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Biomedical subjects

J G Olson

Publications and source records attributed to J G Olson.

At least 55 records · Page 3Linked to original sources
PubMed1994

Evaluation of specificity of indirect enzyme-linked immunosorbent assay for diagnosis of human Q fever.

Ninety-five acute- and convalescent-phase serum specimens from 48 patients suspected of having rickettsial or Legionella infections were assayed for antibodies to Coxiella burnetii, the causative agent of Q fever. To evaluate the specificity of the indirect enzyme-linked immunosorbent assay (ELISA) for human Q fever, we compared the ELISA results with those of the indirect immunofluorescence antibody (IFA) test. The ELISA data were analyzed by two different criteria for a positive test. The first criterion for positive results by ELISA was based upon diagnostic titers established in a study of 150 subjects who had no demonstrable cellular or humoral immune responses to C. burnetii phase I or phase II whole cells or phase I lipopolysaccharide. The second criterion was based upon diagnostic antibody titers in a study of 51 subjects who had been diagnosed as having clinical Q fever and had fourfold or greater rises in humoral immune responses to C. burnetii phase I and phase II whole-cell antigens. A comparison of the ELISA and IFA test results of the 95 serum specimens indicated excellent agreement between the tests (Kappa = 92.9%; P < 0.05). None of the 38 patients whose etiologies were confirmed serologically as Legionnaires' disease or rickettsial diseases other than Q fever were classified as positive for C. burnetii by the ELISA. Only one patient identified by the IFA test as having Q fever was not scored positive by the ELISA. These results suggest that the ELISA is useful for epidemiologic screening and as a diagnostic test for human Q fever.

Acute Disease↗
PubMed1994

White-tailed deer as a potential reservoir of Ehrlichia spp.

We determined the antibody prevalence to Ehrlichia spp., in white-tailed deer (Odocoileus virginianus) and the geographic distribution of seropositive animals in 84 counties in Alabama, Arkansas, Florida, Georgia, Illinois, Kentucky, Louisiana, Maryland, Massachusetts, Mississippi, Missouri, North Carolina, South Carolina, Tennessee, Texas, Virginia, and West Virginia (USA). Using an indirect fluorescent antibody test we detected antibodies (> or = 1:128) to this bacterium in 544 (43%) of 1269 deer. Presence of antibodies to Ehrlichia spp. was related to a southerly latitude, low elevation, and resulting milder climatic conditions. It appears that white-tailed deer were naturally infected with Ehrlichia spp.; the infection was widely distributed throughout the southeastern United States. Based on these data, we propose that white-tailed deer play a role in the natural history of Ehrlichia spp. infection in the United States.

Animals↗
PubMed1994

Arthropod-borne viral infections associated with a fever outbreak in the northern province of Sudan.

An outbreak of acute febrile illness occurred during August and September 1989 in the Northern Province of Sudan coinciding with a high population density of phlebotomine sandflies. An investigation was conducted to determine whether arboviruses were associated with human illness during this outbreak. Sera were obtained from 185 febrile individuals and tested for IgG and IgM antibody to selected arboviruses by enzyme immunoassay (EIA). The prevalence of IgG antibody was 59% for West Nile (WN), 53% for Sandfly Fever Sicilian (SFS), 32% for Sandfly Fever Naples (SFN), 39% for Yellow Fever (YF), 24% for dengue-2 (DEN-2), 23% for Rift Valley Fever (RVF), 12% for Chikungunya (CHIK) and 5% for Crimean-Congo haemorrhagic Fever (CCHF) viruses. Antibody prevalences tended to increase with age for WN and YF viruses. Antibody rates were about the same for males and females for most of the viruses tested. The prevalence of IgM antibody to SFN was 24% and reciprocal IgM titre exceeded 12,800 for some individuals suggesting that this virus was the cause of recent infection. The prevalence of IgM antibody for the other viruses did not exceed 5%. The study indicated that several arboviruses were endemic and some of them may have caused human disease in the Northern Province of Sudan.

