- Author: Kathy Keatley Garvey
The study, published in the Public Library of Science (PLOS), Neglected Tropical Diseases, contradicts the long-held assumption that once you're infected with a particular dengue serotype, you won't get it again.
“Our most significant result from this study is that immunity to dengue viruses does not always provide perfect protection from reinfection,” said principal investigator and medical entomologist Thomas Scott, distinguished professor and now emeritus, UC Davis Department of Entomology and Nematology. “The public health implications include evaluation of dengue vaccines, interpretation of a person's virus exposure history and susceptibility to new infections, and design of dengue surveillance programs.”
Dengue infects 400 million people worldwide each year, and 4 billion people or nearly half of the world's population are at risk for dengue,” said Scott, who has studied dengue more than 25 years and is recognized as a leading expert in the ecology and epidemiology of the disease. “There is no vaccine nor drug that is effective against this virus.”
“This finding could help explain results of dengue vaccine trials that showed poor efficacy against one of the four serotype,” Stoddard said. “It also has broad implications for vaccine development.”
The research team investigated the "validity of the fundamental assumption" by analyzing a large epidemic caused by a new strain of DENV-2 that invaded Iquitos, Peru, in 2010-2011, 15 years after the first outbreak of DENV-2 in the region.
"Our data indicates that protection from homologous DENV re-infection may be incomplete in some circumstances, which provides context for the limited vaccine efficacy against DENV-2 in recent trials," the research team wrote. "Further studies are warranted to confirm this phenomenon and to evaluate the potential role of incomplete homologous protection in DENV transmission dynamics."
Scott and Amy Morrison of the Scott lab and U.S. Naval Medical Research Unit, co-directed the project in Iquitos. The paper is also the work of Sandra Olkowski and Kanya Long of the Scott lab; Robert Reiner of Andrews University, Berrien Springs, Mich., and the Fogarty International Center; Brett Forshey, Angelica Espinoza, Stalin Vilcarromero, Tadeusz J. Kochel and Eric Halsey of the U.S. Naval Medical Research Unit; Helen Wearing, University of New Mexico, Alburquerque; and Wilma Casanova, Universidad Nacional de la Amazonía Peruana, Iquitos, Perú.
While vaccines are under development, it is not clear how they can be best applied when they are available, including in combination with other interventions like mosquito control, Scott said. “New disease prevention tools, in addition to vaccines, and an improved understanding of virus transmission dynamics, which will enhance surveillance and epidemic response, are needed to reduce the global burden of dengue.”
The paper, “Incomplete Protection against Dengue Virus Type 2 Re-infection in Peru,”
is online at
http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004398
Related Links:
- Author: Kathy Keatley Garvey
The review, co-authored by Nansen and Norman Elliott of the U.S. Department of Food and Agriculture's Agricultural Research Service, Stillwater, Okla., explains remote sensing and highlights how it influences entomological research by “enabling scientists to nondestructively monitor how individual insects respond to treatments and ambient conditions. Furthermore, novel remote sensing technologies are creating intriguing interdisciplinary bridges between entomology and disciplines such as informatics and electrical engineering.”
“To most people, remote sensing refers to imaging-and reflectance-based surveying mounted on airborne devices and vehicles such as airplanes or satellites,” they pointed out. They rely on a broader definition: “The measurement or acquisition of information of some property of an object or phenomenon by a recording device that is not in physical or intimate contact with the object or phenomenon under study.”
“Consequently, even imaging through a microscope may be considered a type of remote sensing,” they wrote. “In many remote sensing applications, the data are collected in parts of the radiometric spectrum that are not detectable by the human eye…We wish to emphasize that entomological remote sensing is expanding in many directions and creating intriguing opportunities for collaborative research between entomology and disciplines such as informatics and electrical engineering. “
Remote sensing has been an established research discipline for more than four decades, Nansen related. “It was Isaac Newton who discovered that light could be separated into a spectrum of colors, and approximately 100 years later, James Clerk Maxwell discovered that light as we see it is part of a very wide radiometric spectrum.”
(See the Nansen/Elliott review at http://www.annualreviews.org/doi/abs/10.1146/annurev-ento-010715-023834)
The Annual Review of Entomology, launched in 1956, reviews significant developments in the field of entomology, including biochemistry and physiology, morphology and development, behavior and neuroscience, ecology, agricultural entomology and pest management, biological control, forest entomology, acarines and other arthropods, medical and veterinary entomology, pathology, vectors of plant disease, genetics, genomics, and systematics, evolution, and biogeography.
