SEARCH · Search USGS

Results for “Vaccine”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources

USGS2010

Enzootic plague reduces black-footed ferret (Mustela nigripes) survival in Montana

Black-footed ferrets ( Mustela nigripes ) require extensive prairie dog colonies ( Cynomys spp.) to provide habitat and prey. Epizootic plague kills both prairie dogs and ferrets and is a major factor limiting recovery of the highly endangered ferret. In addition to epizootics, we hypothesized that enzootic plague, that is, presence of disease-causing Yersinia pestis without any noticeable prairie dog die off, may also affect ferret survival. We reduced risk of plague on portions of two ferret reintroduction areas by conducting flea control for 3 years. Beginning in 2004, about half of the ferrets residing on dusted and nondusted colonies were vaccinated against plague with an experimental vaccine (F1-V fusion protein). We evaluated 6-month reencounter rates (percentage of animals observed at the end of an interval that were known alive at the beginning of the interval), an index to survival, for ferrets in four treatment groups involving all combinations of vaccination and flea control. For captive-reared ferrets (115 individuals observed across 156 time intervals), reencounter rates were higher for vaccinates (0.44) than for nonvaccinates (0.23, p  = 0.044) on colonies without flea control, but vaccination had no detectable effect on colonies with flea control (vaccinates = 0.41, nonvaccinates = 0.42, p  = 0.754). Flea control resulted in higher reencounter rates for nonvaccinates ( p  = 0.026), but not for vaccinates ( p  = 0.508). The enhancement of survival due to vaccination or flea control supports the hypothesis that enzootic plague reduces ferret survival, even when there was no noticeable decline in prairie dog abundance. The collective effects of vaccination and flea control compel a conclusion that fleas are required for maintenance, and probably transmission, of plague at enzootic levels. Other studies have demonstrated similar effects of flea control on several species of prairie dogs and, when combined with this study, suggest that the effects of enzootic plague are widespread. Finally, we demonstrated that the experimental F1-V fusion protein vaccine provides protection to ferrets in the wild.

Vector-Borne and Zoonotic Diseases↗

USGS2009

Effects of avian cholera on survival of Lesser Snow geese Anser caerulescens: An experimental approach

Avian cholera, caused by the bacterium Pasteurella multocida , is one of the most important diseases affecting waterfowl in North America but little is known about the epizootiology of this disease or its impacts on annual survival rates. We ringed Lesser Snow Geese Anser caerulescens nesting at Wrangel Island, Russia and Banks Island, Canada with metal rings and individually coded plastic neck-collars or radio-transmitters to determine survival, movement and cause of death. We vaccinated half of the neck-collared and radiotagged geese to provide protection from avian cholera for up to one year following ringing and thus experimentally determine the impacts of this disease on survival. We found that vaccination did not reduce short-term survival of the experimental birds, compared with control geese. Neck-collared geese vaccinated in 1993 at Wrangel Island had higher survival during winter 1993–94 than control birds. In contrast, we found similar survival during winter 1994–95 between vaccinated and control geese neck-collared in 1994 at Wrangel and Banks Islands. Survival of radiotagged geese on wintering areas during 1994–95 was consistent with the vaccination versus control results for neck-collared geese during the same winter. However, we found that radiotagged geese that were vaccinated had better survival than control geese during winter 1995–96. We believe that harvest and avian cholera are the two principal causes of mortality for Lesser Snow Geese wintering in the Pacific Flyway and that avian cholera may be one of the factors affecting these populations.

Bird Study↗

USGS2009

Immunization of salmonids against the fish pathogen, Aeromonas salmonicida

An avirulent strain of Aeromonas salmonicida was shown to lack “A-layer” protein exterior to the outer cell membrane, but was still immunogenic in fish. After bacteria were inactivated with chloroform, whole cells, soluble antigen and combined whole cell plus soluble antigen vaccines were prepared. Those brook trout ( Salvelinus fontinalis ) that were vaccinated by a 60-second immersion in the combined whole cell plus soluble antigen vaccine were protected against experimental challenges. Further immersion vaccinations of Atlantic salmon ( Salmo salar ) in the combined vaccine indicated that protection conferred by immunization was highly significant, efficacious, and reproducible. In field situations, mortality in brown trout ( S. trutta ) immersion-vaccinated in this preparation was 2.1% whereas that in control fish was 28.9% after natural challenge.

