RESUMO
INTRODUCTION: In the last 18 years, epizootics of Venezuelan equine encephalitis have not occurred in places with historic epidemic register (1925-1995) in the Guajira Peninsula, Colombia. OBJECTIVE: To assess if the Guajira Peninsula, Colombia, still maintains the epidemiological conditions for Venezuelan equine encephalitis virus reemergence. MATERIALS AND METHODS: Research was carried out in places affected by the 1995 epidemic. We evaluated: 1) abundance and seasonal variation of vector mosquito populations; 2) availability of mammals that are potential amplifiers of the virus, and 3) knowledge among the community about the disease and its vectors. RESULTS: Most of the 16 mosquito species were found during the rainy season. Aedes taeniorhynchus and Psorophora confinnis showed direct relation with rainfall and temperature. In contrast, the dominant species, Deinocerites atlanticus , was always present in the collections, regardless of climatic conditions. No IgG antibodies were found in humans younger than 17 years old, goats or bovine sera. One third of those interviewed remembered the last epidemic and had basic understanding of the disease. Only 20% of the families were owners of equines, and 8% was informed of the importance of equine vaccination. CONCLUSIONS: Some epidemiological conditions that eventually could help epizootic Venezuelan equine encephalitis virus reemergence are maintained. However, an abrupt decrease in the number of susceptible equines was found in the area. Apparently, this new condition has not allowed the virus reemergence and is the biggest observed change.
Assuntos
Doenças Transmissíveis Emergentes/epidemiologia , Doenças Transmissíveis Emergentes/veterinária , Encefalomielite Equina Venezuelana/epidemiologia , Encefalomielite Equina Venezuelana/veterinária , Doenças dos Cavalos/epidemiologia , Adolescente , Adulto , Animais , Anticorpos Antivirais/sangue , Criança , Colômbia/epidemiologia , Culicidae , Vírus da Encefalite Equina Venezuelana/imunologia , Encefalomielite Equina Venezuelana/sangue , Cavalos , Humanos , Insetos Vetores , Estações do Ano , Adulto JovemRESUMO
Introducción. En los últimos 18 años, no se han vuelto a registrar epizootias de encefalitis equina venezolana en áreas con antecedentes históricos de epidemia (1925-1995) en la península de La Guajira. Objetivo. Establecer si en la Alta Guajira colombiana se mantienen las condiciones que favorecen la reaparición de las cepas epizoóticas del virus de la encefalitis equina venezolana. Materiales y métodos. La investigación se realizó en las localidades afectadas por la epidemia de 1995, y se evaluaron los siguientes aspectos: 1) abundancia y variación estacional de las poblaciones de los mosquitos vectores; 2) disponibilidad de mamíferos sensibles amplificadores del virus, y 3) conocimiento de los habitantes sobre la enfermedad y sus vectores. Resultados. La mayoría de las especies de mosquitos, incluidas las de los vectores, se encontraron durante la estación lluviosa. Aedes taeniorhynchus y Psorophora confinnis presentaron relación con la precipitación y la temperatura. Deinocerites atlanticus estuvo siempre presente, independientemente de las condiciones climáticas. No se encontraron anticuerpos de tipo IgG en los sueros de humanos menores de 17 años, tampoco en los de los animales caprinos y bovinos analizados. En la encuesta sobre conocimientos, se detectó que la tercera parte de los encuestados recordaba la última epidemia y tenía conocimientos básicos sobre la enfermedad. Solamente 20 % de las familias poseía équidos y el 8 % estaba informado sobre la necesidad de vacunarlos. Conclusiones. Se mantienen algunas condiciones epidemiológicas que eventualmente podrían favorecer la reaparición del virus, pero el número de equinos en riesgo es escaso, lo cual constituye el cambio más notable y lo que, aparentemente, ha impedido la reaparición del virus.
Introduction: In the last 18 years, epizootics of Venezuelan equine encephalitis have not occurred in places with historic epidemic register (1925-1995) in the Guajira Peninsula, Colombia. Objective: To assess if the Guajira Peninsula, Colombia, still maintains the epidemiological conditions for Venezuelan equine encephalitis virus reemergence. Materials and methods: Research was carried out in places affected by the 1995 epidemic. We evaluated: 1) abundance and seasonal variation of vector mosquito populations; 2) availability of mammals that are potential amplifiers of the virus, and 3) knowledge among the community about the disease and its vectors. Results: Most of the 16 mosquito species were found during the rainy season. Aedes taeniorhynchus and Psorophora confinnis showed direct relation with rainfall and temperature. In contrast, the dominant species, Deinocerites atlanticus , was always present in the collections, regardless of climatic conditions. No IgG antibodies were found in humans younger than 17 years old, goats or bovine sera. One third of those interviewed remembered the last epidemic and had basic understanding of the disease. Only 20% of the families were owners of equines, and 8% was informed of the importance of equine vaccination. Conclusions: Some epidemiological conditions that eventually could help epizootic Venezuelan equine encephalitis virus reemergence are maintained. However, an abrupt decrease in the number of susceptible equines was found in the area. Apparently, this new condition has not allowed the virus reemergence and is the biggest observed change.