Nansen, who joined the UC Davis Department of Entomology and Nematology in 2015, is focusing on four major themes: host plant stress detection, host selection by arthropods, pesticide performance, and use of reflectance-based imaging in a wide range of research applications.
He is using his international expertise to zero in on more sustainable farming systems, better food production and fewer pesticides.
“The agricultural sector in California is so exciting, because of its diversity and economic importance,” said Nansen, whose agricultural entomology expertise encompasses seven countries including his native Denmark. “Secondly, there is a strong spirit of innovation in this region, and I hope to contribute to the development of highly advanced crop monitoring systems and decision support tools, so that farming practices can become less reliant on pesticides.”
Born and educated in Denmark, Nansen received his master's degree in biology from the University of Copenhagen in 1995 and his doctorate in zoology from the Royal Veterinary and Agricultural University in Denmark in 2000. He accepted positions in Portugal, Benin, United States, UK and Australia before joining the UC Davis Department of Entomology and Nematology in January as an assistant professor. Nansen previously held faculty positions at Texas A&M, Texas Tech, and most recently at the University of Western Australia.
His international experience also includes being an international exchange student at the University of Lisbon, Portugal and a visiting professor at Northwest A&F University, Yangling, China.
Related Link:
Christian Nansen's Website
- Author: Kathy Keatley Garvey
The AMCA, founded in 1935, is a scientific and educational public service organization. Its mission is “to provide leadership, information, and education leading to the enhancement of health and quality of life through the suppression of mosquitoes and other vector-transmitted diseases, and the reduction of annoyance levels caused by mosquitoes and other vectors and pests of public health importance.”
The plaque reads: “In recognition of outstanding service to the AMCA and for contributions to the science of mosquito ecology and bionomics and to the epidemiology and control of arboviruses."
Working closely with the Mosquito and Vector Control Association of California and the California Department of Public Health, he was instrumental in molding the California arbovirus surveillance diagnostics, data management and reporting statewide into an effective decision support system for intervention.
Reisen accepted the award on behalf of his collaborators, colleagues and staff at UC Berkeley and UC Davis, and acknowledged “the important impact that the Mosquito and Vector Control Association of California and the California Department of Public Health has had on our program's success.”
Reisen, who retired from UC Davis in 2014 from some of his responsibilities, is a professor emeritus with the Department of Pathology, Microbiology and Immunology (PMI), School of Veterinary Medicine, and a former director of the Center for Vectorborne Diseases. He continues to serve as editor-in-chief of the Journal of Medical Entomology, published by Entomological Society of America. He has served as a graduate student advisor for the UC Davis Department of Entomology and Nematology as well as the Epidemiology Graduate Group.
Reisen earlier received the 2015 Meritorious Service Award from the Mosquito and Vector Control Association of California (MVCAC). He has published more than 300 peer-reviewed publications and book chapters in the field of medical entomology.
Throughout his career, he directed collaborative projects ranging from field evaluations of genetically modified mosquitoes to aerial applications of insecticides, the vector competence of mosquitoes for endemic and newly introduced viruses, established new molecular surveillance testing paradigms for arboviruses, and initiated interactive networks for sharing surveillance data with mosquito control agencies and public health officials to speed mosquito control response times and to minimize disease risk to humans, according to Craig Downs, general manager of the Contra Costa MVCAC District.
“Several examples of his continual scientific contributions include: the effects of climate variation on arthropod-borne pathogen transmission, modeling efforts for predicting arbovirus risk, the application of insecticides for reducing the disease burden of West Nile virus in California, the use of liquid suspension array technologies for the identification of mosquito blood meals and his keen observation of the role of stagnant swimming pools as breeding sites for Culex spp. vectors in Kern County,” Downs said.
Reisen's medical entomology career includes the U.S. Air Force, University of Maryland School of Medicine, UC Berkeley School of Public Health and the Center for Vectorborne Diseases at UC Davis School of Veterinary Medicine. He directed the Arbovirus Field Station in Bakersfield from 1980-2013 and the Center for Vectorborne Diseases, based at UC Davis, from 2009 to 2014.
In recognition of his contributions to research, service and graduate training, he was awarded Lifetime Award for Achievement in Medical Entomology and the Distinguished Service Award by the Society for Vector Ecology; Fellow, Entomological Society of America; Academic Federation Award for Excellence in Research, University of California, Davis; John N. Belkin Award for Excellence in Vector Ecology, American Mosquito Control Association; and the Harry Hoogstraal Medal, American Society of Tropical Medicine and Hygiene.
