[Emerging viral diseases]. / Enfermedades virales emergentes.

In the last few years an increasing rise of new infectious diseases or of other diseases considered to be under control has been observed. The so called emerging and reemerging diseases are those new infections that have come up in a population or those existing diseases which incidence and geographic extension are on a rapid increase. Factors such as social and economic situations, medical assistance, food production, changes in human behaviours, environmental changes, health systems deterioration, and adaptation and changes of microorganisms are related with the emergence or reemergence of a number of entities. This paper sets forth an analysis of the emergence and reemergence of viral diseases and of those factors that have had an impact on this situation.

Urbanisation of yellow fever in Santa Cruz, Bolivia.

BACKGROUND: Reinvasion by Aedes aegypti of cities in the Americas poses a threat of urbanisation of yellow fever. After detection of yellow-fever infection in a resident of the city of Santa Cruz, Bolivia, in December, 1997, we investigated all subsequent suspected cases. METHODS: We introduced active surveillance of yellow fever in the Santa Cruz area. Hospitals and selected urban and rural health centres reported all suspected cases. Patients were serologically screened for yellow fever, dengue, hepatitis A and B, and leptospirosis. We collected clinical and epidemiological information from patients' records and through interviews. We also carried out a population-based serosurvey in the neighbourhood of one case. FINDINGS: Between December, 1997, and June, 1998, symptomatic yellow-fever infection was confirmed in six residents of Santa Cruz, five of whom died. Five lived in the southern sector of the city. Two had not left the city during the incubation period, and one had visited only an area in which sylvatic transmission was deemed impossible. Of the 281 people covered in the serosurvey 16 (6%) were positive for IgM antibody to yellow fever. Among five people for whom this result could not be explained by recent vaccination, there were two pairs of neighbours. INTERPRETATION: Urban transmission of yellow fever in Santa Cruz was limited in space and time. Low yellow-fever immunisation coverage and high infestation with A. aegypti in the city, and the existence of endemic areas in the region present a risk for future urban outbreaks. We recommend immediate large-scale immunisation of the urban population, as well as tightened surveillance and appropriate vector control.

PIP: Until recently, urban yellow fever had not been reported from the Americas since 1954, but jungle yellow fever increasingly affects forest dwellers in Bolivia, Brazil, Colombia, Ecuador, and Peru. The reinvasion by Aedes aegypti of cities in the Americas now threatens to urbanize yellow fever. After yellow fever infection was identified in a resident of Santa Cruz, Bolivia, in December 1997, all subsequent suspected cases were investigated. Active surveillance of yellow fever was introduced in the Santa Cruz area, with hospitals and selected urban and rural health centers reporting all suspected cases. Patients were serologically screened for yellow fever, dengue, hepatitis A and B, and leptospirosis; clinical and epidemiological data were collected from patients' records and through interviews; and a population-based serosurvey was conducted in the neighborhood of one case. Between December 1997 and June 1998, symptomatic yellow fever infection was confirmed in 6 residents of Santa Cruz, of whom 5 died. 5 lived in the southern sector of the city. 2 cases did not leave the city during their incubation period, and 1 had visited only an area in which sylvatic transmission was deemed impossible. Of the 281 people covered in the serosurvey, 16 (6%) were positive for IgM antibody to yellow fever. Among 5 people for whom that result could not be explained by recent vaccination, there were 2 pairs of neighbors. This instance of urban yellow fever transmission was limited in both time and space.

Detection and genetic relationship of dengue virus sequences in seventeen-year-old paraffin-embedded samples from Cuba.

This study describes the use of the reverse transcriptase-polymerase chain reaction (RT-PCR) to generate dengue 2 amplicons from paraffin-embedded autopsy tissues collected in Cuba 17 years ago. The presumptive diagnoses had been made only by clinical evolution without serologic confirmation. This study confirms once again that dengue 2 virus was directly associated with the fatal cases in children and illustrates the potential of the RT-PCR for retrospective diagnosis of dengue cases 17 years after death. A close similarity in the genomic sequences of the dengue 2 RNA detected in tissue samples from fatal cases and those dengue 2 Cuban strains that had been previously investigated confirms the appropriate genomic classification of the etiologic agent associated with the 1981 dengue hemorrhagic fever Cuban epidemic.

[Epidemic outbreak of dengue virus 2/Jamaica genotype in Bolivia]. / Brote epidémico de denguevirus 2, genotipo Jamaica, en Bolivia.

