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Biomedical subjects

E C Greiner

Publications and source records attributed to E C Greiner.

At least 55 records · Page 3Linked to original sources
PubMed1993

Vector competence parameters of Culicoides variipennis (Diptera: Ceratopogonidae) for bluetongue virus serotype 2.

Culicoides variipennis (Coquillett), the only proven vector of bluetongue virus (BLU) in the western hemisphere, was evaluated as a vector of bluetongue virus serotype 2 (BLU 2). This serotype was isolated from sentinel cattle in south Florida at a site devoid of C. variipennis. Culicoides variipennis readily fed on a mixture of defibrinated blood and BLU 2 through chicken skin membrane. An infection rate of 46.2% was obtained. A growth curve of virus titers recovered from orally infected flies showed a linear relationship between the virus titers and the period of extrinsic incubation. Culicoides variipennis also became infected when inoculated intrathoracically with BLU 2. Peak titers were higher and more rapidly attained in inoculated flies when compared with orally infected flies. Infected C. variipennis also transmitted BLU 2 to sheep via bite. These results demonstrate that C. variipennis is a potential biological vector of BLU 2 in the laboratory. The implication of this on the epidemiology of BLU 2 in the United States is that BLU 2 should have become more widespread in ruminants in the United States. The fact that this has not occurred during the past 10 yr is discussed.

Animals↗
PubMed1993

Epidemiology of bluetongue in Central America and the Caribbean: initial entomological findings. Regional Bluetongue Team.

Forty-four species of Culicoides (Diptera: Ceratopogonidae) were caught in insect light traps during the first 2 years of studies on the epidemiology of bluetongue virus in the Caribbean and Central America. Traps were operated near sentinel ruminants which were bled monthly for serologic evaluation and then virus isolation. More than 570,000 individuals were identified. Culicoides insignis Lutz accounted for 90% of the catch, C. filarifer Hoffman/C. ocumarensis Ortiz 5%, C. furens Poey 3% and C. pusillus Lutz 2%. Other species accounted for less than 1% of the total catch. Sentinel ruminants became seropositive when C. insignis populations were high at many study sites. At a few sites C. pusillus and C. filarifer/C. ocumarensis were predominant or were present in large numbers during seroconversions of sentinels. Virus isolations were obtained from sentinel ruminants during times when these same species were present in large populations.

Animals↗
PubMed1992

Epidemiology of bluetongue viruses in the American tropics. Regional Bluetongue Team.

A study of the epidemiology of bluetongue viruses is in progress with the collaboration of 11 Central American and Caribbean countries. To date, over 200 bluetongue virus isolates have been obtained from cattle and sheep in sentinel groups distributed in the participating countries. Bluetongue serotypes identified include 1, 3, 6, and 12, virus types not previously recorded in the Western Hemisphere. Although the clinical impact of bluetongue virus infections in this hyperendemic environment appears to be minimal, the ubiquity of infection causes restrictions on the export of ruminant livestock and germ plasm. The stability of the Caribbean region ecosystem and the long-range implications of the interface with the northern temperate bluetongue virus ecosystem are reviewed.

Animals↗
PubMed1992

Comparison of febantel tablets and Vercom paste against gastrointestinal nematodes of dogs.

Thirty adult dogs with naturally acquired gastrointestinal nematode infections were assigned at random to ten replicates and treated daily for 3 days with either a combination febantel/praziquantel (Vercom) paste, febantel tablets or placebo tablets. Numbers of hookworm and whipworm eggs after treatment were reduced similarly for both drug formulations when compared with pretreatment egg counts, whereas these counts increased in the controls. Vercom paste reduced the hookworm egg count by 99.9% and the whipworm egg count by 99.6%. The febantel tablet decreased the hookworm egg count by 99.9% and the whipworm egg count by 100%. As determined at necropsy, the controlled test efficacy against adult hookworms and whipworms was similar for the Vercom paste and the febantel tablets. The controlled test efficacies of Vercom paste against Ancylostoma caninum, Ancylostoma braziliense, and Trichuris vulpis were, respectively, 99.7%, 100% and 95.8% and those of febantel tablets were 98.2%, 100% and 99.7%. These results indicate that the nematocidal efficacy of febantel against these nematodes remains unchanged in these two formulations. No adverse reactions to either febantel tablets or to Vercom paste were observed.

