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Biomedical subjects

D J Forrester

Publications and source records attributed to D J Forrester.

At least 19 recordsLinked to original sources
PubMed2001

Leucocytozoon toddi and Haemoproteus tinnunculi (Protozoa: Haemosporina) in the Chimango caracara (Milvago chimango) in southern Chile.

Two species of blood protozoans were identified from blood smears collected from 15 specimens of the Chimango caracara (Milvago chimango) on Isla Grande de Chiloé in southern Chile. These included Leucocytozoon toddi in 13 birds, including all 5 of the 4-6 week old nestlings examined, and 8 of the subadults or adults. One of the nestlings also had a dual infection of L. toddi and Haemoproteus tinnunculi. These are the first reports of blood parasites from M. chimango.

Animals↗
PubMed2001

Altered predation susceptibility of mosquitofish infected with Eustrongylides ignotus.

Eustrongylides ignotus is a parasitic nematode whose definitive hosts are often piscivorous wading birds (Ciconiiformes). Several species of small fishes are intermediate hosts, while larger predatory fish may be paratenic (transport) hosts. We examined predation susceptibility of infected mosquitofish (Gambusia holbrooki) to three species of predatory fishes, including juvenile largemouth bass (Micropterus salminoides), warmouth (Lepomis gulosus), and bluegill (Lepomis macrochirus). A 250 L aquarium with removable plexiglass divider and remote observation windows was constructed. Aquatic macrophytes were placed in the tank to provide refuge for the fishes. Predatory fish were allowed to acclimate to one half of the tank, while one infected and one uninfected mosquitofish were placed in the other. The divider was removed and an observer recorded the number of capture attempts and time required for capture. Predators were observed for behavioral alterations for 4 days after ingestion of infected mosquitofish, then examined at necropsy. Infected prey were selected preferentially in 31 of 38 (82%) trials. The number of capture attempts was 2.7+/-0.2 (x +/- SE) for infected fish and 3.9+/-0.4 for uninfected fish. Mean time of capture was 12.4+/-1.6 min for infected fish and 21.7+/-2.9 for uninfected fish. Because of these differences, infected mosquitofish were more susceptible to predation (P < 0.01) than uninfected fish. Aberrant behavior including lethargy, convulsions, and buoyancy abnormalities was observed in eight (67%) predatory fish. At necropsy, larvae of E. ignotus were found in the coelomic cavity, viscera, and swim bladders of predators. Parasite-induced behavior modification of intermediate hosts may predispose them to predation by wading birds and thereby facilitate the transmission of this nematode in natural populations.

Animals↗
PubMed2001

Newcastle disease virus in double-crested cormorants in Alabama, Florida, and Mississippi.

In order to understand the epidemiology of Newcastle disease (ND) outbreaks in double-crested cormorants (Phalacrocorax auritus), a study was conducted on wintering migratory cormorants (P. a. auritus) in Alabama and Mississippi (USA) and non-migratory cormorants (P. a. floridanus) that breed in Florida (USA). Antibodies against ND virus were detected by the hemagglutination-inhibition method in sera from 86 of 183 (47%) migratory cormorants over-wintering in eight roosting sites in Alabama and Mississippi between November, 1997 and April, 1999. Titers ranged from 5 to 40. Antibody prevalences in sera collected from females in early winter (November and December) (26%) and late winter (February and March) (56%) were significantly different (P = 0.0007). None of 45 serum samples from 1- to 7-wk-old nestlings from 11 colonies in Florida during the 1997-98 and 1998-99 breeding seasons was positive. However, antibodies were detected in yolk samples from 98 of 126 (78%) eggs collected in these same colonies. Titers ranged from 4 to 256. The prevalence of antibodies in eggs collected from fresh-water colonies (63% prevalence, n = 30) and salt-water colonies (82% prevalence, n = 96) was significantly different (P = 0.041). ND virus was not isolated from tissues of 18 cormorants and cloacal and tracheal swabs from 202 cormorants collected in Alabama and Mississippi; virus was also not isolated from cloacal and tracheal swabs from 51 nestlings from Florida.

