobacterium tuberculosis fue encontrado en 5%. Conclusiones: La comparacion de los metodos diagnosticos para P. jiroveci mostro una mayor sensibilidad de la IF y tincion de plata en LBA que en esputo; sin embargo, la RPC fue igualmente sensible en ambos tipos de muestras. Con esta estrategia se logro establecer etiologia en la gran mayoria de los pacientes. La etiologia mas comun fue P. jiroveci. IF en LBA sigue siendo el estandar para el diagnostico de la neumonia por P. jiroveci.

Seroprevalencia de Legionella pneumophila en Santiago: evidencias de exposición durante la infancia

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%. 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 (Rev Med Chile 2001; 129: 620-625)

ULTRASONOGRAFIA DOPPLER COLOR EN EL DIAGNOSTICO DE MONONUCLEOSIS INFECCIOSA EN EL NIÑO

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 elsewhere 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.

Evaluación de cuatro métodos para detección de rotavirus en deposiciones en niños chilenos

Evidence of past exposure to i. pneumcphila was evaluated in a 1 20 chiiean subjects less than 20 yeais old stratified by socioeconomic background and age. Serum samples were analyzed for /. pneumophila antibodies by indirect immunofluorescence using serogroup 1 to 6 antigens; tilers equal or greatci than 1:64 were considered positive. Overall, 1 2 out of 1 20 samples (10%) were positive for (. pneumcphila antibodies and different prevalence rates were recorded among individuals of low [0/40], middle (2/40; 5%} and high j 10/40; 25%) socioeconomic groups. The highest liters observed in this heallhy population based survey were 1:128. High socioeconomic background is associated with highest prevalence of anfi-i. pneumophila antibodies in chilean population.

Hantavirosis: Caracterizacin clnica-epidemiolgica de pacientes peditricos en Chile

Infectious mononucleosis is a common disease in children and in most cases, the diagnosis can be suspected with clinical findings alone and confirmed with serologic study. However, in some patients, clinical pesentation can be atypical. When presented with poliadenopahy, high-resolution color- Doppler ultrasonography (US) could be helpful in the differential diagnosis. We present the US characteristics of 10 children who presented with lymphadenopathy and had infectious mononucleosis, confirmed by serologic study. US findings were relatively constant in all patients. When sonographic findings are correlated with clinical and laboratory findings , a correct diagnosis can be suspected.