Orange County Vector Control District

Costa Mesa, CA, United States

Orange County Vector Control District

Costa Mesa, CA, United States
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Jourdain E.,Linnaeus University | Jourdain E.,French National Institute for Agricultural Research | Olsen B.,Linnaeus University | Olsen B.,Uppsala University | And 10 more authors.
Vector-Borne and Zoonotic Diseases | Year: 2011

A total of 1935 migratory birds from 104 different species were captured in southeastern Sweden in 2005-2006 and tested for antibodies against West Nile virus (WNV). Overall, 46 birds (2.4%; binomial confidence limits, 1.8-3.2) were positive by blocking-ELISA, but only 2 (0.10%; binomial confidence limits, 0.0-0.4) had antibodies detectable by both blocking-ELISA and WNV neutralization test. ELISA-positive birds included long-and short-distance migrants likely exposed to WNV while wintering in or migrating through areas enzootic for WNV. Exposure to a cross-reactive Flavivirus was suspected for short-distance migrants of the Turdidae family, but no cross-neutralization with tick-borne encephalitis and Usutu viruses was observed. © Copyright 2011, Mary Ann Liebert, Inc.

Boyce W.M.,University of California at Davis | Vickers W.,University of California at Davis | Morrison S.A.,Nature Conservancy | Sillett T.S.,Smithsonian Conservation Biology Institute | And 5 more authors.
Vector-Borne and Zoonotic Diseases | Year: 2011

Transmission of West Nile virus (WNV) on mainland California poses an ongoing threat to the island scrub-jay (ISSJ, Aphelocoma insularis), a species that occurs only on Santa Cruz Island, California, and whose total population numbers <5000. Our report describes the surveillance and management efforts conducted since 2006 that are designed to understand and mitigate for the consequences of WNV introduction into the ISSJ population. We suspect that WNV would most likely be introduced to the island via the movement of infected birds from the mainland. However, antibody testing of >750 migrating and resident birds on the island from 2006 to 2009 indicated that WNV had not become established by the end of 2009. Several species of competent mosquito vectors were collected at very low abundance on the island, including the important mainland vectors Culex tarsalis and Culex quinquefasciatus. However, the island was generally cooler than areas of mainland California that experienced intense WNV transmission, and these lower temperatures may have reduced the likelihood of WNV becoming established because they do not support efficient virus replication in mosquitoes. A vaccination program was initiated in 2008 to create a rescue population of ISSJ that would be more likely to survive a catastrophic outbreak. To further that goal, we recommend managers vaccinate >100 ISSJ each year as part of ongoing research and monitoring efforts. © Copyright 2011, Mary Ann Liebert, Inc.

Greenberg L.,University of California at Riverside | Martinez M.,Orange County Vector Control District | Tilzer A.,Orange County Vector Control District | Nelson K.,Orange County Vector Control District | And 2 more authors.
Southwestern Entomologist | Year: 2015

The Orange County Vector Control District treats infestations of red imported fire ants, Solenopsis invicta Buren, with two granular baits, Amdro Pro and Distance, at residences with the ant. Some treatments are subcontracted to pestmanagement professionals who received red imported fire ant certification by the Orange County Vector Control District. During this study, we compared four treatment protocols and assessed their efficacy at suppressing red imported fire ants. At the first post-treatment survey at 3 months, homes in three of the protocols received a single treatment of Amdro Pro. Homes in two of the protocols subsequently received either one follow-up treatment with Distance at 3 months or two follow-up treatments with Distance at 3 and 6 months, respectively. Homes in the fourth protocol received a single treatment of a 50:50 mixture of Amdro Pro and Distance. Most reinfestation by red imported fire ants occurred within the first 3 months after the initial treatment, with failure ranging from 29-40%. Although the failure rate was slightly higher for the treatment with the mixture compared to Amdro Pro alone (40 versus 33%, respectively), failure rates did not differ significantly between these treatments. Thereafter and until 9 months later, treatment failures were <10% among residences without red imported fire ants at 3 months. The differences among the protocols were not significant for any of the time periods. At 9 months, there was a small increase in failures compared to 6 months, indicating more red imported fire ants had moved in from surrounding areas or the original colonies were starting to recover. Additional treatments would be necessary to maintain a low level of infestation. We also recorded the identification and frequency of other ant species seen at homes inspected for red imported fire ants.