Assuntos
Adolescente , Adulto , Animais , Criança , Humanos , Adulto Jovem , Doenças Transmissíveis Emergentes/epidemiologia , Doenças Transmissíveis Emergentes/veterinária , Encefalomielite Equina Venezuelana/epidemiologia , Encefalomielite Equina Venezuelana/veterinária , Doenças dos Cavalos/epidemiologia , Anticorpos Antivirais/sangue , Culicidae , Colômbia/epidemiologia , Vírus da Encefalite Equina Venezuelana/imunologia , Encefalomielite Equina Venezuelana/sangue , Cavalos , Insetos Vetores , Estações do AnoRESUMO
Considerable efforts have been directed to clarify the main protective and recovery mechanisms in acute viral infections and, the possible role of the cytokines involved in the primary immune response induced by an epizootic strain of the Venezuelan Equine Encephalitis (VEE) virus. This study examined the levels of TH1 cytokines Interleukin-2 (IL-2) and Interferon-gamma (IFN-gamma), TH2 cytokines Interleukin-4 (IL-4) and proinflammatory cytokines (IL-1beta, TNF-alpha) in serum and brain of mice infected with the VEE virus during different post infection periods. NMRI albino male mice infected with a suspension (10 DL50) of the Guajira strain of the VEE virus, and a control group (without infection) were used. At one, 3 and 5 days post-infection, whole blood and brains were extracted to obtain sera and brain homogenates, respectively. IL-2, IFN-gamma, IL-4, IL-beta and TNF-alpha were determined by ELISA. A significant increment in the levels of IL-1beta, IFN-gamma and TNF-alpha was observed (p<0.01) in serum and brain homogenates at 1, 3 and 5 day post-infection, when compared with the control group. The levels of IL-2 and IL-4 did not show any significant statistical difference when compared to the controls. These results suggest that IL-1beta, IFN-gamma and TNF-alpha, could be involved in the early immunitary response to VEE virus during the primary infection.
Assuntos
Encéfalo/imunologia , Encefalomielite Equina Venezuelana/imunologia , Interferon gama/análise , Interleucina-1beta/análise , Fator de Necrose Tumoral alfa/análise , Animais , Vírus da Encefalite Equina Venezuelana , Encefalomielite Equina Venezuelana/sangue , Interferon gama/sangue , Interleucina-1beta/sangue , Masculino , Camundongos , Fatores de Tempo , Fator de Necrose Tumoral alfa/sangueRESUMO
BACKGROUND: Lymphocytes provide invaluable whistle blowers of changes due to infections. We use the information registered by these cells using their mRNAs as they encounter the pathogen to develop patterns of expression that correspond to that specific pathogen. Venezuelan equine encephalitis (VEE) is a mosquito-borne viral disease characterized by fever and one or more of the following: severe headache, back pain, myalgias, prostration, chills, nausea, vomiting, weakness and other flu-like symptoms. Screening for host mRNA obtained from blood samples after exposure to VEEV may provide the means for early detection of surrogate markers of the impending illness and provide appropriate strategies for treatment. RESULTS: We have been carrying out gene expression analysis of PBMC exposed to VEEV to extract signatures and diagnostic markers of early exposure to be used in non invasive blood analysis methods. In this study, we used high throughput gene expression analysis to identify markers of early and late exposures to VEEV in vivo in Cynomolgus macaques (Macaca fascicularis). We carried out cDNA microarrays and real time PCR on blood samples obtained from the NHP model resulting in a panel of host genes that are altered in response to VEEV. CONCLUSION: Screening for host mRNA obtained from blood samples after exposure to VEEV may provide the means for early detection of surrogate markers of the impending illness and provide appropriate strategies for treatment.
