Portuguesa State Research Articles

Incidental Genital Leptospirosis in Bubalus bubalis males from Portuguesa State, Venezuela

La leptospirosis constituye una importante causa de infertilidad en bóvidos. En Bubalus bubalis, Leptospira spp. infecta el tejido renal, así como los órganos sexuales, por lo que puede excretarse, tanto en orina como en semen. Solo un número limitado de estudios en todo el mundo han investigado la seroprevalencia de la enfermedad en machos bovinos y los riesgos reproductivos relacionados con la eliminación del patógeno en el semen. Se reportan aquí los resultados de la evaluación serológica, microbiológica, seminal e histopatológica de machos bufalinos adultos del municipio Esteller, estado Portuguesa, Venezuela, infectados naturalmente con Leptospira spp. Se evaluaron 17 búfalos mestizos Murrah de 40 meses de edad, previo al beneficio, con 500 kilos de peso promedio, no vacunados, a los cuales se les tomaron muestra de suero sanguíneo, orina, semen y se midió circunferencia escrotal junto a otros parámetros reproductivos. Exclusivamente 15 animales mostraron títulos entre 50 y 200 en la MAT, exclusivamente para L. hebdomadis. Los 2 animales negativos a MAT resultaron positivos en cultivo bacteriológico de orina o semen a Leptospira spp. De 6 animales beneficiados, MAT y bacteriológicamente positivos a leptospira en semen y orina, se extrajeron riñones, testículos y epidídimos para examen histopatológico. De epidídimos y riñónes se aislaron Leptospira spp., no así de testículos. Sin embargo, el diagnóstico histopatológico en testículo y epidídimo indicó degeneración de células seminíferas compatible con infección bacteriana. El riñón presentó nefritis intersticial crónica. Hubo disminución en el promedio de la circunferencia escrotal, baja intención de monta, baja concentración espermática, ausencia de ondas, pocos espermatozoides móviles, baja motilidad espermática y más de 30 % de mortalidad espermática de las muestras de semen evaluadas, indicando baja calidad del eyaculado. Las anomalías seminales mayores y menores superaron las escalas recomendadas para la especie. Se reportan aquí resultados exclusivos de búfalos machos infectados individualmente con L. hebdomadis, excretada por orina y semen, responsable de afectar el tracto reproductivo de manera incidental, ocasionando daños espermáticos, del epidídimo y daño renal, en una explotación mixta arrocera, con presencia de roedores, potenciales transmisores de la leptospirosis.

Standardized Precipitation Index (SPI) For The Characterization Of Meteorological Droughts In The Town Of Guanare, Portuguesa State, Venezuela

The objective of this study was to characterize the meteorological drought in the town of Guanare, Portuguesa state. The information used for the study was obtained from the meteorological data record, from the monthly precipitation series of the Aeropuerto-Guanare meteorological station of the Portuguese state for the period 1982-2015. The Standardized Precipitation Index (SPI) was used for a monthly scale of the period under study, which allowed the identification and description of the drought phenomenon, specifying its intensity, duration, magnitude and frequency of occurrence. According to the SPI values ​​obtained, it was obtained that the level of extreme drought intensity in the locality during the 1982-2015 period was very low, not exceeding 2% and being rare with extremely strong magnitudes. These meteorological drought events occurred coincidentally for the period evaluated between the months of December and March; while the months of highest humidity were between the months of May, June and July. By virtue of the results obtained, it is important to take into account the vulnerability to drought events of the social, water and agricultural sectors of the area.