Acute Disease↗
PubMed1993

Isolation of Batai virus (Bunyaviridae:Bunyavirus) from the blood of suspected malaria patients in Sudan.

From August through November 1988, 77,500 patients with fever presented to the municipal hospital and to eight government health centers in Kassala, a town of approximately 400,000 individuals in eastern Sudan. A diagnosis of malaria, based primarily on clinical presentation, was made in 14,395 individuals during this four-month period; fevers of unknown origin were diagnosed in 29 patients. A Bunyavirus that was antigenically similar or identical to Batai virus by complement fixation and plaque-reduction neutralization tests was recovered from two of 196 sera collected from patients with acute fever admitted to the municipal hospital in Kassala in October 1988. IgM antibody against this virus was detected by enzyme-linked immunosorbent assay in 7% of the sera from patients with acute fever tested and IgG antibody was detected in 61%.

Adult↗
PubMed1993

Amblyomma americanum: a potential vector of human ehrlichiosis.

Polymerase chain reaction primers specific for Ehrlichia chaffeensis were used to amplify DNA from extracts of pooled ticks. Amplification was performed on extracts from 140 pools (1,579 total ticks) consisting of three tick genera collected from five states. The characteristic 389-basepair product was observed after amplification of extracts from seven different pools of adult Amblyomma americanum (117 pools, 1,462 ticks), but not from pools of nymphs. No specific product was observed after amplification of 20 pools (105 ticks) of Dermacentor variabilis and three pools of Ixodes scapularis (12 ticks). Ehrlichia chaffeensis was present in A. americanum at a minimum frequency of > or = 0.48%, suggesting that A. americanum may be a vector of human ehrlichiosis.

Animals↗
PubMed1992

Serological response to "Rochalimaea henselae" antigen in suspected cat-scratch disease.

There are no generally accepted diagnostic tests for cat-scratch disease (CSD), the cause of which is unknown. During the development of an indirect fluorescence antibody (IFA) test for detection of antibodies to "Rochalimaea henselae", sera from patients with CSD were found to have high titres to R henselae antigens. Further tests with this assay showed that 36 (88%) of 41 patients with suspected CSD had serum titres of 64 or more to R henselae antigen, that there was a low prevalence (3%) of substantial titres to R henselae in healthy controls (n = 107), and that the immune responses to R henselae antigens were specific. These data suggest that the R henselae IFA test, or other serological assays based on R henselae, may be useful for diagnosis of CSD.

Antigens, Bacterial↗
PubMed1992

Detection of the etiologic agent of human ehrlichiosis by polymerase chain reaction.

Polymerase chain reaction (PCR) primers derived from a variable region of the 16S rRNA gene sequence were used to amplify DNA specifically from Ehrlichia chaffeensis (the recently proposed name for the etiologic agent of human ehrlichiosis). The 389-bp product defined by the specific primers was not detected when DNA samples from any of the other recognized species of Ehrlichia were used as amplification templates. When the PCR was applied to five suitable blood specimens obtained from patients subsequently shown to be serologically positive for E. chaffeensis, all five were positive. The same technique was applied to a total of six control blood specimens, three from febrile patients who had no serologic evidence of infection with Ehrlichia or Rickettsia species and three from patients diagnosed with Rocky Mountain spotted fever, and all six were negative. A chemiluminescent, group-specific oligonucleotide probe was shown to hybridize only with the PCR products obtained upon amplification of the five blood specimens from patients serologically diagnosed as having human ehrlichiosis. The results indicate that PCR, coupled with a nonisotopic method of confirming the identity of the PCR product, is a highly specific and efficient method of detecting the agent of human ehrlichiosis in blood. The results also suggest that E. chaffeensis is the sole etiologic agent of human ehrlichiosis in the United States. The technique was also applied to four ticks that were positive by direct immunofluorescence for Ehrlichia species, and one tick was PCR positive, indicating that E. chaffeensis DNA can be detected in ticks harboring this organism, although the sensitivity may be low.