Thomas Scott, emeritus professor of entomology at UC Davis and known for his work on the yellow-fever or dengue mosquito, described Reisen as “an international leader in mosquito ecology and arbovirus epidemiology. His contributions to his field of study are stunning. His prolific, detailed field and laboratory studies have reshaped the way we think about mosquito-borne pathogen transmission dynamics. He has greatly improved disease prevention programs.”
A native of New Jersey, Reisen holds a doctorate in zoology (1974) from the University of Oklahoma, Norman, with a focus on medical microbiology and ecology.
- Author: Kathy Keatley Garvey
Integrated pest management specialist Frank Zalom, distinguished professor of entomology, UC Davis Department of Entomology and Nematology, and plant pathologist Mysore "Sudhi" Sudarshana with the U.S. Department of Agriculture's Agricultural Research Service, based at UC Davis, organized the webinar. The event is supported by the Regional IPM centers as part of the U.S. Department of Food and Agriculture's National Institute of Food and Agriculture (NIFA).
Registration is underway at https://attendee.gotowebinar.com/register/536624718414291457
GRB and the virus associated with it have been confirmed in many major grape production regions of the United States and Canada, said Zalom, the lead author of the newly published Regional Pest Alert on the North Central IPM Center website. Several research teams across North America, Zalom said, “have been intensely characterizing the disease and effects on grapevines, as well as characterizing the virus, its spread and potential management” since the discovery of the virus in 2011.
Zalom cited considerable progress, “but much remains unknown. Speakers representing many of the labs will present their work and what it means for the grape industry.”
“Red leaf symptoms that differed from other known red leaf diseases affecting grape foliage were first noticed in vineyards planted with red wine grape cultivars in Napa County, California, in 2008,” he wrote in the Regional Pest Alert. “A virus now known as Grapevine Red Blotch-associated virus (GRBaV) was subsequently identified in grapevines exhibiting red blotch symptoms in 2011. It is now confirmed that red blotch disease is present in many major grape production regions of the United States and Canada.”
The agenda:
- 10 a.m.: Welcome and Introduction
Frank Zalom, UC Davis - 10:05: History of red blotch, symptoms and significance
Mysore "Sudhi" Sudarshana, USDA's Agricultural Research Service, USDA-ARS, Davis, Calif. - 10:20: Etiology of red blotch
Marc Fuchs, Cornell University, Geneva, N.Y. - 10:35: Detection and genetic diversity of the virus
Keith Perry, Cornell University, Ithaca, N.Y. - 10:50: Effect of red blotch on grapevine performance
Rhonda Smith, UC Cooperative Extension, Sonoma County - 11:05 Red blotch situation in Oregon
Vaughn Walton, Oregon State University and Bob Martin, USDA-ARS, Corvallis, Ore. - 11:20: Red blotch and the virus in Canada
S. Poojari, T. Lowery, A-M. Schmidt, M. Rott, W. Mcfadden-Smith, L. Stobbs, and J.R. Urbez-Torres, Agri-Canada - 11:35: Red blotch and the virus in Europe
Jean-Sebastian Reynard, Agroscope, Switzerland - 11:50: Virus spread, disease gradient, and insects
Brian Bahder, Frank Zalom lab, UC Davis - 12:05: Foundation Plant Services (FPS) and National Clean Plant Network (NCPN) protecting the supply chain of grapevines from red blotch
Deborah Golino, FPS, UC Davis - 12:20: Questions and answers
Moderated by Frank Zalom
Related Links:
- Regional Pest Alert on Grapevine Red Blotch-associated virus (PDF on North Central IPM Website)
- Link to Webinar registration: https://attendee.gotowebinar.com/register/536624718414291457
- Biosketches on speakers: http://www.ipmcenters.org/index.cfm/center-products/ipm-eacademy/upcoming-events/red-blotch-speakers/
- Author: Kathy Keatley Garvey
“It's an issue of great concern, especially as current control methods do not appear to be working well,” said Cornel, who does research on the mosquito in Clovis, Fresno County, where it was discovered in June 2013. Simultaneously, the insect was found in the cities of Madera and San Mateo.
“This ongoing widespread invasion and establishment proves that this is no longer a regional issue and has affected many cities and towns in California,” he wrote Feb. 8 in F1000 Research, http://f1000research.com/slides/5-149.
But Cornel is optimistic that the pest management intervention strategies and surveillance and control tactics now underway will help control its spread. Infected Aedes aegypti can transmit dengue, yellow fever, Zika and chikungunya viruses.
The Zika virus, now spreading throughout the Western hemisphere, is an emerging mosquito-borne virus that was first identified in Uganda in 1947 in rhesus monkeys, according to the World Health Organization. It was subsequently identified in humans in 1952 in Uganda and the United Republic of Tanzania. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific.