Administration, Oral↗
PubMed1992

Evaluation of Culicoides insignis (Diptera: Ceratopogonidae) as a vector of bluetongue virus.

Based upon epidemiological evidence, Culicoides insignis Lutz is a probable biological vector of bluetongue viruses (BTV) in South Florida, the Caribbean Region and Central America. The vector potential of this species for BTV was evaluated in the laboratory in a series of experiments using insects caught in the field. Although there was great variation in the percentage of flies that fed from any one catch, it was demonstrated that C. insignis became infected after membrane feeding on a mixture of blood and virus. The infection rates ranged from 20 to 62.5%. Following intrathoracic inoculation, BTV replicated to high titres in C. insignis. Such flies were also shown to be capable of transmitting BTV to susceptible sheep and embryonated chicken eggs. This series of experiments provides the first conclusive evidence that C. insignis is a biological vector of bluetongue virus. This is the first proven vector of BTV in the neotropics.

Animals↗
PubMed1992

Sarcocysts in the Florida bobcat (Felis rufus floridanus).

Sarcocysts were found in the tongue, diaphragm, heart, intestinal tunica muscularis, and skeletal muscle of bobcats (Felis rufus floridanus) collected in Florida (USA). The tongue was found to be the best indicator tissue for sarcocysts (P less than 0.005). Thirty of 60 bobcats screened were found to contain sarcocysts in at least one of the muscle tissues examined. Of the positive bobcats, 28 of 28 tongues contained sarcocysts, while only 10 of 27 (37%), and 8 of 26 (31%) contained sarcocysts in the diaphragm or cardiac muscle, respectively. Although immune suppression has been suggested as a possible reason for formation of sarcocysts in some carnivores, no such correlation was evident in the bobcats. Comparisons of prey species taken by the panther and bobcat, and overlap of geographical range by the two species leave questions as to the source of infection, and the species of Sarcocystis that is infecting both felids.

Animals↗
PubMed1991

Seroepidemiology of Bivens Arm virus infections of cattle in Florida, St. Croix and Puerto Rico.

Bivens Arm virus (BAV) is a newly discovered rhabdovirus infecting cattle and water buffalo in Florida. The virus is classified as a member of the Tibrogargan group, members of which have hitherto been found only in Australasia. They are considered to be transmitted by Culicoides species. Bivens Arm virus was first isolated from Culicoides insignis which suggests that BAV is also transmitted by this genus. A serological survey of two small groups of cattle raised in St. Croix and Puerto Rico, in the Caribbean, established that antibody to BAV, or a closely related virus, exists on both island. A retrospective analysis of seroconversions to BAV in sentinel calves in Florida, relative to populations of potential Culicoides vectors, failed to demonstrate any statistically significant correlation.

Animals↗
PubMed1991

Nasitrema sp.-associated encephalitis in a striped dolphin (Stenella coeruleoalba) stranded in the Gulf of Mexico.

An immature female striped dolphin (Stenella coeruleoalba) found dead on a northwestern Florida beach in 1988 exhibited severe inflammation bilaterally in the dorsal and mid-thalamus in association with adult trematodes (Nasitrema sp.) and trematode eggs. Numerous specimens of Nasitrema sp. also were present in the pterygoid sinuses. Pneumonia in association with a heavy growth of Vibrio damsela was observed also. This report confirms the occurrence of Nasitrema sp.-associated encephalitis in striped dolphins and in small cetaceans from the Gulf of Mexico.

Animals↗
PubMed1991

Verminous mastitis in a mare caused by a free-living nematode.

Verminous mastitis was the reason for euthanasia of a 22-yr-old Paso Fino mare from Miami, Florida. The etiologic agent was a species of Cephalobus (Rhabditida: Cephalobidae), a genus of soil-inhabiting nematodes that were obviously multiplying in the mammary gland. Only females and larvae were detected in the tissues by histologic section or by teasing the tissue to liberate the worms. At least 12,900 individuals were present per gram of tissue. This is the first case of Cephalobus infecting horses and it indicates that not all histiotropic infections of horses by rhabditoid nematodes are by Halicephalobus deletrix ( = Micronema deletrix).

