Geology topics

Thomas M. Yuill

Publications and source records attributed to Thomas M. Yuill.

7 recordsLinked to original sources

USGS2004

Detection of Clostridium botulinum type C cells in the gastrointestinal tracts of Mozambique tilapia (Oreochromis mossambicus) by polymerase chain reaction

We established a method of directly detecting Clostridium botulinum type C cells, while minimizing spore detection, in the intestinal contents of Mozambique tilapia ( Oreochromis mossambicus ). This technique involved extraction of predominantly cellular DNA from tilapia intestinal tracts and used a polymerase chain reaction assay to detect presence of type C 1 toxin gene. We consistently detected C. botulinum type C cells in tilapia gastrointestinal contents at a level of 7.5×10 4 cells per 0.25 g material or 1.9×10 3 cells. This technique is useful for determining prevalence of the potentially active organisms within a given population of fish and may be adapted to other types of C. botulinum and vertebrate populations as well.

California↗

USGS1999

Foreword

No abstract available.

Information and Technology Report↗

USGS1998

The inhibition of Clostridium botulinum type C by other bacteria in wetland sediments

Bacteria with inhibitory activity against Clostridium botulinum type C were isolated from 32% of sediment samples ( n = 1600) collected from 10 marshes in a northern California wetland over a 12 mo period. Aerobic and anaerobic bacteria with inhibitory activity were isolated from 12% and 23% of the samples, respectively. Bacteria with inhibitory activity were isolated from all 10 study sites and throughout the year. This study demonstrates that bacteria with inhibitory activity against C. botulinum type C occur naturally in wetland sediments.

California↗

USGS1990

Mortality from duck plague virus in immunosuppressed adult mallard ducks

Environmental contaminants contain chemicals that, if ingested, could affect the immunological status of wild birds, and in particular, their resistance to infectious disease. Immunosuppression caused by environmental contaminants, could have a major impact on waterfowl populations, resulting in increased susceptibility to contagious disease agents. Duck plague virus has caused repeated outbreaks in waterfowl resulting in mortality. In this study, several doses of cyclophosphamide (CY), a known immunosuppressant, were administered to adult mallards (Anas platyrhynchos) to determine if a resultant decrease in resistance to a normally sub-lethal strain of duck plague virus would occur, and induce mortality in these birds. Death occurred in birds given CY only, and in birds given virus and CY, but not in those given virus only. There was significantly greater mortality and more rapid deaths in the duck plague virus-infected groups than in groups receiving only the immunosuppressant. A positively correlated dose-response effect was observed with CY mortalities, irrespective of virus exposure. A fuel oil and a crude oil, common environmental contaminants with immunosuppressive capabilities, were tested to determine if they could produce an effect similar to that of CY. Following 28 days of oral oil administration, the birds were challenged with a sub-lethal dose of duck plague virus. No alteration in resistance to the virus (as measured by mortality) was observed, except in the positive CY control group.

Journal of Wildlife Diseases↗

USGS1988

Experimental Mycoplasma gallisepticum infections in captive-reared wild turkeys

The effects of Mycoplasma gallisepticum (MG) infections on egg production, fertility, and hatchability were studied in captive-reared wild turkeys ( Meleagris gallopavo ). Three groups of adult birds, each consisting of four hens and two toms, were exposed to MG by the respiratory route at the beginning of their breeding season. Fourteen control birds received sterile growth medium. Although no mortality of infected or control birds occurred, egg production during the first breeding season after infection was reduced. The mean number of eggs/hen/day produced by infected groups the first breeding season postexposure (PE) was significantly lower than the control value. The mean number of eggs produced daily by the same hens 1 yr later was unaffected by MG infection. The pecentage of fertile eggs produced by infected groups was slightly reduced in both the first and second breeding seasons PE. Hatchability of fertile eggs from infected hens was significantly lower than eggs from control hens. Productivity may be impaired if MG infections occur in free-ranging wild turkey populations.

Journal of Wildlife Diseases↗

USGS1988

Serologic response of Rio Grande wild turkeys to experimental infections of Mycoplasma gallisepticum

The serologic response of Rio Grande wild turkeys (Meleagris gallopavo intermedia) to Mycoplasma gallisepticum (MG) was determined. Free-ranging turkeys were caught in southern Texas, shipped to the University of Wisconsin, Madison, and housed in isolation facilities. Fourteen birds were exposed to MG, by intratracheal and intranasal inoculation. Eight birds received sterile broth only. Two wk prior to the end of the experiment, MG exposed turkeys were stressed by challenge with a serologically unrelated mycoplasma. Serum from all exposed birds reacted positively for MG antibody by the rapid plate agglutination (RPA) procedure within 2 mo postexposure (PE) and all but one remained positive for 14 mo PE. Less than one half of the exposed birds developed positive MG antibody titers detectable by the hemagglutination inhibition (HI) test within 2 mo PE, and by 10 mo PE, none had positive titers. Antibody was detected by the HI test in two of 11 infected turkeys, 14 mo PE, and titers increased significantly within 2 wk. MG was isolated from tracheal swabs from two infected birds 2 mo PE, but attempts thereafter failed. However, at the termination of the experiment 15 mo later, MG was isolated from lung tissue of three of 11 exposed turkeys and from a blood clot found in the lower trachea of one bird.

Texas↗

USGS1987

Microbial infections in a declining wild turkey population in Texas

A survey was conducted at 5 locations in Texas for avian pathogens that might adversely affect wild turkey ( Meleagris gallopavo ) productivity and survival. At 1 site, the Rob and Bessie Welder Wildlife Refuge (WWR), turkeys have declined precipitously in recent years. During the winters of 1983-85, 442 wild turkeys were caught with cannon and drop nets, 161 of these on WWR. Blood samples were drawn for serologic evaluation, and cloacal and tracheal swabs were collected for isolation attempts. Salmonella spp. bacteria, Newcastle disease virus (NDV), and avian influenza virus (AIV) were not detected in any samples tested. Serologic tests for antibodies to NDV and AIV also were negative. Many mycoplasma isolates were recovered from turkeys from every location. Characterization of these isolates indicated that several species were present. None were species typically associated with mycoplasmosis in domestic turkeys, such as Mycoplasma gallisepticum (MG), M. meleagridis (MM), or M. synoviae (MS), although antibodies to these pathogens were detected in turkeys at every location sampled. There was no evidence to link any of these disease causing agents to the decline observed in the population of wild turkeys on the WWR.

Texas↗