Animals↗
PubMed1992

The epidemiology of hepatitis C virus antibody in Yemen.

A cross-sectional survey of 348 subjects without evidence of liver disease was conducted to investigate the prevalence and risk factors for hepatitis C virus antibody (anti-HCV) seropositivity in the Yemen Arab Republic. The mean age of study subjects was 28.7 years (range 3-80), and 61% were males. Using commercial enzyme-linked immunosorbent assays (ELISA), 6.0% (95% confidence interval [CI] 3.8-9.1) of subjects were anti-HCV-positive, 13.5% were hepatitis B surface antigen-positive (HBsAg-positive), and 51.4% were positive for at least one serologic marker of prior hepatitis B infection. Nine (2.6%; 95% CI 1.2-4.9) of the 21 ELISA-positive sera were confirmed to be anti-HCV positive by a recombinant immunoblot assay. Anti-HCV seropositivity was significantly associated with age (odds ratio [OR] 2.0 for each 10-year increase in age) and prior surgery (OR 10.1), but was not associated with a history of prior blood transfusion or markers of hepatitis B infection. These preliminary data suggest that hepatitis C may pose a substantial health threat in Yemen.

Adolescent↗
PubMed1991

Immunogenicity of Salmonella typhi Ty21a vaccine for young children.

An attenuated Salmonella typhi Ty21a vaccine was administered to 18 infants and toddlers (less than or equal to 24 months old) to determine its safety and immunogenicity. The vaccination (10(9) CFU per dose, three doses) was well tolerated. However, after the vaccination there was no evidence of a humoral or cellular immune response to S. typhi. The vaccine used was known to be immunogenic for older children and adults. The results support the view that the immunogenicity of Ty21a is age dependent.

Administration, Oral↗
PubMed1991

Enzyme immunoassay for detection of antibodies against eastern equine encephalomyelitis virus in sentinel chickens.

We developed an enzyme immunoassay (EIA) for the detection of immunoglobulin M (IgM) and IgG subclass antibodies directed against eastern equine encephalomyelitis (EEE) virus in chickens. The assays were compared with the serum plaque reduction neutralization test (PRNT) and the hemagglutination inhibition (HI) test for ability to detect antibodies against EEE virus in laboratory-infected birds. No cross-reactivity was detected in serum from chickens inoculated with St. Louis encephalitis or Highlands J virus. The interval after infection when EEE virus-specific antibodies were first detected by IgM and IgG EIAs was found to be similar to that determined by the PRNT and HI tests: 2 to 4 days. The IgG EIA, PRNT, and HI test detected antibodies to EEE virus for at least 27 to 30 days after inoculation. In contrast, serum from five of seven chickens did not contain detectable IgM 30 days after infection. Similarly, in all three naturally infected sentinel chickens from Maryland, IgM class antibody was undetectable 1 to 5 weeks after IgM was initially detected. EIAs provide simple and rapid alternatives to traditional tests for monitoring EEE virus infections in sentinel chicken flocks. Moreover, the IgM EIA provides a means to separate recently infected chickens from those infected greater than or equal to 1 month earlier.

Animals↗
PubMed1989

Detection of murine typhus infected fleas with an enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) for the detection of Rickettsia typhi antigen in homogenates of pooled or individual laboratory infected fleas is described. The assay uses a double sandwich technique, employing a pool of monoclonal antibodies to capture the antigen and a hyperimmune rabbit serum for antigen detection. Using pools of R. typhi infected Xenopsylla cheopis, Ctenocephalides felis, and Leptopsylla segnis, the sensitivity of the ELISA was compared with direct fluorescent antibody examination of individual fleas for rickettsiae and with rickettsial titers determined by plaque enumeration on primary chicken embryo fibroblasts (PFU). Pooled samples with less than 4 PFU of viable rickettsiae gave ELISA results which were not significantly above background. Both ELISA OD and ELISA titer (last dilution giving an OD that was 2 SD above the control) of a 1:10 dilution of homogenate (4 fleas/ml) were linearly related to rickettsial titer up to 10(6.8) PFU/sample. Multiple freeze-thaws of pools of infected fleas led to a rapid loss of ELISA sensitivity. ELISA assays on single fleas demonstrated large individual variability in rickettsial content. This was independent of the number of days postinfectious feeding or the mean number of PFU/flea (10(1.7-6.9) found for pooled fleas in the same cohort. The sensitivity and ease of performance of ELISA should make it usable under field conditions.

