RESUMO
This study describes the first multicentered study of acute lower respiratory infection viral etiology in young children from four different geographical areas of Argentina. A total of 1,278 children under 5 years of age, hospitalized in primary care centers from Buenos Aires, Córdoba, Santa Fé and Mar del Plata cities during a 2-year period were studied (1993-1994). Nasopharyngeal aspirates were investigated for respiratory syncytial virus (RSV), adenovirus, parainfluenza, and influenza A and B viruses by indirect immunofluorescence. Out of the patients studied, 946 (74%) were under 1 year of age. Viruses were detected in 399 patients (32%). RSV was observed in 25.3% of the samples, representing 78.2% of all viral positive cases. Adenoviruses were detected in 2.5% of the cases, parainfluenza in 2.2%, influenza A in 2.1%, and influenza B in 0.2%. Compared with other viruses, the higher RSV frequency was statistically significant (P < 0.000). Most RSV cases were detected between May and September with a significant peak in July (P < 0.000). Pneumonia was observed in 46% of the patients, bronchiolitis in 41% and other entities in 13%. The case fatality rate observed during the 2 year study was 0.73%. Most of the above respiratory viruses were detected in the four cities, however, the frequency of RSV and influenza were different in the southern city.
Assuntos
Infecções Respiratórias/virologia , Viroses/virologia , Doença Aguda , Adenoviridae/isolamento & purificação , Assistência Ambulatorial , Argentina , Bronquiolite Viral/epidemiologia , Bronquiolite Viral/virologia , Pré-Escolar , Feminino , Humanos , Lactente , Vírus da Influenza A/isolamento & purificação , Vírus da Influenza B/isolamento & purificação , Masculino , Nasofaringe/virologia , Pneumonia Viral/epidemiologia , Pneumonia Viral/virologia , Pneumovirus/isolamento & purificação , Vírus Sinciciais Respiratórios/isolamento & purificação , Infecções Respiratórias/epidemiologia , Estações do Ano , Viroses/epidemiologiaRESUMO
In immunocompromised patients, diagnosis of Cytomegalovirus (CMV) active infection is of utmost importance for the initiation, monitoring and ending of antiviral therapy. Therefore, the presence of viral replication should be demonstrated. Isolation in tissue culture is one of the standard methods. The objective of the present paper was to compare two isolation procedures for CMV: conventional cell culture (CC) and rapid shell vial (SV) assay in human fibroblasts. A total of 584 clinical samples were studied between 1991 and 1998. CMV was isolated in 14.4% of the samples, 11.8% of which were positive by SV and 7.7% by CC. Out of 84 positive samples, concordance between both methods was observed in 36% of the cases. We found that 46% of the samples were positive only by SV, while 18% were positive only by CC. The average time required for obtaining the results by CC was 22.6 +/- 2.3 days. Out of the 69 samples positive by SV, 43% were already positive after 24 hours and the rest after 48 hours. These results indicate that SV was more sensitive and rapid than CC. The main advantage of CC, despite its time-consuming process, is the ability to recover the viral strain for both antiviral susceptibility phenotypical tests and strain characterization. Furthermore, in this study, absence of CC would have resulted in the loss of 18% of the positive diagnoses. In conclusion, simultaneous use of both methods is suggested in order to obtain a rapid result and the highest sensitivity.
Assuntos
Infecções por Citomegalovirus/diagnóstico , Citomegalovirus/isolamento & purificação , Humanos , Sensibilidade e Especificidade , Cultura de Vírus/métodos , Replicação ViralRESUMO
In immunocompromised patients, diagnosis of Cytomegalovirus (CMV) active infection is of utmost importance for the initiation, monitoring and ending of antiviral therapy. Therefore, the presence of viral replication should be demonstrated. Isolation in tissue culture is one of the standard methods. The objective of the present paper was to compare two isolation procedures for CMV: conventional cell culture (CC) and rapid shell vial (SV) assay in human fibroblasts. A total of 584 clinical samples were studied between 1991 and 1998. CMV was isolated in 14.4
of the samples, 11.8
of which were positive by SV and 7.7
by CC. Out of 84 positive samples, concordance between both methods was observed in 36
of the cases. We found that 46
of the samples were positive only by SV, while 18
were positive only by CC. The average time required for obtaining the results by CC was 22.6 +/- 2.3 days. Out of the 69 samples positive by SV, 43
were already positive after 24 hours and the rest after 48 hours. These results indicate that SV was more sensitive and rapid than CC. The main advantage of CC, despite its time-consuming process, is the ability to recover the viral strain for both antiviral susceptibility phenotypical tests and strain characterization. Furthermore, in this study, absence of CC would have resulted in the loss of 18
of the positive diagnoses. In conclusion, simultaneous use of both methods is suggested in order to obtain a rapid result and the highest sensitivity.
