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Results for “RICKETTSIAL DISEASES”

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At least 1,099 records · Page 61Linked to original sources
PubMed1994

Serum concentrations of soluble intercellular adhesion molecule-1 and progress towards disease in patients infected with HIV.

Intercellular adhesion molecule-1 (ICAM-1) is a membrane-bound molecule that is primarily involved in cell to cell adhesive interactions of the immune system. Concentrations of soluble ICAM-1 (s-ICAM-1) shed into the circulation were measured by a quantitative ELISA in HIV-infected persons without AIDS, patients with AIDS with or without evidence of acute opportunistic infection at the time of sampling, and HIV-seronegative patients with toxoplasmosis, community-acquired pneumonia, leishmaniasis and rickettsial infections. Patients were classified on the basis of clinical condition and CD4+ T-cell counts according to the 1993 revised HIV classification of the USA Centers for Disease Control. Concentrations of s-ICAM-1 in the serum of HIV-infected persons without AIDS-indicator conditions (categories A1, A2, B1 and B2) as well as in the serum of patients with AIDS (categories A3, B3, C1, C2 and C3) were significantly higher than normal (mean +/- S.E.M. 469 +/- 23, n = 60 and 780 +/- 73, n = 56, respectively, versus 329 +/- 15 ng/ml, P < 0.0001 and < 0.0001 respectively) and differed also significantly from each other (P < 0.0001). Raised concentrations of s-ICAM-1 in the serum of afebrile patients with AIDS but without acute opportunistic infection at the time of sampling (mean +/- S.E.M. 672 +/- 76, n = 29) did not differ from those of the remaining patients with AIDS or from those of HIV-seronegative patients with the infections studied. A steady and significant increase of serum concentrations of s-ICAM-1 with progress of disease according to clinical category (categories A-->B-->C, p = 0.0007) as well as with the loss of circulating CD4+ T-cells (categories 1-->2-->3, p = 0.009) was observed. Individual serum concentrations of s-ICAM-1 showed negative correlations with individual total lymphocyte (P = 0.004), CD4+ T-cell (P = 0.05), CD8+ T-cell counts (P = 0.03) as well as positive correlation with serum concentrations of soluble interleukin-2 receptors (P < 0.0001), an indirect marker of progress of HIV-related disease. Serum concentrations of s-ICAM-1 did not differ between patients with AIDS who were receiving or not receiving zidovudine at the time of sampling. A longitudinal survey is needed in order to determine whether measuring serum concentrations of s-ICAM-1, although not specific, has any predictive or prognostic value in these patients as well as whether this bioactive molecule has any pathogenetic role in the progress of disease in HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1999

An assessment of the economic impact of heartwater (Cowdria ruminantium infection) and its control in Zimbabwe.

Heartwater, caused by the rickettsial organism Cowdria ruminantium, is a serious constraint to livestock development in much of sub-Saharan Africa. Traditionally, the disease has been controlled by the use of chemical acaricides to control the vector tick. The University of Florida/USAID-supported heartwater research project (based in Zimbabwe) is developing a new inactivated vaccine to control the disease. In order that the vaccine is used effectively, the project has been studying the epidemiology of the disease in different livestock production systems of Zimbabwe, and evaluating the economic impact of the disease and of its future control using a vaccine such as the one under development. Initially, field studies were conducted to characterise the communal and commercial livestock-productions systems at risk from heartwater and to understand the epidemiology of the disease. The data from these studies were then applied to an infection-dynamics model of heartwater, which was used to provide estimates of disease incidence and impact under various scenarios over a period of 10 yr. Two principal outputs of the epidemiological model (cumulative annual heartwater incidence and infection-fatality proportion) were key inputs into an economics model. The estimated total annual national losses amount to Z$ 61.3 million (US$ 5.6 million) in discounted value terms over 10 yr. Annual economic losses per animal in the commercial production system (Z$ 56 discounted values) are 25 times greater than the losses in the communal system (Z$ 2.2). The greatest component of economic loss is acaricide cost (76%), followed by milk loss (18%) and treatment cost (5%). Losses in outputs other than milk (beef, traction and manure) appear to be minimal. A new vaccine has the promise of a benefit: cost ratio of about 2.4:1 in the communal and 7.6:1 in the commercial system. A control strategy based on a new vaccine would yield additional non-financial benefits to farmers and the government resulting from reductions in the use of chemical acaricides.

Animals↗
PubMed1979

Evaluation of a killed Rocky Mountain spotted fever vaccine in cynomolgus monkeys.

A nonhuman primate model of Rocky Mountain spotted fever infection was developed in cynomolgus monkeys (Macaca fascicularis) infected by the subcutaneous route or by aerosol. Clinical responses, hematology and serum chemistry values, and pathological findings were similar to those found in humans ill with Rocky Mountain spotted fever. The clinical model was then used to test the efficacy of a killed Rocky Mountain spotted fever vaccine grown in chicken embryo cells. Monkeys were immunized with varying dilutions of the vaccine with a two-dose schedule and then challenged at 2 months with virulent Rickettsia rickettsii by the subcutaneous route or by aerosol. The undiluted vaccine totally protected monkeys against both challenges, even at extremely high doses.

Agglutination Tests↗
PubMedDate not supplied

Prevalence of tick-borne pathogens in Ixodes scapularis in a rural New Jersey County.

To assess the potential risk for other tick-borne diseases, we collected 100 adult Ixodes scapularis in Hunterdon County, a rapidly developing rural county in Lyme disease endemic western New Jersey. We tested the ticks by polymerase chain reaction for Borrelia burgdorferi, Babesia microti, and the rickettsial agent of human granulocytic ehrlichiosis (HGE). Fifty-five ticks were infected with at least one of the three pathogens: 43 with B. burgdorferi, five with B. microti, and 17 with the HGE agent. Ten ticks were coinfected with two of the pathogens. The results suggest that county residents are at considerable risk for infection by a tick-borne pathogen after an I. scapularis bite.

Animals↗
PubMed2004

Bullis fever: a vanished infection of unknown etiology.

Camp Bullis, Texas, is an active training facility for the U.S. Army and Air Force with a storied history dating back to the late 19th century. In the early 1940s, an epidemic of a seasonal tick-borne rickettsial-like illness occurred at Camp Bullis; the last case was reported in 1947. To date, the etiology of this disease has remained elusive. In an attempt to retrospectively identify the causal pathogen, we surveyed Camp Bullis for the presumed tick vector with intent to screen molecularly for Rickettsia and Ehrlichia. However, no ticks were recovered from primary dragging attempts in the spring or from harvested deer in the fall. Moreover, pathologic and microbiologic materials obtained during the epidemic are no longer extant, making them unavailable for analysis. In this study, we review potential circumstances that impact emerging and, in this case, vanishing infections. The etiology of Bullis fever will probably remain undetermined, and this once-emerging infection may have vanished into history. However, given Camp Bullis' status as an active medical training site, awareness of and surveillance for the disease should continue.

Animals↗
PubMedDate not supplied

[Rickettsiales--modern findings].

The term rickettsiae has as a rule encompassed the intracellular bacteria. Molecular studies brought new data to rickettsial taxonomy. Many new data on rickettsia have been accumulated over recent years, and a comparison of the newly discovered diseases with previously known rickettsioses, as well as with their agents is of interest. The number of "new" agents that have been discovered in the last few years is remarkable. This review discusses the current knowledge of bacterial species that historically belonged to the order Rickettsiales, as well as the role of these agents as human and animal pathogens.

Alphaproteobacteria↗