False-positive rapid plasma reagin testing in patients with acute Plasmodium vivax malaria: a case control study.

Non-treponemal tests such as the rapid plasma reagin (RPR) assay are mainstays of syphilis diagnosis, but false-positive tests are common. We identified false-positive RPR titers in 8.2% of patients with malaria due to Plasmodium vivax in northern Peru. Similar rates were not detected in patients with other acute febrile illnesses.

Reaginic antibodies from horses with recurrent airway obstruction produce mast cell stimulation.

Reaginic antibodies (IgE and some IgG subclasses) and mast cells play important roles in the induction of type I immediate hypersensitivity reactions. These antibodies bind through their Fc fragment to high affinity receptors (FcεRI) present in the membrane of mast cells and basophils. The cross-linking of the receptor initiates a coordinated sequence of biochemical and morphological events that results in exocytosis of secretory granules containing pre-formed inflammatory mediators, secretion of newly formed lipid mediators, and secretion of cytokines. Previously, several studies have investigated the role of reaginic antibodies in the pathogenesis of Recurrent Airway Obstruction (RAO). However, whereas the immunological aspects of RAO have been extensively studied, the precise sequence of events involved in the pathogenesis remains not completely understood, and the role of IgE in this disease remains controversial. Therefore, in this study, several bioassays were conducted to determine whether reaginic antibodies from RAO-affected horses have the ability to activate mast cells. These bioassays involved measuring degranulation of rat peritoneal mast cells, activation of NF-κB and morphological changes in basophilic leukemia cells (RBL-2H3) following incubation with horse serum from RAO-affected horses that were sensitive and insensitive to Aspergillus fumigatus (A. fumigatus) or from unaffected horses. Our results show that reaginic antibodies from horses sensitive to A. fumigatus were able to degranulate rat peritoneal mast cells. In additon, there was an increase in the activity of the transcription factor NF-κB in RBL-2H3 cells, and morphological changes were observed in these cells once cross-linking was produced. These findings were not found in horses not sensitive to A. fumigatus and healthy horses. These bioassays demonstrate the ability of reaginic antibodies to stimulate mast cells and indicate that these antibodies could be involved in the immunological mechanisms leading to RAO.

Secondary syphilis in cali, Colombia: new concepts in disease pathogenesis.

Venereal syphilis is a multi-stage, sexually transmitted disease caused by the spirochetal bacterium Treponema pallidum (Tp). Herein we describe a cohort of 57 patients (age 18-68 years) with secondary syphilis (SS) identified through a network of public sector primary health care providers in Cali, Colombia. To be eligible for participation, study subjects were required to have cutaneous lesions consistent with SS, a reactive Rapid Plasma Reagin test (RPR-titer > or = 1 : 4), and a confirmatory treponemal test (Fluorescent Treponemal Antibody Absorption test- FTA-ABS). Most subjects enrolled were women (64.9%), predominantly Afro-Colombian (38.6%) or mestizo (56.1%), and all were of low socio-economic status. Three (5.3%) subjects were newly diagnosed with HIV infection at study entry. The duration of signs and symptoms in most patients (53.6%) was less than 30 days; however, some patients reported being symptomatic for several months (range 5-240 days). The typical palmar and plantar exanthem of SS was the most common dermal manifestation (63%), followed by diffuse hypo- or hyperpigmented macules and papules on the trunk, abdomen and extremities. Three patients had patchy alopecia. Whole blood (WB) samples and punch biopsy material from a subset of SS patients were assayed for the presence of Tp DNA polymerase I gene (polA) target by real-time qualitative and quantitative PCR methods. Twelve (46%) of the 26 WB samples studied had quantifiable Tp DNA (ranging between 194.9 and 1954.2 Tp polA copies/ml blood) and seven (64%) were positive when WB DNA was extracted within 24 hours of collection. Tp DNA was also present in 8/12 (66%) skin biopsies available for testing. Strain typing analysis was attempted in all skin and WB samples with detectable Tp DNA. Using arp repeat size analysis and tpr RFLP patterns four different strain types were identified (14d, 16d, 13d and 22a). None of the WB samples had sufficient DNA for typing. The clinical and microbiologic observations presented herein, together with recent Cali syphilis seroprevalence data, provide additional evidence that venereal syphilis is highly endemic in this region of Colombia, thus underscoring the need for health care providers in the region to be acutely aware of the clinical manifestations of SS. This study also provides, for the first time, quantitative evidence that a significant proportion of untreated SS patients have substantial numbers of circulating spirochetes. How Tp is able to persist in the blood and skin of SS patients, despite the known presence of circulating treponemal opsonizing antibodies and the robust pro-inflammatory cellular immune responses characteristic of this stage of the disease, is not fully understood and requires further study.