OBJECTIVE: To confirm an epidemic outbreak of Dengue virus in the city of Santa Cruz, Bolivia, and to determine the serotype of the virus, to estimate the rate of attack and the proportion of symptomatic infections. MATERIAL AND METHODS: In March 1997, a seroepidemiological survey was conducted with random sampling in a central district of the city of Santa Cruz, Bolivia. Information on recent acute illness and febrile episodes was gathered, and venous blood samples were obtained. Levels of antidengue IgM were determined by MAC Elisa and the virus was typified with RT-PCR. RESULTS: IgM antibodies were detected in 6.5% of adults (CI 95% 3.4-9.6) and 5.1% of children (CI 95% 2.0-8.2). Circulating virus was identified as Dengue serotype 2, subgroup Jamaica. Less than half of the infected children experienced a symptomatic infection compared to almost 90% of adults. CONCLUSIONS: The estimated attack rates are compatible with a Dengue epidemic outbreak in Santa Cruz. The introduction of the serotype 2/ subgroup Jamaica virus into the country increases the risk of hemorrhagic Dengue.

Viral isolation from cases of epidemic neuropathy in Cuba.

OBJECTIVE: To investigate the possibility of a viral agent in the central nervous system of patients with epidemic neuropathy. DESIGN: Virus isolation attempts, in cell cultures and suckling mice, from cerebrospinal fluid (CSF) of neuropathy patients and controls undergoing lumbar puncture for unrelated reasons. Serologic studies in patients, contacts, and controls. SETTING: An epidemic of optic and peripheral neuropathy affected more than 50,000 people in Cuba in 1991 through 1993. Illness was associated with dietary limitations and increased physical demands accompanying the shortages of food and fuel experienced in Cuba since 1989. Most patients responded to parenteral vitamin therapy, and the epidemic began to subside when oral vitamin supplementation was begun for the entire Cuban population. RESULTS: Coxsackievirus A9 (five isolates) and a similar, less cytopathic virus (100 isolates) were recovered from 105 (84%) of 125 CSF specimens from neuropathy patients. The strains with light cytopathic effect were antigenically related to Coxsackieviruses A9 and B4 by cross-neutralization and immunoblotting assays. Virus persisted in CSF of some patients for 1 to 12 months. Cerebrospinal fluid from patients and both types of virus from cell culture produced illness, including complete posterior flaccid paralysis, in newborn mice, and virus was reisolated from the mice. Mouse tissues and sural nerve biopsy specimens from patients were stained by immunoperoxidase and colloidal gold techniques using hyperimmune rabbit antisera against the virus with light cytopathic effect. CONCLUSIONS: Coxsackievirus A9 or an antigenically related agent with a light cytopathic effect was present in CSF of 84% of 125 patients with epidemic neuropathy. The role of these agents, probably in combination with nutritional factors, in the pathophysiology of the disease requires further investigation.

[Dengue in Panama, 1993]. / Dengue en Panamá, 1993.

Up to 1993, Panama was the only country in Central America where the autochthonous transmission of dengue virus had been detected without experimenting an explosive epidemic despite being reinfected with the Aedes aegypti mosquito since 1985. The characteristics of this first outbreak reported on November 19, 1993, are described in this paper. It is shown that even when there is a Program for the Surveillance and Control of Dengue, which considers low levels of Aedes aegypti infection and a system for the early detection of the virus, the epidemics appear if the community does not take an active part as it happened in 1994, 1995, and 1996. The 14 cases reported were located in an area under the responsibility of the Health Center in San Isidro, Belisario Porras, Special District of San Miguelito, in Panama City (13 cases in 4 blocks of the sector of Santa Librada and 1 case in San Isidro Valley). 3 patients were under 15 and 8 over 36, the other 3 were between 15 and 24.9 were females. The dengue type 2 virus was isolated in 3 patients. The presence of IgM and IgG antibodies to dengue was demonstrated in 11 patients, whereas in 8 over 20 it was observed a secondary type answer. According to the clinical picture, the epidemic was classified as dengue fever. The seroepidemiological survey carried out in the sector of Santa Librada and its surroundings 5 months after the appearance of the symptoms in the first case showed a prevalence of antibodies to dengue of 5.7% (46/802), mainly among individuals over 44. These results confirmed that the outbreak was geographically limited.

