Rudy Bueno

Biological and phylogenetic characterization of pigeon paramyxovirus serotype 1 circulating in wild North American pigeons and doves.

ABSTRACT As part of West Nile virus surveillance programs in Rhode Island and eastern Texas between 2000 and 2007, brain tissue was collected from 5,608 dead birds representing 21 avian orders found in public places or reported by homeowners. Fifteen Newcastle disease virus isolates were recovered only from birds of the order Columbiformes and were positively identified by the USDA-validated real-time reverse transcription-PCR assay targeting the matrix gene and more specifically as pigeon paramyxovirus serotype 1 (PPMV-1) by hemagglutinin inhibition with monoclonal antibodies. Based upon partial genomic sequencing and phylogenetic analysis, the newly isolated viruses represent a distinct sublineage within class II genotype VIb. All of the viruses (15/15) were classified as virulent based upon their fusion cleavage site motif (112RRKKRF117) and intracerebral pathogenicity indices of >0.7 (ranging from 0.98 to1.35); however, these viruses escaped detection by the fusion gene-based real-time PCR test for virulence. Modifications introduced to the probe site of the fusion gene-based assay allowed rapid virulence detection within this distinct sublineage.

Evolution of New Genotype of West Nile Virus in North America

Previous studies of North American isolates of West Nile virus (WNV) during 1999–2005 suggested that the virus had reached genetic homeostasis in North America. However, genomic sequencing of WNV isolates from Harris County, Texas, during 2002–2009 suggests that this is not the case. Three new genetic groups have been identified in Texas since 2005. Spread of the southwestern US genotype (SW/WN03) from the Arizona/Colorado/northern Mexico region to California, Illinois, New Mexico, New York, North Dakota, and the Texas Gulf Coast demonstrates continued evolution of WNV. Thus, WNV continues to evolve in North America, as demonstrated by selection of this new genotype. Continued surveillance of the virus is essential as it continues to evolve in the New World.

Human Plague in the Southwestern United States, 1957–2004: Spatial Models of Elevated Risk of Human Exposure to Yersinia pestis

Abstract Plague is a rare but highly virulent flea-borne zoonotic disease caused by the Gram-negative bacterium Yersinia pestis Yersin. Identifying areas at high risk of human exposure to the etiological agent of plague could provide a useful tool for targeting limited public health resources and reduce the likelihood of misdiagnosis by raising awareness of the disease. We created logistic regression models to identify landscape features associated with areas where humans have acquired plague from 1957 to 2004 in the four-corners region of the United States (Arizona, Colorado, New Mexico, and Utah), and we extrapolated those models within a geographical information system to predict where plague cases are likely to occur within the southwestern United States disease focus. The probability of an area being classified as high-risk plague habitat increased with elevation up to ≈2,300 m and declined as elevation increased thereafter, and declined with distance from key habitat types (e.g., southern Rocky Mountain piñon—juniper [Pinus edulis Engelm. and Juniperus spp.], Colorado plateau piñon-juniper woodland, Rocky Mountain ponderosa pine (Pinus ponderosa P.& C. Lawson var. scopulorum), and southern Rocky Mountain juniper woodland and savanna). The overall accuracy of the model was >82%. Our most conservative model predicted that 14.4% of the four-corners region represented a high risk of peridomestic exposure to Y. pestis.

Identification of Dengue Fever Cases in Houston, Texas, with Evidence of Autochthonous Transmission Between 2003 and 2005

Houston, Texas, maintains an environment conducive to dengue virus (DENV) emergence; however, surveillance is passive and diagnostic testing is not readily available. To determine if DENV is present in the area, we tested 3768 clinical specimens (2138 cerebrospinal fluid [CSF] and 1630 serum) collected from patients with suspected mosquito-borne viral disease between 2003 and 2005. We identified 47 immunoglobulin M (IgM)-positive dengue cases, including two cases that were positive for viral RNA in serum for dengue serotype 2. The majority of cases did not report any history of travel outside the Houston area prior to symptom onset. The epidemic curve suggests an outbreak occurred in 2003 with continued low-level transmission in 2004 and 2005. Chart abstractions were completed for 42 of the 47 cases; 57% were diagnosed with meningitis and/or encephalitis, and 43% met the case definition for dengue fever. Two of the 47 cases were fatal, including one with illness compatible with dengue shock syndrome. Our results support local transmission of DENV during the study period. These findings heighten the need for dengue surveillance in the southern United States.

Genetic variation of St. Louis encephalitis virus

St. Louis encephalitis virus (SLEV) has been regularly isolated throughout the Americas since 1933. Previous phylogenetic studies involving 62 isolates have defined seven major lineages (I–VII), further divided into 14 clades. In this study, 28 strains isolated in Texas in 1991 and 2001–2003, and three older, previously unsequenced strains from Jamaica and California were sequenced over the envelope protein gene. The inclusion of these new sequences, and others published since 2001, has allowed better delineation of the previously published SLEV lineages, in particular the clades of lineage II. Phylogenetic analysis of 106 isolates identified 13 clades. All 1991 and 2001–2003 isolates from Nueces, Jefferson and Harris Counties (Texas Gulf Coast) group in clade IIB with other isolates from these counties isolated during the 1980s and 1990s. This lack of evidence for introduction of novel strains into the Texas Gulf Coast over a long period of time is consistent with overwintering of SLEV in this region. Two El Paso isolates, both from 2002, group in clade VA with recent Californian isolates from 1998–2001 and some South American strains with a broad temporal range. Overall, these data are consistent with multiple introductions of SLEV from South America into North America, and provide support for the hypothesis that in most situations, SLEV circulates within a locality, with occasional incursions from other areas. Finally, SLEV has much lower nucleotide (10.1 %) and amino acid variation (2.8 %) than other members of the Japanese encephalitis virus complex (maximum variation 24.6 % nucleotide and 11.8 % amino acid).