In vitro bioassay to detect reaginic antibodies from the serum of horses affected with recurrent airway obstruction.

In horses, Recurrent Airway Obstruction (RAO) is an allergic disease that involves IgE mediated Type I Hypersensitivity responses. The development of this type of allergy involves a series of events that begins with reaginic antibodies, mainly IgE and some IgG subclasses. These reaginic antibodies bind with high affinity, via the Fc portion, to FcepsilonRI receptors on the membrane of mast cells and basophils. Once bound, environmental allergens cross-link the antibodies, which results in mast cell degranulation leading to the production of histamine and other chemical mediators that act together to induce airway inflammation. RAO-affected horses present with coughing, respiratory distress, airway obstruction and poor performance. The aspect of the RAO has been extensively studied, yet the precise sequence of events is still not well understood. Therefore, this study proposes a bioassay for reaginic antibody detection from horse serum of RAO-affected individuals, in order to determine the etiology of disease, which mediate immediate type reactions. The technique involves measuring in vitro calcium mobilization in RBL-2H3 cells following incubation with horse serum from affected or unaffected horses and one of the RAO antigens (Aspergillus fumigatus). The results presented here demonstrate that 30% of RAO-affected horses react positively in this in vitro bioassay, whereas unaffected horses do not. This bioassay may facilitate further research on RAO and other allergic diseases in horses.

Secondary syphilis with ocular manifestations in older adults.

We describe 4 patients (age, >50 years) with secondary syphilis. All patients presented with ocular syphilis, and 2 presented with syphilis-negative rapid plasma reagin titers due to a prozone phenomenon. Three male patients reported sildenafil use. The presentation of these patients with ocular syphilis suggests the need for additional clinical studies involving older patients.

Analysis of the operational costs of using rapid syphilis tests for the detection of maternal syphilis in Bolivia and Mozambique.

OBJECTIVE: The objective of this study was to compare the costs of antenatal syphilis screening with the rapid plasma reagin (RPR) test and the immunochromatographic strip (ICS) test in low-resource settings. GOAL: The goal of this study was to assess the costs of introducing rapid syphilis tests to reduce maternal and congenital syphilis. STUDY DESIGN: Cost data were collected from participating study hospitals and antenatal clinics during 4 field visits to the 2 countries in 2003 and 2004. Health utilization outcome data on the number of women screened and treated routinely during the demonstration projects were used with unit cost data to estimate the incremental costs and average cost per woman screened and treated for maternal syphilis. RESULTS: In Mozambique, the average cost per woman screened was U.S. $0.91 and U.S. $1.05 for the RPR and ICS tests, respectively. In Bolivia, the average cost of screening was U.S. $1.48 and U.S. $1.91 using the RPR and ICS test, respectively. In health centers without laboratories, the cost per woman screened using the ICS test ranged from U.S. $1.02 in Mozambique to U.S. $2.84 in Bolivia. CONCLUSIONS: It is feasible to introduce rapid syphilis testing in settings without laboratory services at a small incremental cost per woman screened. In settings with laboratories, the cost of ICS is similar to that of RPR.

Syphilis treatment and HIV infection in a population-based study of persons at high risk for sexually transmitted disease/HIV infection in Lima, Peru.