Journal of the World Mariculture Society↗

USGS2004

Recombinant F1-V fusion protein protects black-footed ferrets (Mustela nigripes) against virulent Yersinia pestis infection

Black-footed ferrets (Mustela nigripes) are highly susceptible to sylvatic plague, caused by the bacterium Yersinia pestis, and this disease has severely hampered efforts to restore ferrets to their historic range. A study was conducted to assess the efficacy of vaccination of black-footed ferrets against plague using a recombinant protein vaccine, designated F1-V, developed by personnel at the U.S. Army Medical Research Institute of Infectious Diseases. Seven postreproductive black-footed ferrets were immunized with the vaccine, followed by two booster immunizations on days 23 and 154; three control black-footed ferrets received a placebo. After the second immunization, antibody titers to both F1 and V antigen were found to be significantly higher in vaccinates than controls. On challenge with 7,800 colony-forming units of virulent plague by s.c. injection, the three control animals died within 3 days, but six of seven vaccinates survived with no ill effects. The seventh vaccinate died on day 8. These results indicate that black-footed ferrets can be immunized against plague induced by the s.c. route, similar to fleabite injection.

Journal of Zoo and Wildlife Medicine↗

USGS2002

Evaluation of Brucella abortus strain RB51 and strain 19 in pronghorn antelope

Free-roaming elk and bison in the Greater Yellowstone Area remain the only wildlife reservoirs for Brucella abortus in the United States, and the large number of animals and a lack of holding facilities make it unreasonable to individually vaccinate each animal. Therefore, oral delivery is being proposed as a possible option to vaccinate these wild ungulates. One of the main problems associated with oral vaccination is the potential exposure of nontarget species to the vaccines. The purpose of this study was to determine the effects of two Brucella vaccines, strain 19 (S19) and the rough strain RB51 (SRB51), in pregnant pronghorn antelope. We conclude that S19 and SRB51 rarely colonize maternal and fetal tissues of pregnant pronghorn and were not associated with fetal death. Oral delivery of either vaccine at this dose appears to be nonhazardous to pregnant pronghorn.

Conference Paper↗

USGS2021

Enzootic plague reduces survival of Mexican woodrats (Neotoma mexicana) in Colorado

Plague is a flea-vectored disease introduced to North America c. 1900. It is lethal to many American mammal species, causes major die-offs (epizootics) in some populations, and may be ecologically disruptive even at lower interepizootic (enzootic) levels of transmission. We sought to determine the effects of enzootic plague on survival of Mexican woodrats ( Neotoma mexicana ) and to test the hypothesis that the causative bacterium Yersinia pestis can be maintained by a highly plague-susceptible species like these woodrats. We compared apparent survival for woodrats in groups with and without plague management. Woodrat groups were (1) treated for vector control with an insecticide (deltamethrin), (2) vaccinated against plague, (3) treated with both vaccine and vector control, and (4) without plague management treatments. Flea prevalence on woodrats was reduced >90% in response to deltamethrin. Apparent survival during May–September, 2010, was 31.1% for non-vaccinated adult woodrats living in deltamethrin-treated nests, compared to 9.6% for woodrats in non-treated nests. During May–September of 2010 and 2011, vaccinated juvenile woodrat survival was 16.8%, compared to 8.4% for non-vaccinated juveniles. Peak numbers of woodrats captured were 139 for the first trapping session of 2010 and 76 for the first session of 2011, suggesting a population decline consistent with the relatively low estimated survival rates. Survival results suggest that this highly plague-susceptible species can locally maintain enzootic plague while encountering substantial rates of mortality.