Leguminous species effect in agroforestry systems in the Portuguesa state. Venezuela

Six leguminous species Frijol bayo (Vigna unguiculata), Frijol white Var. Orituco, Quinchoncho dwarf (Cajanus cajan (L.) Millsp., cv. Aroita), Kudzú tropical (Pueraria phaseoloides), Crotalaria (Crotalaria juncea), Sesbania (Sesbania grandiflora) were established in an agroforest systems to assess his effect on the chemical property of a Alfisol soil at municipality Ospino Portuguese state, at the farm La Yaguara planted with E. urograndis. In a design in random blocks with 7 processings and 4 repetitions, employing STATIXTIS 9.0 to carry out the ANDEVA and for variables where differences are presented the test was employed of Tukey (5%); obtaining as results that in the soil of the farm The Yaguara alone significant differences were found (P<0,05) for the variables relation C/N, CO, Zn, highly significant and differences (P<0,01)for N; being the Sesbania and quinchoncho the best treatment in relation C/N; for CO the frijol blanco and the treatment control; for Zn the quinchoncho and treatment control, frijol blanco and kudzú tropical; in the N quinchoncho and Sesbania. To confirm the generated profit to the agroforestry system analysis were completed foliate to the eucalyptus, finding highly significant differences for P with Frijol blanco and Kudzú and significant for Zn where is quinchoncho and treatment control.

Surveillance for Leishmania asymptomatic infection in endemic foci of cutaneous leishmaniasis in Venezuela: a combination of leishmanin skin test and PCR using blood clots improves detection and enables identification of species.

Little is known about the prevalence of asymptomatic leishmaniasis in Venezuela. The objective of this study was to quantify Leishmania asymptomatic infection in six endemic foci of cutaneous leishmaniasis (CL) in Portuguesa State, Venezuela, where no previous data were available. Study of the prevalence of Leishmania asymptomatic infection was carried out in 841 individuals from six endemic foci of CL in the municipalities Sucre and Ospino, Portuguesa State. We applied the leishmanin skin test (LST) and the internal transcribed spacer 1 (ITS1) PCR to DNA from sera and blood clots of all LST-positive and 20% of LST-negative patients. Of 841 inhabitants tested by LST, 197 returned a positive reaction (23.42%); all of the LST-positives (197) and 121 negatives were screened by nested PCR using serum and blood clots. Among the LST-positive group, 2.54% were PCR-positive with sera, while 44.67% were positive with blood clots. In the LST-negative group, PCR was positive in 2.48% of serum samples and in 38.84% of blood clots. It is recommended that LST and PCR on blood clots are used together to detect exposure and asymptomatic infection and for identification of the Leishmania species.

Seroepidemiological evidence for Taenia solium taeniasis/cysticercosis in three Venezuelan rural communities.

Taenia solium is the most common parasite infection of the brain, causing neurocysticercosis and typically found in rural communities with free-ranging pigs. Identification of transmission in rural areas is essential for its control. Risk factors and transmission of the parasite were evaluated in three rural Venezuelan communities (Valle del Rio and Potrero Largo, Cojedes state; and Palmarito, Portuguesa state) by a questionnaire (112 households) and coprological (492 samples) and serological (433 human and 230 porcine sera) analysis, respectively. Typical risk factors were found in all three communities: free-foraging pig husbandry, deficient sanitary conditions, high open defecation and ignorance of the parasite life cycle. Coprological examinations revealed a high level of soil-transmitted parasites. Importantly, two T. solium adult worm carriers were identified in each of the three communities. Anti-metacestode antibodies and the HP10 secreted metacestode glycoprotein were detected at significant levels in human and porcine sera in Valle del Rio, Potrero Largo and Palmarito. In conclusion, these communities may be considered to be endemic for taeniasis/cysticercosis, and the instigation of an appropriate control programme is recommended.

Transmission of porcine cysticercosis in the Portuguesa state of Venezuela.