Eremeeva M.E.,Rickettsial Zoonoses Branch | Eremeeva M.E.,Georgia Southern University | Karpathy S.E.,Rickettsial Zoonoses Branch | Krueger L.,Center for Infectious Diseases | And 10 more authors.
Journal of Medical Entomology | Year: 2012

Results of an environmental assessment conducted in a newly emergent focus of murine typhus in southern California are described. Opossums, Didelphis virginiana Kerr, infested with cat fleas, Ctenocephalides felis Buch, in the suburban area were abundant. Animal and flea specimens were tested for the DNA of two flea-borne rickettsiae, Rickettsia typhi and Rickettsia felis. R. felis was commonly detected in fleas collected throughout this area while R. typhi was found at a much lower prevalence in the vicinity of just 7 of 14 case-patient homes identified. DNA of R. felis, but not R. typhi, was detected in renal, hepatic, and pulmonary tissues of opossums. In contrast, there were no hematologic polymerase chain reaction findings of R. felis or R. typhi in opossums, rats, and cats within the endemic area studied. Our data suggest a significant probability of human exposure to R. felis in the area studied; however, disease caused by this agent is not recognized by the medical community and may be misdiagnosed as murine typhus using nondiscriminatory serologic methods. © 2012 Entomological Society of America.

Milazzo M.L.,University of Texas Medical Branch | Cajimat M.N.B.,University of Texas Medical Branch | Mauldin M.R.,Texas Tech University | Bennett S.G.,Orange County Vector Control District | And 4 more authors.
Vector-Borne and Zoonotic Diseases | Year: 2015

The objective of this study was to advance our knowledge of the epizootiology of Bear Canyon virus and other Tacaribe serocomplex viruses (Arenaviridae) associated with wild rodents in California. Antibody (immunoglobulin G [IgG]) to a Tacaribe serocomplex virus was found in 145 (3.6%) of 3977 neotomine rodents (Cricetidae: Neotominae) captured in six counties in southern California. The majority (122 or 84.1%) of the 145 antibody-positive rodents were big-eared woodrats (Neotoma macrotis) or California mice (Peromyscus californicus). The 23 other antibody-positive rodents included a white-throated woodrat (N. albigula), desert woodrat (N. lepida), Bryant's woodrats (N. bryanti), brush mice (P. boylii), cactus mice (P. eremicus), and deer mice (P. maniculatus). Analyses of viral nucleocapsid protein gene sequence data indicated that Bear Canyon virus is associated with N. macrotis and/or P. californicus in Santa Barbara County, Los Angeles County, Orange County, and western Riverside County. Together, analyses of field data and antibody prevalence data indicated that N. macrotis is the principal host of Bear Canyon virus. Last, the analyses of viral nucleocapsid protein gene sequence data suggested that the Tacaribe serocomplex virus associated with N. albigula and N. lepida in eastern Riverside County represents a novel species (tentatively named ''Palo Verde virus'') in the genus Arenavirus. © 2015 Mary Ann Liebert, Inc.

Zhong D.,University of California at Irvine | Lo E.,University of California at Irvine | Cummings R.,Orange County Vector Control District | Bonizzoni M.,University of California at Irvine | And 8 more authors.
PLoS ONE | Year: 2013

The Asian tiger mosquito, Aedes albopictus, is an anthropophilic aggressive daytime-biting nuisance and an efficient vector of certain arboviruses and filarial nematodes. Over the last 30 years, this species has spread rapidly through human travel and commerce from its native tropical forests of Asia to every continent except Antarctica. In 2011, a population of Asian tiger mosquito (Aedes albopictus) was discovered in Los Angeles (LA) County, California. To determine the probable origin of this invasive species, the genetic structure of the population was compared against 11 populations from the United States and abroad, as well as preserved specimens from a 2001 introduction into California using the mitochondrial cytochrome c oxidase 1 (CO1) gene. A total of 66 haplotypes were detected among samples and were divided into three main groups. Aedes albopictus collected in 2001 and 2011 from LA County were genetically related and similar to those from Asia but distinct from those collected in the eastern and southeastern United States. In view of the high genetic similarities between the 2001 and 2011 LA samples, it is possible that the 2011 population represents in part the descendants of the 2001 introduction. There remains an imperative need for improved surveillance and control strategies for this species.