Colorado↗

USGS2009

Oral and parenteral immunization of chickens (Gallus gallus) against West Nile virus with recombinant envelope protein

West Nile virus (WNV) causes morbidity and mortality in humans, horses, and in more than 315 bird species in North America. Currently approved WNV vaccines are designed for parenteral administration and, as yet, no effective oral WNV vaccines have been developed. WNV envelope (E) protein is a highly antigenic protein that elicits the majority of virus-neutralizing antibodies during a WNV immune response. Leghorn chickens were given three vaccinations (each 2 wk apart) of E protein orally (20 ??g or 100 ??g/dose), of E protein intramuscularly (IM, 20 ??g/dose), or of adjuvant only (control group) followed by a WNV challenge. Viremias were measured post-WNV infection, and three new enzyme-linked immunosorbent assays were developed for quantifying IgM, IgY, and IgA-mediated immune response of birds following WNV infection. WNV viremia levels were significantly lower in the IM group than in both oral groups and the control group. Total WNV E protein-specific IgY production was significantly greater, and WNV nonstructural 1-specific IgY was significantly less, in the IM group compared to all other treatment groups. The results of this study indicate that IM vaccination of chickens with E protein is protective against WNV infection and results in a significantly different antibody production profile as compared to both orally vaccinated and nonvaccinated birds. ?? 2009 American Association of Avian Pathologists.

Wisconsin↗

USGS1997

Immunization with viral antigens: Infectious haematopoietic necrosis

Infectious haematopoietic necrosis (IHN) is one of the most important viral diseases of salmonids, especially among juvenile fish where losses can be high. For over 20 years, researchers have tested a variety of preparations for control of IHN. Early vaccines consisted of killed virus and were effective when delivered by injection, but too costly to be practical on a large scale. Attenuated vaccines were developed by serial passage in cell culture and by monoclonal antibody selection. These offered excellent protection and were cost-effective, but residual virulence and uncertainty about their effects on other aquatic species made them poor candidates for licensing. Subunit vaccines using part of the IHNV glycoprotein gene cloned into E. coli or into an attenuated strain of A. salmonicida have been tested, appeared safe and were inexpensive. These vaccines were reported to provide some protection when delivered by immersion. Information on the location of antigenic sites on the glycoprotein led to trials using synthetic peptides, but these did not seem to be economically viable. Recently, plasmid vectors encoding the glycoprotein gene under control of a cytomegalovirus promoter were developed for genetic immunization. The constructs were highly protective when delivered by injection, but a more practical delivery system is needed. Thus, while several vaccine strategies have been tried in order to stimulate specific immunity against IHN, more research is needed to develop a commercially viable product for control of this important disease.

Developments in Biological Standardization↗

USGS1977

Immunization of pacific salmon: comparison of intraperitoneal injection and hyperosmotic infiltration of Vibrio anguillarum and Aeromonas salmonicida bacterins

Two methods of immunizing fish, intraperitoneal (i.p.) injection and hyperosmotic infiltration, were compared for control of vibriosis and furunculosis in pen-reared coho salmon ( Oncorhynchus kisutch ) and chinook salmon ( O . tshawytscha ). Both methods provided significant protection against vibriosis under field test conditions. In coho salmon, hyperosmotic infiltration provided the best protection and fastest rise in antibody titer of seven treatments tested. In chinook salmon, hyperosmotic infiltration of Vibrio anguillarum and Aeromonas salmonicida vaccines resulted in 83.3% survival in comparison with 28.7% survival in controls. Both i.p. injection and hyperosmotic infiltration of V . anguillarum and A . salmonicida bacterins resulted in production of serum antibodies specific for each respective pathogen. Vaccination with bivalent V . anguillarum – A . salmonicida vaccines produced antibodies to both pathogens, and provided protection against vibriosis. Growth rates of vaccinated coho salmon were not significantly different from controls.

