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Biomedical subjects

N Pusterla

Publications and source records attributed to N Pusterla.

At least 37 records · Page 2Linked 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.

Animals↗
PubMed2001

Echocardiography of the normal bovine heart: technique and ultrasonographic appearance.

Fifty-one clinically healthy cows were examined ultrasonographically from the third and fourth intercostal spaces on both sides of the thorax. A 3.0 MHz transducer was used and the heart was examined in the caudal long, caudal short and cranial long axes on the right side, and in the caudal and cranial long axes on the left side. In each position the optimal transducer orientation and the images of the structures were recorded. In the caudal long axis view of the heart on the right (transducer positioned at the fourth intercostal space), all four chambers were visible with the transducer positioned 8 to 10 cm dorsal to the level of the olecranon. The left ventricular outflow tract, consisting of the aortic valve and ascending aorta, were visible in the same position with the transducer rotated 10 to 40 degrees clockwise. In the caudal short axis view of the heart on the right, the left and right ventricles were visible in cross-section with the transducer held at right angles to the ribs in the fourth intercostal space, 3 to 6 cm dorsal to the olecranon and tipped slightly dorsally. In the cranial long axis view of the heart on the right, the right ventricular outflow tract, consisting of the pulmonary valve and pulmonary artery, was visible in the third intercostal space, 8 to 10 cm dorsal to the olecranon with the transducer angled craniodorsally and rotated 10 to 20 degrees clockwise. In the caudal long axis view of the heart on the left, the left and right ventricles and the left ventricular outflow tract were visible with the transducer placed in the fourth intercostal space. In the cranial long axis view on the left, the right ventricular outflow tract was visible.

Animals↗
PubMed2000

[Serologic and clinical evidence for endemic occurrences of human granulocytic ehrlichiosis in North-Eastern Switzerland].

BACKGROUND: Tick-borne human granulocytic ehrlichiosis (HGE) has not been diagnosed in Switzerland, although the HGE agent has been identified in ticks and animal reservoirs and human infections have been suspected on the basis of serological surveys. METHODS: We retrospectively tested sera of 48 persons with antibodies to B. burgdorferi and/or tick-borne encephalitis virus for the presence of antibodies to E. phagocytophila (a surrogate marker of the agent of HGE), and reviewed their charts with regard to clinical manifestations possibly associated with a tick-borne infection. We then prospectively examined EDTA blood of 80 patients who presented with fever 7 to 21 days after a tick bite for the presence of the HGE agent (using nested PCR and microscopic examination of blood smears) and anti-E. phagocytophila antibodies. We also collected clinical data. RESULTS: The retrospective study revealed 12 persons (25%) with anti-E. phagocytophila antibody titers > or = 1:80, suggesting coinfection with HGE and either Lyme Borrelia or tick-borne encephalitis virus. Among these, 7 patients presented with clinical manifestations compatible with HGE disease. The prospective investigation identified 8 patients (10%) with anti-E. phagocytophila antibody titers > or = 1:80, and 7 of these presented with signs and symptoms suggesting HGE. The HGE agent, however, was detected neither by PCR nor by microscopic examination. CONCLUSIONS: Serological and clinical data suggest the occurrence of an HGE-like agent as well as of coinfections with HGE and B. burgdorferi or tick-borne encephalitis virus in Switzerland. However, the HGE agent was not identified in persons living in Switzerland.

Adolescent↗
PubMed2000

Molecular detection of an Ehrlichia-like agent in rainbow trout (Oncorhynchus mykiss) from Northern California.

Ehrlichia DNA was identified by nested PCR in rainbow trout (Oncorhynchus mykiss) collected from a creek in northern California where Potomac horse fever is endemic. Ehrlichia DNA was found in tissues from several organs including the gills, heart, spleen, liver, kidneys and intestine of trout and from three different adult digenetic trematodes (Deropegus sp., Crepidostomum sp., Creptotrema sp.) parasitizing the gallbladder and/or the intestine of the trout. Sequencing of PCR-amplified DNA from the 16S rRNA gene indicated that the source organism was most closely related to the sequences of E. risticii (level of sequence similarity 96.0%), the SF agent (95.9%), E. sennetsu (95.8%), and Neorickettsia helminthoeca (95.3%). The data suggest that trout and parasitic trematodes may be involved in the epidemiology of an Ehrlichia-like agent belonging to the E. sennetsu genogroup. Whether the fish agent infects horses, dogs, or human beings, and whether it causes disease, remain to be determined.

Animals↗
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.

Animals↗
PubMed2000

Detection and quantitation of Ehrlichia risticii genomic DNA in infected horses and snails by real-time PCR.

A real-time quantitative PCR using the TaqMan fluorogenic detection system (TaqMan PCR) was established for identification of Ehrlichia risticii, the agent of Potomac horse fever (PHF). The TaqMan PCR identified an 85 base pair section of the 16S rRNA gene by use of a specific fluorogenic probe and two primers. This technique was specific for eight tested E. risticii strains. The TaqMan system identified 10 copies of a cloned section of the 16S rRNA gene of E. risticii. The sensitivity and specificity of the TaqMan PCR were similar to those of conventional nested PCR. The TaqMan PCR was evaluated on horses with infectious colitis and on freshwater stream snails collected from regions with a history of PHF. E. risticii could be detected in 22 of 153 (14.4%) horses with infectious colitis and in 25 of 234 (10.7%) snails in the TaqMan PCR. The same results were obtained in the conventional nested PCR. The Ehrlichia-load was in the range of 10,000-9,000,000 and 35,000-680, 000,000 Ehrlichia equivalents per microg leukocyte DNA and snail DNA, respectively.