Alabama↗
PubMed2000

Myometrial adenylyl cyclase protein decreases on the last day of pregnancy in the rat.

To determine whether gestation-related changes in responsiveness of the rat uterus to beta-adrenergic agonists are mediated at the level of adenylyl cyclase, we measured myometrial adenylyl cyclase activity and protein quantities during pregnancy and labor. In rat myometrial membranes, basal adenylyl cyclase activity increased from the nonpregnant state to mid (Days 12-14) and then late (Days 18-20) gestation and then decreased intrapartum (Day 22). Stimulated adenylyl cyclase activity, at the level of the beta-adrenergic receptor (isoproterenol, 10(-4) M), the G protein (GTP, 10(-5) M), or the adenylyl cyclase enzyme (MnCl(2), 20 mM), was similarly altered during gestation. Total adenylyl cyclase protein was quantified by [(3)H]forskolin binding assay in myometrial membranes from nonpregnant and pregnant (Day 14, Day 20, Day 21, and intrapartum Day 22) rats. Adenylyl cyclase protein increased progressively from nonpregnant rats to pregnant rats at mid (Day 14) and late (Day 20) gestation, but it decreased abruptly to nonpregnant levels on Day 21, the day before parturition, and remained at similar levels on Day 22 (intrapartum). The gestation-related increase in expression of myometrial adenylyl cyclase protein may facilitate uterine quiescence during pregnancy, and the abrupt decrease of adenylyl cyclase protein on the last day of pregnancy may be a contributing mechanism for the initiation of labor.

Adenylyl Cyclases↗
PubMed1998

Geographical distribution of Demodex ursi in black bears from Florida.

From May 1990 to February 1996, 55 black bears (Ursus americanus floridanus) (38 males, 17 females) from 21 counties in Florida (USA), were examined for Demodex ursi (Acari: Demodecidae). The sample included cubs < 1-yr-old (n = 12), juveniles (1 to < 3 yr, n = 20), and adults (3 to 12 yr, n = 23). Demodex ursi was collected from four bears by deep scrapings of 15 sites on the head and forelimb of each bear. All four bears with demodicosis had crusty, scaly skin lesions, and moderate alopecia. No D. ursi were seen in any of the 750 scrapings from the other 51 bears, nor did any of those bears have signs of demodicosis. Demodicosis was found only in bears from or near the Ocala population in north-central Florida.

Animals↗
PubMed1998

A retrospective study of morbidity and mortality of raptors in Florida: 1988-1994.

A retrospective study was conducted on 390 raptors admitted to the University of Florida Veterinary Medical Teaching Hospital (VMTH) during 1988-1994. Representatives of 20 species were admitted; the five most common species were the barred owl (Strix varia, 72), eastern sreech owl (Otus asio, 63), red-shouldered hawk (Buteo lineatus, 49), bald eagle (Haleaeetus leucocephalus, 43), and red-tailed hawk (Buteo jamaicensis, 38). A primary clinical diagnosis was determined in 340 (87%) of the 390 raptors admitted to the VMTH; a diagnosis was not made for the remaining 50 birds. Eighty-two percent (279) had traumatic injuries, and 87% (243) of those were directly related to human activity. The primary clinical diagnoses in the remaining 61 raptors included toxicosis (21), poor nutrition (15), infectious disease (11), orphaned young (11), and electrocution (3). The disposition of the 390 raptors was as follows: 61% (237) died or euthanized, 21% (80) released to the wild, 15% (57) outcome unknown, and 4% (16) permanent captives. Necropsies were performed on 32 of the 237 raptors that died.

Animals↗
PubMed1997

Winter mortality of common loons in Florida coastal waters.