Journal of the Fisheries Research Board of Canada↗

USGS2011

Spatial distribution and risk factors of highly pathogenic avian influenza (HPAI) H5N1 in China

Highly pathogenic avian influenza (HPAI) H5N1 was first encountered in 1996 in Guangdong province (China) and started spreading throughout Asia and the western Palearctic in 2004–2006. Compared to several other countries where the HPAI H5N1 distribution has been studied in some detail, little is known about the environmental correlates of the HPAI H5N1 distribution in China. HPAI H5N1 clinical disease outbreaks, and HPAI virus (HPAIV) H5N1 isolated from active risk-based surveillance sampling of domestic poultry (referred to as HPAIV H5N1 surveillance positives in this manuscript) were modeled separately using seven risk variables: chicken, domestic waterfowl population density, proportion of land covered by rice or surface water, cropping intensity, elevation, and human population density. We used bootstrapped logistic regression and boosted regression trees (BRT) with cross-validation to identify the weight of each variable, to assess the predictive power of the models, and to map the distribution of HPAI H5N1 risk. HPAI H5N1 clinical disease outbreak occurrence in domestic poultry was mainly associated with chicken density, human population density, and elevation. In contrast, HPAIV H5N1 infection identified by risk-based surveillance was associated with domestic waterfowl density, human population density, and the proportion of land covered by surface water. Both models had a high explanatory power (mean AUC ranging from 0.864 to 0.967). The map of HPAIV H5N1 risk distribution based on active surveillance data emphasized areas south of the Yangtze River, while the distribution of reported outbreak risk extended further North, where the density of poultry and humans is higher. We quantified the statistical association between HPAI H5N1 outbreak, HPAIV distribution and post-vaccination levels of seropositivity (percentage of effective post-vaccination seroconversion in vaccinated birds) and found that provinces with either outbreaks or HPAIV H5N1 surveillance positives in 2007–2009 appeared to have had lower antibody response to vaccination. The distribution of HPAI H5N1 risk in China appears more limited geographically than previously assessed, offering prospects for better targeted surveillance and control interventions.

PLoS Pathogens↗

USGS1997

Evaluation by enzyme-linked immunosorbent assay (ELISA) of Renibacterium salmoninarum bacterins affected by persistence of bacterial antigens

Rainbow trout Oncorhynchus mykiss were injected intraperitoneally with a bacterin containing killed Renibacterium salmoninarum cells delivered alone or in an oil-based adjuvant. We evaluated the relative abilities of the batterins to prevent the initiation or progression of infection in fish challenged by waterborne exposure to R. salmoninarum. Sixty-one days after vaccination, fish were held for 24 h in water containing either no bacteria or approximately 1.7 x 103, 1.7 x 105, or 5.3 x 106 live R. salmoninarum cells/mL. An enzyme-linked immunosorbent assay (ELISA) was used to monitor changes in the levels of R. salmoninarum antigen in live fish before and after the immersion challenges. High levels of R. salmoninarum antigens were detected by ELISA in kidney-spleen tissue homogenates from vaccinated fish immediately before the challenges. Levels of those antigens remained high in the tissues of unchallenged fish throughout the study. We found that the ELISA used in this study may be unsuitable for evaluating the efficacy of batterins because it did not distinguish antigens produced by the challenge bacteria during an infection from those of the bacterins. Groups of control and vaccinated fish also were injected with either 1.7 x 104 or 1.7 x 106 R. salmoninarum cells and served as R. salmoninarum virulence controls. Relative survival among the various subgroups in the injection challenge suggests that adverse effects might have been associated with the adjuvant used in this study. The lowest survival at both injection challenge levels was among fish vaccinated with bacteria in adjuvant.