[Standardization of immunohistochemical techniques for detecting dengue virus antigens in paraffin-embedded tissues]. / Normalización de técnicas inmunohistoquímicas para la detección de antígenos del virus dengue en tejidos embebidos en parafina.

The immunohistochemical techniques may be very useful for the detection of antigens of the dengue virus in infected tissues. The results obtained with the use of 2 IHC methods: one direct and another indirect amplified with a biotin universal antibody and a streptavidin peroxidase system (LSAB) (the peroxidase enzyme is used in both) are shown in this paper. These methods were applied on paraffin-embedded tissues from mice that were inoculated with the dengue virus intracerebrally. Our objective is to have a technique at the laboratory allowing to identify these antigens in the tissues in order to apply them on the diagnosis and on the studies connected with the obtention of immunogens.

Dengue en Santa Cruz de la Sierra-Bolivia / Dengue in Santa Cruz de la Sierra-Bolivia

Se presentan los resultados del programa de vigilancia epidemiologica de dengue implementado en Santa Cruz, desde enero de 1996 a abril de 1997 se analizaron 522 muestras de sangre de casos con sospechas sospecha clinica de dengue obteniendose un test Mac-Elisa positivo en 233 (44,6 por ciento). Usando el procedemiento de reaccion en cadena de la polimerasa (RCP) se identifico el serotipo DEN-2 y por estudios geneticos realizados en el CDC de Puerto Rico se identifico a la cepa Jamaica como el agente causal del brote. Las manifestaciones clinicas con mejor valor predictivo positivo fueron el rash maculo-papular (VPP 65 por ciento), dolor ocular (VPP 51 por ciento) y mialgias (VPP 46 por ciento). la mayor incidencia de caso se observo los meses de mayor calor y lluvias copiasas. Se registraron casos en diferentes localidades de la region tropical del pais. Dado el antecedente de un brote por DEN-1 en 1987-88 y ante la presencia actual del DEN-2 en el pais, existe riesgo de observar casos de dengue hemorragico

Capacidad diagnostica para Dengue del Centro Nacional de Enfermedades Tropicales / Diagnostic capacity for dengue at the National Center of Tropical Diseases of Santa Cruz

Mientras mayor capacidad diagnostica tenga el centro de referencia en un pais (variedad de tecnicas confiables y personal calificado), y cuente con la posibilidad de un sistema de vigilancia epidemiologica acorde a las caracteristicas de circulacion viral que tenga el mismo, mejor sera su capacidad de respuesta rapida ante cualquier emergencia o cambio en los acontecimientos duarnte la vigilancia. Con el empleo de las tecnicas descritas, el CENETROP COMO CENTRO de referencia posee actualmente las herramientas necesarias para monitorear con base de laboratorio, la situacion del dengue en el pais y dar informacion certera y fidedigna de lo que acontece. Esto posibilita tomar las medidas necesarias por los organizmos competentes acorde a la situacion epidemiologica que exista en el pais

[Direct sequencing of an amplified product from a serum sample]. / Secuenciación directa de un producto amplificado de una muestra de suero.

It is reported the nucleotide and amino acidic sequence of a great variability region in the dengue 2 virus genome, starting from the RNA of the original virus with no passage in the isolation systems. It is compared with the first strain of dengue 2 isolated during the 1981 epidemic with 4 passages in lactating mouse. Results show that the nucleotide sequence of serum and of strain A15 are the same.

[Surveillance of St. Louis encephalitis, Eastern equine and Western equine in the province of Ciego de Avila]. / Vigilancia de las encefalitis de San Luis, equina del este y equina del oeste en la provincia Ciego de Avila.

Serological studies were carried out using the haemagglutination inhibition and neutralization tests so as to know the circulation dynamics of some arboviruses with the use of Western and Eastern equine encephalitis antigens and St Louis encephalitis antigens in human serum from sound and symptomatic individuals, as well as from sentinel birds, between 1987 and 1991, and during 1994. 1.7% of the asymptomatic subjects tested presented neutralizing antibodies to to Eastern equine and 4.8% to St Louis encephalitis. 16 patients with seroconversion by haemagglutination inhibition to St Louis virus were detected. Surveillance of sentinel birds showed that during 1988, 1989, and 1994. St. Louis circulated in the municipalities of Morón, Bolivia and Chambas; whereas in the latter the Eastern equine encephalitis circulated in 1988 and 1989. Antibodies to Western equine encephalitis were detected in sound individuals by haemagglutination inhibition due seemingly to heterologous antibodies, since there were no neutralizing antibodies against this virus.