The aim of this study was to assess transmission of Taenia solium cysticercosis in Palmarito Arriba, a small village in the rural area of the Portuguesa state of Venezuela, through (1) an evaluation of T. solium transmission risk factors present in the community and (2) serological detection of the secreted metacestode HP10 antigen (HP10 Ag) and of anti-metacestode antibodies in sera from rural pigs. Risk factors associated with transmission of cysticercosis were the following: 100% (23/23) of the households lacked piped water, 87.0% (20/23) of households lacked latrines, 88.0% (100/114) of inhabitants routinely defecated in the open/air, 19.05% (12/63) of the interviewed population had observed proglottids in their stools. More significantly, 9/13 householders breeding pigs reported seeing proglottids in their stools. Of the 25 pigs available for bleeding and serological testing, 64% (16/25) were free roaming and 36% (9/25) were "backyard" animals; 28% (7/25) were seropositive for both the HP10 Ag and antibody, 20.0% (5/25) were seropositive for HP10 Ag alone, and 36.0% (9/25) were seropositive for antibody alone. Given this clear evidence of endemic porcine cysticercosis, further studies are needed to assess and control the level of porcine and human taeniasis and cysticercosis in this and neighboring communities.

A new Miocene vertebrate assemblage from the Río Yuca Formation (Venezuela) and the northernmost record of typical Miocene mammals of high latitude (Patagonian) affinities in South America

Geological explorations of the basal beds of the Río Yuca Formation (Tucupido region, Portuguesa State, western Venezuela) resulted in the recognition of a new vertebrate assemblage that includes eight taxa: the toxodont cf. Adinotherium, a Peltephilidae armadillo, the freshwaters fishes Platysilurus and Phractocephalus, the caiman Purussaurus, an indeterminate dolphin, turtles, and the previously recognized sloth Pseudoprepotherium venezuelanum. When compared with the higher latitudes faunas of Argentina and Chile, the presence of cf. Adinotherium and peltephilids in the Rio Yuca Formation is consistent, but not conclusive, with a Santacrucian to Frisian SALMA age. The associated fauna, as well recent apatite fission track analysis, indicates that the Río Yuca assemblage is more likely younger in age, specifically Middle to Late Miocene. So far, the Miocene localities of the northern part of South America have provided a less prolific fossil record compared to the southern part of the continent (e.g., Santacrucian and Friasian faunas of Patagonia), but the present work documents the surprising occurrence of two taxa (Peltephilidae and Nesodontinae) common in southern high latitude faunas of South America, implying the persistence of the Santacrucian-Friasian genus Adinotherium in younger strata from northern South America, and that peltephilids were much more widespread during the Miocene than previously recognized. The presence of these common Patagonian taxa (Peltephilidae and Nesodontinae) in Río Yuca also supports the hypothesis of prior researchers for the existence of biogeographical connections between the northern and southern portions of South America during the Late Oligocene or Early Miocene, which facilitated faunal interchange between the two regions. Finally, the biogeographical affinities of the freshwater fishes and the giant caiman (Purussaurus) indicate close relationships of the Tucupido region with the ancestral distribution of the Orinocoan–Amazonian drainage system.

5. EL CURRÍCULO EN ACCIÓN COMO CONSTRUCCIÓN SOCIAL Y LA CONTRIBUCIÓN DOCENTE CON LA TRANSFORMACIÓN CURRICULAR

El presente ensayo aborda el currículo en acción como construcción social de los docentes ante la transformación curricular de educación básica que propician los entes gubernamentales del Estado Venezolano. La temática se relaciona con hallazgos en una investigación cualitativa relativa a la referida transformación en la Educación Primaria del Estado Portuguesa. Ante un sistema educacional en constante dinámica comunicacional y de cambios sociales que permean la práctica docente, los profesionales construyen socialmente un conjunto de significados en relación con su accionar ante las directrices oficiales. La tesis opuesta sería suponer a los docentes como entes estáticos frente a las incorporaciones de cambios tecnocráticos educacionales, operarios de los diseños curriculares o reproductores acríticos de informaciones. Desde tal perspectiva dialéctica, se genera una mirada diferente de la labor del docente no solo como actor social comunitario sino como profesional reflexivo, albacea de la excelencia académica

Evolutionary and Ecological Characterization of Mayaro Virus Strains Isolated during an Outbreak, Venezuela, 2010.

