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Research about Maryland

Source-linked reports with geographic coverage including Maryland.

At least 397 records · Page 22Linked to original sources
USGS1966

Trichinosis in Maryland raccoons

During recent studies of experimental Chagas’ disease, trichinosis was found in 2 out of a total of 44 Maryland raccoons ( Procyon lotor ) examined histologically following necropsy. All raccoons were trapped near the towns of Beltsville or Laurel. The raccoons found to have trichinosis were trapped in the area of the Agricultural Research Center, Beltsville. Cysts containing larvae of Trichinella spiralis were found in sections of diaphragm in one raccoon and in sections of diaphragm, skeletal muscle, and ocular muscle in the other. Three to five cysts could he seen in sections of skeletal muscle or diaphragm within a single low-power (scanning lens X 40) field. There was little if any inflammatory reaction to most of these cysts, but inflammatory cells were present adjacent to an occasional cyst (Fig. 1). Foci of calcification were found in some sections of muscle and may represent old calcified cysts.

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USGS1965

Epizootiologic studies on filarioids of the raccoon

Filarioid worms ( Dirofilaria immitis , D. tenuis , Dipetalonema procyonis , and D. llewellyni ) were discovered in raccoons ( Procyon lotar ) in Maryland. Raccoons were trapped in lowland, upland, and agricultural-residential areas, which were further classified as stream borders, poorly drained, and well drained. Data on incidence of D. llewellyni were analyzed on basis of host distribution within these areas to indicate type of habitat in which one might seek the vector. It was concluded that exposure takes place in the spring of the year. The arthropod found associated most often with the raccoon in spring was Ixodes texanus . Larvae of this tick which were fed on infected raccoons presented no evidence of development of the microfilariae. Feeding experiments were also conducted with mosquitoes: Aedes aegypti , A. canadensis , A. sollicitans , A. triseriatus , A. vexans , Culex pipiens , Anopheles punctipennis , and A. quadrimaculatus . Although microfilariae remained alive and active in the gut contents of all these mosquitoes for 2 days, only in Aedes aegypti did they enter the hemocele, but no developmental changes were noted and all microfilariae were dead by the eighth day. Although the intermediate host of D. llewellyni was not determined, evaluation of the accumulated data provides criteria for seeking the vector. It appeared unlikely that exposure of the raccoons took place in the den or that the filarioids were transmitted by an ectoparasite commonly found in raccoon dens. The data suggest that the vector is available only early in spring, although there are infected raccoons throughout the year. Prevalence in juveniles was 21 percent; in subadults, 64 percent; in adults, 87 percent.

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USGS1965

Relation of electrochemical potentials and iron content to ground-water flow patterns

This study was undertaken to develop means of measuring oxidation potentials in aquifer systems and to use the measured values in interpreting the behavior of iron in ground water. Anne Arundel County, Md., was selected as the area of study because of the wide range of concentration of iron-nearly zero to about 35 ppm-in the ground water and the rather complete information on the geology and hydrology. The regional geology consists of coastal plain sediments ranging in age from Early Cretaceous through the Recent. Most of the pH and oxidation-potential measurements were made in nonmarine Cretaceous deposits, only a few in the marine Eocene. Iron-bearing minerals in the area are primarily hematite or limonite and glauconite with a small amount of pyrite. Equipment was developed that permits the measurement of oxidation potentials by use of saturated calomel and platinum electrodes in ground-water samples uncontaminated by oxygen of the atmosphere. Measured Eh values range from about +700 mv to -40 mv. Approximately 2 to 3 hours are required to measure a stable or nearly stable oxidation potential. The mineralogy and organic content of the deposits and the ground-water flow pattern are the primary controls on the oxidation potential and pH of the water. A correlation exists between the oxidation potential and the concentration of iron in ground water; the higher concentrations occur in waters with the lowest values of Eh. The concentration of iron in the water tested shows little correlation with the pH of the water. The highest oxidation potentials were measured in water produced from shallow wells and those wells in recharge areas. The lowest potentials were measured farthest downgradient in water associated with gray and green sediments. The Eh values measured in the field are between values predicted from the solubility of Fe(OH) 2 (c) and values predicted from the solubility of hematite.

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USGS1964

Notes on the ecology of the opossum in Maryland

Livetrapping of opossums at the Patuxent Research Refuge in Maryland over an 8-year period resulted in the capture of 224 opossums, with 541 trap records. The maximum recorded trap life was 29 months, and the greatest estimated age was 36 months. Opossums did not enter traps readily, and the average period between consecutive captures was 31 days. Trap records indicated that opossums range over long, narrow areas rather than circular ones, probably associated with stream courses. Opossums begin to breed in Maryland in early February and young are found in the pouch until August. Evidently the first breeding period accounts for most of the young produced. The sex ratio of those trapped was slightly higher for males than females, but did not differ significantly from an expected sample from an even sex ratio. The trapping results indicated a production rate of from 4 to 5.4 young per adult female, but this is based on the assumption that young and adults have the same trap response. Opossums appear to favor low, damp woods rather than upland woods or open areas.

Maryland↗
USGS1963

Natural radioactivity in Washington County, Maryland

Natural gamma- radioactivity patterns in Washington County , Maryland , reflect the principal variations in lithology. The highest radioactivity is associated with the more argillaceous parts of the geologic section and with soils derived from high-potassium carbonate rocks. Surface radiation intensity ranges from about 5 to 30 microroentgens per hour, of which the rocks contribute 30 to 90 percent. From the aerial survey data, the surface radiation intensity from extended sources can be estimated to within about three microroentgens per hour and the equivalent uranium content can be estimated to within approximately 5 ppm.

Maryland↗
USGS1962

Occurrence of Trypanosoma cruzi in Maryland

During 1954-1960, 2005 mammals of 18 species collected at the Patuxent Wildlife Research Center, Maryland, were examined for trypanosomes. T. cruzi was found in 10 raccoons between October 31 and November 30. Infection occurred in 2 percent of all raccoons sampled, and in 11.3 percent of the 80 raccoons sampled in November. Examination was by direct smears, stained smears and cultures of heart blood. Although, in previous studies, at least two experimentally infected raccoons exhibited extended parasitemia (14 and 8 weeks), no such continuing parasitemia was observed in the natural infections. No trypanosomes were found in any of the other mammals examined.

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USGS1961

Trichomonad infection in mourning doves, Zenaidura macroura, in Maryland

During the 10-year period 1950-1960 the incidence of Trichomonas gallinae among several series of mourning doves shot or trapped in Maryland has varied from zero to 12 1/2 percent. Prior to 1959, all isolations of T. gallinae from doves during such surveys had been from birds with well-developed lesions. In 1959, trichomonads were demonstrated in three of 54 normal hunter-killed doves examined in Howard County. The incidence of trichomonad infection among doves which were submitted to the laboratory because they were obviously diseased was much higher. Of 44 clinically ill doves submitted during the period 1950-1960,25 were found to be infected with T. gallinae. In the Maryland area the incidence of trichomonad infection among mourning doves appears to be low, but when infection does occur it is usually due to a pathogenic strain which produces a typical fatal canker.

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