Diagnostic findings are presented for 434 common loons (Gavia immer) found sick or dead on Florida beaches from 1970 through 1994, primarily during the months of December to April. The most commonly recognized problem was an emaciation syndrome (66%), followed by oiling (18%), aspergillosis (7%), trauma (5%) and miscellaneous disease entities (1%). The cause-of-death for 3% of the birds was not determined. Many of the carcasses examined (n = 173) were obtained during an epizootic which occurred from January to March of 1983 in which more than 13,000 loons were estimated to have died. An emaciation syndrome, characterized by severe atrophy of pectoral muscles, loss of body fat and hemorrhagic enteritis, was the primary finding in this epizootic. It was postulated to have a complex etiologic basis involving synergistic effects and energy costs of migration, molting and replacement of flight feathers, food resource changes, salt-loading, intestinal parasitism, environmental contaminants, and inclement weather.

Animals↗
PubMed1996

Ectoparasites (Acari, Mallophaga, Anoplura, Diptera) of white-tailed deer, Odocoileus virginianus, from southern Florida.

During a 7-yr period (1984-1990), 300 white-tailed deer, Odocoileus virginianus (Zimmermann), from 7 localities in Collier, Dade, and Monroe counties in southern Florida were examined for ectoparasites. Eight species were identified: 4 ticks [Ixodes scapularis Say, I. affinis Neumann, Amblyomma maculatum (Koch), and Dermacentor variabilis (Say)], 1 chigger mite [Eutrombicula splendens (Ewing)], 1 ked (Lipoptena mazamae Rondani), 1 chewing louse [Tricholipeurus lipeuroides (Megnin)], and 1 sucking louse [Solenopotes binipilosus (Fahrenholz)]. The most widely distributed and prevalent species were the deer ked L. mazamae and the blacklegged tick I. scapularis, both of which occurred in all 7 localities, in all years, and in all age classes of deer. Their overall prevalences were 82 and 22%, respectively. The prevalence of L. mazamae varied significantly by month. L. mazamae should be considered a core ectoparasite species of white-tailed deer in southern Florida because of its specificity, distribution, and high prevalence.

Animals↗
PubMed1996

A comparison of parasitic helminths and arthropods from two subspecies of fox squirrels (Sciurus niger) in Florida.

The faunas of parasitic helminths and arthropods of 87 Sherman's fox squirrels (Sciurus niger shermani) and 32 Big Cypress fox squirrels (Sciurus niger avicennia) collected from Florida (USA) over a 6-yr period (1988 to 1993) were compared. One acanthocephalan, one cestode, nine nematodes, one flea, three sucking lice, three mites, one tick, and one dipteran larva were identified. Citellinema bifurcatum and Physaloptera massino were new records for Florida and Gongylonema pulchrum, Neotrombicula whartoni, and Eushoengastia diversa were new host records. Three core species of nematodes (distributed widely, highly host specific, and very prevalent) were identified from Sherman's fox squirrels. These included Strongyloides robustus, Heligmodendrium hassalli, and C. bifurcatum, which were higher in prevalence and intensity in Sherman's fox squirrels than in Big Cypress fox squirrels. One core species of cestode (Raillietina bakeri) was collected from 32% of Sherman's fox squirrels, but was not observed in Big Cypress fox squirrels. The number of species, prevalences, intensities, and abundances of parasites from Sherman's fox squirrels were greater than those from Big Cypress fox squirrels.

Animals↗
PubMed1995

Selenium status of white-tailed deer in southern Florida.

Samples of serum, liver, kidney, and heart were collected for selenium analysis from 174 white-tailed deer (Odocoileus virginianus) in southern Florida (USA), 1984 to 1988, to determine the selenium status of these animals. Deer were obtained from eight sites and classified by five age-class groups. For serum and the three tissues analyzed, selenium concentrations varied significantly (P < 0.001) among sites. Differences between years (P < 0.0004) were found for heart and kidney, age-class (P < 0.004) for kidney and season (P < 0.02) for liver. Low selenium concentrations were evident, in that 75% of all serum samples analyzed contained less than the critical concentration (< 0.06 ppm) by livestock standards, with 50% of serum samples less than 0.03 ppm, evidence of a severe deficiency. Likewise, tissue selenium concentrations (dry basis) were below critical livestock concentrations in 13% of the liver samples (< 0.25 ppm), 36% in kidney (< 3.0 ppm) and 19% in heart (< 0.15 ppm). Based on serum and tissue data, selenium dietary intake was low and may have been deficient for white-tailed deer in southern Florida.