In 2010, an outbreak of febrile illness with arthralgic manifestations was detected at La Estación village, Portuguesa State, Venezuela. The etiologic agent was determined to be Mayaro virus (MAYV), a reemerging South American alphavirus. A total of 77 cases was reported and 19 were confirmed as seropositive. MAYV was isolated from acute-phase serum samples from 6 symptomatic patients. We sequenced 27 complete genomes representing the full spectrum of MAYV genetic diversity, which facilitated detection of a new genotype, designated N. Phylogenetic analysis of genomic sequences indicated that etiologic strains from Venezuela belong to genotype D. Results indicate that MAYV is highly conserved genetically, showing ≈17% nucleotide divergence across all 3 genotypes and 4% among genotype D strains in the most variable genes. Coalescent analyses suggested genotypes D and L diverged ≈150 years ago and genotype diverged N ≈250 years ago. This virus commonly infects persons residing near enzootic transmission foci because of anthropogenic incursions.

Mortalidad de vertebrados en la carretera Guanare-Guanarito, estado Portuguesa, Venezuela

Roads directly or indirectly affect the structure, dynamics and function of ecosystems that they traverse. Most studies on the effect of roads on wildlife focus on the evaluation of mortality of vertebrates by vehicle collisions. Despite the extensive road network that exists in Venezuela, studies of wildlife mortality in them are scarce. In this paper, we analyzed the temporal and spatial pattern of vertebrate's collisions along the road Guanare-Guanarito, in Portuguesa state. We travelled 26 times between these towns (74 km) to localize dead vertebrates, at a speed of 50-60km/h. of those trips were conducted from March 13 to October 26, 2010, and 10 additional trips from December 7, 2009 to December 14, 2010; these ones, with the aim to include months and seasons that were insufficiently sampled during the first period. The elapsed time between trips varied from 14 to 37 days. The total distance traveled was 1 924 km. Dead animals found amounted 464 individuals, 66 of them were birds (25 identified species), 130 mammals (15 species) and 268 reptiles (18 species). The species with the highest number of individuals were the snake Leptodeira annulata (n=119), the oppossum Didelphis marsupialis (n=39) and the spectacled caiman Caiman crocodilus (n=33). Excluding domestic animals, the rate of road-killed vertebrates was 0.2282 indiv./km, a figure 28.3% higher than previous studies in the same road. Changes in the relative number of collisions for some species, respect to the numbers reported 20 years ago, were linked to the increase in traffic flow and changes in land use. Road segments with collision rates higher than expected by chance were identified. Collition by cars may be the principal cause of mortality for species like the tamandua (Tamandua tetradactyla) and the giant anteater (Myrmecophaga tridactyla), the last considered a vulnerable species. Some basic measures are proposed to reduce wildlife mortality on the road.

Antibody to Arenaviruses in Rodents, Caribbean Colombia

Antibody to Arenaviruses in Rodents, Caribbean Colombia

Divergence Between Sympatric Rice- and Maize-Infecting Populations of Rhizoctonia solani AG-1 IA from Latin America

ABSTRACT The basidiomycetous fungus Rhizoctonia solani anastomosis group (AG)-1 IA is a major pathogen in Latin America causing sheath blight (SB) of rice. Particularly in Venezuela, the fungus also causes banded leaf and sheath blight (BLSB) on maize, which is considered an emerging disease problem where maize replaced traditional rice-cropping areas or is now planted in adjacent fields. Our goals in this study were to elucidate (i) the effects of host specialization on gene flow between sympatric and allopatric rice and maize-infecting fungal populations and (ii) the reproductive mode of the fungus, looking for evidence of recombination. In total, 375 isolates of R. solani AG1 IA sampled from three sympatric rice and maize fields in Venezuela (Portuguesa State) and two allopatric rice fields from Colombia (Meta State) and Panama (Chiriquí State) were genotyped using 10 microsatellite loci. Allopatric populations from Venezuela, Colombia, and Panama were significantly differentiated (Phi(ST) of 0.16 to 0.34). Partitioning of the genetic diversity indicated differentiation between sympatric populations from different host species, with 17% of the total genetic variation distributed between hosts while only 3 to 6% was distributed geographically among the sympatric Venezuelan fields. We detected symmetrical historical migration between the rice- and the maize-infecting populations from Venezuela. Rice- and maize-derived isolates were able to infect both rice and maize but were more aggressive on their original hosts, consistent with host specialization. Because the maize- and rice-infecting populations are still cross-pathogenic, we postulate that the genetic differentiation was relatively recent and mediated via a host shift. An isolation with migration analysis indicated that the maize-infecting population diverged from the rice-infecting population between 40 and 240 years ago. Our findings also suggest that maize-infecting populations have a mainly recombining reproductive system whereas the rice-infecting populations have a mixed reproductive system in Latin America.