RESUMO
Present knowledge points to horizontal transmission as the most significant mechanism for Junín virus maintenance in the main natural reservoirs, namely Calomys musculinus and Calomys laucha. The existence of naturally infected Akodon azarae, both within and outside the endemic area, as well as the finding that other species, ecologically and phylogenetically related to the main reservoirs, such as Akodon molinae and Calomys callidus, can experimentally develop persistent infections with virus shedding through fauces, suggest a potential role for these cricetids as alternative reservoirs. Furthermore, since those rodents inhabit the borders of the area in which Argentine Hemorrhagic fever is endemic, the risk of spread of this area is to be expected. Whether the establishment of Junín virus persistence in Calomys musculinus and other reservoirs depends on viral or host factors, such as a selective defect in L3T4+ lymphocytes as recently shown for mice, remains to be explored.
Assuntos
Febre Hemorrágica Americana/epidemiologia , Animais , Arenavirus do Novo Mundo/isolamento & purificação , Argentina , Modelos Animais de Doenças , Febre Hemorrágica Americana/transmissão , Humanos , Roedores/microbiologiaRESUMO
Guinea pigs infected by the peripheral route with the XJ pathogenic strain of Junin virus showed viscerotropism mainly in reticulo-phagocytic rich organs. By immunofluorescence, heavy infection of reticular-phagocytic cells was demonstrated, supporting the leading role of these cell types. Absence of neurotropism was demonstrated by the inability to recover infectious virus, as well as the absence of antigens, immunoglobulins, or 3rd component of complement deposits, in cells, vessels, or meninges. The correlation between infectivity and antigen expression observed in organs, and the absence of evidence of immunopathologic mechanisms, strongly suggest a direct viral effect in these experimental conditions. The results show that infection of guinea pigs by the peripheral route is an adequate model for human Argentine hemorrhagic fever with the exception of central nervous system involvement. Comparisons are made with infections produced in guinea pigs by attenuated strains, as well as with the disease in primates and humans.
Assuntos
Modelos Animais de Doenças , Cobaias/microbiologia , Febre Hemorrágica Americana/microbiologia , Glândulas Suprarrenais/microbiologia , Animais , Antígenos Virais/imunologia , Arenavirus do Novo Mundo , Medula Óssea/microbiologia , Callitrichinae/microbiologia , Cebus/microbiologia , Imunofluorescência , Humanos , Macrófagos/microbiologia , Camundongos , Microscopia de Fluorescência , Glândulas Salivares/microbiologiaRESUMO
Two Cebus sp surviving acute Junin virus infection, one after intramuscular inoculation with pathogenic XJ and the other after intracerebral inoculation with XJ Clone 3, failed to exhibit persistent infection. Although treatment with immunosuppressive drugs was carried out, no Junin virus was detected in blood or organs in spite of blind passages in mice for the former as well as cocultivation with permissive Vero cells for the latter. Viremia was also ruled out by immunofluorescence on BHK/21 cell culture. These findings correlate with the lack of long-lasting virus in blood observed in humans following the acute phase of Argentine Hemorrhagic Fever.
Assuntos
Arenaviridae/fisiologia , Arenavirus do Novo Mundo/fisiologia , Cebidae/microbiologia , Cebus/microbiologia , Febre Hemorrágica Americana/microbiologia , Animais , Antígenos Virais/análise , Arenavirus do Novo Mundo/imunologia , Arenavirus do Novo Mundo/isolamento & purificação , Arenavirus do Novo Mundo/patogenicidade , Convalescença , Feminino , Imunossupressores/farmacologia , Masculino , CamundongosRESUMO
Two Cebus sp surviving acute Junin virus infection, one after intramuscular inoculation with pathogenic XJ and the other after intracerebral inoculation with XJ Clone 3, failed to exhibit persistent infection. Although treatment with immunosuppressive drugs was carried out, no Junin virus was detected in blood or organs in spite of blind passages in mice for the former as well as cocultivation with permissive Vero cells for the latter. Viremia was also ruled out by immunofluorescence on BHK/21 cell culture. These findings correlate with the lack of long-lasting virus in blood observed in humans following the acute phase of Argentine Hemorrhagic Fever.