Despite the mosquito's invasion in parts of the United States, there are no reported cases of locally transmitted Zika virus in California or in the contiguous United States, according to the Centers for Disease Control and Prevention. The cases have all involved travelers returning home from countries plagued with disease outbreaks.
Cornel works with the Consolidated Mosquito Abatement District, based in Fresno County, to tackle the spread of the mosquito there. The district covers 1,058 square miles, including part of Kings County.
How far north in California will the mosquito, commonly known as yellow fever mosquito, spread?
“I don't want to exclude the possibility that it may spread as far north as Sacramento,” said Cornel, who collects, rears and researches mosquitoes from all over the world, including the United States, Mali, Cameroon, Comoros, Tanzania, South Africa and Brazil. “We need to see if it overwinters as eggs or adults or both.”
It's troubling that the mosquito is becoming more and more resistant to pesticides, Cornel said. “We have found that the Aedes aegypti have insecticide resistance genes which likely explains why their ultra-low volume and barrier spray applications have not worked as well as expected.”
At Clovis, Cornel and his colleagues trap mosquitoes in gravid or ovitraps; study overwintering and flight dispersal; and employ mark-release-capture trials to estimate dispersal and population size, needed to plan biological (Wolbachia) and chemical auto-dissemination control strategies. They also engage in “recruiting” mosquitoes to kill other mosquitoes. “We have mosquitoes spread insecticides for us, that is, we turn them into mosquito-control workers through the use of insect growth regulators and biopesticides.”
Their 27-slide document, “Surveillance and Control of Aedes aegypti Mosquito in Clovis, Calif.,” published in F1000 Research details their research with text and maps. It is work of Cornel and Yoosook Lee of UC Davis; Stephen Dobson of the University of Kentucky; Corey Bansfield of MosqMate Inc. and Jodi Holeman, Mark Amireno, Charles Smith and Stephen Mulligan III of the Consolidated Mosquito Control District. In the document, Mulligan, director of the Consolidated Mosquito Control District, describes Aedes aegypti as “the rat of the mosquitoes.”
The California team works with University of Kentucky scientists to develop novel control strategies. One trial involves coating male mosquitoes with insect growth regulators, which are passed on to the females. Males are also infested with a biopesticide or “a good bacteria-like organism,” Wolbachia. “The male transfers it to the female, which affects the ovaries and negatively affects immature development,” Cornel explained. “It's not new, but it's not been employed in large trials.”
Regarding flight dispersal, Cornel has found that “males can fly well over 200 meters in one night from their breeding site. We previously thought it was no more than 60 to 100 meters.”
“The Aedes aegypti fly predominantly during cooler periods of the day,” the medical entomologist said. “When it's too hot, they hang around the shade.” When residents walk at dusk, both male and female mosquitoes can follow them. “Only the females bite but the males will hang around your ankle waiting for the females to arrive.”
The researchers target mosquito breeding sites, primarily yard drains. “Despite the drought and the elimination of visible bodies of water, such as bird baths, pet bowls and flower pots, there's a major issue: yard drains,” Cornel said. “Yard drains installed in new home developments empty into the gutter or street and are cryptic breeding sites for mosquitoes.” He speculates that these mosquitoes are breeding underground.
“These drains are not easily accessible and we can't see the mosquitoes,” Cornel pointed out. “We need to blow out the water and plug these yard drains to eliminate these breeding sites.” He suggests that cities everywhere address this public safety issue and “redesign the yard drains.”
Cornel works with the Consolidated Mosquito Abatement District in setting gravid or “killing traps” in the front yards of homes in Clovis. The traps, which look like five-gallon buckets, contain orchard grass and water. “When the orchard grass decomposes, it releases a plume of chemicals that attracts female Aedes aegypti to lay their eggs in,” Cornel said. A screen prevents them from reaching the water to lay their eggs. The insects adhere to black sticky paper.
It's crucial for the public to become involved, Cornel said. “We have to focus on public education. We have to get the message across to eliminate mosquito breeding sites. We can't go to every house. We must rely on the public to eliminate the breeding sites.”
It's possible—but he hopes not—that what is now a “mosquito nuisance” will result in a disease outbreak.
Related Links:
- Anthony Cornel: Mosquito Man UC Davis Department of Entomology and Nematology
- Anthony Cornel, Kearney Agricultural Research and Extension Center
- Yoosook Lee, UC Davis Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine
- F1000 Research
- Traps Tested in Clovis (UC ANR)
- Aedes aegypti, California Department of Public Health, Aedes aegypti
- Consolidated Mosquito Control District, based in Fresno County