Normas preliminares DRIS desarrolladas para caña de azúcar a partir de un bajo número de muestras

El objetivo de este trabajo fue evaluar la posibilidad de elaborar normas preliminares DRIS, a partir de un bajo número de muestras foliares provenientes de caña de azúcar cultivada en una unidad homogénea de suelos, como alternativa de diagnóstico del equilibrio nutricional en este cultivo. La investigación fue desarrollada en el área de influencia del Central Azucarero Portuguesa, estado Portuguesa, Venezuela. Entre mayo y julio de 2004, se colectaron y analizaron los contenidos de nitrógeno, fósforo, calcio, magnesio, boro, cobre, hierro, manganeso, zinc y sodio de muestras foliares provenientes de 32 áreas de producción de caña de azúcar, con registros históricos de altos rendimientos en tallos, cultivadas en suelos de la serie Agua Blanca (Aquic Haplustoll). Se verificó la normalidad del banco de datos, lo que dio confiabilidad a las normas preliminares DRIS elaboradas, que presentaron diferencias y coincidencias con sus similares encontradas para la caña de azúcar en la literatura. Se reportó la participación del sodio como norma de diagnóstico. Es posible elaborar bancos de datos normales y normas preliminares DRIS para el diagnóstico nutricional de cultivos de caña de azúcar, a partir de un bajo numero de muestras.

Seasonal reproductive biology of two species of freshwater catfish from the Venezuelan floodplains

Oxydoras sifontesi and Pimelodus blochii are seasonal breeder fish. Spawn occurs once a year over a short interval of time, at the beginning of the rainy season. The gonadosomatic index (GSI), and plasma levels of steroid hormones of P. blochii and O. sifontesi were studied from fish samples, collected from the Portuguesa River (Portuguesa State, Venezuela) in 1998 and 2004–2005, respectively. Gonadal tissue samples were obtained and processed for histology. A macroscopic classification of the degree of gonadal maturation was performed using a six-stage maturity scale. Data was analyzed and compared as a function of the gonadal maturation stage. The GSI of both O. sifontesi and P. blochii increases from stages II to V (preparatory and prespawning periods) and decreases in the stage VI (postspawning). In males, the GSI was usually lower than in females. In both species, the higher plasmatic concentration of 17β-estradiol (17β-E) and testosterone (T) were obtained from specimens in stages IV or V. A significant decrease in both hormones was observed in stage VI, except for the males of P. blochii where T concentration did not change between gonadal stages IV–VI. The relevance of these results is discussed in relation to the seasonality and the particular hydrological conditions of the region.

Phytochemical Characterization of Six Sesame (Sesamum indicum L.) Genotypes and Their Relationships with Resistance against the Sweetpotato Whitefly Bemisia tabaci Gennadius

To determine the phytochemical relationship of six sesame (Sesamum indicum L.) genotypes and their resistance against whiteflies (Bemisia tabaci Gennadius), a randomized complete block field trial with six treatments (genotypes) and four replications was conducted in the Microsur growing area of the Municipio Santa Rosalìa, Portuguesa State, Venezuela. Whitefly eggs and nymphs were counted weekly during 6 wk in each experimental plot. At the end of the crop cycle, the presence or absence of eight secondary metabolites from each plant organ in experimental plots was determined. The relationship among the genotypes was observed by means of a phenogram and the respective analyses of principal coordinates. Significantly different characterizations were found on the 19x10 and 43x32 genotypes. An analysis of principal components was conducted with metabolites in the leaves and the values of foliar acidity. This analysis separated the genotypes 19x10 and 43x32 from the other genotypes with the lowest foliar acidity values. These two genotypes harbored the lowest incidence of eggs and nymphs of whiteflies (nearly 10 and 50% of the total incidence in the other genotypes), demonstrating the importance of foliar acidity values of sesame as resistance mechanisms against whiteflies.