Genetic Stasis of Dominant West Nile Virus Genotype, Houston, Texas

The accumulation and fixation of mutations in West Nile virus (WNV) led to the emergence of a dominant genotype throughout North America. Subsequent analysis of 44 isolates, including 19 new sequences, from Houston, Texas, suggests that WNV has reached relative genetic stasis at the local level in recent years.

Continued evolution of West Nile virus, Houston, Texas, USA, 2002-2012.

We investigated the genetics and evolution of West Nile virus (WNV) since initial detection in the United States in 1999 on the basis of continual surveillance studies in the Houston, Texas, USA, metropolitan area (Harris County) as a surrogate model for WNV evolution on a national scale. Full-length genomic sequencing of 14 novel 2010–2012 WNV isolates collected from resident birds in Harris County demonstrates emergence of 4 independent genetic groups distinct from historical strains circulating in the greater Houston region since 2002. Phylogenetic and geospatial analyses of the 2012 WNV isolates indicate closer genetic relationship with 2003–2006 Harris County isolates than more recent 2007–2011 isolates. Inferred monophyletic relationships of these groups with several 2006–2009 northeastern US isolates supports potential introduction of a novel WNV strain in Texas since 2010. These results emphasize the need to maintain WNV surveillance activities to better understand WNV transmission dynamics in the United States.

ASSOCIATIONS BETWEEN TWO MOSQUITO POPULATIONS AND WEST NILE VIRUS IN HARRIS COUNTY, TEXAS, 2003–06

ABSTRACT Associations between Culex quinquefasciatus, Aedes albopictus and West Nile virus (WNV) activity, temperature, and rainfall in Harris County, Texas 2003–06 are discussed. Human cases were highly correlated to Cx. quinquefasciatus (r = 0.87) and Ae. albopictus (r = 0.78) pools, blue jays (r = 0.83), and Ae. albopictus collected (r = 0.71), but not Cx. quinquefasciatus collected (r = 0.45). Human cases were associated with temperature (r = 0.71), not rainfall (r = 0.29), whereas temperature correlated with Ae. albopictus and Cx. quinquefasciatus collections (r = 0.88 and 0.70, respectively) and Cx. quinquefasciatus pools (r = 0.75), but not Ae. albopictus pools (r = 0.55). Both species (collections and pools) and blue jays were weakly correlated (r ≤ 0.41) with rainfall, but blue jays were better correlated with Cx. quinquefasciatus pools (r = 0.87), compared with Ae. albopictus pools (r = 0.67), Ae. albopictus collections (r = 0.69), and Cx. quinquefasciatus collections (r = 0.46). Peak minimum infection rate for Cx. quinquefasciatus (4.55), and Ae. albopictus (4.41) was in August with highest human cases (17.87), blue jays (55.58), and temperature (29.01°C). Between both species, blood meal analysis indicated 68.18% of Cx. quinquefasciatus mammalian hosts were dog, while 22.72% were human, whereas Ae. albopictus had higher human (44.44%) but fewer dog hosts (22.22%). Ten bird species were identified as hosts for Cx. quinquefasciatus, with northern cardinal and blue jay representing 26.66% and 20.00%, respectively. No bird feeding activity was observed in Ae. albopictus. The earliest and latest human blood meal occurred in May (Ae. albopictus) and November (Cx. quinquefasciatus); 66.66% of human host identifications between both species occurred in October–November, after the seasonal human case peak. Based upon our data, WNV activity in both mosquito species warrants further investigation of their individual roles in WNV ecology within this region.

Changing Socioeconomic Indicators of Human Plague, New Mexico, USA

Plague, a rare but severe disease spread by rodents and fleas, has been traditionally associated with poor, unsanitary living conditions. To test this association, researchers in New Mexico used census data to determine the geographic and socioeconomic status of plague patients. Although they confirmed that most cases occurred in areas where the habitat supports rodents and fleas, they also found a surprising shift to more middle- to upper-class neighborhoods. In the 1980s, most cases occurred where housing conditions were poor. By the 2000s, cases were occurring in the affluent Santa Fe and Albuquerque regions. Although the cause of this shift is unknown, possibilities include relocation of affluent families to plague-prone areas or improved socioeconomic conditions among those already living in plague-prone areas.

A Multiunit CO2 Anesthetizing System for Use in Transferring Mosquitoes During Field Cage Insectcide Efficacy Tests

ABSTRACT A multiunit CO2 delivery and anesthetizing system that supports expanded cage testing of mosquitoes is described. This system has proven more efficient than pipetting for conducting multiple tests and has facilitated the tripling of cage testing capabilities.