Journal of Aquatic Animal Health↗

USGS2021

Estimating abundance and simulating fertility control in feral burros

Overabundant populations of feral equids are negatively impacting rangelands in the western United States. To effectively manage these populations, robust estimates of abundance and demography are necessary, as well as cost-effective methods of reducing abundance. We used a double-observer-sightability aerial survey method to estimate the number of feral burros (Equus asinus) occupying the Fort Irwin National Training Center (NTC), California, USA. We examined the efficacy of using porcine zona pellucida (PZP) immunocontraception as a control agent and used matrix population models to simulate how changes in demographic rates would influence abundance. We estimated there were 690 (CI: 618–752) feral burros within the surveyed area, but these are part of a much larger population that is not geographically isolated from those in the survey area. Sighting probabilities ranged from 0.19–0.98 and were most strongly influenced by distance from observer and group size. We estimated age-specific demographic rates at the NTC and compiled mean rates across burro populations in arid environments from the literature. Mean fecundity varied from 0.17 to 0.58 foals per adult female with younger females having lower fecundity. Mean survival was 0.90 for foals, 0.98 for yearlings, and 0.96 for adults. PZP vaccine treatment strategies that suppressed fertility for up to 10 years, predicted that burro abundance would be reduced by 67–88% after 15 years (compared with no treatment), but none of these strategies resulted in population extirpation. Our fieldwork also highlights the difficulty of administering PZP vaccination to large, free-ranging animals. Burro growth rates shifted from increasing to decreasing at adult survival rates below 0.84 and the population was predicted to become extirpated when adult survival declined below 0.60. In the absence of other methods to reduce burro numbers, our findings indicate that current formulations of PZP immunocontraception, which require multiple doses, would be inadequate for controlling population growth rates at the NTC and perhaps elsewhere. Development of longer-term fertility reduction agents and/or more efficient vaccine delivery techniques would likely improve the efficacy of fertility control for overabundant ungulate populations. Lack of geographic closure (physical barriers to migration) further complicates management efforts to reduce burro numbers.

California↗

USGS2023

Management of vampire bats and rabies: Past, present, and future

Rabies virus transmitted via the bite of common vampire bats ( Desmodus rotundus ) has surpassed canine-associated cases as the predominant cause of human rabies in Latin America. Cattle, the preferred prey of D. rotundus , suffer extensive mortality from vampire bat associated rabies, with annual financial losses estimated in the tens of millions of dollars. Organized attempts to manage or curtail vampire bat populations and rabies virus transmission have been conducted since the early 1900s, when vampire bat-associated rabies cases in humans and livestock were first recognized. However, these attempts largely failed, as the distribution of vampire bat populations expanded geographically with the intensification of livestock production, and the incidence of vampire bat rabies (VBR) increased. Current methods of control rely primarily on culling vampire bat populations using poisons (vampiricides) that are transferred from bat to bat after topical application. Despite widespread use of vampiricides for the last 50 years, little evidence exists to demonstrate their effectiveness in reducing the incidence of VBR. Culling may further result in dispersion of bats, which could have an unintended consequence of spreading VBR. New methods to manage VBR are being developed or considered, including topical rabies vaccine that transfer among bats, much like vampiricides or a transmissible vaccine that would spread naturally among bats. Vaccination of vampire bats against rabies could lower the incidence of VBR and prevent viral transmission to cattle and humans without the animal welfare concerns and potential negative effects of culling. However, this approach would not deter vampire bat bites, and some form of population reduction (e.g., fertility control) would likely also be needed. An integrated strategy to reduce both the incidence of VBR and the abundance of vampire bats would be ideal for protecting both human and animal health.

Book chapter↗

USGS1977

Immunization of sockeye salmon (Oncorhynchus nerka) against vibriosis using the hyperosmotic infiltration technique

Various procedures of hyperosmotic infiltration (HI) and intraperitoneal injection were used to vaccinate sockeye salmon ( Oncorhynchus nerka ) with killed Vibrio anguillarum . Excellent protection was evident against experimentally induced vibriosis in the groups immunized by HI with 10 × Hanks' balanced salt solution (HBSS), 1 × HBSS with 8.0% NaCl and 5.3% NaCl, as well as in the injected groups. Comparisons were made among the various immunization methods by vaccinating fish with ten-fold serial dilutions of bacterin, then challenging them by the water contact method after 6 or 9 weeks. Protection was somewhat better with 10 × HBSS than with 5.3% NaCl, and 1 × HBSS containing 8.0% NaCl was markedly superior to the vaccination of fish without hyperosmotic treatment. Agglutinin titers did not exceed 1 : 8 in any group.