Occurrence of Fusarium moniliforme and fumonisins in kernels of maize hybrids in Venezuela

Fusarium moniliforme (FM) incidence and fumonisins (FUM) content were determined in white kernel samples of maize hybrids, harvested in farms of Guarico and Portuguesa states, Venezuela. FM incidence was estimated in subsamples placed on a malt-salt-agar medium. Values in the range of 0-15 % were considered low, from 15-30% intermediate, and more than 30% high. FUM content was quantified through specific immunoassay (Fumonitest, VICAM Sci. Tech., USA) and values above 1 ppm were considered high. The hybrids were compared using a completely randomized design and results were subjected to analysis of variance and mean comparisons. The correlation between FUM content and FM incidence was also estimated. FM and FUM were detected in all of the 89 samples. Mean incidence of FM among hybrids ranged from 26.0 to 72.0% in Portuguesa state (PS) and from 28.7 to 55.7 in Guarico state (GS). Significant differences among hybrids were determined in farms of El Playon and Turen, PS, and El Sombrero and El Socorro, GS. The incidence of FM was high in all hybrids. FUM contents ranged from 0.80 to 10.00 ppm in PS, and from 1.50 to 13.00 ppm in GS. Significant differences among hybrids were found in El Playon, PS, and in both locations of GS. Only in Ospino, PS, the content of FUM was correlated with FM incidence. This indicates the natural occurence of FM strains with different toxigenic capabilities. The results show that Guarico and Portuguesa states are hazardous regions regarding FM and FUM in maize kernels.

Relación hospedador - parásito entre tres cepas de Schistosoma mansoni y seis cepas de Biomphalaria glabrata de áreas endémicas y no endémicas venezolanas

Six lots of 18 B. glabrata from: La Victoria, Turmero, Cagua in Aragua state; Caserio El 25 in Carabobo state, Chabasquen in Portuguesa state and Humocaro Bajo in Lara state, were experimentally infected with miracidia of SM, C5 and C6 strains of Schistosoma mansoni (18 snails/Schistosoma mansoni strain). The averages of the intramolluscal period (IMP) obtained for the S. mansoni strains were very similar and comprised between 35.4 and 36.1 days. No significative statistical differences in the IMP were found according to the S. mansoni strain and the size of snails: < 7 mm and 7 mm. However, significative statistical differences in the IMP were found, in relation to the B. glabrata strain and between the snails classifiel in two groups according to the S. mansoni dose (5 miracidia/snail and 10 miracidia/snail). The higher percentages of infection (PI) were found for the following parasite-snail combinations: C6-Cas. El 25 (80.7%), SM-La Victoria (73.1%) and C5-Cagua (62%). No significative statistical differences were found for the PI a) between the snail classifiel in two groups according to the size (<7 mm and 7 mm), b) in relation to the miracidium dosification (5 and 10 miracidia/ snail and c) in accord to the S. mansoni strain. However, significative statistical differences were found for the PI obtained with different strains of the snail.