OBJECTIVES: The objective of this study was to characterize syphilis epidemiology and the relationship of HIV status and initial rapid plasma reagin (RPR) titer to syphilis treatment in Lima, Peru. STUDY DESIGN: We screened 1,261 individuals at high risk for sexually transmitted diseases for syphilis and HIV infection. Syphilis was treated with penicillin injection or doxycycline; treatment was repeated in unresponsive cases. RESULTS: : The prevalence of syphilis was 7.7%, 1-year incidence rate was 4.7%, and reinfection rate was 42.7%. The treatment success rate was 93.4% (71 of 76); those with initial RPR titers or=1:16. HIV infection was associated with syphilis, prevalent in 15.6% and 3.7% of those with and without syphilis, respectively (P < 0.001), but did not affect treatment success (90.9% vs. 93.8%). CONCLUSIONS: Syphilis was common, associated with HIV infection, and less responsive to therapy in those with initial RPR titers

Prevalencia de anticuerpos virales y reaginas luéticas en donadores de sangre de un hospital / Prevalence of viral antibodies and serology for syphilis in blood donors from a hospital

Objetivo. Establecer la prevalencia de anticuerpos virales y reaginas luéticas en una población de donadores voluntarios. Sitio. Un hospital general de tercer nivel del ISSSTE en la ciudad de Morelia, estado de Michoacán. Desde 1986 es obligatorio en los bancos de sangre de México, investigar en todos los donadores la presencia de anticuerpos contra el virus de la inmunodeficiencia humana (anti-VIH), antígeno de superficie del virus de la hepatitis B (Ags VHB) y reaginas luéticas (RPR); y desde 1993, es también obligatorio determinar anticuerpos contra el virus de la hepatitis C (anti-VHC). Material y métodos. En siete años (01/01/90 a 31/12/96) se obtuvieron 10,077 muestras de donadores voluntarios sanos para la determinación de anti-VIH, AgsVHB y RPR. De 01/07/92 a 31/12/96 se colectaron 7,256 muestras para investigación de anti-VHC. Resultados. Fueron positivos 19 donadores para anti-VIH (0.18 por ciento), 34 para AgsVHB (0.33 por ciento), 12 para RPR (0.11 por ciento) y 22 para anti-VHC (0.30 por ciento). Estas tasas son similares a las de otros bancos de sangre mexicanos

Inmunoglobulina E (IgE) en sangre del cordón umbilical de recién nacidos con antecedentes de atopia familiar / Imnumeglobulin E (IgE) in umbilical cord blood of newborn with family atopy antecedent

Se determinaron los valores de IgE en sangre del cordón en un grupo de recién nacidos con antecedentes atópicos familiares y un grupo control y sin antecedentes familiares de atopia. Los niveles de IgE en sangre del cordón, mayores de 0,7 UI/ml son considerados como índice predictivo de alergia, especialmente cuando existen antecedentes familiares de alergia y/o el individuo es sometido a sobrecarga de alergenos. Se estudiaron 80 recién nacidos, 40 del grupo experimental y 40 del grupo control, determinándose en ambos grupos concentraciones de IgE (UI/ml, edad gestacional entre 37 y 42 semanas, sexo, peso entre 2500 y más de 3000 gms, y atopia familiar más frecuente relacionada con los niveles de IgE) a concentración de IgE en sangre del cordón, en ambos grupos, fue mayor de 0,7 UI/ml. En relación a las variables edad gestional, peso, y sexo, los valores de IgE no presentaron diferencias significativas. Con respecto a los antecedentes de atopia familiar y los niveles de IgE, la muestra se distribuyó de la siguiente manera, asma con 23 casos (95,83 por ciento), rinitis alérgica con 21 (95,45 por ciento), dermatitis atópica, 4 casos (100 por ciento) y para la urticaria 2 casos (100 por ciento), del total de pacientes en este grupo de atopia familiar 3,85 por ciento presentó cifras de IgE inferiores a 0.7 UI/ml