Harrigan R.J.,University of California at Los Angeles | Thomassen H.A.,University of California at Los Angeles | Buermann W.,University of California at Los Angeles | Cummings R.F.,Orange County Vector Control District | And 2 more authors.
PLoS ONE | Year: 2010

Understanding the conditions underlying the proliferation of infectious diseases is crucial for mitigating future outbreaks. Since its arrival in North America in 1999, West Nile virus (WNV) has led to population-wide declines of bird species, morbidity and mortality of humans, and expenditures of millions of dollars on treatment and control. To understand the environmental conditions that best explain and predict WNV prevalence, we employed recently developed spatial modeling techniques in a recognized WNV hotspot, Orange County, California. Our models explained 85-95% of the variation of WNV prevalence in mosquito vectors, and WNV presence in secondary human hosts. Prevalence in both vectors and humans was best explained by economic variables, specifically per capita income, and by anthropogenic characteristics of the environment, particularly human population and neglected swimming pool density. While previous studies have shown associations between anthropogenic change and pathogen presence, results show that poorer economic conditions may act as a direct surrogate for environmental characteristics related to WNV prevalence. Low-income areas may be associated with higher prevalence for a number of reasons, including variations in property upkeep, microhabitat conditions conducive to viral amplification in both vectors and hosts, host community composition, and human behavioral responses related to differences in education or political participation. Results emphasize the importance and utility of including economic variables in mapping spatial risk assessments of disease. © 2010 Harrigan et al.

Molaei G.,Center for Vector Biology and Zoonotic Diseases | Cummings R.F.,Orange County Vector Control District | Su T.,West Valley Mosquito and Vector Control District | Armstrong P.M.,Center for Vector Biology and Zoonotic Diseases | And 3 more authors.
American Journal of Tropical Medicine and Hygiene | Year: 2010

Southern California remains an important focus of West Nile virus (WNV) activity, with persistently elevated incidence after invasion by the virus in 2003 and subsequent amplification to epidemic levels in 2004. Eco-epidemiological studies of vectors-hosts-pathogen interactions are of paramount importance for better understanding of the transmission dynamics of WNV and other emerging mosquito-borne arboviruses. We investigated vector-host interactions and host-feeding patterns of 531 blood-engorged mosquitoes in four competent mosquito vectors by using a polymerase chain reaction (PCR) method targeting mitochondrial DNA to identify vertebrate hosts of blood-fed mosquitoes. Diagnostic testing by cell culture, real-time reverse transcriptase-PCR, and immunoassays were used to examine WNV infection in blood-fed mosquitoes, mosquito pools, dead birds, and mammals. Prevalence of WNV antibodies among wild birds was estimated by using a blocking enzyme-linked immunosorbent assay. Analyses of engorged Culex quinquefasciatus revealed that this mosquito species acquired 88.4% of the blood meals from avian and 11.6% from mammalian hosts, including humans. Similarly, Culex tarsalis fed 82% on birds and 18% on mammals. Culex erythrothorax fed on both birds (59%) and mammals (41%). In contrast, Culex stigmatosoma acquired all blood meals from avian hosts. House finches and a few other mostly passeriform birds served as the main hosts for the blood-seeking mosquitoes. Evidence of WNV infection was detected in mosquito pools, wild birds, dead birds, and mammals, including human fatalities during the study period. Our results emphasize the important role of house finches and several other passeriform birds in the maintenance and amplification of WNV in southern California, with Cx. quinquefasciatus acting as both the principal enzootic and "bridge vector" responsible for the spillover of WNV to humans. Other mosquito species, such as Cx. tarsalis and Cx. stigmatosoma, are important but less widely distributed, and also contribute to spatial and temporal transmission of WNV in southern California. Copyright © 2010 by The American Society of Tropical Medicine and Hygiene.

Canfield M.S.,Animal Dermatology Clinic | Canfield M.S.,Animal Hospital of Regency Park | Wrenn W.J.,Orange County Vector Control District
Veterinary Dermatology | Year: 2010

The purposes of this study were to determine whether the storage mite, Tyrophagus putrescentiae, could survive and thrive on dog food and if mould growth was important to their survival. All of the chambers (n = 42) were started with 10 female mites and evaluated every other day for mite survival and for the spontaneous development of mould. Ten chambers tested the effect of low moisture on mite survival. Eight chambers were used as positive and negative controls (n = 4 each); positive control mites were fed Fleischmann's® yeast and negative controls had no food source. Three dog foods were evaluated in the same manner. Four chambers had food but mould development was limited by replacing the food kernel every 48 h and four chambers were allowed to grow mould. Mites grown in chambers without moisture died from desiccation within 5 days. The termination point was day 34 when all mites in the negative control group (moisture but no food) died. Although T. putrescentiae survived and grew on all three commercial dog foods, there was no statistically significant difference in mites counts among the dog foods (P < 0.10). Mite counts in the 'no' mould and mould groups ranged from 8 to 11 and 144 to 245, respectively, and differences were significant (P < 0.0001). This study found that T. putrescentiae is a fungivorous storage mite that can grow and flourish on dog food. The study demonstrated that the presence of mould positively influences mite viability, while low relative humidity can result in detrimental consequences for T. putrescentiae. © 2009 The Authors. Journal compilation © 2010 ESVD and ACVD.

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