Compatibility between nine strains of Biomphalaria glabrata coming from endemic and non-endemic areas and one strain of Schistosoma mansoni from Venezuela

Nine lots of 32 B. glabrata snails (5-7mm in diameter) from the following strains from the endemic area: Cagua, Valencia Lake (Puerta Negra Sector), Ingenio Bolívar (Aragua State), Mariara, Caserío El 25 and Güigüe (Carabobo state), and from the non-endemic area: Anzoátegui (Lara state), Chabasquén (Portuguesa state) and Caripe (Monagas state) were experimentally infected (5 miracidiums/snail) with C5 Schistosoma mansoni strain. The intramolluscal prepatent period oscillated between 23 and 25 days for the nine strains. The duration of intramolluscal infection varied a lot, from 20 days in the case of the Chabasquén strain to 93 days for the Güigüe strain. The average cercariae production in the 3rd day of emission varied from X = 74.4 for the Mariara strain to 591.7 in the case of the Chabasquén strain. Significant statistical differences were found in relation to the total number of emitted cercariae in the 3rd day (H = 97.4; P < 0.05), with significant statistical differences detected among most of the 36 strain combinations, except for the following: Mariara/Ingenio Bolívar, Cagua/Cas. El 25, Valencia Lake/Güigüe and Güigüe/Caripe. The strains of Valencia Lake (88.8%), Cagua (85.2), Chabasquén (82.6%) and Caripe (82.6%) showed the highest rates of self-cure, whereas the Güigüe strain showed the lowest: 21.4%.

Isolation, characterization and geographic distribution of Caño Delgadito virus, a newly discovered South American hantavirus (family Bunyaviridae)

Rodents collected from the Venezuelan llanos (plains) during field studies of viral hemorrhagic fever were tested for evidence of hantavirus infection. Hantavirus antibody was found in one (7.7%) of 13 Oryzomys bicolor, one (3.4%) of 29 Rattus rattus, 10 (6.0%) of 166 Sigmodon alstoni and one (2.2%) of 45 Zygodontomys brevicauda. Hantavirus-specific RNA was detected in lung tissues from four antibody-positive rodents: two S. alstoni from Portuguesa State and one S. alstoni each from Cojedes and Barinas States. A hantavirus isolate (herein identified as VHV-574) was recovered from lung tissue from a hantavirus RNA-positive S. Alstoni collected from Portuguesa State. The results of serological tests and analyses of small and medium RNA segment nucleotide sequence data indicated that VHV-574 represents a novel hantavirus (proposed name ‘Caño Delgadito’) that is distinct from all previously characterized hantaviruses. The results of analyses of nucleotide sequence data from the four hantavirus RNA-positive S. alstoni suggested that Caño Delgadito virus is widely distributed in the Venezuelan llanos.

Field Studies on the Epidemiology of Venezuelan Hemorrhagic Fever: Implication of the Cotton Rat Sigmodon alstoni as the Probable Rodent Reservoir

During February 1992, field studies on the epidemiology of Venezuelan hemorrhagic fever (VHF) were carried out in a rural area of Portuguesa State in central Venezuela. The objective of this work was to determine the prevalence of infection with Guanarito virus, the etiologic agent of VHF, among wild rodents and humans living within an endemic focus of the disease. A total of 234 rodents, representing nine different species, were collected and their spleens were cultured for virus. Thirty-one Guanarito virus isolates were made from two rodent species: 19 from 40 Sigmodon alstoni and 12 from 106 Zygodontomys brevicauda. Guanarito virus antibody rates among these two species were 5.1% and 15.0%, respectively. Nine of the 12 Z. brevicauda that yielded virus from their spleens also had Guanarito virus antibodies in their sera. In contrast, none of the 19 Guanarito virus-positive S. alstoni had antibodies to the virus. These data suggest that S. alstoni usually develops a persistent nonimmunizing infection with Guanarito virus, while Z. brevicauda develops an immunizing infection. Based on knowledge of the behavior of other human pathogenic arenaviruses, these results imply that S. alstoni is the principal rodent reservoir of Guanarito virus in nature. To determine the prevalence of Guanarito virus infection among humans in the same region, 195 people living near one of the rodent collecting sites were bled and their sera were tested for antibodies to the virus. Five individuals (2.6%) had Guanarito virus antibodies; all were adults, and two had been diagnosed previously as having VHF.(ABSTRACT TRUNCATED AT 250 WORDS)