Assuntos
Encefalomielite Equina Venezuelana/sangue , Encefalomielite Equina Venezuelana/genética , Perfilação da Expressão Gênica , Leucócitos Mononucleares/metabolismo , Animais , Apoptose/genética , Citocinas/genética , Modelos Animais de Doenças , Encefalomielite Equina Venezuelana/virologia , Regulação da Expressão Gênica , Humanos , Macaca fascicularis , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase , Receptores Androgênicos/genéticaRESUMO
Here we briefly report testosterone and cytokine responses to Venezuelan equine encephalitis virus (VEEV) in macaques which were used as part of a larger study conducted by the Department of Defense to better characterize pathological responses to aerosolized VEEV in non-human primates. Serial samples were collected and analyzed for testosterone and cytokines prior to and during infection in 8 captive male macaques. Infected animals exhibited a febrile response with few significant changes in cytokine levels. Baseline testosterone levels were positively associated with viremia following exposure and were significantly higher than levels obtained during infection. Such findings suggest that disease-induced androgen suppression is a reasonable area for future study. Decreased androgen levels during physiological perturbations may function, in part, to prevent immunosuppression by high testosterone levels and to prevent the use of energetic resources for metabolically-expensive anabolic functions.
Assuntos
Vírus da Encefalite Equina Venezuelana/fisiologia , Encefalomielite Equina Venezuelana/veterinária , Macaca fascicularis/sangue , Macaca fascicularis/virologia , Testosterona/sangue , Animais , Encefalomielite Equina Venezuelana/sangue , Encefalomielite Equina Venezuelana/imunologia , Encefalomielite Equina Venezuelana/virologia , Masculino , Viremia/sangueRESUMO
Five years after the apparent end of the major 1995 Venezuelan equine encephalitis (VEE) epizootic/epidemic, focal outbreaks of equine encephalitis occurred in Carabobo and Barinas States of western Venezuela. Virus isolates from horses in each location were nearly identical in sequence to 1995 isolates, which suggests natural persistence of subtype IC VEE virus (VEEV) strains in a genetically stable mode. Serologic evidence indicated that additional outbreaks occurred in Barinas State in 2003. Field studies identified known Culex (Melanoconion) spp. vectors and reservoir hosts of enzootic VEEV but a dearth of typical epidemic vectors. Cattle serosurveys indicated the recent circulation of enzootic VEEV strains, and possibly of epizootic strains. Persistence of VEEV subtype IC strains and infection of horses at the end of the rainy season suggest the possibility of an alternative, cryptic transmission cycle involving survival through the dry season of infected vectors or persistently infected vertebrates.
Assuntos
Surtos de Doenças , Vírus da Encefalite Equina Venezuelana/isolamento & purificação , Encefalomielite Equina Venezuelana/epidemiologia , Encefalomielite Equina Venezuelana/virologia , Cavalos/virologia , Animais , Bovinos , Culicidae/virologia , Didelphis/virologia , Reservatórios de Doenças/virologia , Vírus da Encefalite Equina Venezuelana/genética , Encefalomielite Equina Venezuelana/sangue , Cavalos/sangue , Humanos , Murinae/virologia , Filogenia , Estações do Ano , Vigilância de Evento Sentinela , Venezuela/epidemiologiaRESUMO
We determined the influence of melatonin (MLT) on the induction of interleukin (IL)-2, IL-1 beta, IL-4, tumour necrosis factor-alpha (TNF-alpha) and gamma interferon (IFN-gamma) on mice infected with the Venezuelan equine encephalomyelitis (VEE) virus. Levels of IFN-gamma in the MLT-treated group were significantly increased (P < 0.001) when compared with the control non-infected group from day 1 to 6 post-infection (p.i.), while in infected mice treated with 500 micrograms MLT/kg of bodyweight enhanced levels of IFN-gamma were evident from 4 to 6 days p.i. No differences were detected in the levels of IL-2 between the controls, the infected mice treated with MLT and the infected untreated group, from day 2 p.i. No changes in serum levels of IL-4 were detected. In infected mice treated with MLT, blood levels of IL-1 beta were elevated almost 10-fold from day 1 to day 6 p.i. when compared to the control, the infected and the non-infected MLT-treated mice (P < 0.001). A highly significant rise (P < 0.001) of TNF-alpha was found in infected mice treated with MLT, from day 1 to 6 p.i. when compared to the other groups. A significant rise (P < 0.001) was also evident in the infected non-MLT-treated group and a less pronounced rise in the non-infected mice treated with MLT when compared to controls. The blockade of IFN-gamma and TNF-alpha did not inhibit the protective effect of MLT but when IL-1 beta was neutralized, 100% of the infected mice died suggesting that IL-1 beta induced by MLT treatment is a target cytokine to generate an immune response against the viral infection.