Animals↗
PubMed2000

Swiss Army Survey in Switzerland to determine the prevalence of Francisella tularensis, members of the Ehrlichia phagocytophila genogroup, Borrelia burgdorferi sensu lato, and tick-borne encephalitis virus in ticks.

A total of 6071 Ixodes ricinus ticks were collected on Swiss Army training grounds in five regions of Switzerland. The aim of the survey was to assess the prevalence of ticks infected with the human pathogens Francisella tularensis, members of the Ehrlichia phagocytophila genogroup, Borrelia burgdorferi sensu lato, and the European tick-borne encephalitis virus. TaqMan PCR (PE Biosystems, USA) and TaqMan RT-PCR (PE Biosystems) analyses were performed on DNA and RNA extracted from pools of ten ticks grouped by gender. Here, for the first time, it is shown that ticks may harbor Francisella tularensis in Switzerland, at a rate of 0.12%. Furthermore, 26.54% of the ticks investigated harbored Borrelia burgdorferi sensu lato, 1.18% harbored members of the Ehrlichia phagocytophila genogroup, and 0.32% harbored the European tick-borne encephalitis virus. A new instrumentation was applied in this study to carry out and analyze more than 2300 PCR reactions in only 5 days. Furthermore, the results reveal that people working in outdoor areas, including army personnel on certain training grounds contaminated with ticks containing tick-borne pathogens, are at risk for different tick-borne diseases.

Animals↗
PubMed2000

Ehrlichial diseases.

Equine granulocytic and monocytic ehrlichiosis caused by Ehrlichia equi and E. risticii, respectively, are seasonal diseases in horses that occur throughout the United States E. equi is transmitted by lxodes ticks and causes high fever, depression, anorexia, limb edema, petechiation, icterus, ataxia, and stiffness in gait. E. risticii, also known as the agent of Potomac horse fever, causes a febrile illness with a colitis of variable severity. Its occurrence is associated with aquatic habitats. The natural route of transmission is oral, through the ingestion of E. risticii infected trematode stages either free in water or in an intermediate host, such as aquatic animals.

Animals↗
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.

Animals↗
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.

Animals↗
PubMed2000

Infection of aquatic insects with trematode metacercariae carrying Ehrlichia risticii, the cause of Potomac horse fever.

We provide evidence of Ehrlichia risticii Holland, the agent of Potomac horse fever, in trematode stages found in aquatic insects collected from a pasture stream in northern California, using nested polymerase chain reaction (PCR) amplification and sequence analyses of the 16S rRNA, 51 kDa major antigen and groEL heat shock protein genes. E. risticii was detected in metacercariae found in the immatures and adults of the following insects: caddisflies (Trichoptera), mayflies (Ephemeroptera), damselflies (Odonata, Zygoptera), dragonflies (Odonata, Anisoptera), and stoneflies (Plecoptera). The prevalence of E. risticii was 31.9% (n = 454 individuals) in aquatic insects (13 of 17 species were positive). Prevalence within orders was as follows: 43.5% (n = 207) in caddisflies, 15.2% (n = 92) in mayflies, 13.9% (n = 115) in damselflies, 10.0% (n = 10) in dragonflies, and 80.0% (n = 30) in stoneflies. This study demonstrates a broad intermediate host range for trematodes that act as vector for E. risticii. Insects are likely to play an important role in the epidemiology of this disease.

Animals↗
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.

Animals↗
PubMed2000

Serologic and molecular evidence of Ehrlichia spp. in coyotes in California.

In order to determine the role of coyotes in the epidemiology of granulocytic and monocytic ehrlichial agents in California (USA), we tested 149 serum samples for antibodies against Ehrlichia equi, E. risticii, and E. canis, using an indirect immunofluorescent antibody test. Polymerase chain reaction (PCR) assay was used to survey for the presence of members of the E. phagocytophila genogroup, E. risticii and E. canis in blood samples of 95 coyotes. Sixty-eight (46%) samples were seropositive for E. equi, two (1%) for E. risticii and none of the samples had antibodies reactive to E. canis. Two and one coyote were positive for E. risticii and members of the E. phagocytophila genogroup by PCR assay, respectively. In contrast, the 95 samples were negative for E. canis by PCR. Ninety-five percent of the 68 E. equi seropositive coyotes and the one coyote PCR positive for members of the E. phagocytophila genogroup originated from a coastal area. However, the two E. risticii seropositive coyotes and the two coyotes PCR positive for E. risticii were from northern California. Sequence analysis of the three amplified PCR products revealed the agent to be similar in two coyotes to the sequences of E. risticii from horses originating from northern California and identical in one coyote to the agent of human granulocytic ehrlichiosis and E. equi from California. Thus, coyotes are exposed to granulocytic ehrlichiae and E. risticii and may play a role in the epidemiology of these ehrlichial agents in California.

Age Factors↗
PubMed2000

[Ehrlichiosis in Switzerland--significance for veterinary medicine].

Ehrlichiosis is a rickettsial disease of animals and humans caused by various species of Ehrlichia. These obligate intracellular microorganisms infect granulocytes or monocytes of mammalian hosts and are transmitted mostly by ticks. The febrile disease is often undiagnosed and characterized by leukopenia, anemia and thrombocytopenia. The diagnosis of ehrlichiosis is based on clinical findings, tick infestation, direct or indirect detection of the agent, and serology. The role of native and imported ehrlichiae of animals in Switzerland is discussed.

Animals↗
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.

Animals↗