Annual vaccination against influenza is an essential strategic action to reduce morbidity, complications and mortality due to this disease. This practice is specially recommended in risk groups, mainly in the elderly with high risk to develop a severe or complicated influenza. Taking into account this condition and after the application of a single dose (0.5 mL by intramuscular route) of the Aggrippal S1 vaccine/ Chiron vaccine, according to WHO for 1997-1998, the anti-hemagglutinin humoral response was evaluated in 38 women aged ³ 65 from a care center for old ladies (state institution) of the City of Havana, Cuba. It was used the Hemagglutination Inhibition technique in serum samples from blood extracted in three stages: pre-vaccination (immediately after the application), post-vaccination (30 days after), and one year after vaccination during the influenza season 1997-1999. The Student test was applied in the results and statistically significant differences were observed (p=0.00094 and p= 0.0018, respectively) when comparing the protective antibodies levels in post-vaccine stage (78.94%) and those of one year after vaccination (42.11%) with the ones of the pre- vaccination stage. The comparison of positivity detected in the three stages (28.94%; 97.36% and 86.34%) was also significant by Chi-squared test (p<0.00001). Response to anti-flu immunization achieved in this group supports re-vaccination practice in the elderly who shows the higher mortality rates due to influenza and pneumonia.

La vacunación anual contra la influenza es una acción estratégica fundamental para reducir la morbilidad, la mortalidad y las complicaciones ocasionadas por esta enfermedad. Su aplicación se recomienda en los grupos de riesgo, sobre todo en los ancianos con peligro de desarrollar una influenza severa o complicada. Atendiendo a esta condición se evaluó, después de aplicar una dosis única (0,5 mL por vía intramuscular) de la vacuna Agrippal S1/Chiron, recomendada por la OMS para la temporada 1997-1998, la respuesta inmune humoral antihemaglutinina en 38 mujeres con una edad ³ a 65 años, todas pertenecientes a un hogar de ancianas (institución estatal) de La Habana, Cuba. Para ello se utilizó la técnica de inhibición de la hemaglutinación en muestras de suero, obtenidas a partir de la sangre extraída en tres etapas: prevacunación (inmediatamente antes de su aplicación), posvacunación (30 días después) y un año después de la inmunización durante la temporada de influenza 1997-1998. Al aplicar el test de Student en los resultados obtenidos se observó que al comparar los niveles de anticuerpos protectores detectados en la etapa posvacunal (78,94%) y al año de la inmunización (42,11%), con los identificados en la etapa prevacunal, existían diferencias estadísticamente significativas (p=0,0094 y p=0,0018), respectivamente. La comparación de los porcentajes de positividad detectados en las tres etapas investigadas (28,94%; 97,36% y 86,84%) fue también significativo mediante el test de Chi cuadrado (p<0,00001). La respuesta a la inmunización antigripal obtenida en este grupo de riesgo apoya la política de revacunación en los ancianos, individuos donde se observan las mayores tasas de mortalidad por influenza y neumonía.

A polyclonal antiserum with high titer, great specificity and sensitivity was obtained against the hemagglutinin of Influenza A/Johannesburg/33/94, belonging to subtype A (H3N2). The obtaining process of the antigen or immunogen, the immunization schedule and its administration to Wistar rats as animal model are described. All of these were validated by the hemagglutinin inhibition technique. The antiserum obtained was treated with receptor-destroying enzymes of national production (EDR/IPK) in order to eliminate the unspecific inhibitors of the hemagglutinin inhibition. Validation was carried out in front of a panel including 9 influenza reference strains belonging to subtypes A(H3N2), A(H1N1), and to type B. No unspecific reactions against strains A(H1N1) and of type B were detected. Five autochthonous isolates were satisfactorily typed and subtyped.

Se obtuvo un antisuero policlonal con alto título, alta especificidad y sensibilidad, contra la hemaglutinina de la cepa de influenza A/Johannesburg/33/94 que pertenece al subtipo A (H3N2). Se describe el proceso de obtención del antígeno o inmunógeno, el esquema de inmunización y su aplicación a las ratas Wistar como modelo animal; y se validó mediante la técnica de inhibición de la hemaglutinación (IH). El antisuero obtenido fue tratado con enzima destructora de receptores de producción nacional (EDR/IPK) para la eliminación de inhibidores inespecíficos de la IH. La validación se realizó frente a un panel que incluyó 9 cepas de referencia de influenza de los subtipos A(H3N2), A(H1N1) y el tipo B. No se detectaron reacciones inespecíficas frente a cepas A(H1N1) y del tipo B. Se determinó el tipo y subtipo de aislamientos autóctonos con resultados satisfactorios.

Twenty-six human respiratory syncytial virus strains (subgroup A) isolated from three outbreaks in Havana City during the period 1994/95, 1995/96 and 1996/97 were analyzed to determine their antigenic and genetic relationships. Analyses were performed by monoclonal antibodies and restriction mapping (N gene) following amplification of the select region of the virus genome by polymerase chain reaction. All isolated strains were classified as subgroup A by monoclonal antibodies and they showed a restriction pattern NP4 that belonged to subgroup A. Thus the results obtained in this work, showed a close relation (100%) between antigenic and genetic characterization of the isolated strains in our laboratory. These methods permit the examination of large numbers of isolates by molecular techniques, simplifying the researchs into the molecular epidemiology of the virus.

The aim of this study was to develop a polymerase chain reaction (PCR) for the detection of respiratory syncytial virus (RSV) genomes. The primers were designed from published sequences and selected from conserved regions of the genome encoding for the N protein of subgroups A and B of RSV. PCR was applied to 20 specimens from children admitted to the respiratory ward of "William Soler" Pediatric Hospital in Havana City with a clinical diagnosis of bronchiolitis. The PCR was compared with viral isolation and with an indirect immunofluorescence technique that employs monoclonal antibodies of subgroups A and B. Of 20 nasopharyngeal exudates, 10 were found positive by the three assayed methods. In only two cases, samples that yielded positive RNA-PCR were found negative by indirect immunofluorescence and cell culture. Considering viral isolation as the "gold standard" technique, RNA-PCR had 100% sensitivity and 80% specificity. RNA-PCR is a specific and sensitive technique for the detection of the RSV genome. Technical advantages are discussed

The results obtained in the study of an aoutbreak of fever and reash ocurred in Havana City in March, 1995, are reported. Dengue, measles, rubella, herpes simplex, and Epstein Barr were discarded as causal agents of the outbreak in the samples of 35 patients. Parvovirus B19 was identified as the causing agent of the outbreak by the detection of IgM antibodies and the polymerase chain reaction technique (PCR). The infection produced by this agent was confirmed in 14/18 samples (77,7 %) by some of the techniques used. This study makes reference to the first outbreak of Parvovirus B19 that was proved in Cuba.

Se reportan los resultados obtenidos en el estudio de un brote de fiebre y rash ocurrido en Ciudad de La Habana en marzo de 1995. En las muestras de 35 pacientes se descartaron dengue, sarampión, rubéola, herpes simple y Epstein Barr como agentes causales del brote. Mediante la detección de anticuerpos IgM y la técnica de reacción en cadena de la polimerasa (RCP) se identificó al Parvovirus B19 como agente causal del brote. En 14/18 muestras (77,7 %) se comprobó la infección por este agente por alguna de las técnicas empleadas. Este estudio se refiere al primer brote confirmado de Parvovirus B19 en Cuba.