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Articles by Joseph P. Dudley in JoVE
JoVE Immunology and Infection
Snabb diagnos av aviär influensavirus hos vilda fåglar: Användning av en bärbar RRT-PCR och Frystorkad reagenser i Field
1USGS Western Ecological Research Center, 2Wildlife Health Center, University of California, Davis, 3Department of Population Health and Reproduction, University of California, Davis, 4Department of Veterinary and Biomedical Sciences, University of Minnesota, 5Science Applications International Corporation
Denna studie beskriver diagnos av aviär influensa hos vilda fåglar med hjälp av en bärbar RRT-PCR-system. Metoden drar nytta av frystorkat reagens skärmen vilda fåglar i en icke-laboratoriemiljö, typiskt för ett utbrott scenario. Användning av molekylära verktyg ger exakta och känsliga alternativ för snabb diagnos.
Other articles by Joseph P. Dudley on PubMed
New Challenges for Public Health Care: Biological and Chemical Weapons Awareness, Surveillance, and Response
Recent events in the United States have demonstrated a critical need for recognizing nurses and emergency health care providers as important elements of the nation's first line of defense and response against terrorist attacks involving biological, chemical, or radiological weapons. The anthrax letter attacks of September/October 2001 demonstrate the importance of vigilance and attention to detail while interviewing and attending patients and when entering, reviewing, and cataloging patient records. Nursing professionals, emergency care responders, and physicians can perform a crucial role in our first-line defense against terrorism by detecting and reporting unusual or anomalous illness(es) consistent with possible exposure to biological or chemical agents. Nursing professionals should become more familiar with the etiology and clinical symptoms of biological agents of greatest current concern (smallpox, anthrax, tularemia, plague) and be alert for potentially anomalous or unfamiliar combinations of symptoms that could point to unwitting exposure to biological toxins, toxic chemicals, or cryptic radiological agents. Public health surveillance systems must be developed that encourage and facilitate the rapid reporting and follow-up investigation of suspect illnesses and potential disease outbreaks that will ensure early identification and response for covert attacks involving biological, chemical, or radiological weapons.
Long-distance Dispersal and Accelerating Waves of Disease: Empirical Relationships
Classic approaches to modeling biological invasions predict a "traveling wave" of constant velocity determined by the invading organism's reproductive capacity, generation time, and dispersal ability. Traveling wave models may not apply, however, for organisms that exhibit long-distance dispersal. Here we use simple empirical relationships for accelerating waves, based on inverse power law dispersal, and apply them to diseases caused by pathogens that are wind dispersed or vectored by birds: the within-season spread of a plant disease at spatial scales of <100 m in experimental plots, historical plant disease epidemics at the continental scale, the unexpectedly rapid spread of West Nile virus across North America, and the transcontinental spread of avian influenza strain H5N1 in Eurasia and Africa. In all cases, the position of the epidemic front advanced exponentially with time, and epidemic velocity increased linearly with distance; regression slopes varied over a relatively narrow range among data sets. Estimates of the inverse power law exponent for dispersal that would be required to attain the rates of disease spread observed in the field also varied relatively little (1.74-2.36), despite more than a fivefold range of spatial scale among the data sets.
Aerial Dispersal and Multiple-scale Spread of Epidemic Disease
Disease spread has traditionally been described as a traveling wave of constant velocity. However, aerially dispersed pathogens capable of long-distance dispersal often have dispersal gradients with extended tails that could result in acceleration of the epidemic front. We evaluated empirical data with a simple model of disease spread that incorporates logistic growth in time with an inverse power function for dispersal. The scale invariance of the power law dispersal function implies its applicability at any spatial scale; indeed, the model successfully described epidemics ranging over six orders of magnitude, from experimental field plots to continental-scale epidemics of both plant and animal diseases. The distance traveled by epidemic fronts approximately doubled per unit time, velocity increased linearly with distance (slope ~(1/2)), and the exponent of the inverse power law was approximately 2. We found that it also may be possible to scale epidemics to account for initial outbreak focus size and the frequency of susceptible hosts. These relationships improve understanding of the geographic spread of emerging diseases, and facilitate the development of methods for predicting and preventing epidemics of plants, animals, and humans caused by pathogens that are capable of long-distance dispersal.
Field Detection of Avian Influenza Virus in Wild Birds: Evaluation of a Portable RRT-PCR System and Freeze-dried Reagents
Wild birds have been implicated in the spread of highly pathogenic avian influenza (HPAIV) of the H5N1 subtype, prompting surveillance along migratory flyways. Sampling of wild birds is often conducted in remote regions, but results are often delayed because of limited local analytical capabilities, difficulties with sample transportation and permitting, or problems keeping samples cold in the field. In response to these challenges, the performance of a portable real-time, reverse transcriptase-polymerase chain reaction (rRT-PCR) unit (RAPID((R)), Idaho Technologies, Salt Lake City, UT) that employed lyophilized reagents (Influenza A Target 1 Taqman; ASAY-ASY-0109, Idaho Technologies) was compared to virus isolation combined with real-time RT-PCR conducted in a laboratory. This study included both field- and experimental-based sampling. Field samples were collected from migratory shorebirds captured in northern California, while experimental samples were prepared by spiking fecal material with an H6N2 AIV isolate. Results indicated that the portable rRT-PCR unit had equivalent specificity to virus isolation with no false positives, but sensitivity was compromised at low viral titers. Use of portable rRT-PCR with lyophilized reagents may expedite surveillance results, paving the way to a better understanding of wild bird involvement in HPAIV H5N1 transmission.