Animals↗
PubMed1991

Efficacy of clorsulon for the treatment of experimentally induced infections of Fasciola hepatica in goats.

A dose titration study was undertaken to determine the efficacy of clorsulon against the adult stage of Fasciola hepatica in goats. Thirty-nine goats were experimentally infected with metacercariae of F hepatica. At 14 weeks after infection, each goat was assigned randomly to 1 of 5 groups. Goats in groups 1 to 4 received a single oral administration of clorsulon at dosages of 3.5, 7, 11, and 15 mg/kg of body weight, respectively. The fifth group of goats (control group) was infected with F hepatica, but were not treated with clorsulon. Postmortem examination of goats at 3 weeks after treatment revealed mean reductions in numbers of flukes of 83, 98, 99, and 100% for groups 1 to 4, respectively. Mean percentage of reduction in eggs following treatment of groups was 82, 98, 100, and 100%, respectively. The clinical effects of clorsulon in 24 goats that were not infected with F hepatica were studied. Goats in groups 1 to 3 received a single oral administration of clorsulon at dosages of 7, 21, and 35 mg/kg, respectively, every other day for a total of 3 doses/goat. Group-4 goats (control group) received a vehicle placebo. Goats in group 3 were subject to postmortem examination at 14 days after dosing. Abnormal signs or lesions that could be attributed to clorsulon were not found in any goat.

Animals↗
PubMed1990

Culicoides spp. (Diptera: Ceratopogonidae) associated with cattle in St. Croix, Virgin Islands, and their relevance to bluetongue virus.

Potential biting midge vectors were collected at two sites on St. Croix as part of an ongoing study on the epidemiology of bluetongue viruses in the Caribbean region. Six species of Culicoides were trapped in a New Jersey light trap (mean = 173 biting midges/trap night) near cattle on a dairy farm. C. furens (Poey) and C. insignis Lutz were the predominant phototactic species, and C. pusillus Lutz, C. trilineatus Fox, C. jamaicensis Edwards, and C. phlebotomus (Williston) were collected less frequently. Four species of Culicoides were aspirated from bovine bait during the morning and evening crepuscular periods with a modified car vacuum. C. furens was aspirated primarily from the ventral portions of the bovine host, whereas C. insignis and C. pusillus were collected principally from the dorsum, and C. trilineatus was collected equally from all aspects. At least one individual of each of these aspirated species was blood engorged. Because C. furens, C. insignis, C. pusillus, and C. trilineatus were most abundant and feed on cattle, they deserve further consideration as vectors of bluetongue virus on St. Croix.

Animals↗
PubMed1990

Bluetongue epidemiology in the Caribbean region: serological and entomological evidence from a pilot study in Barbados.

Variation in the percentage of lambs seroconverting to bluetongue viruses was seen between sites and years in Barbados. Transmission at some sites was nearly absent whereas all lambs at one site became seropositive. The agar gel immunodiffusion test for bluetongue gave consistent results in series of serum samples from 112 of 121 sentinel lambs. Collections of biting midges in association with sheep yielded six species: Culicoides insignis Lutz, C. pusillus Lutz, C. phlebotomus (Williston), C. furens (Poey), C. jamaicensis Edwards and C. trilineatus Fox. The first two species comprised 92% of those caught during a sentinel lamb study and were the predominant species trapped for virus isolation. No viruses were recovered from 5517 C. insignis, 614 C. pusillus, three C. trilineatus and two C. furens placed into pools during two brief intensive trapping operations.

Animals↗
PubMed1990

Equine Culicoides hypersensitivity in Florida: biting midges aspirated from horses.

Nine species of Culicoides were aspirated from horses in Florida during the second phase of a study of equine Culicoides hypersensitivity (CHS). Approximately 90% of the 2933 midges were Culicoides insignis Lutz, 4% were C.stellifer (Coquillett), 3% were C.niger Root and Hoffman, 2% were C.alachua Jamnback and Wirth and the remaining 1% included C.venustus Hoffman, C.scanloni Wirth and Hubert, C.lahillei Iches (= C.debilipalpis Lutz), C.pusillus Lutz, and C.edeni Wirth and Blanton. Culicoides were sampled on seven farms located throughout Florida. The location and seasonality of lesion development on horses with CHS correlated with the Culicoides spp. collected directly from the horses as to their sites of attack, their seasonality and geographical distribution.