Partial nucleotide and amino acid sequences of the envelope and the envelope/nonstructural protein-1 gene junction of four dengue-2 virus strains isolated during the 1981 Cuban epidemic.

In 1981, an epidemic of dengue hemorrhagic fever (DHF) caused by dengue-2 virus occurred in Cuba. This was the first DHF epidemic reported in the Western Hemisphere. In this study, we have analyzed four dengue-2 Cuban strains for two short genomic fragments: one on the envelope (E) glycoprotein and one at the E/nonstructural protein-1 (NS1) gene junction. The E segment of these 1981 Cuban isolates were more closely related to older dengue-2 virus strains such as New Guinea C 1944, Thailand 1964, Sri Lanka 1968, and Burma 1976 than to more recent isolates of this virus from Jamaica and Vietnam. More than 9% of the divergence with strains isolated from Jamaica and Vietnam was observed at the E/NS1 gene junction. One nucleotide change was observed between the first strain isolated during the epidemic and the rest of the Cuban strains. This mutation induced a nonconserved amino acid change from phenylalanine to leucine at position 43 that was not observed in any of the other strains with which it was compared.

[Cuban epidemic neuropathy. I. Viral isolation]. / Neuropatía epidémica cubana. Parte I. Aislamiento viral.

From the end of 1991 to June, 1993, an epidemic neuropathy affecting 50,963 persons occurred in Cuba. Two clinical forms of the disease were observed: the optic form (with or without peripheral manifestations, 52% of the cases) and the peripheral form (48%). The epidemiological studies revealed nutritional disorders, mainly a vitamin B complex deficiency due to economic difficulties faced by the country in the "special period". Smoking habit and alcohol consumption were identified as risk factors, particularly for the most severe forms of the disease. In the virological studies of the cerebrospinal fluid (CSF) a Coxsackie 9 virus was isolated in Vero cells in 4% of the cases, as well as another agent with mild cytopathogenic effect in 80% of the samples. Sixty seven percent of the CSF samples inoculated to lactating mice caused the disease or the death of the animals. The viral persistence was confirmed in the cerebrospinal fluid during al least 21 days in a group of patients, and for a year in another group.

[An immunoenzyme assay for the detection of monoclonal antibodies against the E and NS1 proteins of the dengue virus]. / Ensayo inmunoenzimático para la detección de anticuerpos monoclonales contra las proteínas E y NS1 del virus dengue.

The ELISA was standardized to detect monoclonal antibodies of dengue virus proteins E and NS1. One indirect ELISA was applied, using C6-36 cells inoculated with the A-15 strain, isolated during the dengue 2 epidemic in 1981 as an antigen source. These cells were fixed in ELISA plates at a 200,000 cell/well concentration. A cell control in similar conditions was used. Specific monoclonal antibodies to both proteins were used to standardize the system. Studies at different incubation periods, to determine the highest expression moment of these proteins in the cell membrane, were carried out. The results show a full response at 72 hours postinoculation for both proteins; a 14.7 ng/mL sensitivity was obtained for the detection of NS1, and of 1.43 ng/mL for E protein. This system allows the monoclonal antibodies primary screening to dengue 2 virus E and NS1 proteins.

[The use of ELISA and indirect immunofluorescence technics for the rapid detection of eastern equine encephalomyelitis]. / Utilización de las técnicas ELISA e inmunofluorescencia indirecta para la detección rápida de la encefalomielitis equina del este.

We present the results attained in the identification of Eastern equine encephalomyelitis virus isolations in Vero and XL-2 cell systems, using a double-antibody ELISA technique and the indirect immunofluorescence method. The results attained through these two techniques coincided by 100% with identification through neutralization. With the former, the virus was detected within 6-8 hours after inoculation. Better results were attained with XL-2 cells.

[Ecological parameters of arbovirus circulation on the north coast of Havana. I. Collection of culicids in the Guajaibon region]. / Apuntes ecológicos sobre la circulación de arbovirus en la costa norte de la provincia La Habana. I. Colecta de culícidos en la región de Guajaibón.

We show the culicids collected in the Guajaibón zone, in Havana Province, in order to characterize the present population according to ecological parameters and the possible risk for man. We show that Aedes scapularis is numerically and ecologically dominant over the rest of the species that attack men, as well as the possible indirect influence of culicid populations in crab caves upon human beings.