Age Factors↗
PubMed1994

A species of Plasmodium from sandhill cranes in Florida.

Infections of a species of Plasmodium (subgenus Giovannolaia) were diagnosed in 3 sandhill cranes (Grus canadensis) from north-central Florida. This parasite is close morphometrically to Plasmodium polare; this finding constitutes the first report of a species of Plasmodium from sandhill cranes in North America.

Animals↗
PubMed1993

Demodicosis in black bears (Ursus americanus) from Florida.

Demodicosis was diagnosed in five black bears (Ursus americanus) from north-central Florida. The first bear examined, a 5-yr-old male, had severe alopecia except for the dorsal neck, paws, and ears. The skin was characterized by moderate orthokeratotic hyperkeratosis, and mild to moderate follicular hyperkeratosis. Superficial dermatitis, follicular pustules, and epidermal pustules were present, but rare. Specimens of Demodex sp. were seen most commonly within hair follicles devoid of hair and at the infundibulum of sebaceous glands. Four additional bears from the same area also had some degree of alopecia and skin scrapings were positive for Demodex sp. This mite may be common, although its prevalence is not known.

Animals↗
PubMed1993

Seroprevalence of infectious disease agents in free-ranging Florida panthers (Felis concolor coryi).

Serum samples obtained from 38 free-ranging Florida panthers (Felis concolor coryi) in southern Florida, March 1978 through February 1991, were tested for antibodies against eight bacterial, parasitic, and viral disease agents. Sera were positive for antibodies against feline panleukopenia virus (FPV) (78%), feline calicivirus (56%), feline immunodeficiency virus/puma lentivirus (37%), feline enteric coronavirus/feline infectious peritonitis virus (19%), and Toxoplasma gondii (9%). All samples were seronegative for Brucella spp., feline rhinotracheitis virus, and pseudorabies virus. In addition, all the animals tested were negative for feline leukemia virus p27 antigen as determined by enzyme-linked immunosorbent assay. Feline panleukopenia virus was considered to be a potentially significant disease agent; FPV antibodies occurred in the highest prevalences in older age classes (P = 0.027) and in panthers living in the dense mixed hardwood swamps in the western portion of their range compared to the open cypress and sawgrass prairies to the east (P = 0.096). Because < 50 animals remain in this relict population and the probable resultant depression of genetic diversity and lowered disease resistance, FPV or other disease agents could contribute to the extinction of this endangered subspecies.

Animals↗
PubMed1993

Morphology, prevalence, and distribution of Sarcocystis spp. in white-tailed deer (Odocoileus virginianus) from Florida.

Three morphologically distinct types of sarcocysts (I, II, and III) were identified by light microscopy in tongues from 403 white-tailed deer (Odocoileus virginianus) collected in Florida (USA) over a 7-yr-period. Based on electron microscopy of representative examples of these sarcocysts, there were four distinctive wall structures. We concluded that one of these (Type I) was representative of Sarcocystis odocoileocanis and another (Type III) was representative of an unnamed species previously described from white-tailed deer in Montana. Type II could be divided further into two forms (IIA and IIB) that may represent two underscribed species or developmental stages of the same species. Sarcocystis odoi, another previously recognized sarcosporidian from white-tailed deer, was not found. Sarcocysts of Types I and II were distributed nonrandomly in tongue muscle, being more common in the basal portion, whereas Type III was distributed randomly throughout the tongue. Single infections (one of the three types) accounted for 63% of the infected deer, while double infections occurred in 28% and triple infections in 4%. Types I and II were found in deer throughout the state, but Type III occurred only in deer from southern Florida. In 1988 and 89, the statewide prevalences for Types I, II, and III were 57, 20, and 6%, respectively. Prevalences of Type I ranged from 94% in the panhandle region (northern Florida) to 34% in the southern part of the state. Prevalences of all three types increased with age.

