Biomedical subjects

J B Pusterla

Publications and source records attributed to J B Pusterla.

10 recordsLinked to original sources

PubMed2001

Susceptibility of cattle to infection with Ehrlichia equi and the agent of human granulocytic ehrlichiosis.

OBJECTIVE: To determine susceptibility of cattle to infection with Ehrlichia equi and the agent of human granulocytic ehrlichiosis (HGE). DESIGN: Experimental disease and prevalence survey. ANIMALS: 6 cattle, 2 horses, and 2,725 serum samples from healthy cattle. PROCEDURE: 2 cattle and 1 horse were inoculated with E equi, 2 cattle and 1 horse were inoculated with the HGE agent, and 2 cattle served as sham-inoculated controls; inoculated animals were evaluated via clinical, hematologic, serologic, and real-time polymerase chain reaction tests. Prevalence of antibodies against E equi in 2,725 healthy cattle was determined by use of an indirect immunofluorescent technique. RESULTS: No abnormal clinical or hematologic findings or inclusion bodies within granulocytes were observed in the cattle after inoculation, and results of all polymerase chain reaction tests were negative. Seroconversion in inoculated cattle developed 10 to 12 days after inoculation (reciprocal titers, 160). Both horses developed clinical signs of ehrlichiosis. Five of 2,725 (0.18%) cattle were seropositive for E equi, with titers ranging from 20 to 80. All seropositive cattle originated from the same tick-rich region in the Sierra Nevada foothills. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cattle are not susceptible to infection with E equi or the agent of HGE and that prevalence of exposure to E equi in healthy cattle is low. Therefore, E equi and the agent of HGE are likely of negligible importance for cattle in North America.

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PubMed2000

Infection rate of Ehrlichia risticii, the agent of Potomac horse fever, in freshwater stream snails (Juga yrekaensis) from northern California.

Juga yrekaensis freshwater snails were tested for trematode stages and for Ehrlichia risticii DNA using a nested PCR assay. Snails were collected monthly from two Potomac horse fever (PHF) endemic locations in northern California (Montague and Weed). The trematode infection rate varied between 40 and 93.3% in large snails (shell size >15mm) and between 0 and 13.3% in small snails (<15mm). The highest trematode infection rate for large and small snails was recorded in September and the lowest infection rate for large snails was recorded in June (Weed) and October (Montague). The E. risticii PCR infection rate among small snails from both sites was similar and varied monthly between 0 and 3.3%. The PCR infection rate for large snails from Weed was high in May (20.0%) and decreased progressively until November (10.0%). The PCR infection rate for large snails from Montague was 5.0% in May, 26.3% in August and 16. 7% in October. PCR-positive snails were always related to the microscopic detection of trematode stages (virgulate cercariae). This study provides evidence that J. yrekaensis are infected with trematode cercariae that harbor E. risticii. The number of snails harboring trematode stages and the number of PCR positive snails varied with the size of the snails, the month of collection, and the geographic origin.

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PubMed2000

Experimental inoculation with human granulocytic Ehrlichia agent derived from high- and low-passage cell culture in horses.

We report the successful infection throughout intravenous inoculation with low and high passage of in vitro-grown human granulocytic ehrlichiosis (HGE) agent in horses. Differences in disease severity but not in incubation time, hematological changes, PCR detection, ehrlichial load, seroconversion time, and titer range were noted between horses infected with a low and a high passage of in vitro-grown HGE agent.

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PubMed2000

Helminthic transmission and isolation of Ehrlichia risticii, the causative agent of Potomac horse fever, by using trematode stages from freshwater stream snails.

We report successful helminthic transmission of Ehrlichia risticii, the causative agent of Potomac horse fever, using trematode stages collected from Juga yrekaensis snails. The ehrlichial agent was isolated from the blood of experimentally infected horses by culture in murine monocytic cells and identified as E. risticii ultrastructurally and by characterization of three different genes.

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PubMed2000

Transmission of Ehrlichia risticii, the agent of Potomac horse fever, using naturally infected aquatic insects and helminth vectors: preliminary report.

Ehrlichia risticii, the agent of Potomac horse fever (PHF), has been recently detected in trematode stages found in snail secretions and in aquatic insects. Based on these findings, horses could conceivably be exposed to E. risticii by skin penetration with infected cercariae, by ingestion of infected cercariae in water or via metacercariae in a second intermediate host, such as an aquatic insect. In order to test this hypothesis, horses were challenged with infectious snail secretions and aquatic insects collected from a PHF endemic region in northern California. Two horses stood with their front feet in water harbouring E. risticii-infected cercariae, 2 horses drank water harbouring E. risticii-infected cercariae, and 6 horses were fed pools of different aquatic insects harbouring E. risticii-infected metacercariae. In this preliminary study, only the one horse infected orally with mature caddisflies (Dicosmoecus gilvipes) developed the clinical and haematological disease syndrome of PHF. The agent was isolated from the blood of the infected horse in a continuous cell line and identified as E. risticii by characterisation of the 16S rRNA gene. Therefore, E. risticii is maintained in nature in a complex aquatic ecosystem and transmission to horses can occur through accidental ingestion of insects such as caddisflies containing infected metacercariae. At present, the small number of horses used in this study does not exclude other insects and free trematode stages as potential sources of infection.

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PubMed1999

Experimental cross-infections with Ehrlichia phagocytophila and human granulocytic ehrlichia-like agent in cows and horses.