Animals↗
PubMed1988

A rapid dot immunoassay for the detection of serum antibodies to eastern equine encephalomyelitis and St. Louis encephalitis viruses in sentinel chickens.

A dot enzyme-linked immunosorbent assay utilizing a novel membrane, polyvinylidene difluoride, is described. This assay was developed for the rapid detection of serum antibodies to eastern equine encephalomyelitis virus and St. Louis encephalitis virus in sentinel chickens. Antigens were spot-filtered through the membrane. Membranes were dipped into small vials of sera. Antigen-antibody complexes were detected with enzyme-conjugated antiglobulin which, when exposed to substrate, produced a colored insoluble product. The antibody detection protocol was completed within 50 min and was compared with a standard plate enzyme immunoassay. Chickens were experimentally infected with eastern equine encephalomyelitis and St. Louis encephalitis and bled on a daily basis. The dot immunoassay correctly identified 99% (123/124) of the eastern equine encephalomyelitis virus and 100% (67/67) of the St. Louis encephalitis virus antisera. Sera from sentinel chicken flocks in Maryland were also assayed. These data indicate that the dot immunoassay should be considered as an alternative to current assays for the screening of sera for antibodies to virus antigens. This assay could easily be performed in the field and allows for the screening of antibodies to several different viruses in one test.

Alphavirus↗
PubMed1988

Detection of eastern equine encephalomyelitis virus antigen in equine brain tissue by enzyme-linked immunosorbent assay.

Sensitivity and specificity of an antigen-capture ELISA vs virus isolation in cell culture were evaluated for the detection of eastern equine encephalomyelitis (EEE) virus in the brain tissue of naturally infected equids. Brain specimens from 16 equids with neurologic disease were examined by ELISA and by inoculation onto baby hamster kidney cell cultures. Of 10 brain samples from which virus was isolated in the cell culture bioassay, all were correctly identified as containing EEE virus antigen by ELISA. None of the remaining 6 specimens, without detectable infectious EEE virus, contained detectable antigen. Sensitivity and specificity of the ELISA were 100% with no false-positive or false-negative results. The antigen-capture ELISA was a rapid, sensitive, specific, and simple alternative to a traditional bioassay for the detection of EEE virus.

Alphavirus↗
PubMed1987

A prospective field evaluation of an enzyme immunoassay: detection of eastern equine encephalomyelitis virus antigen in pools of Culiseta melanura.

A prospective field study was conducted to determine the sensitivity and specificity of an enzyme immunoassay (EIA) compared to virus isolation in cell culture for the detection of eastern equine encephalomyelitis (EEE) virus in naturally infected mosquitoes. A total of 10,811 adult female Culiseta melanura were collected in light traps during 1985 from four locations in Maryland. Eastern equine encephalomyelitis virus was isolated from 5 of 495 mosquito pools in African green monkey kidney and baby hamster kidney cell cultures. All five virus-infected pools were detected by the EIA, and all 490 uninfected pools were correctly scored as not containing virus. The EIA did not produce false positive or false negative results. Results support the assertion of previous researchers that the antigen detection EIA is a rapid, sensitive, specific, and simple alternative to traditional bioassays for the detection of EEE virus in mosquitoes.

Alphavirus↗
PubMed1986

Acute lobular nephronia.

Acute lobular nephronia is an unusual form of localized renal infection, which has a characteristic computerized tomographic and ultrasonographic appearance, and should be distinguished from abscess or other renal masses. Treatment is nonoperative, consisting of intensive antibiotic therapy.

Acute Disease↗