Aquaculture↗

USGS2014

Behavior of feral horses in response to culling and GnRH immunocontraception

Wildlife management actions can alter fundamental behaviors of individuals and groups,which may directly impact their life history parameters in unforeseen ways. This is especially true for highly social animals because changes in one individual’s behavior can cascade throughout its social network. When resources to support populations of social animals are limited and populations become locally overabundant, managers are faced with the daunting challenge of decreasing population size without disrupting core behavioral processes. Increasingly, managers are turning to fertility control technologies to supplement culling in efforts to suppress population growth, but little is quantitatively known about how either of these management tools affects behavior. Gonadotropin releasing hormone (GnRH) is a small neuropeptide that performs an obligatory role in mammalian reproduction and has been formulated into the immunocontraceptive GonaCon-BTM. We investigated the influences of this vaccine on behavior of feral horses ( Equus caballus ) at Theodore Roosevelt National Park, North Dakota, USA, for a year preceding and a year following nonlethal culling and GnRH-vaccine treatment. We observed horses during the breeding season and found only minimal differences in time budget behaviors of free-ranging female feral horses treated with GnRH and those treated with saline. The differences observed were consistent with the metabolic demands of pregnancy and lactation. We observed similar social behaviors between treatment groups, reflecting limited reproductive behavior among control females due to high rates of pregnancy and suppressed reproductive behavior among treated females due to GnRH-inhibited ovarian activity. In the treatment year, band stallion age was the only supported factor influencing herding behavior (P < 0.001), harem-tending behavior (P < 0.001), and agonistic behavior (P = 0.02). There was no difference between the mean body condition of control females (4.9 (95% CI = 4.7–5.1)) and treated females(4.8 (95% CI = 4.7–4.9)). Band fidelity among all females increased 25.7% in the year fol-lowing vaccination and culling, despite the social perturbation associated with removal of conspecifics. Herding behavior by stallions decreased 50.7% following treatment and culling (P < 0.001), while harem-tending behavior increased 195.0% (P < 0.001). The amount of available forage influenced harem-tending, reproductive, and agonistic behavior in the year following culling and treatment (P < 0.04). These changes reflected the expected nexus between a species with polygynous social structure and strong group fidelity and the large instantaneous change in population density and demography coincident with culling.Behavioral responses to such perturbation may be synergistic in reducing grazing pressure by decreasing energetically expensive competitive behaviors, but further investigation is needed to explicitly test this hypothesis.

Applied Animal Behaviour Science↗

USGS2023

Plague mitigation for prairie dog and black-footed ferret conservation: Degree and duration of flea control with 0.005% fipronil grain bait

Sylvatic plague, a primarily flea-borne zoonosis, is a significant threat to prairie dogs ( Cynomys spp., PDs) and their specialized predators, endangered black-footed ferrets ( Mustela nigripes , BFFs). Host-fed fipronil baits have proven effective in controlling fleas on PDs for the purposes of plague mitigation and BFF conservation. Currently, annual treatments are the norm. We tested the long-term efficacy of fipronil bait treatments with black-tailed PDs ( C. ludovicianus , BTPDs) and BFFs in South Dakota, USA. During 2018–2020, we provided BTPDs on 21 sites with grain bait formula, laced with 0.005% fipronil (50 mg/kg); 18 non-treated sites functioned as baselines. In 2020–2022, we live-trapped, anesthetized, and combed BTPDs for fleas. Flea control was significant for at least 639–885 days. Flea abundance on the treated sites was < 0.5 fleas/BTPD for ∼750 days. During 2020–2022, we sampled BFFs for fleas on 4 BTPD colonies treated with fipronil grain bait and 8 non-treated colonies. Flea control was significant with BFFs, but flea abundance began to rebound within ∼240 days post-treatment. When feasible, the combination of insecticide treatments, such as fipronil baits, and BFF vaccination against plague provide a “two-pronged” protection approach for these endangered carnivores. If fipronil bait treatments are less effective with predatory BFFs than PDs, as found herein, the “two-pronged” approach might be used to protect BFFs and biennial fipronil bait treatments might be used to protect PDs. If BFF vaccination is not possible, or few BFFs can be vaccinated, annual fipronil bait treatments might be used as a precaution to protect BFFs. Flea densities might be surveyed to determine when/where more frequent treatments seem useful.