Four cows and four horses were infected experimentally with Ehrlichia phagocytophila, the cause of tickborne fever in ruminants, and with human granulocytic ehrlichia-like agent, a recently discovered species that infects people, horses and dogs in the USA and Europe. They were infected in either order, 30 days apart, to investigate serological cross-reactivity within the Ephagocytophila genogroup. The course of infection was assessed by routine clinical, haematological, serological and polymerase chain reaction (PCR) examinations. Two of the cows infected with Ephagocytophila and two of the horses infected with granulocytic ehrlichia-like agent, developed characteristic signs of ehrlichiosis. When the same animals were infected with their heterologous ehrlichial isolate 30 days later, they did not develop clinical signs of disease. The infection of the other two cows with human granulocytic ehrlichia-like agent and the other two horses with Ephagocytophila, resulted in asymptomatic seroconversion. When the same animals were infected with their homologous ehrlichial isolate 30 days later, they remained asymptomatic and had normal haematological results and negative PCRS until the end of the monitoring period, 60 days after the first infection. In these animals, there was an increase in antibody titre after the second infection which was interpreted as a specific immune response, and as a reactivation of the immune response to the first infection.

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PubMed1998

Serological, hematologic, and PCR studies of cattle in an area of Switzerland in which tick-borne fever (caused by Ehrlichia phagocytophila) is endemic.

The purpose of this study was to examine the seasonal variations in seroprevalence to Ehrlichia phagocytophila in cattle pastured during the summer months in an area where tick-borne fever is endemic. The study was performed during a 1-year period from April 1996 to March 1997 and involved 34 cows, 22 pregnant heifers, and 14 calves. Blood samples, collected from all 70 cattle once a month, were used to determine serum immunoglobulin G titers by indirect immunofluorescence. In addition, blood smears were examined for Ehrlichia organisms, and PCR amplification was performed for the molecular detection of E. phagocytophila. Prior to the pasture period, the seroprevalence was 16%. Two weeks after the start of pasturing, it was 43%, after which it progressively increased and reached a maximum of 63% in September. The seroprevalence progressively decreased after the end of pasturing to a low of 23%. The variation in antibody titers was similar to that of seroprevalence. E. phagocytophila organisms were detected in blood smears of 7 animals and by nested PCR in 12. Only four cows, which were on the pastures of endemicity for the first time, had clinical signs of ehrlichiosis. This study demonstrated marked seasonal variations in seroprevalence and in serum titers of antibody to E. phagocytophila in cattle. The incidence of clinical signs of ehrlichiosis was increased in cattle grazing on the pastures of endemicity for the first time.

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PubMed1998

Seroprevalence of Ehrlichia canis and of canine granulocytic Ehrlichia infection in dogs in Switzerland.

Serum samples from 996 dogs in Switzerland were examined for antibodies to Ehrlichia canis and to the agent causing canine granulocytic ehrlichiosis (CGE). Ehrlichiosis, borreliosis, and systemic illness not associated with ticks were suspected in 75, 122, and 157 of these dogs, respectively. The remainder of the serum samples were obtained from clinically healthy dogs which resided north (n = 235) or south (n = 407) of the Alps. The serum samples were tested by an indirect immunofluorescence technique for antibodies to the two agents incriminated, E. canis and Ehrlichia phagocytophila, a surrogate marker of the agent of CGE. Twenty-two of 996 (2.2%) serum samples had antibodies to E. canis and were distributed as follows: 20 of 75 (26.7%) samples from dogs suspected of having ehrlichiosis, 1 of 122 (0.8%) from dogs suspected of having borreliosis, and 1 of 407 (0.2%) from healthy dogs which resided south of the Alps. Of the 75 (7.5%) serum samples that had antibodies to E. phagocytophila, significantly more samples were from ill dogs than from healthy dogs. Among the sera from healthy dogs, antibodies to E. phagocytophila were significantly more prevalent in the north. Because seropositive dogs had a history of travel outside Switzerland and because Rhipicephalus sanguineus is found exclusively south of the Alps, it was presumed that, in contrast to the agent of CGE, E. canis is not indigenous to Switzerland.

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PubMed1998

[Video-assisted theloscopic electroincision of a high teat stenosis].

Results of surgery of high teat stenosis remained disappointing until nowadays. The aim of this pilot study was to elaborate a new theloscopic surgical resection. A 5.5 year old swiss milk cow was suspected to have posttraumatic high teat stenosis. Diagnosed was ascertained by teat sonography. Animal was sedated and local anesthesia was performed at the base of the teat. After a teat side incision, resectoscope was introduced. Stenosis was electro-divided under continuity saline-solution irrigation and coagulation of bleeding vessels. After a follow-up period of 4 months, the cow was milked without residual. No intercurrent infections occurred. There were no signs of recurrence in the control teat sonography. Theloscopic electroresection of teat stenosis is a possible new, surgical, minimal invasive, option, to treat high teat stenosis.

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PubMed1996

[Chylothorax in a calf].

A case of chylothorax caused by fracture of thoracal vertebrae in a two-day-old Swiss Braunvieh male calf ist described. The clinical symptoms were those of a unilateral, progressive pleural effusion. This was confirmed by radiological and ultrasonographic examinations. Thoracocentesis was performed under ultrasonographic assistance. The liquid obtained from the pleural cavity was turbid and contained chylomicrons, lymphocytes and neutrophilic granulocytes as well as a high concentration of triglycerides. These qualities go together with chylus. Immunohistological examination for BVD virus turned out to be positive. An intrauterine disturbance of osteogenesis due to BVD virus must be considered a possible cause for fracture of vertebrae during delivery.

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