Animals↗
PubMed1990

Specific immunotherapy in the treatment of Culicoides hypersensitive horses: a double-blind study.

Fourteen privately owned horses completed a six month, controlled, double-blind trial to assess the efficacy of immunotherapy using an aqueous extract of whole, unfed Culicoides variipennis in the treatment of Culicoides hypersensitivity. Selected horses had a history of a seasonal, pruritic dermatitis, clinical signs and distribution compatible with Culicoides hypersensitivity, failed to improve in response to ivermectin therapy, and reacted to several dilutions of Culicoides extracts without significant reactivity to other possible allergens including insects, moulds and feeds. One horse from the control group (n = 8) and one from the test group (n = 6) improved. Statistically, there was no significant difference between horses on Culicoides antigen and control horses. In each group, four owners thought that their horses had improved.

Animals↗
PubMed1990

Equine insect hypersensitivity: skin test and biopsy results correlated with clinical data.

Forty-four seasonally pruritic horses and 21 asymptomatic horses in Florida, USA, were tested for insect, grass and mould hypersensitivity by intradermal injection of allergenic extracts. The affected horses ranged in age from 10 months to over 30 years and included a variety of breeds. Affected horses reacted to varying dilutions of extracts made from Culicoides, mosquitoes, horse flies and black flies. Reactions to Culicoides were more intense than those caused by injection of antigens from other arthropods. Mild pruritus existed from the end of February until the end of June when the condition worsened and remained severe until November when it improved to an asymptomatic state. Histopathological examination of skin biopsies demonstrated changes compatible with arthropod hypersensitivity. Three clinical syndromes associated with insect hypersensitivity were described as follows: 1) horses with lesions on face, ears, mane, withers, rump and tail; 2) horses with lesions on face, ears, intermandibular space, chest, belly and groin, and 3) those with a combination of dorsal and ventral lesions.

Animals↗
PubMed1990

Epidemiologic study of bluetongue viruses in Central America and the Caribbean: 1986-1988. Regional Bluetongue Team.

Results of a prospective serologic and virologic study of ruminant livestock in Central America and the Caribbean islands revealed bluetongue virus (BTV) to be enzootic in the 9 countries participating in the study. Bluetongue virus serotypes 1, 3, 6, and 12 were isolated from sentinel animals. To the authors' knowledge, these are the first isolations of BTV from the region studied and the first isolations of these serotypes in the Western Hemisphere. Clinical disease attributable to BTV infection was not observed in sentinel animals. The incidence pattern, with respect to age and geographic location, was determined. The need to evaluate the epizootiologic features or arthropod-borne viruses (arboviruses) on a regional ecologic basis is stressed.

Animals↗
PubMed1989

Bivens arm virus: a new rhabdovirus isolated from Culicoides insignis in Florida and related to Tibrogargan virus of Australia.

During field studies in 1981 on the transmission of bluetongue viruses in ruminants in Florida, a virus was isolated from Culicoides insignis collected near water buffalo (Bubalus bubalis) recently imported from Trinidad. Electron microscopy showed that this isolate, for which the name Bivens Arm virus is proposed, has rhabdovirus morphology. Serologic comparisons were made with recognized rhabdoviruses from terrestrial vertebrates and hematophagous arthropods. Indirect fluorescent antibody, complement fixation and neutralization tests indicated antigenic reactivity between Bivens Arm virus and two rhabdoviruses found only in Australia, Tibrogargan and Coastal Plains viruses. The Australian isolates cause subclinical infections in cattle and water buffalo and are believed to be transmitted by Culicoides. Initially, it was thought that Bivens Arm virus may have been introduced to Florida with the water buffalo from Trinidad, but a serologic survey of cattle serum, collected before the importation of the buffalo revealed antibody to the virus in cattle on farms located in diverse areas of Florida.

Animals↗