Age Factors↗
PubMed1993

The epizootiology of eustrongylidosis in wading birds (Ciconiiformes) in Florida.

A total of 2,167 individuals representing 15 species of wading birds was examined for infection with the nematode Eustrongylides ignotus in Florida (USA). Ten of the species were infected with the greatest prevalences occurring in great blue herons (Ardea herodius) (33%), great egrets (Casmerodius albus) (22%), and snowy egrets (Egretta thula) (19%). Among nestlings, prevalences increased with age. This parasite was estimated to cause at least 80% mortality among nestling ciconiiforms at one colony in Everglades National Park, and was found in 15% of nestling ardeids throughout the state. Despite wide sampling efforts, infected fish (second intermediate hosts) were only found at six sites in Florida, all of which had been physically altered, such as with canals and ditches, and had an anthropogenic (human-caused) source of nutrient pollution. Colonies near sources of infected fish experienced significantly higher prevalences of eustrongylidosis that did colonies for which no source of infected fish could be found within 20 km. Higher prevalences were found at freshwater and estuarine mainland colonies than at marine colonies. Densities of aquatic oligochaetes, which may act as first intermediate hosts, were highest at sites containing infected fish and at sites with a source of nutrient pollution. Conservation and management of wading bird species should include consideration of this disease, epizootics of which seem to be linked to nutrient pollution.

Age Factors↗
PubMed1993

Pathogenesis of Eustrongylides ignotus (Nematoda: Dioctophymatoidea) in Ciconiiformes.

Natural (n = 157) and experimental (n = 5) infections with the nematode Eustrongylides ignotus are described for ciconiforms collected in Florida (USA). Larvae perforated the ventriculus in 3 to 5 hr and caused hemorrhage and bacterial peritonitis that sometimes progressed to a fibrous peritonitis with extensive adhesions. Severity of the disease was related inversely to the age of the bird and directly to the number of parasites involved. Some infections in adult birds were resolved. As a consequence of eustrongylidosis, anorexia and behavioral abnormalities resulted in emaciation and may have predisposed birds to traumatic death. Host-parasite adaptations apparently were not adequate for nestling ciconiforms as death of nestlings usually occurred before infections become patent (longer than 14 days, less than 23 days). Patent infections were found in both color morphs of the great blue heron (Ardea herodius), and in great egrets (Casmerodius albus) and snowy egrets (Egretta thula). We propose that birds of the family Ardeidae are the primary definitive hosts.

Age Factors↗
PubMed1991

Ectoparasites of a population of urban gray squirrels in northern Florida.

Ectoparasites infesting a population of urban gray squirrels (Sciurus carolinensis Gmelin) in northern Florida were collected monthly during 1974. Eleven species were identified: one flea (Orchopeas howardi (Baker], three suckling lice (Enderleinellus longiceps Kellogg & Ferris, Hoplopleura sciuricola Ferris, and Neohaematopinus sciuri Jancke), one tick (Dermacentor variabilis Say), two mesostigmatid (gamasid) mites (Androlaelaps casalis (Berlese) and A. fahrenholzi (Berlese], and four chiggers (Eutrombicula alfreddugesi (Oudemans), E. splendens (Ewing), Leptotrombidium peromysci Vercammen-Grandjean & Langston, and Parasecia gurneyi (Ewing]. The flea and three suckling lice represent core species of ectoparasites for the gray squirrel; the remainder are probably satellite species. Only E. longiceps varied significantly in prevalence or intensity of infestation among host age groups; subadult squirrels had higher intensities than adults. Peak prevalence of O. howardi occurred in January and attained maximum intensity in March, whereas both prevalance and intensity were minimum in August. Prevalence of H. sciuricola was maximum in November and remained at similar levels through June. It then declined significantly to its minimum in September-October. Intensity of infestation, however, was greatest in August, September, and January. Maximum prevalence of N. sciuri occurred from January to March and was minimum in September; intensity of infestation reached maxima in January, June, and August.

Animals↗