South Dakota↗

USGS2014

Adaptive management and the value of information: learning via intervention in epidemiology

Optimal intervention for disease outbreaks is often impeded by severe scientific uncertainty. Adaptive management (AM), long-used in natural resource management, is a structured decision-making approach to solving dynamic problems that accounts for the value of resolving uncertainty via real-time evaluation of alternative models. We propose an AM approach to design and evaluate intervention strategies in epidemiology, using real-time surveillance to resolve model uncertainty as management proceeds, with foot-and-mouth disease (FMD) culling and measles vaccination as case studies. We use simulations of alternative intervention strategies under competing models to quantify the effect of model uncertainty on decision making, in terms of the value of information, and quantify the benefit of adaptive versus static intervention strategies. Culling decisions during the 2001 UK FMD outbreak were contentious due to uncertainty about the spatial scale of transmission. The expected benefit of resolving this uncertainty prior to a new outbreak on a UK-like landscape would be £45–£60 million relative to the strategy that minimizes livestock losses averaged over alternate transmission models. AM during the outbreak would be expected to recover up to £20.1 million of this expected benefit. AM would also recommend a more conservative initial approach (culling of infected premises and dangerous contact farms) than would a fixed strategy (which would additionally require culling of contiguous premises). For optimal targeting of measles vaccination, based on an outbreak in Malawi in 2010, AM allows better distribution of resources across the affected region; its utility depends on uncertainty about both the at-risk population and logistical capacity. When daily vaccination rates are highly constrained, the optimal initial strategy is to conduct a small, quick campaign; a reduction in expected burden of approximately 10,000 cases could result if campaign targets can be updated on the basis of the true susceptible population. Formal incorporation of a policy to update future management actions in response to information gained in the course of an outbreak can change the optimal initial response and result in significant cost savings. AM provides a framework for using multiple models to facilitate public-health decision making and an objective basis for updating management actions in response to improved scientific understanding.

PLoS Biology↗

USGS1993

Effect of vitamin E on the immune response of channel catfish to Edwardsiella ictaluri

Three-month-old fingerling channel catfish Ictalurus punctatus were fed purified diets supplemented with ∝-tocopherol acetate to provide 0, 60, and 2,500 mg vitamin E/kg for 180 d. A 30-s immersion bath and an oral booster were used to deliver a bacterin of formalin-killed Edwardsiella ictaluri to half of the fish from each dietary treatment. Resistance of red blood cells to peroxidation was used as an index of antioxidant status. The susceptibility of red blood cells to oxidative hemolysis decreased with increasing levels of dietary vitamin E. Vaccinated and nonvaccinated fish were evaluated for agglutinating antibody titers and macrophage activity. Humoral antibody titers in response to E. ictaluri were significantly (P ≤ 0.05) higher in vaccinated fish than in nonvaccinated fish; however, no such differences in agglutinating antibody titers were detected among any of the dietary treatment groups. Both vaccination and vitamin E significantly enhanced the ability of macrophages to phagocytize virulent E. ictaluri . Results of this study indicate that elevated levels of dietary vitamin E may affect the ability of channel catfish to respond immunologically to bacterial pathogens.

Journal of Aquatic Animal Health↗