RESUMO
BACKGROUND: Influenza-associated illness results in increased morbidity and mortality in the Americas. These effects can be mitigated with an appropriately chosen and timed influenza vaccination campaign. To provide guidance in choosing the most suitable vaccine formulation and timing of administration, it is necessary to understand the timing of influenza seasonal epidemics. OBJECTIVES: Our main objective was to determine whether influenza occurs in seasonal patterns in the American tropics and when these patterns occurred. METHODS: Publicly available, monthly seasonal influenza data from the Pan American Health Organization and WHO, from countries in the American tropics, were obtained during 2002-2008 and 2011-2014 (excluding unseasonal pandemic activity during 2009-2010). For each country, we calculated the monthly proportion of samples that tested positive for influenza. We applied the monthly proportion data to a logistic regression model for each country. RESULTS: We analyzed 2002-2008 and 2011-2014 influenza surveillance data from the American tropics and identified 13 (81%) of 16 countries with influenza epidemics that, on average, started during May and lasted 4 months. CONCLUSIONS: The majority of countries in the American tropics have seasonal epidemics that start in May. Officials in these countries should consider the impact of vaccinating persons during April with the Southern Hemisphere formulation.
Assuntos
Vacinas contra Influenza , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Pandemias/estatística & dados numéricos , Clima Tropical , Brasil/epidemiologia , Monitoramento Epidemiológico , Humanos , Vacinas contra Influenza/química , Influenza Humana/virologia , Nicarágua/epidemiologia , Pandemias/prevenção & controle , Peru/epidemiologia , Vigilância da População , Estações do Ano , Fatores de Tempo , Estados Unidos/epidemiologia , VacinaçãoRESUMO
We estimate the proportion of patients hospitalized for suspected dengue that tested positive for influenza virus in El Salvador during the 2012 influenza season. We tested specimens from 321 hospitalized patients: 198 patients with SARI and 123 patients with suspected dengue. Among 121 hospitalized suspected dengue (two co-infected excluded) patients, 28% tested positive for dengue and 19% positive for influenza; among 35 with suspected dengue and respiratory symptoms, 14% were positive for dengue and 39% positive for influenza. One percent presented co-infection between influenza and dengue. Clinicians should consider the diagnosis of influenza among patients with suspected dengue during the influenza season.
Assuntos
Coinfecção/diagnóstico , Dengue/complicações , Influenza Humana/complicações , Adolescente , Criança , Pré-Escolar , Estudos Transversais , Dengue/diagnóstico , El Salvador , Feminino , Humanos , Lactente , Influenza Humana/diagnóstico , Masculino , Vigilância de Evento SentinelaRESUMO
El Salvador is a Central American country that has been affected by several dengue outbreaks. This study investigated the levels of IgM, IgA, and IgE anti-dengue antibodies in serum samples from children in El Salvador, with a clinical and serological diagnosis of dengue infection during the dengue 4 outbreak in 2002-2003. Seventy one serum samples were tested by ELISA and cases were classified in three groups: 13 primary dengue fever (PDF), 21 secondary dengue fever (SDF), and 37 secondary dengue hemorrhagic fever (SDHF). Also, the specificity of anti-dengue IgM for the different serotypes was tested. No significant differences in the IgM response were found between PDF and SDF, but these were detected between PDF and SDHF (P = 0.0053) and between SDF and SDHF (P = 0.0003). The IgA and IgE values showed a statistically significant difference between primary and secondary groups. The highest positivity percentage of IgA was between 95% (SDF) and 100% (SDHF) towards day 7 of onset of fever. All secondary cases were positive for IgE antibodies. The specificity of IgM was determined for DENV-4 virus in primary and secondary DF groups. This is the first study on dengue cases in Salvadorian children related to the immune response of different immunoglobulins to the type of infection and the clinical picture. Further prospective studies are needed to define if the pattern of immunoglobulins can determine early dengue infection and/or severity.
Assuntos
Anticorpos Antivirais/sangue , Vírus da Dengue/imunologia , Imunoglobulina A/sangue , Imunoglobulina E/sangue , Imunoglobulina M/sangue , Dengue Grave/sangue , Criança , Vírus da Dengue/genética , Surtos de Doenças , El Salvador/epidemiologia , Humanos , Dengue Grave/epidemiologia , Dengue Grave/imunologiaRESUMO
OBJECTIVE: To estimate the incidence of influenza-virus-associated severe pneumonia among Salvadorian children aged < 5 years. METHODS: Data on children aged < 5 years admitted with severe pneumonia to a sentinel hospital in the western region were collected weekly. Nasal and oropharyngeal swab specimens were collected from a convenience sample of case patients for respiratory virus testing. A health-care utilization survey was conducted in the hospital catchment area to determine the proportion of residents who sought care at the hospital. The incidence of influenza-virus-associated severe pneumonia among all Salvadorian children aged < 5 years was estimated from surveillance and census data, with adjustment for health-care utilization. Influenza virus strains were characterized by the United States Centers for Disease Control and Prevention to determine their correspondence with northern and southern hemisphere influenza vaccine formulations. FINDINGS: Physicians identified 2554 cases of severe pneumonia. Samples from 608 cases were tested for respiratory viruses and 37 (6%) were positive for influenza virus. The estimated incidence of influenza-virus-associated severe pneumonia was 3.2 cases per 1000 person-years (95% confidence interval, CI: 2.8-3.7) overall, 1.5 cases per 1000 person-years (95% CI: 1.0-2.0) during 2008, 7.6 cases per 1000 person-years (95% CI: 6.5-8.9) during 2009 and 0.6 cases per 1000 person-years (95% CI: 0.3-1.0) during 2010. Northern and southern hemisphere vaccine formulations matched influenza virus strains isolated during 2008 and 2010. CONCLUSION: Influenza-virus-associated severe pneumonia occurred frequently among young Salvadorian children during 2008-2010. Antigens in northern and southern hemisphere influenza vaccine formulations corresponded to circulating strains.