Assuntos
Adjuvantes Imunológicos/farmacologia , Citocinas/metabolismo , Encefalomielite Equina Venezuelana/sangue , Melatonina/farmacologia , Animais , Interferon gama/metabolismo , Interleucinas/metabolismo , Masculino , Camundongos , Células Th1/metabolismo , Células Th2/metabolismo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Following a 19-year hiatus, Venezuelan equine encephalitis (VEE) reemerged in western Venezuela in December 1992. This outbreak is important in understanding VEE emergence because phylogenetic studies imply that sympatric, enzootic, subtype ID VEE viruses mutated to generate the epizootic/epidemic. Although the 1992-1993 strains belong to subtype IC, a serotype implicated in extensive outbreaks during the 1960s and in 1995, relatively small numbers of human and equine cases occurred in 1992-1993. We, therefore, evaluated the pathogenicity of these Venezuelan enzootic ID and epizootic IC viruses to determine 1) if they exhibit phenotypes like those described previously for more distantly related enzootic and epizootic strains, and 2) if the 1992-1993 outbreak was limited by the inability of these IC viruses to exploit equines as amplification hosts. All strains were virulent in mice and guinea pigs, but were benign for cotton rats, natural hosts of enzootic viruses. However, only the IC strains produced equine disease, with mean peak viremias of 10(5) suckling mouse 50% lethal doses per mL serum, and some titers exceeding 10(7). These viremias approximate those observed previously with VEE strains isolated during more extensive epizootics, suggesting that efficient equine amplification did not limit the scope and duration of the 1992-1993 outbreak. Enzootic ID virus infection protected all horses from challenge with epizootic strain P676, supporting the hypothesis that epizootics bypass regions of enzootic transmission due to natural immunization of equines by enzootic VEE viruses.
Assuntos
Surtos de Doenças/veterinária , Vírus da Encefalite Equina Venezuelana/patogenicidade , Encefalomielite Equina Venezuelana/epidemiologia , Encefalomielite Equina Venezuelana/virologia , Doenças dos Cavalos/virologia , Viremia/virologia , Animais , Anopheles , Chlorocebus aethiops , Cricetinae , Vírus da Encefalite Equina Venezuelana/classificação , Encefalomielite Equina Venezuelana/sangue , Feminino , Cobaias , Doenças dos Cavalos/sangue , Doenças dos Cavalos/epidemiologia , Cavalos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Distribuição Aleatória , Ratos , Doenças dos Roedores/virologia , Sigmodontinae , Venezuela/epidemiologia , Células Vero , VirulênciaRESUMO
When mice infected with the Venezuelan equine encephalomyelitis (VEE) virus were exposed to 2500 lux with a 12 h light: 12 h dark photoperiod, the serum levels of melatonin (MLT) remained constantly elevated. In mice exposed to 400 lux low levels of serum MLT were detected during the day and high levels during the night. An increase in the survival rate of the infected mice from 6 to 13 days after virus inoculation was also observed. The significant increment in the concentration of serum MLT produced by the high intensity light could be responsible for the longer survival rate of mice infected with the VEE virus.
Assuntos
Encefalomielite Equina Venezuelana/sangue , Luz , Melatonina/sangue , Animais , Ritmo Circadiano , Relação Dose-Resposta à Radiação , Masculino , Camundongos , Taxa de SobrevidaRESUMO
A survey was conducted from October 1, 1993 to June 30, 1995 to determine the arboviral etiologies of febrile illnesses in the city of Iquitos in the Amazon River Basin of Peru. The study subjects were patients who were enrolled at medical care clinics or in their homes by Peruvian Ministry of Health (MOH) workers as part of the passive and active disease surveillance program of the MOH. The clinical criterion for enrollment was the diagnosis of a suspected viral-associated, acute, undifferentiated febrile illness of < or = 5 days duration. A total of 598 patients were enrolled in the study. Demographic information, medical history, clinical data, and blood samples were obtained from each patient. The more common clinical features were fever, headache, myalgia, arthralgia, retro-ocular pain, and chills. Sera were tested for virus by the newborn mouse and cell culture assays. Viral isolates were identified initially by immunofluorescence using polyclonal antibody. An ELISA using viral-specific monoclonal antibodies and nucleotide sequence analysis were used to determine the specific variety of the viruses. In addition, thin and thick blood smears were observed for malaria parasites. Venezuelan equine encephalitis (VEE) virus subtype I, variety ID virus was isolated from 10 cases, including three cases in October, November, and December 1993, five cases in January and February 1994, and two cases in June 1995. The ELISA for IgM and IgG antibody indicated that VEE virus was the cause of an additional four confirmed and four presumptive cases, including five from January through March 1994 and three in August 1994. Sixteen cases were positive for malaria. The 18 cases of VEE occurred among military recruits (n = 7), agriculture workers (n = 3), students (n = 3), and general laborers (n = 5). These data indicated that an enzootic strain of VEE virus was the cause of at least 3% (18 of 598) of the cases of febrile illnesses studied in the city of Iquitos in the Amazon Basin region of Peru.